I am trying to set the camshafts and timing chain on the bike but I'm having some trouble lining everything up correctly. The manual has me line up the signal generator on the right side of the bike to find top dead center. When its aligned it will look like this:
(http://www.gstwins.com/photogallery/albums/userpics/18533/normal_Proper_Alignment.jpg)
The exhaust cam has a number 1 and number 2 notched on it for alignment, you are supposed to line number 1 up parallel with the gasket surface like this:
(http://www.gstwins.com/photogallery/albums/userpics/18533/normal_Proper_Exhaust_Cam.jpg)
And the end of the exhaust cam has a notch that is supposed to face like this:
(http://www.gstwins.com/photogallery/albums/userpics/18533/normal_Proper_Exhaust_Cam_Notch.jpg)
However, the left lobe on the exhaust camshaft hits the valve buckets when I try to align the number 1 parallel with the gasket surface and without depressing the valve there is no way to tighten the camshaft down in that position! If I align the signal generator properly to find top dead center, this is the closest I can get the cams to aligning properly:
(http://www.gstwins.com/photogallery/albums/userpics/18533/normal_Improper_Exhaust_Cam.jpg)
And the notch is off:
(http://www.gstwins.com/photogallery/albums/userpics/18533/normal_Improper_Exhaust_Cam_Notch.jpg)
Once I rotate the engine around to line up the cams properly, the stator is off by a bunch of top dead center!
(http://www.gstwins.com/photogallery/albums/userpics/18533/normal_Improper_Alignment.jpg)
What the hell can I do???? Am I doing something wrong??? Should I figure out how much I should turn the crank before TDC and align the cams like I have been and try to get it so that when I turn to TDC the cams are aligned??? HELP!
if you have a valve shim removal tool, use it to depress the bucket
I dont have that tool. Should the left exhaust cam lobe be pointing towards the shim/bucket/valve with the number 1 parellel to the gasket surface? I don't see how you can tighten the cam down as it is forced to turn because it hits the valves?
dont have a clue, never had to tear my motor down that far
im pretty sure you set the exhaust cam and then count like 18 links in the timing chain laying it in place as the manuel says. then release the spring on the cam chain tensoiner, ill check tomorrow. shouldnt be that confusing. its layed out pretty good in the clymers.
So... You're saying that the timing marks on the cam don't line up with the valve when your crankshaft is at top dead center for the #1 piston?
It sounds like your valve timing is off - most likely because the previous valve adjustment was performed incorrectly. Always rotate your engine through a few full revolutions and re-check all your timing marks.
First... For the initial measurment, the only thing that matters is that the cam lobes are pointing away from the shims. Simply rotate until the lobes are in the correct place, and measure. It sounds like you're going to pull the cams when you replace the shims. Fix your timing then.
My advise... Get the crankshaft to TDC, and adjust your cams to match the crank. Once the chain is loose and the cams are out, the only way you can really rotate the crank is by removing both cams... Which sucks to do.
It sounds like you're worried that when you have everything aligned one of the cam lobes is going to push down on a valve bucket as you tighten the cam bearing caps. Do I have that right?
If so, that is normal, just tighten the bearing caps down evenly and the valve will gradually depress. There's no position you can set it up where no cam lobes are facing down!
Don't worry, be happy :thumb:
I have an idea, how about you remove the left ex shim. Then that lobe could face directly downwards and you could set the timing and get everything buttoned down, then rotate the engine some, loosen the cam cap and slip the shim in, retighten the cap, and test rotate a few revolutions. Maybe?
I would be worried about breaking the cam cap if I had to screw them in so it depresses the bucket, I followed another thread about someone breaking the cam cap. Is it possible to release the tension on that chain so you can make it skip a tooth or two until it is lined up?
I've taken my cams on and off with no problem the way the manual says, also done it to cars with bucket and shim systems. I wouldn't do it without the shim in there, because the cam will press on the edges of the bucket and likely scratch the cam. Your cap will only break if its already faulty, in which case better it does it now than when you're riding.
Thanks for all the replies, but I'm not sure if I'm explaining this correctly or not but I'll try again while adressing each response.
