low Compression (Engine Rebuild) Please help! ;)

[EJD]

Ok, So my compression kit came today and my 1999 RS 50 blew 92ish PSI in first gear pushed down hill and 50ish on starter motor (dead battery)

For those who havn't read my oil "fuck up" thread. I basically put to much oil in and the bike has ran shit ever since.

I have cleaned the carb, tank, filters, pipes, exec exec out and all seemed pretty good.
I have also took of the cylinder head and removed the piston.
The piston was quite oily but not damaged AT ALL!

Havn't managed to get to the bottom of the crank case yet so not sure if a seal is bust.
The bike revs to 10K+ revs in neutral fine but can't go up a hill and struggles along the flat until it gets past 6K revs.


I am going to order some new reeds and piston rings and I have a Doppler WR7 Exhaust Kit coming tomorrow.

Any ideas? Also, spaek plug gets black quite quick but somtimes stays brownish.
It is also very oily the plug.

Thanks

[RS_Patrick]

Crankseals blow? thats what can happen if you put to much oil in and the oil stays behind in the crankcase.

[EJD]

Crankseals blow? thats what can happen if you put to much oil in and the oil stays behind in the crankcase.

Not to sure, Compression blew 92 without throtle open so +10-15 more with throttle open compression should be ok.
I stuck a special small camera that is attached to a rod down into the crank and it looks spotless and as clean as anything.

Ordered a Doppler exhaust kit, new 0.30mm reeeds, filter sheet, petrol hose, 12 front sprocket, new jets and some instant gasket.
Going to put it all back together tomorrow and see how she runs. Compression should be a good 105+ when its all back together.

Nothing drips from the bike and I did that petrol test in the crank and nothing leaked at all.
Think that exhaust had passed it days and that caused the issue.

[RS_Patrick]

omg... please use your brain before starting a thread or posting, and read/look up instructions on how to do something, or ask here...

you need to do a comprasiontest using the electric starter or by pushing the bike in 3rd gear (easier to push) with the throttle Fully Open!

[chrism15]

fully charged battery, or hooked up to something with more life

throttle wide open to allow air into the system


crank starter motor until the gauge peaks

[EJD]

omg... please use your brain before starting a thread or posting, and read/look up instructions on how to do something, or ask here...

you need to do a comprasiontest using the electric starter or by pushing the bike in 3rd gear (easier to push) with the throttle Fully Open!

The instructions on the box never mentioned opening throttle.
I later found out online that I should open the throttle.

Also, I never knew about 3rd gear but once the bike is re built I shall try again tomorrow.

[RS_Patrick]

Normal bumpstart is done in second gear, that doesnt push as hard as first gear but the engine turns round slightly slower, if you want to test compresion you dont actualy want to start the bike so 3rd gear goes round just fast enough than and pushes a good bit lighter than 2nd gear. (keep in mind you meed to push it at a fast pace, not to slow)

[EJD]

Normal bumpstart is done in second gear, that doesnt push as hard as first gear but the engine turns round slightly slower, if you want to test compresion you dont actualy want to start the bike so 3rd gear goes round just fast enough than and pushes a good bit lighter than 2nd gear. (keep in mind you meed to push it at a fast pace, not to slow)

Oh ok, Is rolling it down a hill ok?

[RS_Patrick]

... no, just bump it if the electric starter doesnt work mate to check the compresion, thats all.

[EJD]

... no, just bump it if the electric starter doesnt work mate to check the compresion, thats all.

ok, sounds good.
I will do all that tomorrow. Oh and does having the airfilter/tank hooked up make any difference to compression?

[ToraTora]

Crankseals blow? thats what can happen if you put to much oil in and the oil stays behind in the crankcase.

Yup do the crank seals. You really don't need to mess around with testing compression (since you pulled the top end already) unless you see scoring on the cylinder (in which case you'd replace or fix), and from too much oil you wouldn't see scoring happen.

[RS_Patrick]

He did not open the throttle at all wen doing a compresion test so i think that solved the compresion problem, i just think this kid is messing a bit to much with a good running bike with out knowing what hese doing...

@EJD: no the tank or airfilter not being on there wont matter to much.

[EJD]

He did not open the throttle at all wen doing a compresion test so i think that solved the compresion problem, i just think this kid is messing a bit to much with a good running bike with out knowing what hese doing...

@EJD: no the tank or airfilter not being on there wont matter to much.

To be honest I'm one if those people I think ask a few too many questions.
In terms of what I have done to the bike it isn't much, but I have asked about allot more if that makes sense

Not being hatful, but they don't teach much about motorbikes at school
however, I thank you very much Patrick for everything you have helped me out with

[nicketynoo]

EJD keep asking mate, if people get fed up with answering your questions they can just ignore them! It shows you're eager to learn about your bike. By asking questions your getting answers that will probably help loads of other people that are afraid to ask.
You've just made a load of people aware of how to do a compression test and what readings to expect

[EJD]

EJD keep asking mate, if people get fed up with answering your questions they can just ignore them! It shows you're eager to learn about your bike. By asking questions your getting answers that will probably help loads of other people that are afraid to ask.
You've just made a load of people aware of how to do a compression test and what readings to expect

haha, I guess that is true