I am working on a old Yamaha Moto 4 and I need some help. I am not shure of the year but I think it is a 85 or 86 model, with the 200 engine. My problem is getting the thing to start. It runs great after it does start, but most of the time it will not start. It just cranks and cranks away, but will not start. I put a new plug in it, and pulled it back out after It started and it was covered in soot. The spark looks extreamly weak, so I am thinking it is in the ignition. What should I change first? Coil? Any way to test it? Thanks for any and all help!

 

Misadjusted valves will cause the symptoms you indicate.

 

Make sure the choke isn't stuck on, they do that. Also, pull the carb, and make sure it clean, needle and seat, and float aren't sticking. How long has it been since it ran? I bought a new Swisher mower, and let is sit for 3 weeks between uses, and it wouldn't start. Did nothing but drain gas, and fill with fresh and it ran. Gas is so bad these days! Good Luck

 

Anyone know the valve specks? I have tried to change the gas and it did not help. I took the carb apart and it is as clean as a new one. I sprayed some starting fluid into the carb after I got it started and it almost killed it. This 4 wheeler had been starting great for the last 2 years every week, untel last month. I guess it is time to check the valves. Thanks for all the help!

 

Please, I need to find the valve settings. Can anyone pass on this info? Can they get too tight over time? Thanks

 

Yes.

 

Hey, I just bought an '86 Moto-4 like a month ago. It had been sitting for aprrox. 8 or 9 years.

It would not start for sh|t. My brother took the carbs apart and cleaned them up.

Runs like a champ (Most of the time)

Here's a Pic

 

I don't know for sure either, but 6 thou on the intake and 8 on the ex. should get you close. On those small motors, the valves wear into the head, and the clearance goes away. What you notice is the bike getting harder and harder to start over time. My first experience with this was when I was a kid, on my Honda 70. Pull the caps, spin the engine over to tdc, and wiggle the rockers. But you say the plug has soot on it, after it runs for a short time, with a new plug, that tells me, it's running pig rich (carb). Or is it burning oil? Your question on the coil, you can check it with a meter. For a weak spark, maybe look at the cap, cracked, end of wire corroded.

 

Take the carb off and clean it out. Might even need a new float kit. We had an 85 200 a long time ago, and we had to keep the carbs cleaned on a regular basis. Finally just bought an in line fuel filter and put on it. Worked a lot better.

For a quad that old, you could do a few quick things and probably get it going ok. Valves & carb are small fixes that can clear up a lot of problems. Adjust the valves, clean the carb and possibly put a new float kit in it, and put a new plug in. Also, check out that air filter too.

 

i had the same prob. uprgade to a hotter plug. then pull start it and ride it for about 15 minutes. that should fix it right up.

btw: a moto 4 200 was my last quad bfore the blaster