• Required reading for all forum users!!!

    Welcome!
    Register to access the full functionality of the GSResources forum. Until you register and activate your account you will not have full forum access, nor will you be able to post or reply to messages.

    A note to new registrants...
    All new forum registrations must be activated via email before you have full access to the forum.

    A Special Note about Email accounts!
    DO NOT SIGN UP USING hotmail, outlook, gmx, sbcglobal, att, bellsouth or email.com. They delete our forum signup emails.

    A note to old forum members...
    I receive numerous requests from people who can no longer log in because their accounts were deleted. As mentioned in the forum FAQ, user accounts are deleted if you haven't logged in for the past 6 months. If you can't log in, then create a new forum account. If you don't get an error message, then check your email account for an activation message. If you get a message stating that the email address is already in use, then your account still exists so follow the instructions in the forum FAQ for resetting your password.

    Have you forgotten your password or have a new email address? Then read the forum FAQ for details on how to reset it.

    Any email requests for "can't log in anymore" problems or "lost my password" problems will be deleted. Read the forum FAQ and follow the instructions there - that's what we have one for...

  • Returning Visitors

    If you are a returning visitor who never received your confirmation email, then odds are your email provider is blockinig emails from our server. The only thing that can be done to get around this is you will have to try creating another forum account using an email address from another domain.

    If you are a returning visitor to the forum and can't log in using your old forum name and password but used to be able to then chances are your account is deleted. Purges of the databases are done regularly. You will have to create a new forum account and you should be all set.

Story so far and next steps..

  • Thread starter Thread starter mpencegs
  • Start date Start date
M

mpencegs

Guest
Ok.. So I have a 1981 GS450TX. The history is that is sat in a barn for 25 years with no love. I moved the bike to my garage and started giving it some love..

Replaced spark plugs, Air filter and oil.
Bike compression was 140-150 on each cylinder.

Bike was hanging at about 3500 RPM and decided to rebuild carbs and O-rings as well as install new O-rings in the intake boots.

Removed Engine to allow for removal of Intake boots.

Replaced intake O-rings and soaked carbs for 24 hours. Cleaned carbs and replaced all O-Rings.

Reinstalled all components and the bike ran like crap. Bogged at all levels and need starter fluid to even get running.

New compression test shows that both cylinders are now running at 90 PSI compression.

Current belief is that the Head Gasket may have blown of a vavle adjustment is needed.

Current plan of action.
Perform a Valve adjustment. Once complete test compression.

If compression still low then add marvel mystery oil to cylinders to see if compression increases. If no increase then head gasket. If increase then piston rings are to blame.

I believe this may all arise from the need for a new head gasket but another factor is that I had to have the valve cover bolts removed using and EDM machine as they broke during removal. This may have introduced metal shavings and I am concerned that the compression issue is due to metal gouging the piston area.. Is there anyway to rule this out..

At this point I feel like my only option if the vavle adjustment does not correct this situation is to replace the head gasket. I have no basis for this except cars and it a pain on cars so not sure what it may take for my bike.

Let me know your thoughts or ideas here. Is the head gasket a valid troubleshooting area or should I start somewhere else?
 
Adjust your valves first. They'll have some bearing on your compression readings. If it's not smoking I'd be hesitant to think you've got gouges in the cylinder walls. They're cast iron, so they're gonna be tougher than some Alu shavings I'd think.

You could simply have some sticky rings from sitting for so long. Adjust the valves then ride/run it a bit. They may loosen up and your #s come up.

You can also do a leak down test to check your gasket if you're still suspecting it. These are much much easier to change a headgasket on provided you have a manual to follow. :)
 
Throw some MMO in it before you start on the valve adjustment.
When you are finished, it will have had some time to work. ;)

Daniel
 
Might as well check valves now- but I'd think the running like crap is due to disturbing the carb boots and getting air leaks from 30 year old boots. Of course, this doesn't explain the compression drops. But I wouldn't expect metal shavings to show up so fast. Sort out why it's running poorly and avoid starting fluid.
 
As to compression ? You must have the throttle wide open !!
 
well I moved and had to let this take a break but I am back in it again. New updates are that added some oil to the cylinders and the compression increased to 100's.. This would mean that my rings are stuck or bad correct? To get a look at the the pistons and what not doesn't sound too bad, pull the valve cover and camshafts then head bolts and that should get me in there correct?? Any gotchas along the way I should know about now??
 
Last edited:
mpencegs said:
well I moved and had to let this take a break but I am back in it again. New updates are that added some oil to the cylinders and the compression increased to 100's.. This would mean that my rings are stuck or bad correct? To get a look at the the pistons and what not doesn't sound too bad, pull the valve cover and camshafts then head bolts and that should get me in there correct?? Any gotchas along the way I should know about now??
Click to expand...
After 25 years the rings are bound to be sticky- might clear up with some running. Before you go looking at pistons, get to the valve adjustment now- won't take long, and you can always dig deeper later. I know you said that you clean carbs , etc., but some folks have had to do it twice. Lots of tiny little passages to clog and firm up after so many years.
 
You must log in or register to reply here.

Similar threads

brit7.11
GS425 Oil Consumption. Problem?
Replies
14
Views
305
brit7.11
brit7.11
S
Psyching myself up for the top end - any veteran eyes up to read borescope pictures?
Replies
16
Views
403
DimitriT
DimitriT
T
1980 GS850GT top end rebuild - head machining
Replies
3
Views
113
first timer
first timer
W
Free random parts!
Replies
6
Views
141
wkmpt750
W
L
Hanging Idle (I know, but bear with me) and different carbs
Replies
10
Views
158
bwringer
bwringer
Back
Top