realgasket damaged my camshaft tach drive??!!?

[79-GS550-L]

Ok, so I finished my valve job, installed my nifty new realgasket valve cover gasket, started it up, and it made a bit of a clicking noise, and the tach was reading much too slow (a jittery 0 rpm at idle, 500 rpm with a bit of gas). So I figured the tach gear was not seating in the cable properly, pulled it, re-oiled it, and installed it again making sure it was in the cable properly. I started it, it read 1500 rpm, I thought great I fixed it! Gave it a few decent revs (all of this in neutral, just testing out my freshly cleaned but wrongly set carbs), and it started making a snapping noise on decel. At first I thought it was a bit of detonation or something. Then the noise got louder and more regular, and I noticed the tach had gone funny again...

I pulled the cam cover off and looked... the raised edges (are they called splines?) on the exhaust camshaft that engage the spiral tach gear that you insert is pretty mangled. The spiral gear itself is perfect. It seems that with the realgaskets gasket, the added height (it's gotta be about 1/8" thick) means that the spiral gear doesn't engage the splines properly, it kinda skips over the tops of them. I tried tightening the gasket down a little more (although I know they are not SUPPOSED to be compressed), and it started leaking oil. So I'm pretty sure I had the gasket installed correctly.

Has anyone else experienced this? Maybe my tach-drive splines were already worn a little and so they were lowered? (They didn't LOOK worn before, but I wasn't examining them closely). Maybe they usually make the gasket out of thinner material? I am going to email them and ask about it. Meanwhile, I think I will order a regular gasket and hope the splines aren't too mangled to engage anymore with the regular gasket. Otherwise I guess I need a new exhaust camshaft...

[demark]

I have a Real Gasket on my 1980 GS1100E and the same thing happened to me, though not at the time I initially installed the gasket.

About a year after I first installed it, I had just checked valve clearances and put the cover back on. When I started up the bike, the same thing as you described happened.

Why isn't the exhaust camshaft the softer of the two?

I ended up replacing my gauge cluster with an Acewell unit that uses inductance for RPM so it didn't matter anyway.

Thanks,
- Tony

[t3rmin]

Man that stinks. I've never heard of that happening. Never had trouble with my RealGasket except when I over-torqued it...

Maybe the tach gear didn't mesh properly and was either not totally seated, or too much force was applied when trying to seat it, thus mangling the gear?

Camshafts are fairly easy to replace and you can probably find one on eBay. Just get those metal bits cleaned up before they take out a bearing or something. Or, as mentioned, just go the electronic tach way.

[79-GS550-L]

Why isn't the exhaust camshaft the softer of the two?

you mean why isn't it harder? I was wondering the same thing myself!

Maybe the tach gear didn't mesh properly and was either not totally seated, or too much force was applied when trying to seat it, thus mangling the gear?

Camshafts are fairly easy to replace and you can probably find one on eBay. Just get those metal bits cleaned up before they take out a bearing or something. Or, as mentioned, just go the electronic tach way.

I don't think it was because of excess force while trying to seat it, since the mangling occurs all the way around the shaft. Even without the engine running, if I put the cover on and stick the spiral gear into the hole and try to turn it with my fingers, it will not move, then as I turn the crankshaft with a wrench (still trying to turn the spiral gear) I can feel the spiral gear move a little then skip across to the next spline, making a "clack!" sound as it does it.

I'm going to try to cut a new gasket out of some 1/32" hi temp silicone gasket material I have with an x-acto (it looks EXACTLY like the real gasket stuff but thinner, same color and all). If that doesn't work I'll buy a stock one and try that. I'm hoping I don't have to replace the camshaft, although I suppose it wouldn't be the worst thing!

Electronic tach is an interesting idea but I'd like to try to keep the bike oldschool and mechanical for now... correct me if I'm wrong but isn't the electronic tach part of an elecronic ignition upgrade (using the same magnetic crank position sensors that go where the points were)? Maybe after I get sick of adjusting points all the time I'll go that route!

[tkent02]

I'm going to try to cut a new gasket out of some 1/32" hi temp silicone gasket material I have

Where did you get this stuff?
I want some!

[t3rmin]

Good luck cutting out a gasket. I tried that once and it was a miserable failure! ;-)

I'd just use a thin layer of RTV (not too much so it squishes out a bunch).

[Guest]

I don't think you meshed the gears and tore them up. I always turn the tach gear a little to seat it before tightening down the cover.

[Nessism]

One comment is to make sure the tach gear spins easily when the cam cover is off.

Maybe I'm just spouting off but the idea of a silicone gasket on a GS cam cover does not appeal to me. All the Japanese manufactures have gone to rubber gaskets captured in a groove on cam covers and they also use shouldered bolts so the crush is controlled. With the silicone gasket the crush is torque related which means the various screws are very loose - basically hand tight. If the screws are too tight the gasket squishes out. A factory gasket with grease on the head side will not leak for a good long time and hot have any of these drawbacks.

