Backfiring !

[russell_allen]

Assistance/Advice gratefully received

I have a Greeves with Villers 37A engine with a Greeves alloy barrel and head. Its has started to backfire when trying to start it, but only when its been run and then left standing for a bit (warmish). Starts fine when hot and fine from cold, Ive checked the points gap, timing, cleaned the carb, even had the head off to check the piston and bore and new plug but no joy. The bottom end was recently rebuilt by Villiers Services and the barrel was rebored and had a new piston/rings. Once running it runs fine and shows no sign of being sick. When i start it from mid warm it can be difficult to start and backfires. Sometimes it will catch but then die and backfire.

i'm at a bit of a loss and seeking advice from those more knowledgable

Im due to ride it in the Lands End Trial in April and really want to get this sorted - or I may have to resort to using my brother in laws KTM 450

many thanks

Russell Allen

[John Wakefield]

If it was previously OK then something has changed or breaking down. You say you have checked timing, points and plug, what about the condenser or ignition coil? Is the coil the original one inside the flywheel casing, or a remote one on the frame? If the latter its easy and cheap to replace less than ?15 on line also worth changing condenser if you have not done so.

[russell_allen]

Hi John

Thats what i was thinking - both the coil and condesor have done less than 200 miles, so until now id kind of assumed they were good.

Thanks

Russell

[John Wakefield]

Electrical components can fail at any time, just had to replace the ignition coil on a chainsaw, was working perfectly, then refused to start again and no spark. But replacement only cost GBP 9.50 from China

[russell_allen]

I fitted a new condensor and ordered a new coil. Hopefully it will sort the problem

Thanks

Russell

[russell_allen]

Now sorted - turns out that the points terminal on the coil was intermittently touching the tank - took a bit of finding - I did 60 problem free miles on it today

thanks for your help

Russell

[John Wakefield]

Usually the simple things, glad you have found the problem.

[iansoady]

On the bright side you have new spare components.