Alright, so I bolted my nice fixed up p&p-ed head to my bike today. I then proceeded to do the 1,2,3 cam chain timing stuff. So, I thought id test it to make sure it turned nice and whatnot. So as i turned the motor over i heard a click and my chain jumped about 5 links on the exhaust cam. Hmmmm so this is why i bent all my valves in the first place i thought. So I turned my cam chain tensioner screw counter clockwise a until my chain got nice and tight. I then turned the motor over with a wrench and then :click: :jump: and my chain has jumped a bunch of links.
SO... Why is it doing this? Is my tensioner shot? How are these things supposed to act? or is my cam chain bad? or the chain guides? the bike only has 20k miles on her.
And in a side note, how does this cyllinder look?
(http://i545.photobucket.com/albums/hh395/Weston07/GS500%20Head/DSCF2053.jpg)
Bumpedy. Hey, I had another idea/question. Those manual cam chain tensioners: are those good? Could i make one by cutting out an aluminum plate and drilling/tapping it? or do they have some sort of seal on the bolt? Do they need to be adjusted often?
I have never had experience with a bad CCT but your description of the chain jumping sounds like it is bad. The GS has a reliable CCT but they can fail. I do not have a service manual handy to look at the proceedure to check it.
Manual CCT's do have an o-ring seal. I used manual CCT's on all of my race motors, less likely to fail. Keeping it adjusted is more of a concern but not too difficult. Adjust it when the valves are checked.
The cylinder looks like it has some rust pitting, about 3/4" down from the top. Probably cleaned up with a light hone. Was the motor stored for a time?. Other than that, looks like normal use.
How much tension do you have on the chain between the cams? I know that when I took out the cam chain tensioner when I rebuilt my head, when I put it back it my cam chain was looser then heck. A small twist of the CCT bolt thingy and it tightened it right back up.
Yeah, it was loose, so i turned the tensioner deal counterclockwize, and it tightened right up, then i tested it again and it jumped back-- weird. I dont even really want to risk having it come undone again and bending all 4 valves. ugh. And i am looking for a cheap fix. And I may be able to sneak a small project into the school machine shop. SO, Dgyver: Where is this o ring located on the tensioner? could one be machined without too much headache do you think? And as far as the cyllinder, I cant really afford fixing it right now, will the pitting cause any major problems? I am hoping to put in some 78mm pistons someday, so i dont know if i want to dig into that part of the engine just yet. I think the prior owner lied to me about how long it was stored just based on what i saw in the carbs but idk...
My crystal balls are a bit foggy today; but do you suppose that one of the drive cogs is bent or has a damaged tooth or bad bearing? Same with the chain, a bad link or such. Good luck!
prs
If the cam chain is tight, it shouldn't jump teeth. I would give it another shot, once you have the cams positioned, then tighten up the cam chain tensioner and see if when you crank it over it jumps teeth. It shouldn't unless something else is wrong.
But heres the thing: after it jumps teeth, the chain is all loose again. As if the tensioner just suddenly let go, and the pressure from the valve springs just spun the cam arround. Does that make sense? I know that the cam gears are good, I havent looked over the whole chain yet, but perhaps i will now when i get time.
Is the chain ON the teeth on the crank? Or, does the chain slip off the crank? How are ALL the teeth on the crank?
The ring around the top of the cylinder looks more like carbon build-up, than rust; harmless. And, the crosshatch in that cylinder looks great.
Quote from: scratch on February 02, 2009, 12:44:56 PM
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The ring around the top of the cylinder looks more like carbon build-up, than rust; harmless. And, the crosshatch in that cylinder looks great.
Ignore the top 1/4"... look a little lower... there is what appears to be rust pitting.
Hmmm.... I cant really see down there. I suppose it is possible that the chain wasnt completely on it right. But It shouldnt have skipped when i tried it a second time. The chain is not skipping on the crank sprocket, its slipping on the exhaust sprocket I can tell this by looking at the marks. Ill have to go check it again though, now that i have a better idea of what to look for.
Quote from: dgyver on February 02, 2009, 02:12:11 PM
Quote from: scratch on February 02, 2009, 12:44:56 PM
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The ring around the top of the cylinder looks more like carbon build-up, than rust; harmless. And, the crosshatch in that cylinder looks great.
Ignore the top 1/4"... look a little lower... there is what appears to be rust pitting.
Ah, it looks to be the same color as the ring above it, so I thought they might be flakes from the ring. I'd really have to see it "in person".
Weston, how are the teeth on the exhaust sprocket?
Is the chain worn in one certain area? Stretched in one area?
Alright, I went and visited my gs again today. Deffinately the tensioner is bad. It dosent take up the tension, because the little curley spring was messed up. So, I have 3 options:
Option A: Buy a used automatic tensioner. $20-$30 shipped
Option B: Buy a used manual tensioner. $30-$50 shipped
Option C: Make a manual tensioner. I was thinking of machining out a block, and drilling and tapping it. The only issue is getting it to seal. I was thinking of using a locknut along with an O ring to get it to seal. <$5 in hardware and some spare time.
Opinions?
Personally, I'd spend the 20-30 on the stock tensioner and be done with it. No further headaches, no more worries. Its not like your talking about saving 200 dollars, its 20.
Nick