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Yamaha Ty 250 Not Running Well At 3/4 - Full Throttle


austin6728
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I have a Yamaha TY250 Twinshock around a 1974 -1975 it is in mint condition with only 500 miles on it. The bike starts no problem and sounds good it's only when riding and at 3/4 - full throttle that it seemd to start pinking and looses power.

I've had the carb out countless times and cleaned it also checked the reed valves, air filter and the exhaust and there all fine

someone mentioned it could be a timing problem but i'm not sure

I love this bike but and want it fixed Anyone any ideas?????

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The bike is 35 yrs old, with only 500 miles on it......maybe its done 15 miles per year, or maybe it did 500 miles in 1975 then sat around in garage.

The point is the bike has done an awful lot of sitting around, not running, I wouldn't be at all surprised to find out it was a carby problem !

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The bike is 35 yrs old, with only 500 miles on it......maybe its done 15 miles per year, or maybe it did 500 miles in 1975 then sat around in garage.

The point is the bike has done an awful lot of sitting around, not running, I wouldn't be at all surprised to find out it was a carby problem !

Yip the bike is 35 years old i bought it when it had 300 miles on it from the origonal owner (friend of the family) and it ran great for a while with no problems. I have done some reserch and remembered that instead of using the seperate oil tank for the 2 stroke oil i have just been pre mixing the fuel and had the oil tank out of use. Now i'm thinking that i maybe suckin/ pumping air into the carb.

Could this be so???????

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Yip the bike is 35 years old i bought it when it had 300 miles on it from the origonal owner (friend of the family) and it ran great for a while with no problems. I have done some reserch and remembered that instead of using the seperate oil tank for the 2 stroke oil i have just been pre mixing the fuel and had the oil tank out of use. Now i'm thinking that i maybe suckin/ pumping air into the carb.

Could this be so???????

Thats more than likely exactly what it is - try just blocking up the hole in the tank, then set your mixture accordingly, as this will remove air from the lower acceleration band, causing your mix to go off slightly.

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  • 3 weeks later...

You don't say what model this is. If its a TY250A then the oil is injected into the barrel directly on the right hand side. A simple bolt in this hole will fix the problem. If it is a later model then the oil was injected into the front of the carb and you will need a small blanking rubbber over this inlet.

Other problems could be the needle clip position and the size of the main jet. Use a 150-160 main jet and set the needle clip on the central position.

The timing on ALL of these TY's is a fixed stator plate so unless someone had modified it this will not move.

Make sure you are using the correct plug (NGK B7ES) and set the gap to 22 thou and make sure the points are 15 thou.

Tony

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  • 8 years later...
 
15 minutes ago, austin6728 said:

Extremely ate in my reply but all sorted it was a small O ring in the carb changed it out and running sweet now

I've been waiting on tender hooks for 9 years waiting for the outcome ??

  • Haha 2
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