03 WR250 Problems

I am having some strange problems with my Yamie 250. I started out thinking it was carb related on the low circuit (fuel screw related). It tends to bog or a better term might be blubber when cracking the throttle at lower RPMS. When you stop and idle for 30 seconds or so, it will then clear up until run a few seconds and then when you back off the throttle to slow down and and crack the throttle again, it will blubber. The fuel screw adjustment does not seem to effect the problem but once you are on the main jet, it seems to run great. I replaced the fuel screw when I noticed a little ring forming through the anodized finish but it did not help. The pilot jet is stock. The o-ring, washer and spring were confirmed it in the right stack order. I torn down the carb and blew it out the jets and passages but that did not help either. No dirt, sediment, or water was found in the float bowl and I run a gravity type in-line fuel filter also (changed it too). I removed the air cleaner temporarily and it does not seem to have an effect.

This is not the 1st time I noticed this issue but the last 2 times it seemed to go away after the bike sat for several days. The bike normally runs good again until I go through some deeper water crossings and then the problem starts again. I went through deep water 2 days ago when it started again and the problem still persists. This time (but not last time) I found some water down in the spark plug/coil hole. I dried it all out but it did not help. I then replaced the new plug but that did not help. I cleaned all the electical connectors (CDI, coil, etc.) with contact cleaner under the tank but that did not help either. I keep thinking it is possible coil related but both coil resistance resistance measurements were in spec. If the coil is breaking down under power, why does it recover when the RPMs increase (on the main)?

Any Ideas? :bang: I fell like I am missing something or have possible more than 1 problem.

Fixed!! I opened up the carb and blew out all the jets and passages with carb cleaner and then compressed air while checking everything the manual suggested without finding any issues. This give the coil a chance to dry out overnight also. When I started the bike the next day, the problem was gone.

Was it the coil or a carb issue?

03 WR250F blubber Issue?

I originally posted this in another section. Does this make sense?. Please give me your feedback.


I am having some strange problems with my Yamie 250. I started out thinking it was carb related on the low circuit (fuel screw related). It tends to bog or a better term might be blubber when cracking the throttle at lower RPMS. When you stop and idle for 30 seconds or so, it will then clear up until run a few seconds and then when you back off the throttle to slow down and and crack the throttle again, it will blubber. The fuel screw adjustment does not seem to effect the problem but once you are on the main jet, it seems to run great. I replaced the fuel screw when I noticed a little ring forming through the anodized finish but it did not help. The pilot jet is stock. The o-ring, washer and spring were confirmed it in the right stack order. I torn down the carb and blew it out the jets and passages but that did not help either. No dirt, sediment, or water was found in the float bowl and I run a gravity type in-line fuel filter also (changed it too). I removed the air cleaner temporarily and it does not seem to have an effect.

This is not the 1st time I noticed this issue but the last 2 times it seemed to go away after the bike sat for several days. The bike normally runs good again until I go through some deeper water crossings and then the problem starts again. I went through deep water 2 days ago when it started again and the problem still persists. This time (but not last time) I found some water down in the spark plug/coil hole. I dried it all out but it did not help. I then replaced the new plug but that did not help. I cleaned all the electical connectors (CDI, coil, etc.) with contact cleaner under the tank but that did not help either. I keep thinking it is possible coil related but both coil resistance resistance measurements were in spec. If the coil is breaking down under power, why does it recover when the RPMs increase (on the main)?

Any Ideas? I fell like I am missing something or have possible more than 1 problem.

Fixed!! I opened up the carb and blew out all the jets and passages with carb cleaner and then compressed air while checking everything the manual suggested without finding any issues. This give the coil a chance to dry out overnight also. When I started the bike the next day, the problem was gone.

Was it the coil or a carb issue?

I opened up the air box after getting out of the deep water and found water in the bottom of the air box and in drain tube stub but the filter itself was dry to touch. I drained the water out and wiped it with a dry rag before restarting the bike.

Once home, I found the lower corner of the air box not sealing properly. I bought a new air box cover thinking it was distorted for some reason and it did not seal either. I removed all the number plate side covers so I could examine the air box seal area better and found it not sealing, but only in the one lower corner, and it was not a very big gap (just not sealing well). I started to pull out the air box and lossened all hardware while working with the new cover and the cover sealed back up. By slowing tighten the bolts back up one at a time I noticed the air box seal area getting distorted again. It was an issue with the sub frame. It was slightly bent where the lower corner of the air box bolted up. I carefully worked on the frame with a rubber mallet to bend it back into shape and the was able to make the air box seal again.

Need another high water test.

I loaded all the electrical connections up with dielectric grease too.