CR125 lags before power band

[krasher]

Hello. I am new but would appreciate some advice.

I am a new rider and have purchased my first bike. Honda CR125 2002.

It starts first or second pump, idles fine when warmed up and in neutral. It has a fairly good sized dent in the side of the exhaust. It hoons round pretty scary fast in power band. BUT.

Just before hitting powerband it lags in power, and sounds really rough, then powerband kicks in and it takes off.

I hear it shouldn't be doing this but i don't know where to start looking to fix it. I am practical enough to be able to take things apart and put them back together as long as I have clear instructions and I plan to learn how to fix this thing myself.

A bike mechanic suggested it probably wasn't the dent in the exhaust but didn't know after that without looking. Any suggestions?

[krasher]

Nobody can help me?

[k14]

Have you ridden any other 2 stroke 125's? Their nature is to have a very peaky powerband and virtually no power below. Could be that its just running at too low revs.

If there is a problem it could be a heap of things. Very hard to diagnose on that little info. Does it have any aftermarket exhaust parts etc?

[krasher]

Fair enough. No I have not ridden anything else. That is the prob. It isn't just powerless, it has some power, then none/little, then hits powerband and has plenty.

It has the stock exhaust. I am not sure where to look next. I want to learn, not just pay somebody to fix it. I know its the hard way but with some pointers I can go check stuff and figure it out. Well, that's what I am hoping.

[F5 Dave]

Well it's an old competition engine, where are you starting from?

The often need regular maintenance, but this gets neglected when sold on.

Air filter should be premo clean & oiled with proper filter oil. new spark plug, clean out carb checking pilot jet is clear. Check not flooding through worn float valve. this is all easy stuff.


then would be nice to confirm power valve is working & muffler clean & repacked. Pipe can be undented but shouldn't be the issue.

then do a search on jetting, there will be heaps of info online.

[Rupe]

Fair enough. No I have not ridden anything else. That is the prob. It isn't just powerless, it has some power, then none/little, then hits powerband and has plenty.

It has the stock exhaust. I am not sure where to look next. I want to learn, not just pay somebody to fix it. I know its the hard way but with some pointers I can go check stuff and figure it out. Well, that's what I am hoping.

hey mate if you post your question in the off road section you'll get loads of help. You should be able to get it sorted, 2strokes are pretty simple

[driftn]

I had a 2000 cr125 with an fmf fatty I think it was and came to the conclusion that its a 125 2 stroke and in order to keep them going good you just have to keep them happy. Or buy a 250.