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78 GS550E valve clearance problem

  • Thread starter Thread starter dtkeith
  • Start date Start date
D

dtkeith

Guest
Howdy y'all,
First post here, but I've been browsing for a while. I have already found BikeCliff's (awesome!) web page, and have used a few of the guides already. I am currently having an issue with adjusting my valve shim clearance. I have gotten almost all of my clearances measured, shims recorded, and I know what shim I need for most everything. The intake side on my #3 cylinder has a MASSIVE clearance. It had a 2.80mm shim in the bucket before, and I measured the clearance at .42mm. The bucket and shim also seems to be difficult to turn by hand. Seems like the bucket isn't coming all the way up to the cam lobe? I tried using a hammer and pry bar to gently tap on the bucket rim to try to reset the spring, and that seems to narrow the clearance with every tap, but still over .20mm at the tightest.

Any ideas on what could be causing this?
 
Sticking for some reason, sometimes the buckets get bent out of round, sometimes the valve gets a tiny bit bent, could be something else… carbon or cooked oil in there jamming things up maybe. How about a litte history? Have you ever seen it run? How long has it sat? How long since it's been a reliable daily driver? Anything else you know about?

You could pull the bucket up to see if it's free once it's up off the valve, or pull it out completely, if the valve is still stuck at least you will know.
 
A little history: I bought the bike last summer. It ran, but had issues starting when the weather is cold (under 50 degrees or so). It has been sitting since November of last year (I think... around then!) while I slowly tinkered with it over the winter.. been slowly working on the valve clearances, added electronic ignition, etc. Before I bought it, the previous owner reported that he had traded for it from a guy who found it in a barn, he had it running pretty well and it ran well for me as well. I don't think its had a valve clearance adjustment ever, it only has ~10k miles on it.

Previous owner went through and rebuilt and balanced the carbs (not just him bull****ting, he sent pictures of the whole process) and did a few other things. Once it gets running, it runs quite well (at least, last year it did).

I just had the idea to use a pair of channel locks or vice grips to try and pull the bucket up. Do you think this will work?
 
dtkeith said:
A little history: I bought the bike last summer. It ran, but had issues starting when the weather is cold (under 50 degrees or so). It has been sitting since November of last year (I think... around then!) while I slowly tinkered with it over the winter.. been slowly working on the valve clearances, added electronic ignition, etc. Before I bought it, the previous owner reported that he had traded for it from a guy who found it in a barn, he had it running pretty well and it ran well for me as well. I don't think its had a valve clearance adjustment ever, it only has ~10k miles on it.

Previous owner went through and rebuilt and balanced the carbs (not just him bull****ting, he sent pictures of the whole process) and did a few other things. Once it gets running, it runs quite well (at least, last year it did).

I just had the idea to use a pair of channel locks or vice grips to try and pull the bucket up. Do you think this will work?
Click to expand...

If the bucket itself isn't sticking, needle nose pliers will pull it right up, without damaging it. If the bucket itself is stuck, might need something stronger, vice grips may bend it. Maybe the needle nose vice grips would work. If yours is damaged, I have a bucket of buckets if you need a better one. Once the cam is removed you can push the valve itself down and let it spring back up, maybe free it up a little better. Make sure the piston isn't up!
 
Something drastically wrong happening. I'd pull the cam and see about getting that bucket out. I have some spare buckets if you damage the one that's in there.
 
Maybe you could try to free the bucket up by applying penetrating oil (not WD40) around its circumference and let it sit for a while. Use the notch in the bucket to move the bucket back and forth by small amounts, and see if it will free up. Apply more penetrating oil and repeat.
 
I will give that a shot. How much more in-depth is removing the cam over just doing the valve clearance job? I'm confident in my mechanical ability, I just want to get this done before I lose much riding weather!
 
dtkeith said:
Howdy y'all,
First post here, but I've been browsing for a while. I have already found BikeCliff's (awesome!) web page, and have used a few of the guides already. I am currently having an issue with adjusting my valve shim clearance. I have gotten almost all of my clearances measured, shims recorded, and I know what shim I need for most everything. The intake side on my #3 cylinder has a MASSIVE clearance. It had a 2.80mm shim in the bucket before, and I measured the clearance at .42mm. The bucket and shim also seems to be difficult to turn by hand. Seems like the bucket isn't coming all the way up to the cam lobe? I tried using a hammer and pry bar to gently tap on the bucket rim to try to reset the spring, and that seems to narrow the clearance with every tap, but still over .20mm at the tightest.

