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-   -   Carb, intake mods, and nakman's quest for a well running motorcycle (http://www.risingsun4x4club.org/forum2/showthread.php?t=17431)

nakman 03-05-2012 03:34 PM

Carb, intake mods, and nakman's quest for a well running motorcycle
 
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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

Quote:

Originally Posted by subzali (Post 206015)
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.



edit2: here's a picture from the JD site
http://ic2.pbase.com/g3/20/347520/2/...9.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

Quote:

Originally Posted by nakman (Post 206018)
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/1...-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.


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