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Disclaimer: I know nothing about 2 stroke engines and Mikuni carburetors. Stupid questions may follow.
I recently purchased a pair of 2001 Yamaha XL 700s. The seller asserts that they ran fine but recommended that I rebuild the carburetors due to winter lay up time of 7 months.
On seller’s advice, I have set hi-speed screws to 2.5 turns out and idle screws to 1.5 turns out. (This seems like a lot to me and everyone I talk to.)
Both skis are boggy with no power, although one runs great after it finally struggles to full throttle. In the tech articles I find settings specified as:
Low Speed – 5/8 +/- ¼
High Speed – 5/8(M), 1-1/8(P) +/- ¼
1. Is this right? Am I off by that much? The seller runs a waverunner rental business and I assumed he knew what he was talking about.
2. Why is there such a big difference between hi speed screw settings on fore and aft carbs?
3. I am afraid of running them too lean, as people say this can burn up the engine. Is this really a concern? I fail to see how, since the 2 stroke oil is dripped into the top of the carb and has nothing to do with the fuel/air mixture. This warning seems more applicable to a premix setup.
4. Compression readings are 180/180, 180/140 (performed on cold and dry cylinders). Is this is a concern? The 180/140 engine is a recently installed SBT engine.
Thank you in advance for any advice.
I recently purchased a pair of 2001 Yamaha XL 700s. The seller asserts that they ran fine but recommended that I rebuild the carburetors due to winter lay up time of 7 months.
On seller’s advice, I have set hi-speed screws to 2.5 turns out and idle screws to 1.5 turns out. (This seems like a lot to me and everyone I talk to.)
Both skis are boggy with no power, although one runs great after it finally struggles to full throttle. In the tech articles I find settings specified as:
Low Speed – 5/8 +/- ¼
High Speed – 5/8(M), 1-1/8(P) +/- ¼
1. Is this right? Am I off by that much? The seller runs a waverunner rental business and I assumed he knew what he was talking about.
2. Why is there such a big difference between hi speed screw settings on fore and aft carbs?
3. I am afraid of running them too lean, as people say this can burn up the engine. Is this really a concern? I fail to see how, since the 2 stroke oil is dripped into the top of the carb and has nothing to do with the fuel/air mixture. This warning seems more applicable to a premix setup.
4. Compression readings are 180/180, 180/140 (performed on cold and dry cylinders). Is this is a concern? The 180/140 engine is a recently installed SBT engine.
Thank you in advance for any advice.
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