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Low compresion rate

Posted: Wed May 16, 2012 8:24 am
by shoryzo
hello,

I have a question regarding the compresion ratio of my zxr 400 L6 from 1996

Due to my idle problems (viewtopic.php?f=166&t=13657) i took the bike to a mechanic. There i don't know the reason (could be lack of interest for my bike or lazyness) the mecanic
said that i have a low compresion rate in my cylinders and said he will check it.
Yesterday he called me and said that my compresion rate is 2 bar (around 29 psi....1bar=14.5 psi) . i didn't understand if it was in total - 0.5 per cylinder or per one cylinder.

Anyway i read the manual and there it specifyes that the comp rate per cylinder is from 99 to 156 psi ( 6-10 bar) which had me puzzeled.

Can a motor run and behave nice whith such low comp rate? ( 3 to 5 times lower than normal)

There are no signs of low comp rate - plenty of power from 3000 rpm all way to 10.000
Easy start - hot and cold
The only problem is with idle rpm @ 1.5 k (above 2.2 k idles without a problem)

Could the mecanic be wrong? And just said that cause he is not in mood to fix my bike? (and ofcourse to make easy money)

Worst case scenario - if indeed the mecanic is right and the comp rate is 2 bar (29 psi) what are the steps to solve my problem?


thanks!

Re: Low compresion rate

Posted: Wed May 16, 2012 1:03 pm
by Tirpitz
If I was you I'd collect your bike from the garage and have nothing more to do with them. You wouldn't even get an engine to run with that compression, let alone run reasonably well. You're being ripped off by an idiot / crook.

Re: Low compresion rate

Posted: Fri May 18, 2012 6:13 pm
by RedexRobB
Yes, totally agree. Get the bike back and have a look at balancing the carbs and maybe changing the plugs yourself. Ive replied in your other post. :smt002