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View Full Version : Carb, intake mods, and nakman's quest for a well running motorcycle


nakman
03-05-2012, 03:34 PM
Well after my induction into the world of intake mods at 60wag's house yesterday, and the successful installation of the "o-ring mod," I am now going to attempt to dive further into the world of carbureted tuning. Ordered these parts just now:

Red_Chili
03-05-2012, 03:42 PM
Kewl.
I went with an Edelbrock unit on the XR... not really a carb per se... uses a needle for all the metering. With an accellerator pump. The thing absolutely rocks, you can dump it and it won't flood (which is nice for those of us with a big piston and no pink panty button.... :lmao:).

But if you get in a pinch I am an old carb tuner from waaaaay back.

Do the Katooms come lean or something? Did you change your exhaust? Free up the intake? Or change something else?

subzali
03-05-2012, 03:44 PM
They come a little lean from the factory, from what I understand.

Tim, what kinds of intake mods did you do? And what's the "o-ring" mod?

nakman
03-05-2012, 03:58 PM
They come a little lean from the factory, from what I understand.

Tim, what kinds of intake mods did you do? And what's the "o-ring" mod?

Ha! search, ya noob! :lmao: laughing because I just learned this yesterday... man my head is spinning with new info, feel like a kid who just bought an 80 posting up "what are lockers for." :D

So there's this little thingy that your throttle cable turns, and when it turns away it allows this accelerator pump doo dad to move over. Well you put an o-ring around both of them, so the two move together a little quicker and you get a little faster throttle response? To be honest, I can't really tell the difference.. :o

edit: Here, found this video.. I only did 1, not 2, so maybe a second would be more impactful.

5UNCLW6WUPI

edit2: here's a picture from the JD site
http://ic2.pbase.com/g3/20/347520/2/87669959.gx3CThkO.jpg

subzali
03-05-2012, 04:03 PM
Yeah, my approach with the KTM has been, "Can I ride it on the trail?" "Yes?" "Then I don't need to mess with it" :D

In other words, I've mostly been working on riding technique rather than bike modifications. It can go fast enough to get me into trouble, so all I try to do is keep from getting into too much trouble. shrug.

nakman
03-05-2012, 04:11 PM
If I bought a new one, I'd be in the same camp. In my case I am trying to undo some PO specials, learn a whole new machine, plus get it to run properly.. as I have learned I've got some hot start, intermittent dying issues. Which means hit the mods early to get my hands dirty & my brain engaged, and figure out what's really going on in there.

edit: I mean what's going on in the bike, not my brain. We know about the brain.

subzali
03-05-2012, 04:38 PM
If I bought a new one, I'd be in the same camp. In my case I am trying to undo some PO specials, learn a whole new machine, plus get it to run properly.. as I have learned I've got some hot start, intermittent dying issues. Which means hit the mods early to get my hands dirty & my brain engaged, and figure out what's really going on in there.

edit: I mean what's going on in the bike, not my brain. We know about the brain.

:lmao:

:thumb:

baja1d
03-06-2012, 04:31 AM
The accelerator pump modification is a great/cheap upgrade and will definitely improve your skills. It basically "syncs" (for lack of a better term) your carb so that when you get on the gas it doesn't hesitate/bog. The 4-strokers power band is great in mid range but when you're riding technical trails at lower speeds they all want to hesitate when you really need that front wheel in the air to get over an obstacle. It improved my riding skills in that since that I was finally able to wheelie over things rather than bash it with my front tire and deal with the repercussions. Just remember to change out the o-rings every season and carry a couple in your riding bag. They seem to dry out/break easily.

