Vintage and Classic Hondas

COMPRESSION TEST

_‹ Previous Topic Next Topic _›

Classic

List

Threaded

7 messages Options

jamman18

COMPRESSION TEST

I have a 77 750f and it has had trouble running. Did a COMPRESSION test and the readings are about 95 psi and then 135 psi when I add a bit of oil to the cylinders. It's my understanding that the results indicate worn rings. What are my options to correct the issue? Any links to videos that I can watch?

Phil. 4:13 " I can do all things through Him who strengthens me"

TOOLS1

Re: COMPRESSION TEST

Administrator

For clarification, what were the readings dry between the cylinders, and wet between the cylinders? Also, did you have the throttle open when doing the test?
TOOLS

Life is not about the number of breaths, you take, but the moments that take your breath away.
I don't have an anger problem. I have an idiot problem. Hank Hill
Never confuse education for intelligence.
Happiness is a belt fed weapon.
I just can't imagine what could go wrong.
No fire? No explosions? So whats the point of your story?
Those who are too smart to engage in politics are punished by being governed by those who are dumber. ~Plato
It couldn't be done, but the darn fool didn't know it, and did it anyway.
We all got problems. Ksharp
I like vintage bikes because they take me away from the clutter of technology that I work with everyday and back to a simpler time of mechanical elegance and simplicity.. "ninadm"
Darkwing Duck: The worst part of public transportation is the Public.
"That is awesome shit there" Re-Run
"Fear nothing, attack everything" Eric Berry
" Oh, you read that on the internet? Clearly it IS a massive problem. Of course it CAN’t be normal operation."

1976 CB 750-A X 2
1977 CB 750-A X 4
1977 CB 750-K
1976 CB 750 F
1981 CB 750
1966 Kawasaki SG 250
1981 KZ 750 LTD
1973 CB 350
1979 CM 185 Twinstar
1982 Honda XL 80
South of Eden (Kansas City MO)

jamman18

Re: COMPRESSION TEST

Throttle wide open, 95 dry and 135 wet. Pretty close to that on all cylinders

Phil. 4:13 " I can do all things through Him who strengthens me"

TOOLS1

Re: COMPRESSION TEST

Administrator

That is quite a jump. However since you say that they are all even across in the readings, your tester might be reading low. How many miles are on the engine? You might get away with just new rings and honing the cylinders, but it might be time for an 836cc kit. You will need to have a machine shop measure the cylinders to see if they are within spec to know for sure.
TOOLS

Truck

Re: COMPRESSION TEST

Just for clarification, when is it not the time for a big bore kit?

It's only illegal if you get caught.

If at first you don't succeed, use more lighter fluid

95% of Harley Davidsons ever made are still on the road... The other 5% made it home.

New Baltimore, Va '82 CB900c, 1980 CB985F/K 'Mutt"

jamman18

Re: COMPRESSION TEST

In reply to this post by TOOLS1

Got about 47,000 on the engine

Phil. 4:13 " I can do all things through Him who strengthens me"

shinyribs

Re: COMPRESSION TEST

Administrator

In reply to this post by Truck

Truck wrote

Just for clarification, when is it not the time for a big bore kit?

This guy get's it.

jamman18 wrote

Throttle wide open, 95 dry and 135 wet. Pretty close to that on all cylinders

IMO, that's worn rings all day long. If the engine is still quiet ( no piston-slap, knocking,etc) I'd just ring and hone it. I'd definitely measure your cam chains for spec per the FSM and consider replacing cam chain tensioners just due to age.