How bad did I mess up?

[Johnny K]

I took the valve cover off and notice that their were chain marks on the inside of the valve cover. I did my valves just last summer. I took my tensioner off and the knob doesn't twist either way, it just stays locked. I also rebuilt that last summer. Well I wanted to check TDC and couldn't with the cam bridge so I loosened the 4 bolts and took the cam bridge off. When I was cranking the engine over by hand it went a couple of rotations and then it stopped abruptly. I think it's at the 19th pin as well. Not too certain. I cranked the engine backwards some to see what would happen. A little worried, I bolted the cam bridge back on and now when I rotate the engine it stops at the same place and now there is even more of a slack in the chain. I can physically move the chain a pin up or pin down. I could never before. Before all of this the slack was normal happening a couple of times during complete rotation of the engine. What the heck did I do when I removed the bridge, rotated the engine, and now its stopped at a certain point. And the chain is loose. I'll be back on here later on when I get out of work. Thanks in advance.

 

[Suzuki mad]

Did you rotate the engine with the cam chain tensioner off the bike? Sounds like it from your post.

Are we talking about a GS750 too?

 

[TheCafeKid]

What it sounds like to me, and this is pretty common of POs who mess with the cam chain tensioner when they have no business and no idea what it is or what it does or how it works, is that someone has locked the tensioner down with the set screw and lock nut. If you've read or looked at BWringers tutorial on rebuilding a automatic tensioner (something i think all the GSs had right?) you will see that the shaft that actually presses against the cam chain guide in the motor is grooved. In that groove rides the set screw which is visible from the left side of the tensioner when it is mounted (it has a nut over it) That screw rides inside that groove, and keeps the shaft from extending all the way out of the spring loaded tensioner. Often times people just torque that set screw and lock nut down (the whole "tighter is better" philosophy, youll find it quite common on these old bikes, along with broken exhaust studs, stripped cover bolts etc that accompanies this mentality) If that sucker is torqued down, then the tensioner shaft cant move, if it cant move, it cant do its job, which is to apply tension to the cam chain to take up the slack to keep it tight while rotating. If the cam chain isnt tight, it COULD skip teeth. One tooth isnt so bad (like you think yours may have) but a couple teeth could lead to catastrophic failure... Since your cam chain has slack in it, its likely binding on the crank down in the cases where you cant see, which would allow the motor to rotate till it binds..get where im going here??

Soooo what I would suggest you do is to first, remove the tensioner (this will require you remove the carbs..yes, it sucks, but you must do it) Then look up BWringers rebuild tutorial on BassCliff's website (i dont have the link, and im lazy, sorry) and clean and adjust your tensioner as per his instructions... THEN, set you cam chain as it should be (20 pins, starting over the "2" mark on the front cam, and ending AT the '3" mark on the back cam) THEN reinstall your tensioner, with the shaft completely retracted and locked down. Bolt the tensioner down, then release the set screw...the tensioner should spring out to where it should be, then turn the set screw all the way back in, back off a half turn, and while holding the screw in place, lock down the nut... That should take care of your troubles....

Also, when setting your cam chain, take care that you get the bind out of it. This may require you to borrow a set of hands from your girl or your buddy to act as human cams... They need to pull the chain taught, and you need to rotate the motor FORWARD a couple times to assure that the chain is free...

Hope this helps...

TCK

 

[Steve]

Whatever you do, do NOT force the engine to turn right now.

It sounds like it is not turning because the pistons are hitting valves that are not properly timed. The "bridge" as you call it, pulls the intake cam forward. Removing the bridge will delay the intake cam, probably to the point that the pistons are hitting the valves. As CafeKid mentioned, you will have to remove the chain tensioner (after removing the carbs), remove the cams (hey, this would be a GREAT time to inventory all your shims, see the last part of my sig), set the cam timing properly, install the bridge, install the cam chain tensioner, set it correctly, then leave it alone.

Since you seem to have the tendency to move things that shouldn't be moved, I will caution you before you do it:
once the chain tensioner is installed and set, do NOT play with the knob on the right side of it, especially if the engine is running.

.

 

[Johnny K]

I did take the carbs and tensioner off before my problem earlier. When I took the tensioner off, I loosened the nut and tightened the set screw; took the tensioner off and when I loosened the set screw, it did pop out even more. That means it was working right? Just wondering why I have chain marks on the inside of my cover. TCK - I must have messed up the tensioner when I took it apart and rebuilt it last summer. I followed putting it back together right where I bolt the tensioner down, release the set screw and it pops out then turn the set screw all the way in, back off the screw and then tighten the lock nut. Its the knob that wouldn't budge for me. Maybe I tightened that little nut at the wrong time and now it will not twist at all. I will go through and make sure the tensioner is working properly. What harm am I doing rotating backwards the engine by hand a couple of times? Steve are you saying I should loosen the cam caps and then set the IN and EX cam for TDC? Or 20 pins??

