Bike holding back

[AcID ZeR0]

When the bike is in low revs it feels like it's getting held back, It starts vibrating and pulling back untill I get the revs up to about over 4k then it goes fine.
What could this be? It's a 100cc Speedfight.

[Scotsman37]

Have you checked your brakes as they maybe needing cleaned because they maybe binding!

[bish777]

plug could be a bit knackered?

[AcID ZeR0]

Hi guys, I'm pretty sure it's not the brakes because it only does it at a certain period regardless if I've recently touched the brakes or not. However I'm intreged to find out more about the spark plug being naff how would that affect it in low revs only? Although I do think it's time for a new one anyhow.

[Scotsman37]

Oh well, if you've checked the brakes then that eliminates that possibility.

The theory that the spark plugs maybe causing you problems may actually be true because spark plugs only last for so long and may not fire properly as they did before when they were initially new. Other things could be causing problems for the spark plugs is that your air/fuel mixture could actually be wrong!

Have a look NGK's tecnical tips section for further info on this matter;

https://www.ngk.co.uk/

[ts50x0]

its worth changing the plug as its cheap and it will most certainly run better anyway if you havnt changed it for a while, have you left your bike tsanding at all? the carb could need cleaning out, both of those things will cost you very little so do them before trying anything bigger out, you can also play around with the mixture and give your air filter a clean.

[AcID ZeR0]

Hi guys, yeah I'm going to get a new plug tommorow. Also how'd I go about cleaning the carb is there something I can get to put in my petrol?

[Scotsman37]

[AcID ZeR0]

Okay mate I'll give it a shot. Cheers!

[bish777]

If the plug is worn it required more current to create a spark-so if the engine is running slowly, you get a weak spark because the generator puts out less current, then when u rev up more current, and it runs better.

[DM]

Also sounds like your variator rollers might be worn. I had the same problem with a Runner SP that started having problems "spooling up" at lower rpm, then would take off once i got past a point. Replaced the rollers and it ran great.