Another change I made this last season is switching to a trials tire in the rear. I debated this swap in my head for years and really wish I would have changed years ago. The traction is insane and they last 4-6 times longer than a traditional knobbie. My only complaint is that they look pretty gay and if you make the swap you've really got to consider this http://tubliss.com/

baja1d
03-06-2012, 04:37 AM
Touratech makes the best GPS mounts IMHO http://www.touratech-usa.com/Store/1730/Garmin-Mounts

Here's mine:http://www.touratech-usa.com/Store/1738/PN-065-0094/Touratech-Mount-for-Garmin-eTrex-Color-Vista-and-Legend-C-and-CX-models

Beater
03-06-2012, 08:18 AM
fcr's are a great carb, and I wouldn't get too far into them. They are THE defacto racing carb, and I have a set on the ducati. FWIW, a set of 41mm's goes for as much as 1300, and work off the shelf.

Before I would get into the pump, I would work with the jetting. The FCR usually has no choke or idle circuit per se. Some do not come with a low rpm air screw, others with a jet.

There are tuning manuals out there on the sudco site and others. Trust me, this carb is about jetting. I has razor sharp response, and distinct flow ranges of the jets.

All modern bikes come lean from the factory if they are carbed.

One serious piece of advice. Don't do any more mods until you reach normal temperatures. Again, the fcr is a precision toilet bowl. you need to jet and tune this for the ambient range and mean altitude you will be riding in. There is NO room for error in this carb. Due to the lack of screw adjustments, there is no on the fly.

I have found that airboxes are generally a good thing on modern four strokes. air pressure really helps low end performance, and real world riding is all about low end performance. On the duc, I do not have an airbox lid, but retained the lower portion. best of both worlds, but I sacrifice some "roll on" performance for peak performance.

Another trick with FCR's is to run a heavily soaked pre-filter to help richen the mixture in colder weather. If it warms up, or you increase altitude, just remove it.

Beater
03-06-2012, 08:30 AM
oh - and one more thing - use this.

I can't get it to open with excel 2010, but maybe you can.

Here's a useful link. If you can get the spreadsheet, do it. It's irreplaceable.
http://vma.cape.com/~patrick/brm/carbkei.htm

nakman
03-06-2012, 09:46 AM
Hey cool stuff, thanks John. I'm not sure what it all means yet, but appreciate it looking forward to learning. Here's a .pdf of that spreadsheet for ya.. I'll print one off.

nakman
03-06-2012, 09:47 AM
Touratech makes the best GPS mounts IMHO http://www.touratech-usa.com/Store/1730/Garmin-Mounts

Here's mine:http://www.touratech-usa.com/Store/1738/PN-065-0094/Touratech-Mount-for-Garmin-eTrex-Color-Vista-and-Legend-C-and-CX-models

Dude that's a serious mount, wow.. that's probably 5 mods ahead though honestly, first I need to get this bike running right, then hopefully later I'll worry about getting lost on it. :o

Beater
03-06-2012, 10:45 AM
Hey cool stuff, thanks John. I'm not sure what it all means yet, but appreciate it looking forward to learning. Here's a .pdf of that spreadsheet for ya.. I'll print one off.


Tim -
Printing it is no good. It is a live macro sheet, in which you input changes to formulate results.

In other words, plug in your temp, elevation, stock needle, and you can vary your configurations.

It's a live configurator. it also retails for 20.00 on the jd site, so be judicious in forwarding it.

nakman
03-08-2012, 10:25 PM
Alright, well tonight's efforts included pulling the tank, pulling the plug wire, and trimming back 1/4" of the plug wire at the coil side. I can't really say if I did anything significant here, I guess the wires may have been a little enlarged where they were in contact with the threaded thing coming from the coil, so I guess the new wires may be against that threaded thing a little tighter now. :confused:

the second picture is "before trimming," and the third picture is "after trimming." Not shown is what it looked like after I spread the wires out with an awl, prior to shoving it back onto the coil.

nakman
03-08-2012, 10:30 PM
Here's what my plug looks like. this should have been a brand new plug, per the PO.. looks ok to me? I measured the gap between .018"-.020".

I still can't find the gap spec in the manual. but what I did find is my plug type should be NGK CR 9 EBK.

Beater
03-09-2012, 08:29 AM
tim - slow down a bit.

Seriously, you are going to have to go through this alllll over again when it gets warm. If anything, put it back to stock, then adjust jetting until warmer.