Lopee:
I understand the counting 18 links part, but setting the exhaust cam is the part thats not lining up correctly. Before counting the links you have to line up the marking number "1" on the exhaust cam so that it is parallel with the gasket surface. When you line up that marking the left lobe is pointing at the valve therefore the cam doesn't sit like it is supposed to. When I tighten the left exhaust cap down, the lobe hits the valve and turns the entire cam backwards about 15-20 degrees. I can't figure out how to tighten that cap down with the lobe pointing at the valve and NOT HAVE IT TURN 15-20 degrees counterclockwise.
Burning1:
I had to replace the gasket between the cylinders and the engine case, so I had to disassemble the engine and am now in the process of putting everything back together and can't get the timing set correctly. I did the shim measurement as a by product of having the valve cover off before disassembly.
The Mole:
I think you understand my issue, but HOW DO I TIGHTEN IT WITHOUT THE CAM TURNING? Because of the lobe pointing at the valve, when I tighten it there is nothing preventing it from rotating counterclockwise. It rotates so the lobe is just touching the valve/bucket, but that causes it to be off by 15-20 degrees, which if I count 18 links backwards from there causes the intake cam to be off by the same amount with the engine still at TDC!
Thanks again for all your help! I know I'll get this figured out with all your help!
Anyone?
utgunslinger13,
When I performed my valve adjustment, I had the same problem. When you aligned the exhaust cam to the valve cover surface, and the crank to the timing mark, everything looked okay. As soon as I tightened down the exhaust cam, and ran the engine through a full revolution, the exhaust timing went to shaZam!.
What I ended up doing, was to simply count the number of pins that the exhaust cam needed to be rotated forward in order for the timing marks to line correctly. With the crank at TDC, I loosened up the CCT, and the exhaust cam, rotated the exhaust cam forward, and tightened it back down. Afterwords, I checked the number of pins between the exhaust and intake cams to make sure that the intake timing was correct.
I hope that helps.
With that said, next time I'm simply going to mark the alignment directly on the chain and cam sprockets using a white automotive marker, so that I don't need to deal with this again.
Burning 1,
The problem I run into is that as soon as I tighten the exhaust cam cap I can tell its off by 20 degrees! I don't even have to rotate the engine through a revolution, I start with the exhaust cam lined up with the gasket surface, tighten the cap, and its off by 20 degrees. With the lobe pointing at the valve (just starting to open the valve) as I tighten the cap, there is nothing to stop the cam from rotating backwards to relieve the pressure on the cam lobe.
I don't know if I followed your second paragraph correctly but.....can I start with the number "1" alignment mark below the gasket surface (say 15 degrees clockwise of parallel) and do the timing just like the book says? In my head this would mean that as I tighten the exhaust cap, the lobe is pressed into the valve and it will start to rotate counterclockwise until what little slack there is in the chain between the crank and the exhaust cam is taken up and the cam should stop rotating counter clockwise. My hope is that by figuring out how far clockwise to start will have the alignment marks correct after all is said and done.
do you have the cam chain tensioner off or at least wound back to leave slack on the chain? i would imagine that making everything easier. you could try bolting down the ex-cam first, turning the crank, then placing the chain onto it? then place the in-cam and count the links over. any loose chain should be below the in-cam and tightened when the tensioner is put back in right? that's my logic at least..
i havent gotten to where you are yet but i hope to within this coming month. I havent had time to get back to drilling out the head bolts, but when i do, i'm going to helicoil and put studs in, then just use nuts to hold my exhaust on. im lucky school is over for the semester so i dont NEED my motorcycle, i just walk/get rides everywhere. but the weather's been fantastic and i just want to ride so badly. i hope i dont hit too many hiccups once i finally get my exhaust bolted back on. im probly going to need to pull the head off completely since i lifted it anyways and replace the gasket.. woo.
No, let me clarify...
I ran into the same problem when I performed my last valve adjustment. If I aligned the timing marks as the manual indicated, tightened everything down, and just like in your case, the timing of the valves was off.
But, that gives us a starting point.
So... With everything tight, Align the crank to the timing mark. Now, take a look at your exhaust camshaft - it's going to be aligned incorrectly.
