RM125 97 rm125 low compression on fresh top end

[Rm317]

I helped a friend rebuild his 1997 rm125 it took like 10 kicks to start up the first time. He took it out for a ride today and ran fine for 2minutes then started sputtering. Now the bike wont start and ge said it has low compression. Any causes and how do I fix this? Thank you!

 

[SRAD97750]

Compression reading before rebuild?
Compression reading after rebuild?
Compression reading now?

Let's just start here, the last being the most important.
I suggest a carburetor cleaning checking the float for proper adjustment.. -BIG DAN

 

[Rm317]

The compression was better after the rebuild. But now he said its low. I don't have a compression tester
Thanks

 

[SRAD97750]

I don't have a compression tester

How do you know what the compression is?

 

[Rm317]

According to him the bike kicks over too easily now

 

[SRAD97750]

According to him the bike kicks over too easily now

That is pretty funny.
Get a compression reading in PSI, otherwise using the word 'Compression' is completely useless.

Sounds like you need to clean the carburetor and ride on! -BIG DAN

 

[2Wheels]

Oh no Dan you are being too optimistic. Whenever a new top end lasts 2 minutes there are more expensive reasons. I have seen 2 strokes run really good for about two minutes on straight gas. Then it sputters and loses all compression.

 

[Rm317]

Pulled the pipe off and checked the pison and ring. Looked fine thankfully. The bike turns over and feels like it had better compression with the pipe off.
Could it be the exhaust O rings?

 

[SRAD97750]

Well, once every six months or so I try and help out as the Forum Mechanic...
Perfect example of why I had to quit that...

 

[2Wheels]

Cmon dan could it be the exhaust o rings?

 

[2Wheels]

Ok ok I guess I’m not being helpful.
Is the spark plug loose?

 

[Mihylo33]

According to him the bike kicks over too easily now

We need an actual reading from an actual compression tester.... without it you are beating your dick against the wall hoping it will turn into Megan Fox

 

[Rolls]

We need an actual reading from an actual compression tester.... without it you are beating your dick against the wall hoping it will turn into Megan Fox

You're going to have to come up with another metaphor, Mike. Maybe one that the OP can relate to.

 

[PALMER84ONE]

We need an actual reading from an actual compression tester.... without it you are beating your dick against the wall hoping it will turn into Rosan O'Donald

More mikes type!

Oh, and to help on the thread.

Loose Kanooter Valve.

 

[2strokesteve89]

If you can push the kicker down with one hand the compression is too low. If it takes both hands it's just right. Trust me, it's in the manual.