Get into that spreadsheet, and do some reading on stoichemetric (sp) ratio's. These small cylinders with big carbs don't have much room for error.

also - that plug doesn't look bad at all. well within color range.

nakman
03-09-2012, 09:02 AM
I'm trying to get a new to me bike to e-start when hot, and stay running going down the road. I don't need to wait for summer for that. This isn't exactly fine tuning as much as just cleaning and base lining. The fuel screw and jet kit are means to that end.

One possibility i considered last night is I may have just run out of gas, as I switched to reserve after it died on the road lat Sunday to get home. Looking on the tank, my gas level is below the filter of the fuel valve thing- when you switch to reserve, is it just getting gas from further down that pipe? That could mean my total range with the stock tank is about 50 miles- which I'm thinking is pretty poor mileage.

farnhamstj
03-09-2012, 09:03 AM
Tim likes to take things apart. I get that. That plug looks good to me too.

farnhamstj
03-09-2012, 09:05 AM
Yes on the petcock. Milage seems low. I get 90miles out of a stock tank, 2.4 gal I think.

subzali
03-09-2012, 09:11 AM
Tim, my bike went 97 miles before hitting the reserve once down in New Mexico. That's the only time I've hit the reserve, and I've had one or two other rides that broke 90 miles. Stock 2.43 gallon tank.

nakman
03-09-2012, 09:34 AM
Alright thanks guys, so that clinches it- my mileage sucks, at 50-60 miles before needing to hit the reserve. I didn't completely fill it though, trying to leave a little room at the top, but it was pretty close to full. I will get better at consistency there, and I finally figured out the trip odometer on the speedo thing so can do a better job of tracking that as well.

What was interesting was it was all at once- no sputtering, no hesitation, just went from running to off. Is that how your bike runs out of gas?

Beater
03-09-2012, 09:44 AM
pretty much. most bikes act like you just lost electrical, or will run on idle circuit only and die as soon as you hit primary circuit.

nakman
03-11-2012, 10:43 PM
Ok time for an update: my bike still runs like crap. Bruce came over Saturday night and helped me with the JD jet kit and idle mix screw. Seemed to run ok last night, today though had a tough time starting it and keeping it running. Marco came over and we played with the jets some more, couldn't get it to run any better. Then lost the little washer that pushes the little o-ring on the idle screw. :(

I'm going to punt and call shops this week. Bike won't e-start now either cold or hot, and takes a pretty good effort to kick start, seems to run rich, the idle adjustment screw doesn't seem to do anything, and it still dies for no reason- even with a tank full of gas. So what's a good KTM shop on the north side- Sun Enterprises? Elite in Loveland?

And Bruce I think you're spot on with the torque limiter as the root cause of most of my e-start issues. here's a thread that explains how to fix it:
http://www.thumpertalk.com/topic/864991-ktm-450-530-wont-start-with-e-start-problem-torque-limiter-fix-how-to-article/

It seems straight forward enough, but more than I can take on right now with everything else I need to get done before Moab, and I kinda want a shop to be on the hook for the results on this one. Here's a pic of the part:
http://i568.photobucket.com/albums/ss124/Hodakaguy/Misc/IMG_0687.jpg

Beater
03-12-2012, 08:43 AM
Tim -
Before a shop, dependent on time,
is this a gravity feed system or fuel pump.

Did the bike sit for long periods or period of time before your purchase?

Have you removed and fully disassembled the carb and cleaned?

Did it start prior to your mods, and can you back track to that point?

Did the tank smell like varnish when you got it?

farnhamstj
03-12-2012, 09:48 AM
Tim, that's a different engine than what you have. You have an RFS that pic is a XC4 (2008+)

If you chase down some of those washers, I'd like a spare or 2.

farnhamstj
03-12-2012, 09:50 AM
I always kick start mine the first time. Once it's warm the e-start will work. How is the condition of the battery? That's a high compression engine for a little battery to turn.

nakman
03-12-2012, 09:53 AM
Tim -
Before a shop, dependent on time,
is this a gravity feed system or fuel pump.