Good luck.

[SqDancerLynn1]

From the bikes I have seen The 2 valve motor has the tach drive is in the head. 4 valve the drive is in the cam cover -- clearance is critical to operation of the tach

[Nessism]

From the bikes I have seen The 2 valve motor has the tach drive is in the head. 4 valve the drive is in the cam cover -- clearance is critical to operation of the tach

550 2 valve engines use driven gear in the cover.

[49er]

550 2 valve engines use driven gear in the cover.

You need to stick with the stock gasket thickness on all the cover mounted driven geared engines. Too thin will cause binding, while too thick will cause the gears to jump meshing points. Both conditions will cause tacho drive failure in a short period of time and leave metal particles roaming around the engines internals causing more damage.
IMO realgaskets should only be used on head mounted driven geared engines.

[demark]

you mean why isn't it harder? I was wondering the same thing myself!

Yeah, that too!

[79-GS550-L]

You need to stick with the stock gasket thickness on all the cover mounted driven geared engines. Too thin will cause binding, while too thick will cause the gears to jump meshing points. Both conditions will cause tacho drive failure in a short period of time and leave metal particles roaming around the engines internals causing more damage.
IMO realgaskets should only be used on head mounted driven geared engines.

I wish I had known that before! I used the gasket they listed as compatible with my bike. Today I tried cutting out a cardboard gasket, and it was too thin, I couldn't insert the tach gear with the cover bolted on. Maybe tomorrow I'll try cutting a 1/16th silicone one. Does anyone know the thickness of the stock gasket?

Also, I managed to break a bolt off while tightening the cover back on . I really wasn't tightening it very hard either! Does anyone know of any way to get it out without having to drill an oversized hole and tap it? Not looking forward to that...

[49er]

I wish I had known that before! I used the gasket they listed as compatible with my bike. Today I tried cutting out a cardboard gasket, and it was too thin, I couldn't insert the tach gear with the cover bolted on. Maybe tomorrow I'll try cutting a 1/16th silicone one. Does anyone know the thickness of the stock gasket?

Also, I managed to break a bolt off while tightening the cover back on . I really wasn't tightening it very hard either! Does anyone know of any way to get it out without having to drill an oversized hole and tap it? Not looking forward to that...

You can buy individual cam cover gaskets. Here's one listed on Ebay at present

http://cgi.ebay.com/ebaymotors/SUZUKI-79-81-GS550-GS-550-VALVE-COVER-GASKET-NEW_W0QQitemZ250038224333QQihZ015QQcategoryZ35595QQrdZ1QQssPageNameZWD1VQQcmdZViewItem

I gather your bolt is broken flush with the head casing surface. If so, you will need to accurately center punch the stub and drill a small hole through it. Apply some gentle heat to the adjacent aluminium and use an easyout to extract the bolt, turning it in an anticlockwise direction. Be careful not to over torque the bolt stub or you will brake the easyout causing an even bigger problem. If the stub won't budge after heating, you should drill it out with a 4.5mm drill and re-tap the 6mm thread.
These cover bolts should only be tightened to 6ft lbs of torque.

[79-GS550-L]

You can buy individual cam cover gaskets. Here's one listed on Ebay at present

http://cgi.ebay.com/ebaymotors/SUZUKI-79-81-GS550-GS-550-VALVE-COVER-GASKET-NEW_W0QQitemZ250038224333QQihZ015QQcategoryZ35595QQrdZ1QQssPageNameZWD1VQQcmdZViewItem

I gather your bolt is broken flush with the head casing surface. If so, you will need to accurately center punch the stub and drill a small hole through it. Apply some gentle heat to the adjacent aluminium and use an easyout to extract the bolt, turning it in an anticlockwise direction. Be careful not to over torque the bolt stub or you will brake the easyout causing an even bigger problem. If the stub won't budge after heating, you should drill it out with a 4.5mm drill and re-tap the 6mm thread.
These cover bolts should only be tightened to 6ft lbs of torque.

6 ft lbs? damn! For some reason I had 10 ft lbs in my head. I guess that's why it broke... although 10 still doesn't sound very tight to me. I'm actually not sure where it broke, since it was the last bolt on the cover and I haven't pulled the cover back off yet to look. But that procedure sounds like exactly what I'll need to do.

That gasket, although it says it will work for my bike, is shaped differently. Tomorrow I think I will try silicone one last time, if that doesn't work I'm ordering a new camshaft and stock gasket!

Do I need/want to replace both the intake and exhaust shafts at the same time? Or is just exhaust fine? Will I need to replace all my shims again with different sizes? Anything else I need to replace at the same time?