CARB PROBLEMS



5 replies to this topic
  • HOOLPE

Posted December 17, 2003 - 10:14 AM

#1

I just purchased a new 2002 650r and I uncorked it, removed
the smog, rejetted it to accommodate the free flowing baffle
with the stock exhaust. It has a 175 main, 75 pilot, the
needle is a B53E and it's in the 3rd (middle) position. My
problem is that it doesn't run well at 3/4 throttle and above (in any gear). The bike starts missing and feels like
it's not getting any fuel. I also have 2000 650r with the
exact same jetting and I swapped the carbs and it ran fine
with the old carb. If it makes a difference, I am using a
stock air filter on the bike. I would appreciate any help
or advice.

  • qadsan

Posted December 17, 2003 - 11:34 AM

#2

I swapped the carbs and it ran fine
with the old carb.



If that's the case, then something is wrong with the new carb, the new jets or there's an installation issue.

Make sure you installed the new needle down through the top of the slide and not from the bottom of the slide where it can't be properly adjusted. In regards to the needle seat where the needle seats into the jet, the side that should be facing the top should have a wider opening than the side facing the bottom.

Make certain that your float heights are the same between the two carbs. The 75 pilot seems awefully rich, but that won't cause this problem.

The only other thing that comes to mind is that not all jets are created equal. It's quite possible to have a 175 main jet that flows like a 170 or 180 due to tolerance issues, so as another option, simply swap the main jet from the old working carb into the new carb and see if that takes care of your issue. Let us know what you find :)

Good luck!

  • HOOLPE

Posted December 17, 2003 - 12:06 PM

#3

I installed the needle from the top and I tried running a 170 main and 70 pilot and it had the same problems.
When I installed the needle seat, I put the thinner, tapered side pointing up towards the needle (that's the
way it is on the old carb). How do I check the float levels?

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • qadsan

Posted December 17, 2003 - 12:28 PM

#4

The service manual has all the specs and details on how to check/adjust the float level. It's pretty easy to do if you've never done it before, but I don't recall the exact values off the top of my head since I don't have a service manual sitting in front of me right now.

Here's a link that will give you a basic idea of the procedure, but you'll need the float drop specs specifically for the XR650R.

http://www.hondaxr.c...nda/carbadj.asp

Also make certain that your carb still has the white plastic shroud around the main jet cause they fall off quite easily and are easy to loose.

  • HOOLPE

Posted December 17, 2003 - 01:07 PM

#5

Thanks for the tips...I'll check my manual tonight. I don't what plastic shroud you are talking about. There
is a brass cup that surrounds the main jet.

  • qadsan

Posted December 17, 2003 - 01:23 PM

#6

Hmmm, maybe the 650R has a brass jet holder instead of the white plastic shroud :) Many other XR models have a white plastic shroud around the main jet that's supposed to keep the main jet supplied with fuel under hard acceleration or on rough terrain under WOT. It's been years since I seen my stock carb which is long gone, so my memory of it is a bit fuzzy. If there's a brass cup around the main jet, then you won't have the white plastic shroud like other XR's (XR250, XR400, etc).





Related Content

Forums
Photo

Engine Loping/Sputtering by tcaldwell


Dirt Bike   Make / Model Specific   Honda   XR600/650
  • 2 replies
Forums
Photo

Wiseco 101MM Spark Knock Low Engine Temps by imandrewparks


Dirt Bike   Make / Model Specific   Honda   XR600/650
  • 8 replies
Forums
Photo

XR650L super moto wheels by greggkklee


Dirt Bike   Make / Model Specific   Honda   XR600/650
  • Hot  28 replies
Forums
Photo

Post Apocalypse, ThumperTalk style! by Justin Pearson


Dirt Bike   General Dirt Bike Forums   General Dirt Bike Discussion
  • Hot  35 replies
Forums
Photo

Would a Young Scott Summers still be Competitive today on an XR600R? What would he ride to be competitive today? by Jayzonk


Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  158 replies
 
x

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.