 

[tkent02]

What harm am I doing rotating backwards the engine by hand a couple of times?

Just bending a few valves, maybe.
Don't do anything until you check the cam timing.

 

[Steve]

Steve are you saying I should loosen the cam caps and then set the IN and EX cam for TDC? Or 20 pins??

No, it will take more than just "loosen[ing] the cam caps", you need to remove the cams completely. This will ensure that NONE of the valves are being held open, then hold some tension on the cam chain so it stays on the crank sprocket, rotate the crank to TDC for 1&4. While your cams are out of the way is a perfect time to inventory your shims for the valve adjustment you will likely need to do, too. At this time, it will be a very simple matter to pop a shim out, record the size and pop it back in. No fighting with any tools to hold the valve down so you can wrestle the shim out.

When you are done with all that, put the cams back in place according to the instructions in your service manual. Check your valve clearances. If they are all basically close to specs, you should be OK. If one or more have unusually large clearances, it's probably because the head is bent, which is not allowing the valve to close completely.

.

 

[Johnny K]

Steve, when you say "If one or more have unusually large clearances, it's probably because the head is bent, which is not allowing the valve to close completely." I'm kinda worried that might have happened. Wont know for sure til I take the caps off and inventory shims then correct the TDC again. I'll hope for the best.

 

[Johnny K]

Continue on messing up...

Continue on messing up...

After I bought metal dowel pins for the cam caps and put them in, (yea after the top end rebuild about 2 years ago I misplaced and forgot to put them back .) I put moly paste on the cams and set TDC. I re-did the tensioner right this time because I notice there isn't nearly any slack as before there was noticeably slack when rotating the engine by hand. Finally checked the clearances today and am baffled on EX: 1,2. And IN: 4. EX 1=2.51, 2=2.56. IN 4=2.40. The problem is that there is an EXTREMELY large gap for those clearances and I couldn't get any reading because I don't have any feeler gauge that thick. Honestly it looks to me like I could fit 2 very tiny shims just to get a reading. Every other valve is .06-.08. WTF DID I DO?? Looking through the 1st spark plug hole, I did notice a lot of black crud on the head of my piston. About 2 in 1/2 seasons ago I replaced the rings and beaded the tops of the heads to get the crud off of a 28 yr old pistons. The reason for this was because of the base gasket was leaking and the rings showed signs of wear when I got to them so I replaced them.

 

[Big T]

You probably bent those valves

Got any compression in those cylinders?

 

[Johnny K]

I plan on replacing all 8 valves and seals. Should I buy all new springs too? I'm thinking the springs are going to be okay, but am not sure on those 3 valves. Where would u guys suggest I buy valves and springs? I'm going to replace the base and head gasket. Should I buy a couple of sets of rings in case of sliding the jugs back on I don't bend an oil ring? (I managed to do that 2 years ago when I replaced all of them) What have you guys done to get all the crud off of the piston head and all the ports where the top of the piston and valve heads meet? I would rather buy all the stuff now and have it ready in case something breaks or what not than have something break and not have that particular part to replace it.

 

[Suzuki mad]

Pull it apart and then price up is a better way to go as its less expensive on the pocket. If you can afford all the bits then go out and spend on what you think.

With the possibility of bent valves they are going to be hard to remove so take care as to not damage the head and valve seats.

Price will depend on where you go, either Suzuki genuine or copy stuff. I don't know what new valves will cost but you may get a good 2nd hand head from somebody off here or even some good used valves to keep costs down if thats an issue.

 

[Johnny K]

Yeah, I would like to just buy used valves and springs. I found this guy on e-bay selling a complete head. Here is his link: http://cgi.ebay.com/ebaymotors/suzu...rcycles_Parts_Accessories?hash=item45f1290573

I have an 82'. That shouldn't be a problem if the head is an 80'. There is this other guy who is selling the same head just a little cheaper: http://cgi.ebay.com/ebaymotors/80-S...rcycles_Parts_Accessories?hash=item2eaaace32e

I'm going to put in the wanted section that I am looking for valves and springs. Not sure if people look in there a lot but it can't hurt. What do you guys think of the previous guys on e-bay?

 

[Johnny K]

I just thought it over and decided to just take it apart hopefully by the end of this weekend if I don't have too much planned and assess the situation of what I need and so forth. I think that will be the best bet for me. I will keep you guys updated and if i have any questions with pics.

 

[Suzuki mad]

Go through it slowly and photo all the stages so you can retrace any errant part. You can order gaskets etc for the head, rocker box etc. Once the heads off post a few picture on here and people should be able to suggest what needs changing.

When taking the valves out make sure you number then as to piston and inlet or exhaust so you dont swap them over by mistake.