compression on nu50 ques

I got my nu50 running very well now. It has great pep, everything is stock and she goes about 32 mph. I did a compression text today and I saw its supposed to be about 180. I hooked up a compression tester to the engine, opened the throttle all the way and cranked on the kickstart and I was surprised to see it came in at abt 40! Am I doing somethin wrong or is that really what my compression is??

Re: compression on nu50 ques

Anyone??

Re: compression on nu50 ques

Downhill Harvey (OFMC) /

If it's running very well, and you only get 40lbs, you're doing something wrong. Did you test it while holding the throttle wide open? Theoretically, it shouldn't run with 40lbs.

Re: compression on nu50 ques

yeah wide open. Its a harbor freight compression tester. maybe its just crap. Its 30 without open throttle. 40 with open throttle. and just for the hell of it i tested my parts bike motor ( wich is in great condition only 1000 miles on it) and same thing 30-40.

Re: compression on nu50 ques

Downhill Harvey (OFMC) /

I had a 110lbs on my Urban, so I put new rings on it, and got a 110lbs. The bike has been getting faster and faster, and if I could just find my tester, I'll test it again.

Re: compression on nu50 ques

Downhill Harvey (OFMC) /

I'm getting 120lbs now. Just so ya know, when doing a compression test/turning the engine over, make sure your plug is in the boot and grounded to the head. Cranking an engine without the plug being grounded can fry your CDI.

Re: compression on nu50 ques

Downhill Harvey (OFMC) /

...............and I have a cheap HF tester too.

Re: compression on nu50 ques

I deff didnt do that. I did it with the plug out. Would that give correct psi or just help from frying cdi. When you say ground to the head you mean just rest the electrode on cyl head ( thats how you test spark right?) Thanx for all your help..

Re: compression on nu50 ques

Zeke Rigg /

well if your compression gauge has a long large tube this will throw it off as the volume of the tube is added to the cylinder volume when testing...

Re: compression on nu50 ques

my guess is you're testing it wrong. the point is, fuckit - if it works it works. don't fix whats not broken and dont try to figure out why a working bike works. whatev

Re: compression on nu50 ques

Downhill Harvey (OFMC) /

John Martin Wrote:

-------------------------------------------------------

> I deff didnt do that. I did it with the plug out.

> Would that give correct psi or just help from

> frying cdi. When you say ground to the head you

> mean just rest the electrode on cyl head ( thats

> how you test spark right?) Thanx for all your

> help..

Yes, just like testing for spark.

Re: compression on nu50 ques

yeah now I just wanna know if I bought a bogus tester. Im gonna try it on my VW tonite and see if the numbers are way off or not..

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