Downhill backfire.

[john@theforge]

Hi guys

Pick up has started with the occasional backfire, Seems to be happening when going downhill with foot off the gas.
A little throttle seems to stop it happening (is this the answer?)

Other than this starts fine, ticks over fine and runs fine (other than the pop pop)

Any ideas or is it no big deal.

Thanks

John.

[bmcecosse]

It can suggest a leak in the exhaust pipe - drawing in air. A true backfire is unburned fuel drawn into the exhaust system - and ignited there. So - there would be something hot enough to cause the ignition to take place.

[john@theforge]

It can suggest a leak in the exhaust pipe

Doing it from start up so nothing could be that hot.

Will check out the pipework.

Thanks

J

[Neil MG]

distributer advance mechanism sticking?

[MarkyB]

Another vote for leak in the exhaust pipe, old motor bikes were prone to it.
The exhaust gasses are plenty hot from the get go.

[john@theforge]

Just as you suggest. Seems I didn't give the exhaust clamp a final tighten when I set up the exhaust.

As ever thanks for the advice.

J