78 GS550E valve clearance problem

[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?

[tkent02]

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.

[dtkeith]

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?

[tkent02]

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?

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!

[Nessism]

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.

[2BRacing]

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.

[dtkeith]

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!

[Big T]

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?

Maybe going back to BassCliff's site and downloading a manual for your bike, whatever it is

[tkent02]

Removing the cams is an easy job, but there are pitfalls if you do it wong. Read the manual.

[dtkeith]

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!!

[tkent02]

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.

[dtkeith]

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.

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!!

[Nessism]

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.

[tkent02]

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!!

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.

[Eli69]

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.