Uncorking XR650 - Running poorly - HELP!!

Hey all! I'm new to the XR650 board as I am posting a question regarding a friend's bike...hope someone can help or offer some insight!

Anyway, my friend just got done uncorking his 2001 XR650 and after completion of the mods it spits and sputters past half throttle. The mods included, drilling out and removing the baffle in the silencer, replacing the intake manifold and removing the airbox restriciton. He of course rejetted, changing the pilot jet, raising the needle (lowering clip position) and went up to a 175 main. Sorry I don't have the exact specs on clip osition and pilot, but I believe he used specs posted on this forum. Anyway, when he took it out to see how this newfound power would behave, but all he found was a really bad sputter above half throttle. He lives in MI and the temp was ~20 degrees F when he ran it. I suggested that it may be entirely too lean with all the extra air getting to the motor, since the air temp was only 20 and the jetting specs he got I am thinking were for 65 or so and sea level. He says it feels like it is getting too much fuel but I have not had a chance to take a look at it to confirm one way or the other.

Has anyone else run into a similar symptom when making thses mods? My first suggestion was to go up several sizes on the main and see if it gets better, worse or stays the same...however, my friend then informed me he mistakenly removed the needle jet and moved the hex nut adjuster (which I believe affects the height of the needle jet in the carb?!). He feels he put it back where it was, but I am thinking without measuring and having it set at the correct height +/- 1mm will have an affect on performance?!

So that's the story - ANY input woud be greatly appreciated!! Ride Red!!

I have also made the same modifications to my 01 650,However there are a few differences. In regards to the needle. I was directed to replace the needle with a different HRC needle and seat. As for as clip position I ran it on the 3rd position (this also happens to be the middle). I also used a K&N air filter. For the exhaust modification I used the stock muffler but replaced the tip with the HRC exhaust tip. This combination made both my '00 and '01 650's run great in a variety of elevations. - Good Luck

Use the HRC needle and seat.

Has he taken All of the plastic restriction out of the air box, there are 2 pices to take out.

One of the pisec is plastic and one is a ruber boot type pice.

I had this same type of problem and I had only taken the plastic pice out, after I found the other one it ran great.

Hey 455 rocket,I put the honda power up kit on my 00650r and did just what they said to do and it ran like a rocket ,,,,,no joke

Makeing a long story short :)

I am no jetting master but I do know that if the problem starts at 1/2 throttle it is a problem with the needle , not the main jet which kicks in at 3/4 throttle and more. You can examine the plug to find out if you are lean or rich, black indicates you are too rich and grey is too lean. You should go to the Suzuki DRZ forum where you will find many carb masters.

Thanks for the replies guys!! I will check with my buddy to see about both pieces in the airbox. I hope to take a look at it myself and report back my findings. Additional input is still welcome!!

Did you ever find out what was wrong with your friends boke? I just did the same mods and am having the same problem. It seems to run way rich past 1/4 throttle. It will not rev out. I have tried a 170 and 175 main, If I go back to stock main it will miss at full throttle. I have the HRC neddle and seat, all restrictions, exhaust, intake and airbox out and it still runs rich. The air mixture screw is 2 turns out and does not seem to make any differance. The carb has been cleaned 5 times. Any ideas?

We removed the airbox vents (2), changed the intake boot and the exhaust outlet with a larger diameter outlet (louder) with the Honda stuff, and the main jet (175) and the needle. Also the air injection was removed and plugged. The pilot jet was changed to a 68 from a 65 and ran worse, so back in with the 65. The bike ran much better, so we put a K & N filter and a 178 main jet, she ran even better. We might try a larger main next time out. Remember the colder or higher you are the richer these specs are. We run the bike at a few hundred feet, low humidity, high temps

Bob J

[ March 10, 2002: Message edited by: Bob J ]

Here is a link with pictures on making sure you have all the air box plastic out (there are two parts).


Look under the "Uncorking It!" section of the menu.

Another thing to check, (as this happened to me!) is that the cylinder manifold has a breather tube (brass) coming out of it. This is for the smog recirculating parts (Calif. only?). Mine leaked and the thing backfired and ran lean (but restarted hot much better!) until I found it and plugged it. The smog removal kit that is sold had a cheap rubber cover that leaked. I finally put gasket sealer and a better grommet (from PEP BOYS) on it and it ran fine.

Your jetting seems spot on. Check the manifold plug, remove the plastics from the airbox and put the power up needle kit in it from HRC (available from your dealer) at the #3 position.

Let us know how it turns out!


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