|The information on these pages is accurate to the best of the author's knowledge. The author can assume no responsibility for the use or misuse of this information by the reader. The reader is expected to secure any other information needed from Service Manuals or other sources. It is up to the reader to determine his/her ability to make any modifications noted. If the reader does not feel qualified he/she should enlist professional help.|
ATV carburetor synch
By Chet Walters
Return to Chet's Prairie Pages
|Click any picture to see enlargement|
There are two cylinders and each needs to breathe equally to yield the best performance. If one cylinder is working harder than the other, you risk vibrations, hot running, plug fouling and in the worst case, fuel washdown on the cylinder walls causing the rings to die a quick death - not to mention loss of power. For normal running, twice a year is ok to check the synch. But if you do any modifications to the carbs, top end, intake, or exhaust, then you need to synch as a final step. The most noticeable symptom of out of synch carbs is engine vibration.
Adjustment is easy, but a little tricky. Just putting the long screwdriver on the screw will affect the synch. You need to adjust the screw and watch the gauges. When you get it close, let off the screw with your long phillips and let the motor settle. Blip the throttle very little then let it settle down again. Check the gauges. If they match fairly well, your done. If not, readjust. Note that if the fan comes on at any time, you'll have to shut off the engine and let it cool some before continuing. If you can't get it within range, some pilot screw adjustment may help.
If you're using CarbTune, it must be held perfectly vertical!
Put the caps back on the nipples and re-assemble. After your next days ride - DO IT ONE MORE TIME! (second time's a charm).
|WHAT IT LOOKS LIKE
If you click the pic at the left, you will see what the CarbTune looks like when the synch is correct. You will likely not get an exact match, but if you are within the same full across red lines, that's good enough.
here for a 2meg QT movie of Carbtune running....