Compression Questions

[Guest]

Did the compression test today

Note the bike has not yet been Rode on the road.

Only Idling during all of my repairs has been in storage for more than 20 years, Cleaned carbs reworked electrical and exhaust

Compression
#1 +75PSI Guessing based on hash marks are around 8o
#2 +75PSI Guessing based on hash marks are around 8o
#3 close to 100PSI
#4 +75PSI Guessing based on hash marks are around 8o
all pressure come up fairily quick was warm engine No oil squart

While these are within tolerance or close
Service manual stats that 100PSI is the minimum

Would adjusting the valve shim and replacing valve stems help?

Or is this overhaul of the top end new valves and polishing etc..?

Know we are guessing here without a tear down
But am certain this has been seen before
Your thoughts are appreciated

[Big T]

Recoush

You are the poster boy (i'm assuming you're male) for all the Newbie mistakes

See your other post, go back and start over on everything on the Newbie mistake list

[Recoush]

well i reran the compression test
the manual says wide open throttle and warm enegine
marginally better

1,2,4 are 100
3 is 90

[posplayr]

Crap , I just did all of mine cold engine and forgot to open the throttle. 165-160 on three of the but #3 was down to about 150-155 psi
It has been sitting for almost a year

[Agemax]

well i reran the compression test
the manual says wide open throttle and warm enegine
marginally better

1,2,4 are 100
3 is 90

how has 1, 2 and 4 gone up and 3 gone down? are you sure you are testing correctly?

[Nessism]

Adjust the valves and ride the bike. The compression will most likely come up after some miles (assuming the valves aren't all burned due to neglect).

[tkent02]

What Ed said. Adjust the valves before you burn them up. There can not be good compression if the valves do not close all the way.

[Recoush]

Thanks for the information confirms what I have been thinking my manual is a muddy 2nd copy no real clean photos have to buy a good copy at a show as the PDF are not much better.

Well this project will have to wait once you open a can of worms they expire quickly. As the valve stem seals needed replacing had hoped to ride a while. Ordered a 2nd head mostly complete needs cams when that arrives can start the rebuild better to have a backup plan.

Difference in compression was opening up the throttle up did not do that b4 so it appears that #3 maybe worn

Just need to bite the bullet this bike sat for 20 years after the guy dumped it blowing out the rear tire had hoped it just needed some minor attention his only comment was to replace the seals? He only put 200 miles on the bike before he dumped it after buying it man what a shame basically stock less the Vetter.

so far repaired the fork seals, electrical wiring new bullet connectors, battery, flushed and cleaned carbs, new o-rings, new mac product turned pipes cleaned and painted the pipes black because the chrome was gone south and removed that air box (so much room now) and put in pods and new throttle cables fixed the turn signals and headlight installed, built a new R/R from misc components in my shop for 20 bucks good Battery is now charging keeping a running list with costs, yupp in for a penny in for a pound Love this site.

[tkent02]

NO, do not take the engine apart unless you like doing work for nothing. Adjust the valves and do everything else to get the maintenance caught up... Ride the bike, 1000 miles or so. Ride it hard if you are able. Then check the compression. The engine has sat for years, i needs to run to work correctly.

I have taken a lot of these old GSes back from the dead, they usually run fine, the compression comes up, and they quit smoking after the valves are adjusted and the rings are freed up.

[Recoush]

Ok going with plan B shims 1st :>)

Bummer got the backup head No shims Knew needed camshafts. Everything else intact, backup head in process as plan C gaskets on order prep if needed

Where do I get the o-rings and copper washers?

Will adjust the valve shims
Been reading up on the shims and what you say makes sense
Have the shim chart and shimming sheet from the manual and gauges

Heard something about tyraps not seen that information as yet?
What are the most likely shim sizes I should try first?
Know measure and fit but have nothing to fit?

[Recoush]

found the tyrap suggestion on basscliffs site :>) saved as a favorite Duho