See how, in your picture, it looks like the camshaft is a full link retarded from where it should be? Good. Loosen the CCT, Unbolt the exhaust camshaft. Rotate it forward by a full link on the cam-chain. Ignore the timing marks completely. Bolt it back down. Tighten the CCT. Run the engine through a full revolution - the timing marks should now be correct.
Does that make sense? Essentially, here's what we are doing: 'Oh look! The camshaft is retarded by a full link. Let's advance it by a link.'
Quote from: pandymai on May 26, 2010, 12:31:47 PMcould try bolting down the ex-cam first, turning the crank, then placing the chain onto it?
That doesn't work. There isn't enough clearance between the cam sprocket, the chain, and the wall of the engine to rotate the crank without also turning the cam.
Burning 1,
The only problem I see with your way would again be the fact that the cam would rotate when tightened. Maybe by moving it forward a link, when it rotates it would then in fact line back up. But I see that as no different than starting with the alignment mark slightly below parallel. That seems to me to be exactly what your doing. I have no problem lining things up and counting 18 links. But when I tighten the left exhaust cam cap thats when things move.
Also, by doing it the way you suggest you would then be putting 19 links between the intake and exhaust cams so the timing would still be off. You would need to move the intake forward 1 tooth as well in order to keep 18 teeth between the alignment marks.
You cannot align the intake camshaft until the exhaust camshaft is aligned. I'm ignoring the intake cam for now; we'll fix it later.
Yes, the exhaust camshaft will still rotate when you bolt it down, but the most important thing - the alignment between the exhaust camshaft and the crank should be correct. After you tighten down the cam and rotate the crank through a couple cycles, the exhaust and crank should be aligned correctly. Once the exhaust is aligned, you'll need to re-align the intake camshaft... but that should be trivial, since none of the intake valves will be open during the alignment procedure.
Keep in mind... Once the cam chain is on the exhaust camshaft, the camshaft cannot turn without also turning the crank. What happens with the exhaust is that your initial alignment was incorrect. This can happen for several reasons:
- You have slack between the crank and the camshaft when you set the timing.
- The crankshaft moved when you set the timing.
- The camshaft timing marks gave you a false alignment, because the cam lobe prevents the cam from sitting in place unless bolted down.
Again, so long as the crank and the cams are aligned correctly, it doesn't matter if the exhaust rotates a little when you bolt it down. Hell, because we know from your pictures that the exhaust is exactly 1 chain link retarded from the crank, if you advance the exhaust cam timing by 1 link, even the crank could turn, and everything would work out fine.
Remember - the timing marks are reference points. Those reference points have shown us that your exhaust camshaft is retarded by 1 link. All you have to do is rotate it forward and bolt it down - the marks have already served their purpose.
Edit: Dupe
By the way... I should clarify... It looks like your timing is off by 2 links, not one. I usually think of links in terms of side-plates. So... You need to rotate the camshaft forward by 2 teeth.
Burning1,
I think I'm following you now. When I move the exhaust cam forward 2 links, I don't have to have the crankshaft at TDC so I could theoretically have it so neither lobes hit and when I move it forward 2 links it will still be in correct relation to the crank correct?
Am I on the same page now?
***EDIT*** Just out of curiosity, what effect would it have on the bike by riding it with the timing set like this? I know nothing is hitting as I've rotated the engine as it sits multiple times, but I don't fully understand the effect of "retarding/advacncing" it like this?
Please note I'm not saying I am riding it as it is, I'm curious in a theoretical way!
Yes, exactly.
In fact, you're a little ahead of me. I hadn't even thought of the idea of rotating the crank so that the exhaust lobes were off the cams. That would have made things much easier when I did it.
Quote from: utgunslinger13 on May 26, 2010, 02:13:31 PM***EDIT*** Just out of curiosity, what effect would it have on the bike by riding it with the timing set like this? I know nothing is hitting as I've rotated the engine as it sits multiple times, but I don't fully understand the effect of "retarding/advacncing" it like this?
Your volumetric efficiency would go to shaZam!. Basically, your exhaust wouldn't be open during the first 15-20 degrees of the exhaust stroke, and it would stay open during the first 15-20 degrees of intake stroke... Then, the intake would stay open during part of the compression stroke.