Did the bike sit for long periods or period of time before your purchase?

Have you removed and fully disassembled the carb and cleaned?

Did it start prior to your mods, and can you back track to that point?

Did the tank smell like varnish when you got it?

Gravity.

Don't know.

No- have cleaned from both top & bottom but not removed.

It would e-start when cold before, never e-start hot. The dying at idle and dying while driving symptoms were both before & after. Yes could revert back by removing the JD kit & fuel screw.

no, smelled like gas.

nakman
03-12-2012, 09:57 AM
Far- my battery is good, I measure 12.7 with the multi-meter pretty consistently. I also jumped it yesterday from the 100, which did yield a higher pitched cranking tone, but the same end result of not starting. As for the torque limiter, understood those pics are different but the goal is the same, I am pretty convinced I need to tighten that thing.

Yes, will pick up several of those washers & o-rings.

farnhamstj
03-12-2012, 10:00 AM
I thought jumping from a truck was a no-no.?

Beater
03-12-2012, 10:30 AM
Does this fcr have a choke circuit, or is it a pure pumper?

You're set too rich on idle slash 1/8th throttle is what it sounds like regardless.

Remove carb and clean the whole damn thing, then baseline back to factory, then use the JD sheet for for changes. Remember, needle doesn't affect idle to 1/8th throttle. Pilot jet, air jet, idle screw (in place of air jet) are where your at.

Don't overlook battery on a motorcycle. remember that rectifiers and or most alternators on motorcycles DO NOT charge below 2-3k rpm.

Case in point, just put a "street" battery back in the ducati after the smallest possible was in there for weight concerns. I have no choke on my fcr's, and now it starts much faster, and has much better spark at cold. Just sayin

subzali
03-12-2012, 10:45 AM
Sorry to hear of your troubles Tim :(

Elite did a great job tuning my bike :thumb:

Didn't realize you had a different engine than me.

nakman
03-12-2012, 10:47 AM
I didn't have the truck running, if that matters, just joined the batteries with cables- wanted to rule out lack of cranking amps from the issue.

John not sure what you mean by choke circuit- there's a knob to pull out but that's it? I can pull the carb though as a next step.

Matt we have the same engine- the pic above is from a 450, but posted here to show the torque limiter.

Beater
03-12-2012, 11:17 AM
ok - if it has a manual choke, then you need to make sure that the choke circuit is functioning correctly. There should be some o-rings and such to check. Go to JD's site or Sudco for fcr diagrams.

I highly recommend that you pull and baseline the carb. Highly.

nakman
03-12-2012, 11:23 AM
So is this my carb?
http://i.pbase.com/g3/20/347520/2/53264343.2006FCRCarburetorParts.jpg

Alright I called JD Jetting. They had two thoughts: one is the PO installed a bigger pilot jet, thinking that was solving an issue. I shouldn't run anything bigger than a 42, 40 is stock, they suggest a 42. So I ordered one. The fuel screw washer comes in a kit - spring, washer and 0-ring for $8.95. So I ordered one (could use a new o-ring anyway) once it gets in, I bet I can take some measurements and find a box of them at MSC or something.

Second thought was the slide in the carb, and the fact that a lot of people install the plate on it backwards. The correct way is with the hole towards the brass pin, even though intuitively it looks like it goes the other way because of how it's shaped. They say if you install it backwards, your bike runs terrible at idle and doesn't start well. An enormous picture can be found here: http://www.pbase.com/jdjetting1/image/53264343

I should have the new washer and pilot jet later in the week..

Beater
03-12-2012, 11:53 AM
again - baseline, and go from there. I think you're on the right track. Main CAN affect idle, 1/8th throttle, but it's mainly in the air jets/screws, plus the pilot.

Baseline the carb back to stock on ALL jets, then start over. Your chasing windmills until you do this.

Red_Chili
03-12-2012, 11:55 AM
I am with John. Baseline pure factory setup FIRST. Make sure you roll back any carb changes done by the PO or you will chase your tail. Agreed, sounds like simple rich condition, idle circuit.

