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Low compression Help!!?

  • Thread starter Thread starter ameen
  • Start date Start date
A

ameen

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So i finished testing my compression today. these were my results with the engine cold(rounded):
cylinder #1: 120 psi
#2: 90 psi
#3: 90 psi
#4: 90 psi

I was going to get a baseline before changing my valve shims. What was odd was that cylinder 1 was the only one that really needed a replacement. So i added a little bit of oil down the spark plug hole and tested the compression again to see if it was the rings. Sure enough, the pressure jumped up about 20-30 psi in each cylinder.

My bike is a '82 GS550L with about 18k miles on it and has been sitting for the past6 years or so. I did get it to run when i got the bike, the carbs needed serious help, so i chalked any performance shortcomings to them. I don't remember the bike smoking or anything, so i dint think that the rings were the problem.

This all brings me to my last problem..... While i was testing, the adapter some how got stuck in cylinder 2 and snapped off when i tried to remove it....yeah, my life sucks. So i still haven't been able to get that out, and am planning on drilling it out an putting a heli coil or something in.

What do you think may be the cause of low compression? Is it worth it to fix? I bought the bike cheap and haven't out too much money in it yet, should i just part it out and move on?
Could the engine just need some good miles under it to reseat the rings or something, or is that overly optimistic?

damn, this has been a long week...

Thanks
Ameen
 
Just run it a while, the compression will come up.
Sitting is bad for things.
What got stuck, the adapter in the spark plug hole?
 
Dito on what tkent02 said. I made the same mistake. Also, you have to hold the throttle wide open. This opens the slides all the way for maximum air flow.
 
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Those numbers are ok for a cold motor.
Can you thread a bolt small enough into the adapter and get it out?
 
i thought they should still be around 120 when cold? also what could cause the large difference from cylinder 1 and the others?


i would need a reverse threaded bolt if i wanted to try and thread one in. haven't really looked for one yet. I have a couple extractors that i tried but i cant get a tap handle on them (not long enough) and cant get it to turn with anything else. I don't mind re tapping the threads, i just really want to avoid removing the head if possible.
 
Retapping those threads with the head on is a risky proposition. You pick up some of that in your bearings and you can kiss that motor good bye.
 
they do it on cars all the time. Use a lot of grease on the tap and blow/vacuum as much of the shavings out of the hole as you can. On second thought, i probably shouldn't risk it.

Anything i should do while i have the head off? im trying to keep this project as cheap as possible for now.

The only other thing that i am worried about it removing and reinstalling the cams and cam chain. not really sure why, but it looks daunting to me.
 
I'd try a left handed drill bit and a reversable drill. Did you cross thread the adapter? If so the head is coming off.
The cam chain is not hard. We'll walk you through it.
The hard part is the base gasket.
 
Its not all that tough. Especially if you have a manual. If your bike wasnt/isnt smoking, then just replace the necessary gaskets and be done with it for cost sake. But, if you really want to get into it, most of the gasket kits come with the valve seals. You could changed those while you have the head off. Will require a few more hours of work, but the knowlege that your valve seals are nice and new, and will last another 20 years is worth it IMO.
 
where is a good place to get a the kits?
I checked Z1 and didn't see them for the 550
 
They dont list a kit for the 550? Call them. They can get it. However, *I* would suggest you ask for OEM Suzuki, unless you want to play Russian Roulette with how long a Athena or Vesrah head and base gasket will last...
 
Sounds like gummed rings, usage will clear it and your rings will get better.
As for the adapter stuck in, 2 options,
A:- Take exhaust off the bike, use a drill and a left hand tap to try remove the adapter, if it does come out, get a shop vac and suck on the spark plug hole then the exhaust outlet (shop vac reason is if you get any metal splinters in the cylinder)
Once all metal shavings (if any) have been removed, spray brake parts cleaners in both holes and let dry, bolt exhausts back on (new exhaust gaskets req)

B:- Remove the head and be much safer, dont worry about timing/chain/cams!
It's actually very easy to do, really, it is, once you do it you'll wonder why you were freaking out about the timing issue.
 
OK so i got head off last night. I also pulled the motor....by myself...forgetting to disconnect a couple wires...propping the motor on one knee while groping for tools to get everything apart with the other hand. It was and interesting sight to say the least.

well the head is off and the engine is out. Can i power wash the piston heads and valves? how delicate is this stuff?

Thanks
Ameen
 
ameen said:
OK so i got head off last night. I also pulled the motor....by myself...forgetting to disconnect a couple wires...propping the motor on one knee while groping for tools to get everything apart with the other hand. It was and interesting sight to say the least.

well the head is off and the engine is out. Can i power wash the piston heads and valves? how delicate is this stuff?

Thanks
Ameen
Click to expand...

I can't imagine water is good.
 
Good god no man! sheesh. Take some carb cleaner, some wire brushes (plug up the case side piston holes with towels so you dont drop crap down in there) and go to town on the piston heads and valves, but no, you cant PRESSURE wash it...
 
Ha....i want thinking water should just evaporate out. Good thing i asked.

I saw 'OEM' gasket sets an ebay for around $50; are they legit?

On another note, ill start getting some pictures up tonight
 
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