So basically, exhaust wouldn't be pushed out very efficiently. Then, you'd be slow to start pulling in fresh air. And some of that air would be pushed back out through the carbs. It might be run, but your fueling would be all off, and you'd have horrible power.
On some cars, the timing is run off of the cams, so it could also cause the ignition timing to be too far advanced, or too far retarded, causing further problems.
Also... On an interference engine (a high compression engine, where the piston at top dead center will hit an open cam,) having the timing *too* far off could cause valve damage. The GS is fairly low compression and runs with a lot of clearance, so this is less likely to be an issue. Some engines are tuned with so much compression that the piston has small cutouts for the valves.
Another thing that could happen... If your intake and exhaust camshafts are badly misaligned, the valves could hit each other. In practice, I doubt that would happen on the GS unless you really messed up the timing (as a guess, by 45 degrees or more?)
I didn't pay much attention while disassembling them but I wonder if they were off before and this was the cause of it having a horrible time accelerating? The Buddha and I were working on getting some slides with 1.5 holes plugged to slow the slide opening because it was falling on its face when I opened the throttle quickly. It would eventually accelerate, but slowly.
Thanks for all your input and helping me walk through this in my head Burning1
It could be part of the problem. Bad valve timing would certainly affect fueling. With that said, I'm a FI guy, not a carb guy.
I'm trying to remember how it went when I did this...i don't remember having your problem.
I'm thinking that the trick might be to have the crank at the right position, then get the exhaust cam tightened down (don't worry about the intake), and turn it to the right position and then engage the chain on the sprocket. Now you've got the exhaust cam and the crank in the right relationship. Then you position the intake cam by counting 18 pins between the '2' mark on the EX cam and the '3' mark on the IN cam and engage the chain with it. Note that you count the pin at each mark, so there's only 17 'spaces' between them. Just checking, you have got the CC tensioner out haven't you?
TIP: Replacing the CC tensioner is a PITA if you try and hold the tensioner retracted with a screwdriver as the Haynes manual says. You need three hands and there isn't room for them all. What I did was cut a strip off a tin can that was just wide enough to engage with the slots in the CCT housing. Then, I wound the tensioner back with a screwdriver, held it in with one hand and removed the screwdriver. Then slid my strip of tin in the slot and engaged with the tensioner. It locked the tensioner in place, and then it was easy to install. once in and bolted, just pull the tin strip out!
And valve timing is critical to correct performance. I had a VW Kombi engine rebuilt years ago, and afterwards it ran smoothly but was (even more than usual!) lacking in power. It would start to lose speed if it caught sight of a hill a mile away. After spending hours tuning, rebuilding carb etc etc, the problem was the cam was installed one tooth retarded.
If you're going to pull the cams as part of a valve adjustment, your best bet is to align the crankshaft to the timing marks, and actually mark the alignment of the cam-chain and sprockets using white-out, or a similar marking agent.
What he said^, the Haynes manual mentions that too.
Well I got it set correctly last night! I tried to move the sprocket in relation to the crank as Burnin1 mentioned but I turned it 2 links the wrong direction! lol So I went ahead and took it off, and when I was lining the number "1" mark up I turned it about 5 degrees below parrallel. What this did was take out the slack (what little there actually is) between the crank and the exhaust cam shaft and prevented the cam shaft from turning when I tightened it down!
After buttoning it back up and going for a ride, the hesitation problem is gone and she rides like a dream! I'm guessing when I originally set the timing after the rebuild I had it off by a link or 2 and that was why it was running poorly.
Thanks for all your help!
I'm glad to hear you got it worked out, and resolved a performance problem in the process! :thumb:
Quote from: burning1 on May 27, 2010, 10:32:45 AM
I'm glad to hear you got it worked out, and resolved a performance problem in the process! :thumb:
+1 :thumb: :woohoo:
Good job, so being 1-2 tooth off it still ran and gave you power? Can you decribe how it feels being off by a tooth or two? thanks.
It would idle just ok, and when I would crack open the throttle quickly it would take a second or 2 before it would accelerate. The acceleration was very week but I could still move the bike. It was very similar to lean conditions.