Argh. Tappet screws escaped and broke cam chain. Double Argh.

[t3rmin]

So I finally got all the pieces out. I lost two sets of tappet screw/locknut after a missed shift and over-rev yesterday. Could only find one set last night, but fortunately decided to call it a day before I ripped the oil pan off.

Viewing the thing in daylight really helped -- I found the second nut on top between two valves right away. Must be my lucky day. But then I found the second screw down in the chain valley. After rotating the engine to get pressure off it, I was able to fish it out with a magnet.



Then I turned the motor over a bit to make sure everything looked ok, and found this:


So I need a new tappet adjuster screw and a new cam chain. Haven't dug this far into a motor yet...

You can use a master-link chain and pull it through with the old chain and thus replace without dismantling the motor, right? Do you have to remove the cams for this? I've read several accounts of this procedure, and only some people mention removing the cams. Seems like if you were careful to keep both cams rotating, you wouldn't have any valve-piston contact issues, right?

I REALLY want to take this thing on our PNW St. Helens ride tomorrow. Are there any options for repairing the thing? Like could I replace that bad link with a master link? I know that's a horrible thing to do, but I'm desperate and the rest of the chain looks great. What kind of chain is the cam chain (I assume there's a designation like 630 or 520?)?

Advice, please!

[Calvin Blackmore]

Wow that is nasty but could have been worse I suppose.
I fear this everytime I do valve clearance.

[t3rmin]

Looks like it's "219" chain with 120 links.

[mark]

Give up the idea of going on your ride tomorrow. You need a NEW cam chain....yours is wrecked. Do not even think about fixing that one! If it comes apart your motor is history.

You won't find a master link on your cam chain. They are made as a continuous piece. You have to press out two pins and a link in order to separate it. You need the right tool in order to accomplish this........I'm in the middle of the job myself.

New chains do not have a master link either. When you put your new chain back together, you have to press a link onto your pins and then "swag" it in some way to keep the link from coming off. Again you need the proper tool.

Its not like finding the master link on a drive chain.

I'm doing the job with the cams off, I'm not sure how you'd do it with them on. You would I would think have to remove your cam chain tensioner at the very least and it would be bear to keep everything timed properly as you tried to turn your crank and keep the cams aligned correctly at the same time to avoid hitting your pistons. Maybe its possible, but it doesn't seem like a possibility to me.

Forget the ride, get the right stuff and fix your bike right.

[gustovh]

Since it doesn't add that much time to remove the cams and reinstall them, I would opt to remove them to run a new chain into the engine, master link it and replace the cams. You know it is right and you don't risk anything with valves and pistons. Just be sure to use a master link that doesn't use a keeper, but a flared end.
That is of course you can get one in time.
V

[Dave8338]

Bummmmmmmmmmer! But yes, it could have been a LOT worse. I'd say pull the cams and take a good look at the lobes and also see that you don't have a valve spring or two that have taken on a "New Shape". :shock:

[t3rmin]

Well the GS500 uses that same camchain, even today's models. So maybe I will be able to locate one.

And I've heard you can find a chain breaking/riveting tool at bycicle shops?

[t3rmin]

I was thinking remove the tensioner, then attach the new chain to the old, but have a helper keep tension on the other end of the old chain, then just roll it around, that way the cams would still move in sync. Why wouldn't that work?

[HammerHead]

I was thinking remove the tensioner, then attach the new chain to the old, but have a helper keep tension on the other end of the old chain, then just roll it around, that way the cams would still move in sync. Why wouldn't that work?

Matt,

Which ever way you do it, MAKE SURE ITS RIGHT!!! Take your time buddy. You won't die if you have to ride your Father-in-law's GS. I have never done the chain but all articles I've read on the subject remove the cams. I have thought about doing it the way you've described but do not know if that would work.
Don't despair...............take you time.

[Nessism]

Don’t risk a bent valve, remove the cams and do the job the safe way. As far as bicycle chain rivet tools go, the type that push the pin out are common and fairly cheap but the type that peen over the rivet head are a whole different deal – hard to find and expensive. Good luck with that.

[Dave8338]

I was thinking remove the tensioner, then attach the new chain to the old, but have a helper keep tension on the other end of the old chain, then just roll it around, that way the cams would still move in sync. Why wouldn't that work?

Make sure you take a look at Brian's "Bwringer's" cam tensioner method for removal and install process, as it may save you extra work if not done correctly. Just a heads up.

[t3rmin]

Make sure you take a look at Brian's "Bwringer's" cam tensioner method for removal and install process, as it may save you extra work if not done correctly. Just a heads up.

I'm already "down" with the tensioner, thanks to his page. ;-)

[t3rmin]

Bah. Chain, extra link, and rivet/breaking tool ordered. Bah.

[koolaid_kid]

Wow. I think that you were very fortunate that the link did not break completely. Good thing you were paying attention at the time.
When you go to peen the new master link rivet, just be sure and take your time and make sure it is done well. Those puppies move extremely fast.

[t3rmin]

Yeah, as frustrating as it is, I do have to count my blessings here. Could have been a lot worse.