Are you sure the choke is off? Not intended to make you feel like a dummy... I once disassembled a perfectly good motorcycle only to discover it was out of gas. Overthinking... yeah, been there, done that.

nakman
03-12-2012, 11:57 AM
I'm really hoping my throttle valve plate is on upside-down... that would really make me happy.


Bill after about a minute it runs pretty terrible with the choke still on. In fact last few times I started it while cold, I had the choke on, then after it died, the only way I was able to start again was with the choke off.

subzali
03-12-2012, 01:59 PM
Okay, I'm stupid and confused. Someone help me.

My 2008 has an RC4 engine, which supposedly came out in 2007.

The RFS motor appears to have been around from 2000-2007 in Enduro models (EXC?)

The RFS got replaced by the XC4 in 2008?

So I think Tim and I both have RC4s? What's all this talk about RFS and FCR? I'm so confused...

Tim, FWIW my bike doesn't like the choke much either.

nakman
03-12-2012, 02:10 PM
Confused here too, Matt. FCR is the type of carb, I've figured that out.

I thought RFS was a quality term: regardless of feature size. Stuff like surface finish, concentricity, etc.

rover67
03-12-2012, 02:15 PM
my personal preference is to use modifiers like MMC or LMC. some people think that makes it more confusing.

subzali
03-12-2012, 02:25 PM
:doh: GD&T has nothing to do with this, at least not with what I'm asking...

What I'm asking is more analagous to 2F vs. 3B vs. 2UZ-FE...

60wag
03-12-2012, 02:25 PM
RFS - Racing Four Stroke (or regardless of feature size), single cam motor
LC4 - newer twin cam motor
FCR - Keihin carb, at least 3 different sizes: 37, 39, and 41 mm throat diameter

rover67
03-12-2012, 02:39 PM
:D I was messing around

subzali
03-12-2012, 02:39 PM
I think the smaller new-generation 4-strokes are RC4. My dad's 530 has an LC4. Both his and mine are 2008. And it sounds like Tim has the same RC4 as I do, which means that the RC4 started in 2007?

EDIT: Marco - me too, that's why I had to throw in the GD&T acronym as well...:D

nakman
03-12-2012, 03:32 PM
RC4 it is then, got it!

and it's been a while, but I used to have CQE after my name. :ranger:

subzali
03-12-2012, 03:44 PM
Tim, Mine says RC4 right on the case. Doesn't yours?

nakman
03-12-2012, 05:01 PM
Found another good read for how to set these carbs up http://www.thumperfaq.com/jetting.htm it's for WR's, but same carb.

Beater
03-13-2012, 08:12 AM
that's a good read, but I'm telling you, all you will ever need is the jd spreadsheet once you baseline the carb.

nakman
03-15-2012, 11:34 PM
Tim, Mine says RC4 right on the case. Doesn't yours?
Yes it does, ok RC4 for sure then.

I received my new parts from JD, the new washer, o-ring screw for the fuel screw, and the #42 pilot jet. Draining my tank tonight, will work on washing it out tomorrow night and saturday, then diving into the rest of the cleaning.

If anyone likes searching for fasteners, the washer for the fuel screw is .200" OD, .120" ID, and .020" thick.

nakman
03-16-2012, 12:48 AM
Well my little cover thing was oriented in the right direction, with the hole down. However I did discover my pilot was a #45, which according to JD is way too big. So hey cool I found something, will be putting the 42 back in when this carb is all cleaned up. Going to bed now... :offtobed:

edit: I also drained my tank in prep for washing it out on Saturday, and there was a little black plastic ball jiggling inside it. It's 3/8" diameter. Is that supposed to be somewhere else?

60wag
03-16-2012, 07:58 AM
The ball might be part of a check valve in the tank cap. Many people defeat the check valve to make the tank vent better which makes the bike run better.

Red_Chili
03-16-2012, 08:45 AM
Nak, that much difference in a pilot jet would explain all the issues you are having. Perhaps the guy was trying to solve an overheating issue?

