Hi all went for a good hours ride last night I've all ready changed my air filter after a loss of power at 60 mph couple of weeks ago but tonight I lost power temporary and sparks were coming from exhaust.I pulled over bike idling ok give it a few revs and it seemed to clear and bike rode alright again the rear Dep back box is oldish not had the bike to long haven't checked spark plug at all could,any ideas plz

sparky67

It happens when there is a build up of carbon in the exhaust. It blocks the pipe and spoils performance.

With the way a 2stroke opperates the exhaust gasses are extreemly hot. And loaded with unburnt fuel.

When you give the bike a good long run it can burn off. This comes out the tailpipe as glowing embers. With white smoke too.

My tdr did the same tge first time i rode it propperly. After around 45mins riding with a 600. My tdr started blowing smoke like a red arrow. Was fine afterwards.

Check the plug though. May need a decoke.

Cheers cynic that's exactly what happened it cleared and seems fine now I've ordered a new spark plug and feeler gauge.

But can you tell me if I reach my top end at 60mph will the restriction make the engine loose power temporarily

Might need a decoke. The way a 2 stroke works is some fuel mix ends up in the expansion chamber. Then its sucked back into the engine.

When the smoke which is effectively the gunk in the exhaust catching fire the smoke ruins the fuel mix.

Sounds like a decoke is needed.

Try this first. Get 5 or so feet of garden hose. Then for want of a better plan shove it as far up the exhaust as it will go. So long as it goes into the exp chamber it should help.

Not as good as a proper decoke but helps a lot if its an issue.

many thanks Gerry

Sparky67