By Winston “Boss” McKannick


Dear Boss,

I have a 2005 Yamaha Blaster. For the last few weeks, the only way I can get it to start is to pull it with another quad, my neighbor’s Yamaha Big Bear. Then, it starts right up. I purchased a new spark plug and then a new carburetor, but neither help the starting. Boss, can you tell me what to replace next?

Lenny Davis,

Williamson, WV

Judging by your letter, son, it sounds to me like you have a problem creating a combustible mixture in the cylinder unless you tow your quad. When towing the quad in gear, you artificially increase the pressure inside the cylinder until a combustible mixture of air and fuel is reached and the engine starts. Just kicking the engine over doesn’t spin it fast enough to develop a combustible mixture if there is low compression inside the engine. I would do a compression test on the engine and see what you have. Under 100 psi and it is very hard to get a cold two-stroke engine to start. If you do not have a compression tester, there is always the “rule of thumb” test. Remove the spark plug and place you thumb over the spark-plug hole, sealing it. Have someone kick over your Blaster and see if the engine compression can blow off your thumb. If it does, then that is not your problem, and I would look at the electrics. However, if the engine cannot pop your thumb smartly off the cylinder head, then you generally do not have the minimum 100 psi required to start a two-stroke engine. A fresh bore and the next size over piston and rings will be necessary to restore proper compression. 

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