On the XR, going as rich as possible makes a huge difference in engine temps. But there is a limit of course. It also compensated for the absence of an accelerator pump to a small degree. But the real solution - for me - was putting an Edelbrock Quicksilver on it with an accelerator pump, bigger aftermarket radiators, hotter thermostat (counter-intuitive ain't it?), Redline Water Wetter, and a manual switched KTM fan for slow going. Complete solution. NEVER boils now, never floods, 1-3 kick starting even after dumping.

I got tired of people saying "just ride faster". Some of the places I like to ride, there just AIN'T no faster, and I don't want to boil over. Ride as fast or slow as suits you. It is all about your enjoyment, not measuring up to someone else's standards.

Some of those ideas may serve you well should you find yourself in a similar pickle. It is solvable.

nakman
03-16-2012, 09:05 AM
Interesting Bill, yes if there was an overheating issue that could partially explain the CPU fan, the one that's now a part of our Nation's landfills. That would really make me happy if that was the path here- new pilot makes bike run better, later in life I actually ride to the point of having a heat issue, followed by proper install of KTM fan and other doo dads as necessary.

Going to Sun Ent. at lunch today, hoping to pick up a carb rebuild kit (bunch of o-rings, essentially) and a new side cover for the crankcase. My second issue is the e-start, so my sites are set on tightening that torque limiter as the logical next step. Other than some carb cleaner, any other job-specific tools I should have on hand here?

Red_Chili
03-16-2012, 09:23 AM
Not sure about Katoom SSTs for the torque limiter, but I think for all the rest you are covered. Ask the parts guys or better yet the service guys. They often know lots of shortcuts and better ways to do things.

Actually it will probably be LATER that you actually ride to the point of NOT having heat issues. Until we get you into some gnarly near-trials singletrack that is.

nakman
03-16-2012, 09:28 AM
My point was, on the stand in the garage overheating hasn't exactly been a big issue. :o


edit: Hey, post 8000!

rover67
03-16-2012, 09:43 AM
interesting on the jet man.

we'll have a good look tomorrow in the AM, don't put it together all the way yet.

grab a gasket for the stator cover while you're there too if they have it.

getting my plate today hopefully (if it is as easy as it's supposed to be)

Red_Chili
03-16-2012, 11:21 AM
My point was, on the stand in the garage overheating hasn't exactly been a big issue. :o

Oh. :lmao: :rolleyes: ;)

nakman
03-16-2012, 11:44 AM
Hey check out this picture of the torque limiter of my engine:

http://cyclehuttktm.com/FicheFinderNew/Images/CycleHutt/a80.gif

It's #7... hopefully easy to find once we pull the pesky clutch out of the way..

rover67
03-16-2012, 12:00 PM
and it's just a pair of channel locks to tighten it right?

you have the right sockets? I guess if not home depot is close.

nakman
03-16-2012, 12:06 PM
Yeah, I got sockets. Going to pick up an inch torque wrench at lunch, I think that's the only other tool that we'll need.

Red_Chili
03-16-2012, 02:49 PM
You'll need that for doing your own diffs anyway... ;)
Get a dial type.

nakman
03-16-2012, 05:01 PM
guy at parts counter: what kind of bike you got?

me: 2007 250 XCF-w

parts guy: I had one of those for a while, ended up selling it.

me: why'd you get sell it?

parts guy: couldn't get the carb adjusted right.

:doh:

Red_Chili
03-16-2012, 05:03 PM
Oh... you've just added to our sense of challenge and adventure!!!

It CAN be DONE! Just because he's a wuss... :lmao:

nakman
03-17-2012, 05:03 PM
Woo Hoo!!! :woot: Marco came over today, we blasted every little orifice we could find, set up the carb to stock JD settings with the 42 pilot, found a good bit of gunk in a couple places. Hosed out the gas tank really well, got it all cleaned up everything was feeling good.. then the damn thing wouldn't start or idle, just like before.

