Home. Back. ...... The Gas Gas Guru. Technical Information.
Subject: a case of the bogs

After reading some of the technical articles I feel that you may be able to help me with this one. My ride is a 00 gas gas 280 and the problem that I'm having is that in between sections or if I'm on fast section the motor starts to cut out and bog down. It almost feels like its sucking up a droplet of water or if the tank vent is not breathing. I do most of my riding at sea level to 4,000 ft 80:1 mix 50/50 race gas 36 pilot 114 main. The jetting that I'm running was recommended by another rider in the area if you think that it should be change please advise. If you can be of any help it would be greatly appreciated. Thanks for your time.


Sounds pretty frustrating. Your jetting seems to be in the ballpark, although perhaps a little lean on the pilot jet. You may want to try a 38 or even a 40 if the engine is slow to rev when the throttle is opened quickly and you can't tune it out with the airscrew adjustment. First off, I'm assuming that your engine is not exhibiting any signs of overheating, which can mimic the symptoms you describe. You may want to run about 30% race gas rather the 50% for better throttle response. My first guess is the floatbowl of the carb is slowly being drained at greater fuel demand levels like sustained throttle. Make sure the petcock filter is clean by draining the tank and taking out the petcock assembly and cleaning the screen. The carb also has a disc type filter on the side that should be checked. They rarely get clogged in a bike as new as yours, but it's a good thing to check. Petcocks have a rubber gasket with several holes in it to divert gas (or not) from the pickup tubes to the outlet tube than runs to the carb. Make sure the fuel is flowing sufficiently through the petcock assembly at each setting of the lever when it is turned on. I'd check the float level on the carb. Jim Snell's excellent article on the Gas-Gas webpage will tell you all you need to know about that. Make sure that the gastank cap is vented and the overflow/vent tubes are open and clean. Just to be sure, check the filter, filter box and connecting tubes on the carb for obstructions or misalignments.

Give these a try and let me know if the problem is solved or we need to pursue other possibilities.


Professional tuner and 'Trials Competition' writer Jon Stoodley has very kindly stepped up to the plate to answer your questions. If you're having problems, or need some advice just send an email to Jon. If it's something that could be useful to others, we'll post it on the site.
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