Any ideas on what could be causing this?
Click to expand...

Maybe going back to BassCliff's site and downloading a manual for your bike, whatever it is
 
Removing the cams is an easy job, but there are pitfalls if you do it wong. Read the manual.
 
a little new information:
I put some engine oil on the bucket, shim, cam lobe, really all over and worked it in by turning that bucket. It now spins easily, but still doesn't seem to come up all the way. I will try pulling gently with a needle nose pliers tonight, and report back. I really hope I don't have to pop the cam!!
 
If the bucket is turning easily, it sounds like the valve itself is stuck open a little bit. I have heard if an engine is always run really gently, it can form carbon in such a way as to hold the valve open a tad. If you adjust the valves to that clearance and go ride the crap out of it, the carbon comes off, leaving you with way too tight valves.

Did you take the cam off yet? If so the bucket should just pull off easily?

I'm curious to find out what is the cause of your problem.
 
tkent02 said:
If the bucket is turning easily, it sounds like the valve itself is stuck open a little bit. I have heard if an engine is always run really gently, it can form carbon in such a way as to hold the valve open a tad. If you adjust the valves to that clearance and go ride the crap out of it, the carbon comes off, leaving you with way too tight valves.

Did you take the cam off yet? If so the bucket should just pull off easily?

I'm curious to find out what is the cause of your problem.
Click to expand...

That makes sense to me. Is it normal that the carbon buildup would only happen on one intake cylinder?
I would adjust to that clearance, but there is no shim made (that I can find) that would get that clearance to spec.. I would need around a 3.30mm shim.. largest I can find is a 3.10.
Would a good plan be to toss in a 3.10 shim on that cylinder, setting all the rest to proper clearance (.03-.08mm), riding it hard for 500-1k miles, then re-checking and adjusting?
I'd rather not take the camshaft off, I'm a landscaper by trade and I'm getting into seriously busy season!!
 
Something is wrong. No way the engine should need a shim that thick. The valve is being held open by something. Maybe it's bent.
 
dtkeith said:
That makes sense to me. Is it normal that the carbon buildup would only happen on one intake cylinder?
I would adjust to that clearance, but there is no shim made (that I can find) that would get that clearance to spec.. I would need around a 3.30mm shim.. largest I can find is a 3.10.
Would a good plan be to toss in a 3.10 shim on that cylinder, setting all the rest to proper clearance (.03-.08mm), riding it hard for 500-1k miles, then re-checking and adjusting?
I'd rather not take the camshaft off, I'm a landscaper by trade and I'm getting into seriously busy season!!
Click to expand...

Its not normal at all, but it happens sometimes.

Don't adjust to that clearance, find out why the valve won't close. Bent, or something stuck in it, carbon, whatever it is find out.

Riding it hard 500 miles with a valve hanging open will burn the valve up for sure. Then you have much bigger problems to fix.

Taking off the cam and putting it back in isn't that big of a deal, just read the manual and do it right.
 
maybe do a compression test before you remove the cams. dry and then with a little oil added to the cylinders. it does sound like a bent valve though.
 
The bike ran fine before I tore into it over the winter, I would think if it had a bent valve, it wouldn't run and rev well?
 
I'm not sure if it still runs fine, I haven't tried running it since I took the cam cover off. I also haven't tested compression, what is the process for this?
 
to test compression you need something like this tool:

http://www.walmart.com/ip/Equus-3612-Innova-Compression-Tester/14644667

attach it to plug hole, turn over engine w/ throttle wide open. check reading. if it's low ya know somethings wrong. should be >100psi, then, add a couple squirts of oil to cylinder and repeat. compare to previous measurement. a large increase in pressure usually means bad rings, small change means a valve problem.

so if there is a small difference in dry and wet tests then that valve may not be closing.

don't know if this will help but that's the way i'd play it i think.
 
Just pull the cam and quit monkeying around, I pulled both my cams, swapped a few shims around to get all my clearances in spec and put the cams back in, had the valve cover buttoned up in inside of an hour for the whole job, as Tom says, it really is no biggie, sounds more daunting than it is.
Even if compression is low, you won't know if it is the valve that is bent or the bucket sticking and holding the valve off it's seat, so what you gonna learn from it, other than what you already know, you have a problem.
Even if the valve is closing fully, with a huge gap like that the valve is getting nowhere near its full lift off the seat, so compression will be low anyway.
 
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