Compression and Vacuum on my GL1100A 83....

[wallyworld136]

I rebuilt carbs and was able to balance each side cylinders to each other. But 1,3 Right side to 2,4 Left side could not balance. Checked w/guages and had 8 inch vac on 2 right cyls to 19 vac on 2 left cyls.

BUT!!! When checked compression today, I got around 40-60 psi on left side and 120 psi on right. OPPOSITE of my vacuum problem indications. I did find oil in my coolant reservior a few months back but has subsided to not be any more seen. My head gasket and head have I replaced 3 times on left side in past (head once, gasket 3 times). While Im having second thoughts of my memory being accurate, I did repeat the vacuum test twice and distinctly remember it being low on right side at 8 in of vacuum out of a 30 scale. Book did say that normal for the 1100 would be 19-22.

Conclusion thus far: Vacuum low on right side, Compression lower on left. Can this be or am I in wrong on memory. Got great pain killers and even in repeat analyses I am scratching me head......

Even so, I suspect I have a head gasket out. Can the timing belts have degraded bad enough that my Compression checks would not be up to full snuff, OR valve guide replacement be necessary as well????????????

HELP!

 

[dan filipi]

I would suspect a valve leaking with compression that low.
Have you adjusted the valves? Adjustment out will affect compression.

 

[joedrum]

it could be one tooth off on timing belt on the side of low compression maybe or head gasket . since you had the head off so many times the cylinders must have looked pretty good ?? . we had a situlation on a 1200 that took all kinds of treatment and thought to find the solution of a over heating problem that was head related. it sounds like it might be a slightly warped head that takes a while to blow . if you have the money you sould make the heads right on both sides that would go well with the carb job thats been done .

just thowing things out there to think about good luck

 

[wallyworld136]

RESPONSE TO DAN: Would it be a leaking valve that would affect both cyls 2,4?

I will check the tappet adjmts... and although my mileage is only 28,000, belts came with the bike when I bought it in 2003, so I guess they might be due, huh?

RESPONSE TO JOEDRUM: Did that to orig. head then cam bolts stripped, so I just got a used head from my bike guru I trust implicitly. Has run well till I had to park it at parents to heal from back surgery, then something happened all of a sudden and it wouldn't run as of Oct/Nov 09 so carb rebuild kits were bought for my Christmas present as I spouted off to relative that gas was leaking from carbs and maybe that was it. And its been spend, scratch head, spend since...... I am needing simplest fixes first as I may have to sell her for survival. Girlfriend craves her rolling again and daughter outlawed me ever selling bike, would like to ride couple more times before secome to desparation. TX hillcountry and spring are beconing!

 

[dan filipi]

RESPONSE TO DAN: Would it be a leaking valve that would affect both cyls 2,4?

Well there would have to be a leaking valve in each cylinder 2 and 4.
Are you sure the compression readings are accurate? Flakey gauge, maybe throttle wasn't open full or cranking was slower?
I would first recheck with all plugs out, full battery so it'll crank fast on all 4, and throttle wide open with choke off.

Post your readings then go from there.

 

[wallyworld136]

Ok Mr. Dan,

First, you were right. I opened the throttle completely and that made all the diff.

2 and 4 cyls compressioned at 140-5,
cyl #3 was 145 also,
cyl #1 was 135..........................................much better results and I did adjust the tappets for the left side, 1 intake and 2 exhaust valves were too tight.. I readjusted, put her back together and warmed her up before removing plugs and doing the respective compression checks. Not getting too bent out of shape on the total psi level. 140 area would indicate need for rings but I dont have the wear mileage, and I have feeling things may change more as we continue. Should I recheck vacuum again just for kicks?

 

[dan filipi]

Much better readings!

Has the bike been sitting for more than a year?
Those compression readings may come up after putting some miles on it if it has.

I guess recheck the vacuum for grins but how does it run?
Idle good, return to idle after snapping the throttle?
Out on the road run ok?

 

[wallyworld136]

She's been sitting mostly with 2 or 3 runs around here since beginning of August 2009 before surgery. It runs, smoke sometimes like maybe too rich, but doesn't drop all the way back to lowest idle unless I tap it (idler screw). Want to get a 90 deg pilot driver to adjust carbs. I reset them to 2.25 turns just like 1st time I cleaned them in 2003.

I will say that it was a little smoother after the tappet adjust and compression checks. Don't know about vac balance yet tho.

is still rough and bogs @1/3 throttle and above.

 

[Joep]

while you are letting it sit.. put a few squirts of mmo in the cyclinders and spin it over a few times let sit and then start it it up.. let run for a few minutes.. try that for few days caouple of times a week.. it may free up sticking rings so they seal better..

 

[dan filipi]

is still rough and bogs @1/3 throttle and above.

This sounds like more a carburetor problem, maybe sticking slides or gummed primary jets. That will happen from sitting.
Could also be lack of fuel. Check the flow and pressure out from the fuel pump.

 

[OldWrench]

What concerns me is the number of times you have replaced head gaskets. Did you have the head surfaced and the block surface checked. I never replace head gaskets without first checking head and block surface.

Your timing belts can definitely effect compression if they are stretched or have jumped a tooth. The 83 I just bought recently left hand timing belt was so stretched that the tensioner wouldn’t tighten it up, needless to say the bike didn’t run worth a darn. As has already been said, check your valve adjustment that can also have a big effect on compression. If a valve has been hanging open too long many times they are burnt and need to be ground or replaced.

I would start with the easy things, valve adjustment, and timing belts and if they are ok I would then run a wet and dry compression test on it. Incase you aren’t familiar with a wet and dry test. Once you get your compression squirt a little oil in each cylinder and run the test again, if the compression comes up that indicates a ring problem, if it stays the same or close to it then valves or head gasket problem is likely. I have seen people do complete valve jobs on an engine only to find out they had bad rings.

One other thing, when I install a head I obviously torque it to specs but once I warm the engine up I torque the head again while it is still warm. To me this is really important with aluminum heads.