We pulled both side covers looking for that torque limiter, got that gear out and couldn't figure out how to adjust it, so slapped it back in. Started swapping parts between Marco's 530 and mine, it actually ran a little better with his CDI. thought there is since that's a lower revving engine, maybe it's more tolerant of less current? Started measuring current and my stator output was half of his.. like 6.8 when e-starting. No wonder we couldn't ever see a spark..

So I went to Sun and bought their stator kit upgrade, and another new gasket. $200 later, but wow what a difference. The bike starts, it idles, you can kill it and it starts again. Probably 30 starts in the last 30 minutes, just can't believe it.. plus it rides 1000x better now, way more pep, actually fast feeling (like the first 250 XCF-w I drove but didn't buy).

Now I need to get some miles on, get a feel for how the bike runs then start messing with the jetting a little more to see what changes it makes. But heck it runs pretty good right now, very happy. thanks again Marco for all the help today, that was fun. :bowdown:

rover67
03-17-2012, 05:25 PM
no problem tim!

Glad I could help out!

60wag
03-17-2012, 06:41 PM
Glad to hear that you figured it out. Now we need to ride.

nakman
04-16-2012, 11:06 AM
So I am getting pretty poor mileage- like 48 miles from full to where I run out of gas, and need to switch to reserve. I was hopefully thinking it was because I had the bike leaned onto the kick stand to fill up, but don't think the tipping of the bike is enough to account for almost half the efficiency that Subzali gets. I am likely + 30 pounds though, but is that so significant?

So I experimented with trying to lean out the mixture, and moved the little E-clip on the big long needle from slot #4 to slot #2, essentially shoving it down in further, which in turns lets less gas by. Well that resulted in a bike that almost doesn't start, I did get it to start by flooring the throttle, but then around the block it ran really poorly. So then I moved the needle to slot #3, splitting the difference. Ok that starts a little better, kind of a pain when cold but when hot starts right up. Seemed to run ok.. but I liked how it started before.

so then yesterday I switched back to slot #4, then I changed my main jet from a 180 to the 175. Per the JD documentation, I'm set up now for 6000-9000' elevation. the bike starts fine now, I haven't had a chance to ride it yet though. I'm going to leave it as-is for now then drag it to Utah..

Are there other adjustments that would lean out my mixture, beyond the clip position on the big needle, and the main jet? And what of those would you suggest? Anything else I should look at to try to improve fuel economy?

farnhamstj
04-16-2012, 11:34 AM
How is the float height? That is pretty low for milage. Sure you're not pouring gas out the carb overflow?

nakman
04-16-2012, 11:38 AM
Marco and I inspected the float and thought it looked "fine," can't remember the number but it was within spec. I am definitely not losing gas out of any of those hoses, would have smelled or seen it in the garage, or seen dirt buildup on one, and there is none- definitely no leaks.

60wag
04-16-2012, 12:16 PM
The idle circuit should allow the bike to start even with the needle down low. How many turns from closed is the idle fuel screw?

Did you try starting it cold with the choke on?

nakman
04-16-2012, 01:52 PM
Yes choke on, bike does not start otherwise. I will check the idle fuel screw tonight, that's the new red one on the bottom right? the plastic black one is just idle adjustment?

nakman
04-16-2012, 09:01 PM
Fuel screw was about 2 turns out, I put it back to 1.5. Will do my best to ride to work on Thursday and see if I can notice a difference.

60wag
04-17-2012, 08:30 AM
If you turn the fuel screw in until you get some popping when decellerating in gear, you have leaned out the idle circuit. If you can run the fuel screw nearly closed and the bike still idles without decel popping, then the idle circuit is running too rich for some reason.

Here is a nice summary on Keihin carbs. It's written for a different model but is very similar to the FCR.

http://www.gadgetjq.com/keihin_carb.htm

I like this graphic. I helps isolate the parts of the carb to different throttle positions.

nakman
04-17-2012, 10:15 AM
Yeah that graph is helpful, thanks. So maybe I would have been alright on slot#3 then, if I had spent more time with the idle fuel screw? huh.

