Figured why gs750 not starting

[silverhelme]

If what I am seeing in the pictures is correct and the 1-4 T on the crank is in the correct spot your setup is spot on. It has been 20 years since I've had one apart ( 81 1100E ) so I pulled out my old 1100 manual and my new 750 manual and they both agree you did it right. The number of pins is 20 and pin 1 is the pin over the 2 on the EX cam, the 20 pin is the one directly over the 3 on the IN cam.

[baz666]

Anybody have any clue what the next step should be if the two cams and crank already line up AND the cam chain teeth do not sit in full links?
thanks,
baz

[tkent02]

Show us a pic of the crank marks and of the 1 on the exhaust cam.

[baz666]

Below are photos of the cam chain position and the crank mark position, which are all where they are supposed to be, according to the service manual.
The only thing is - as I've mentioned before- is that cam chain sprockets have one tooth in one link and the next tooth in the following link.
A couple of the photos a are a little blurry due to my fumble fingered camera use but I think you should be able to see the relative positions of the cam sprockets and crank.
thanks for all the help,
baz

[baz666]

If anybody can give me their ideas on the photos below, I'd be most obliged.
thanks,
baz

[Stahlgrau333]

From what I can tell, based on what others have posted (I don't have a manual myself), you're a tooth off. Loosen the tensioner, raise the chain just off either the intake or exhaust cam, and either rotate your exhaust cam counter-clockwise (as it shows in the pic), or your intake cam clockwise (again, from the pic perspective) until the chain fits over the very next tooth in sequence on the cam gear.

The way you'll know for sure which one to adjust will be by the crank mark. If you've got your crank aligned, the cam you just moved should be OBVIOUSLY misaligned. If you've got it right, you should be able to get them where they are both pointed in relatively the same direction.

I can't tell from the pics where your crank is lining up, so I can't give you any suggestions based on that...but, based on the direction the engine spins and the orientation of the cam chain tensioner, I would be willing to bed it's your exhaust cam. At least, that's where I'd start.

What you've described (the loss of pressure across all cylinders, the single 'clunk' sound) is textbook cam timing.

[Stahlgrau333]

Forgot to mention...if you're 'testing' to see if it's one cam or the other, be sure to rotate the engine by hand one complete cycle before trying with the starter. As you do so, feel for resistance to make sure you don't end up bending valves that aren't already, just in case you've adjusted the wrong cam.

[baz666]

I slowly and carefully turned the crank by hand several times and the crank position and cam positions all come back to where they should be.
I know the sprocket teeth should be sitting in full links of the cam chain but my question is this:
How do I move the entire cam chain one link while leaving the cams and crank in their current position? It's like the chain would have to come right off the crank to move.
Or do I take off the tensioner then use the chain slack to move the cam sprocket teeth over 1 link? But then the crank would be off slightly, wouldn't it?
Geez... I know there's something simple I'm not understanding and it's driving me nuts trying to get my head around it!
thanks for everyone's patience,
baz

[Dodik]

if you pull the front tensioner/guide you might be able to get the chain to rotate around the crank. In my opinion the length of chain should be the same as far as you get the right number of pins it should be good but then again i am no expert.
for those who know how many turns of crank does it take for engine to go thru a complete cycle where all the cylinders fire and it comes back to the same spot where you started from. then just mark the chain at some point rotate the engine thru entire cycle and see if your marked spot returns to where it was.

[Stahlgrau333]

How do I move the entire cam chain one link while leaving the cams and crank in their current position? It's like the chain would have to come right off the crank to move.

The theory is that the current position is not the correct position. My guess is that, with everything aligned as close as possible in your current position, your exhaust cam is advanced 1 tooth.

Or do I take off the tensioner then use the chain slack to move the cam sprocket teeth over 1 link? But then the crank would be off slightly, wouldn't it?

Exactly. Use the chain slack to lift the chain off of the exhaust cam, turn the cam 'back' one tooth (counter-clockwise from the perspective of your pics), and tighten her back up again.

After doing so, again rotate by hand to make sure nothing is 'kissing'. If not, try to fire 'er up.

[baz666]

Okay, I'll give it a shot. Keep your fingers crossed for me.
thanks,
baz

[baz666]

Okay, I've finally realized that yes, the exhaust cam is off by 1 tooth. It looks like the cam needs to be moved forward, toward the front of the bike by 1 tooth while the intake cam is good where it is.
I'm going to attempt it later today.
But I have a couple of questions I should have asked earlier on:

1 - When the manual says the "T" timing mark, does it mean the little mark next to the "T" or the "T" mark itself? And does it line up with the protruding little arm on the signal generator?

2 - Can I remove the front cam chain guide after removing the tensioner and then replace the front cam chain guide afterwards?

Thanks again to everyone for your enduring patience. I know I'm a little thick when it comes to things mechanical but I'm learning a ton.

baz

[niclpnut]

The mark next to the T and yep the front guide can be lifted out and replaced pretty easily

[baz666]

Thanks Nic. I'm beginning to build up enough confidence to try this.
One other thing. Do I need that disulphate paste mentioned in the manual to grease the cam journals and shafts when I'm tightening the caps back down? I'm hoping I can just loosen the cam caps and move the cam and sprocket 1 tooth, without removing the caps entirely. Is that possible?
thanks,
baz

[Big T]

Here's what I would try 1st, before pulling any cams

1. Remove cam chain tensioner
2. Pull front guide
3. Mark cam and chain at current position with a sharpy
4. Try to lift cam chain one tooth backward on cam.slight rotation of the crank will aid in tension