850 Thunderbolt starting problem

H

HOGUNN

Recruit
Joined
Jul 31, 2005
Messages
3
Hi, I hope someone out there can help. I own a 1975 850 Thunderbolt Blueband. I have owned this motor for some ten years and has never let me down. At the start of this season I had the motor serviced as normal. As the weeks have progressed the motor is becoming harder and harder to start. There are new plugs and the spark is nice and crisp (bright blue)Timming is bang on, fresh fuel. carbs clean. The motor is the same if hot or cold. Even with the choke it still takes a good cranking to get it to start.When started runs like a dream. Any ideas. Thanks
 
P

papasage

Senior Chief Petty Officer
Joined
Jan 12, 2003
Messages
785
Re: 850 Thunderbolt starting problem

check compression or timming could be off due to wear . i would say compression and or valcum if a seal gits week it cant draw fuel into the piston .
 
H

HOGUNN

Recruit
Joined
Jul 31, 2005
Messages
3
Re: 850 Thunderbolt starting problem

Thanks for the replys. Checked the compresion at the weekend and was fine. The plugs get wet so plenty of fuel getting through. I tried a larger battery and that really wound the motor over but still took a good few turns before it fired. Then ran fine. Turned the motor off turned the key almost straight away and still took a good few turns before it would start again.
 
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