60wag
04-17-2012, 10:49 AM
What I don't get is why the needle position affects starting at all. That why I think something else isn't right.

nakman
04-17-2012, 11:26 AM
I called JD just for fun.. they suggested routing my float bowl overflow tube up and over the carb, just to make any gas travel uphill before it can escape. Maybe I need to create a little back pressure there and gas is escaping out the tube that I just don't know about. the other suggestions was pull the carb and lower the floats, even if they measured in spec, make them lower. But in their opinion, there's nothing in their jetting that would account for such an increase in gas consumption.

60wag
04-17-2012, 11:58 AM
Does the tube from your gas cap to the frame have a check valve in it? You might try venting the tank to atmosphere to be sure that tank pressure isn't pushing fuel past the float valve. Also try the fuel screw thing to confirm that you can create a lean idle with decel popping.

nakman
04-19-2012, 12:19 PM
Success? Rode to work today and I must say the bike's running as well as, or possibly better than, ever. Starts, idles, quickly jumps in RPM, and a slight amount of deceleration popping, all feels right. What's curious is I've learned that the ease of shifting has everything to do with how well the bike is running. I can find Neutral fairly easy now from 1st or 2nd, even while at a complete stop. When the bike runs poorly, it'll do anything from die when I shift into 1st, to just about refuse to go into Neutral either stopped or moving.. so for whatever reason, neutral shifting has become my litmus test.


Ok onto a question: I flipped the float bowl drain line up and over the carb, as directed by JD. while doing so, I realized that I do have some gas in the line that exits the top of the carb, on the other side (near where the throttle cables attach). Is this normal? or am I onto something here... the arrow points to where the gas was this morning when I rolled the bike out of the garage, first time I've touched the bike since Sunday.

60wag
04-20-2012, 08:54 PM
The tube with the arrow is one of the vents higher up on the carb. I think it's hard to get gas in that tube UNLESS the bike is layed over on that side. I've noticed a bit of gas in there when picking my bike up. It also seems to evaporate very slowly.

The bowl drain tube looped over the carb - any gas in it? That's the one that's more important. Fuel will drip out of that one, without tipping the bike, if the level in the bowl is too high.

nakman
04-21-2012, 10:09 AM
No gas in the lower tube from the float bowl, looping over the carb now. And it's possible the gas I saw in the upper tube was from twisting the carb to gain access to the jets.. I may be onto something though, I am pretty sure I reset my trip odometer when I topped off up at the dirt track, which means I rode another 39 miles then put 1.1 gallons in yesterday.

subzali
06-03-2013, 09:35 PM
Still have any extra o rings? ;)

nakman
06-03-2013, 09:51 PM
Probably. Can bring the lot to Argentine? You gonna come up and ride a little?

baja1d
06-03-2013, 09:53 PM
Still have any extra o rings? ;)

Ace Hardware has them. A paper clip also works & last much longer. Better yet, stainless wire or hand grip wire

subzali
06-04-2013, 07:23 AM
Probably. Can bring the lot to Argentine? You gonna come up and ride a little?

Won't make it up to Argentine on the bike. Probably going to be doing some last minute wrenching on the 40 in order to make it Sunday. My "problem" may just be my pilot screw, or may just be that the bike hasn't been exercised in a while. I'm doing some more reading on the oring mod...

nakman
06-04-2013, 10:53 AM
Just thinking out loud here but your Tundra seems like the ideal Argentine choice over the 40 this time... lots of bed space for hauling out trash, easily capable of running all of the open roads in that area, plus it can haul a motorcycle. ok will stop now

subzali
06-04-2013, 11:23 AM
Nope. Trees are too tight on the lower road. Don't want (any more) pinstriping.

nakman
06-04-2013, 11:37 AM
Nope. Trees are too tight on the lower road. Don't want (any more) pinstriping.

Ah, ok. you know there's an app for that :D

http://www.risingsun4x4club.org/forum2/attachment.php?attachmentid=29068&d=1339553359