What are the symtoms of needing a rebuild.

monkeyman · Scooby Slapper Joined: 26 Jan 2004 Karma :

My NSR seems to be slowly loosing power. Its currently derestricted and was able to manage 85 which it could storm up to.
BUt now basically i can just about get 85 down hill with the wind behind me and it takes me longer than usual.

I think the power valve is still working as i get the noise when i start the bike. I haven't checked the air filter but i will do it tomorrow.

Im not sure when or if, it has been rebuilt because the guy i bought it off didn't know much about the bike.

it has currently done 9000 miles.

Any ideas people?

Also what is involed in a rebuild?

How hard is it, i pretty confident with a spanner i could proberbly manage a haynes 3 spanner mabye 4 with help from my dad.
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Danny · Ask Me About Stoppie School Joined: 26 Jan 2003 Karma :

I had about the same symptoms, check the compression before you do a rebuild. Mine was about half the compression it was supposed to be before the rebuild.

The rebuild itself was a horrible matter, took me and Robby ages to do it.

I'm sure Keith will provide more info.

Robby · Dirty Old Man Joined: 16 May 2002 Karma :

Those sound like the symptoms pretty much.

The rebuild was horrible. It goes much more smoothly if you have the manual sitting next to you, but basically its a tight frame, not much room to work in there. Probably easier if you take the whole engine out, but then you need to put it back again.

Shifting the gudgeon pin was a total arse on danny's one. Took me 2 hours of gradually squeezing it out with a long bolt, 2 nuts, and a lot of washers.

And then I went and bought a bike with 250cc version of the engine for myself. Curious.

Kickstart · The Oracle Joined: 04 Feb 2002 Karma :

Hi

Does sound like it might need new rings. Do a compression test on it (it should be 142psi, give or take 28psi).

It is possible to get the top end off the engine on the early models, but the later frame looks like it would make it worse. On the early bikes it is quite easy to drop the engine out.

All the best

Keith
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NSR125-Kid-UK · Attention Whore Joined: 03 May 2003 Karma :

Danny · Ask Me About Stoppie School Joined: 26 Jan 2003 Karma :

I never had problems doing that.

Robby · Dirty Old Man Joined: 16 May 2002 Karma :

No problem at all changing a spark plug on it. Its much easier to use a spanner to change one anyway - its a 2 stroke with a flat cylinder head and the plug sitting proud, no need to use a plug socket.