gs550d tachometer drive on the camshaft stripped

[Stigy]

During the engine rebuild one of many problems I've found is stripped tachometer drive. Looks nasty. I don't think it's safe to drive the tachometer with this gear... What do You think ? Is buying another camshaft my only option here ?

[Cipher]

Did it have a aftermarket gasket?
Id use oem and run it providing the gear in the tach drive is OK.

[Stigy]

Did it have a aftermarket gasket?
Id use oem and run it providing the gear in the tach drive is OK.

The gear in the tach drive is perfectly fine.
What do You mean by oem gasket - which gasket ?
You suggest the gasket might be to thin/thick and the contact between gears was off ?

[Cipher]

The gear in the tach drive is perfectly fine.
What do You mean by oem gasket - which gasket ?
You suggest the gasket might be to thin/thick and the contact between gears was off ?

Yeah there is or was a company that made silicone gaskets to be reusable replacements to oem paper.
being thicker they cause the gears to not mesh properly.

not sure it caused your issue. There maybe some pics of the damaged they caused accessible using the search function.

[rphillips]

Can't tell for sure, but it looks like it took a lick at that 1 spot, like it was dropped on something or something fell and hit that 1 spot. Wear should be roughly the same all the way around. Could you get a screwdriver down in there and kind'f pry those 2 bent over spots straightened back up a little. About using it, worst it could do is ruin the little tach drive gear. They are no longer available from Suzuki, but plenty on ebay if needed.

[GregT]

Nothing there will bend straight - it's cast iron which will simply break. Looks to me like someone put the cam in and got the tacho drive crossed up. Usually they self-align but sometimes not. I'd use the cam as is. IMO there's enough worm drive left to drive the tacho OK.

A repair is actually possible. Build up the missing pieces with bronze weld then carefully file everything back to original shape. But IMO, not necessary.

[rphillips]

"It's cast iron which will simply break" maybe, but in the picture it sure looks more bent than broke. Just thinking, a used cam for that eng. should be pretty cheap.

[Rijko]

You suggest the gasket might be to thin/thick and the contact between gears was off ?

The worm gear seats in fixed points and is not affected by head gasket or valve cover gasket.
It has a oring and oil seal, but those cannot affect gear contact ....

[rphillips]

Rijk, are you sure you have thought that through?

[Rich82GS750TZ]

I think the issue of whether the valve cover gasket's thickness/squishness variation from OEM could cause a mismesh of the tach drive spindle/worm gear and the damage shown in the photo could be answered if we knew whether the tach drive is in the cylinder head cover (where the gasket could be a factor) or if the tach drive is in the cylinder head (where the valve cover gasket could have no effect). I find no record of, or parts fiches for, a GS 550 model D in NA, so that was maybe a EU/other continent-only model? I don't know.

Reading through this thread, this is where my comprehension has led me. (I've not always scored high in reading comprehension tests. ) Quite possibly I'm misunderstanding the issue entirely.

To the OP Stigy, can you answer this question? Does the tach drive enter the engine in the Valve Cover, or in the Head?

[rphillips]

I'd not thought about that, Just thought an "83" as D is the designation for 83 GS models. But you are correct, other parts of the world may have had a tach drive that wasn't in the cover... Just didn't think of that.

[Rijko]

I'd not thought about that, Just thought an "83" as D is the designation for 83 GS models. But you are correct, other parts of the world may have had a tach drive that wasn't in the cover... Just didn't think of that.

hahaha me too ... didn't think about the cover mount .... Rich nailed it mentioning both options.

[Cipher]

The worm gear seats in fixed points and is not affected by head gasket or valve cover gasket.
It has a oring and oil seal, but those cannot affect gear contact ....

Wrong utterly completely.

[Rijko]

Wrong utterly completely.

nope, actually 50% right, guess you did not read Rich his entry.

[Suzukian]

Cast will bend once, but break if you try to bring it back. If you have a lathe, and make a proper tool, you might be able to bring it back, turning it by hand and having the tool push from that direction might coax it back into shape. You would have to have to bits, one in a good thread, and one in the other, parallel, to make it work. It doesn't take much to push a tach, it may work the way it is, for a while, anyways.

It looks dropped though, you would see marks on the mating gear if that had caused it. I don't know what year your bike is, but there are pairs of these camshafts on EBAY for $40 bucks (U.S.)