Author Topic: Winter Project Lost Compression on 1 and 2 cylinder  (Read 582 times)

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Offline ComingInHot

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Winter Project Lost Compression on 1 and 2 cylinder
« on: December 04, 2014, 12:58:41 PM »
Hey guys, I'm new around these parts and I can use some help. Recently starting riding and I decided to pick up a project over the winter, 72 cb500 with a 75 cb550 motor. The bike was running 4 years ago, but the guy I bought it from said it worked for about 45min then lost compression on 1 and 2 cylinder. Don't have a mechanical background, but thought there's no better time to learn than now and the price was right. With something like this where would you guys begin looking at then what direction would you go? What's the simplest thing it could be and what's the worst. Thanks.

Offline flybox1

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Re: Winter Project Lost Compression on 1 and 2 cylinder
« Reply #1 on: December 04, 2014, 01:07:07 PM »
Welcome,
IIWM, id start with completing all the items listed in the shop manual under the periodic maintenance section.

your manual can be found and downloaded here...
http://www.honda4fun.com/materiale-documentazione-tecnica/shop-manual
'78 750K (F3 engine) PD42b's, Modified airbox w/K&N  filter, 40/110 jets, 1 needle shim, IMS@ 1 turn out. Kerker + Cone 18" QuietCore

Past Bikes
1974 550K0 (stock), 1973 CB350F (stock), 1983 Yamaha XS400K (POS)
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"Knowledge without mileage equals bullsh!t" - Henry Rollins

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Offline Vinhead1957

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Re: Winter Project Lost Compression on 1 and 2 cylinder
« Reply #2 on: December 04, 2014, 06:21:02 PM »
Start with some marvel mystery oil and a compression gauge.  The simplest, valves adj too tight. Next a head gasket. Do some detective work. The worst, hole in the piston. Work can be fun it's winter