Where to go for possible Motor overhaul??

[mellco]

Hey all, I did compression check on my 96 RS and found low compression in cylinder #1. Added a little oil to see if it was rings or not and it made no improvement. The motor has 18k miles on it. I talked to the dealer I work with but his proposal is TOO open ended. I dont want to wind up with a $1500.00 + bill without knowing first. I live in Pa. Looking for an alternative to the dealer.

[Flyinfool]

How low is low?

Can you post the wet and dry compressions readings for all cylinders?

[mellco]

How low is low?

Can you post the wet and dry compressions readings for all cylinders?

 

Compression Results:

Cylinder #1: 40psi dry, almost same wet

Cylinder #2: 227 dry

Cylinder #3: 230 dry

Cylinder #4: 219 dry

 

Because all of the dry readings were good wet test was not done

*** Note: these readings were done by 3rd party

Edited March 19, 2010 by mellco

[frogmaster]

In PA... Look up user name Skydoc17 send him a PM or Email see what he can do 4 U.

 

Good Luck

Edited March 19, 2010 by frogmaster
correction

[dingy]

Get SkyDoc17 a PM.

 

He will probably work on it.

 

Gary

[LilBeaver]

In PA... Look up user name Skydoc17 send him a PM or Email see what he can do 4 U.

 

Good Luck

 

 

[RandyR]

18,000 miles and bad compression that looks like rings?

 

If the engine has been maintained correctly this shouldn't be happening...

 

18,000 miles is just broken in for these engines....

 

Maybe you'll be lucky and its just a stuck valve.

[Dano]

That's what it sounds like, a valve thats stuck partially open. If you have access to the parts, get an adapter that will allow you to pressurize the cylinder, then listen at the exhaust and air filters for any air escaping out. Quick and easy check.

[Yammer Dan]

That's what it sounds like, a valve thats stuck partially open. If you have access to the parts, get an adapter that will allow you to pressurize the cylinder, then listen at the exhaust and air filters for any air escaping out. Quick and easy check.

 

:sign yeah that:

 

 

Don't think it could be rings. I want to rebuild one of those things one of these days but how do you wear one out??

[Squeeze]

...18,000 miles is just broken in for these engines....

 

Maybe you'll be lucky and its just a stuck valve.

 

That's what it sounds like, a valve thats stuck partially open. If you have access to the parts, get an adapter that will allow you to pressurize the cylinder, then listen at the exhaust and air filters for any air escaping out. Quick and easy check.

 

Exactly

[dingy]

It won't be rings or the wet reading would have come up significantly.

 

That is reason for putting oil in for second check.

 

Why is compression reading this high for this engine?

 

It is same bore and stroke as a 1st gen MKII which is shown at 10.5:1 compression ratio. Compression for this engine is shown as 171 PSI in service manual.

 

This engine is shown as a 10.0:1 compression ratio, yet shows 216 PSI in service manual.

 

Gary

[Monty]

Sounds like either a stuck or burnt valve. That cylinder could have leaned out and burned the valve. If it's burnt, it won't seal, as it has a hole in the edge of the seat.

 

 

You can put air to the cylinder, and see if you get air out the intake or exhaust. Make sure you are on TDC, with the valves fully seated.

 

 

EDIT: Oops, Dano said basically the same thing.

[V7Goose]

No doubt in my mind that the issue is a valve. Other folks have already explained why. Probably just one too tight and not fully closing. Check the valves, if one is too tight, shim it correctly and re-check the compression - it will probably be fixed. If there is still low compression, you need to pull that head and have a valve job done.

Goose

[mellco]

No doubt in my mind that the issue is a valve. Other folks have already explained why. Probably just one too tight and not fully closing. Check the valves, if one is too tight, shim it correctly and re-check the compression - it will probably be fixed. If there is still low compression, you need to pull that head and have a valve job done.

Goose

 

When I got the bike a mouse had made a nest in the airbox,ate the filter and the prior owner had ran the bike before I picked it up without knowing about the mouse. Could there be something from the mouse nest that the motor sucked up stuck in the exhaust valve( the pop comes from the exhaust not thru the carbs) shells,seeds ect?

[scotty]

This is likely a long shot, but make sure the throttle plate is opening on that cylinder.

Otherwise I agree, it is probable a valve.

[tazmocycle]

mellco, gene weir (tew47) had the same problem you are having and after putting a small camera into the cylinder found a hunk of carbon down in there holding the valve open. you may want to talk to him about it, these engines are known for carboning up if not riden a lot at higher rpms. i sent you an e-mail about a techron flush you may want to try before spending a lot of money for something a lot simplier. hope it's something simple and nothing major, i'm also now looking at a 86 venture with only 11,00 miles on it, which a mechanic told him the rings were bad in it after setting up for a couple of years. i hope to go take a look at it and help him out or buy it for $300 and fix it myself. i only have 5 bikes at the time and really don't need another!!LOL keep us posted as what you find out, don.

[V7Goose]

When I got the bike a mouse had made a nest in the airbox,ate the filter and the prior owner had ran the bike before I picked it up without knowing about the mouse. Could there be something from the mouse nest that the motor sucked up stuck in the exhaust valve( the pop comes from the exhaust not thru the carbs) shells,seeds ect?

The seems pretty unlikely, but lots of things are possible. Heck, I suppose a mouse leg bone could block a valve! A leakdown test on that cylinder would show you pretty fast if the problem was either the intake or exhaust valve, but since I doubt you have one of those tools, you might as well start by checking the clearances on the valves. One too tight could be holding the valve open (depending on just how tight it is) and causing the problem - easy to fix and check quickly. One way too loose could indicate something is stuck in the valve and holding it open. At that point you can think about inspection cameras or whatever else might help to find and extract the item. If you do think something is in there, probably the easiest first step is to just remove the carb and exhaust header and try to inspect the valve with a tiny mirror.

Goose