why do so meney CB550 have bad compreshion

[Scarry Deuce]

why do all the cb550 I finde have bad compression and by bad I mean the last four I have seen are between 75 85 psi is it just a bad engine did people just run them into the ground is it that it was ran on unleaded gas or what ??


my 1977 cb550k is at 75psi in three cylinders ..

 

[lassenc]

An argument could be that motorcycles in the US generally were alot cheaper to acquire in the US compared to Europe. In other words, bikes haven't received the same attention. Just see all those low milage bikes stored in barns. They're also here, don't get me wrong, but still.

Did you check the valve clearance on the bikes prior to testing the compression? Also, did it change with a squirt of oil in the plug holes?

 

[Scarry Deuce]

Oil yes but no change in the cb550k or not any thing big it went from 70psi to 75psi my


cl360 went from 75psi to 100psi after oiling

 

[crazypj]

Usually because people do the compression test wrong.
On 550 its a good idea to remove air filter and make sure throttle is wide open.
The numbers your getting are about right for a closed throttle

 

[Scarry Deuce]

Really that's a big difference ..
I'm told 125psi is ok compression does that sound right to you ??
I can't start it to warm it up and i'm having to use the kick start to turn it over ..


I'll go out and try it now .

 

[crazypj]

You have all the spark plugs out when kicking it?
You need to kick it at least 5~6times, get it spinning if you can

 

[Hoosier Daddy]

Re: why do so many CB550 have bad compreshion

Yep Yep, throttle wide open, no choke, crank it over with the starter using fully charged battery, no plugs in any cylinder. you need a minimum of 4-5 revolutions until it doesn't build anymore.... If you can only kick it you are going to be tired by the end.
You may have seen several good engines!

 

[Scarry Deuce]

throttle wide open, no choke,kick and kick and kick got dizzy fell down regained consciousness got up and kick sum more I got 80psi up from 75psi ..


now my next thought is to put sum heavy oil in the cylinders and see if the compression it goes up if it does it's the rings if not it's the valves ..


how's that for cartoon logic ..

 

[hillsy]

When I read the title I thought this thread was going to be something about bad comprehension

 

[imseamless]

When I read the title I thought this thread was going to be something about bad comprehension

haha!

 

[Scarry Deuce]

;D