Cam sprocket bolts, how to loosen?

[RedBaron]

How do you guys loosen the cam sprocket bolts?

In removing the cams, I've followed the book instructions holding the cam with a 22mm crescent wrench and using a breaker bar to turn the sprocket bolt counter clockwise. The result is the 22mm wrench eventually slipped off the cam. Fortunately, the is only minor damage to the head/cover mating surface and a small mark on the cam where one holds it with a wrench, not the lobs.

So, perhaps it is a clockwise loosening procedure and the book forgot to mention it or mine is just overtight and I need an alternative procedure using an impact wrench?

Looking for ideas and experience on this. I do appreciate it.

Art

[vintage bikeworks]

The bolts retaining the cam sprockets are a normal "right hand" thread (ccw to loosen) but loctite is used during assembly.  You will need to heat the bolt head with a heat gun to soften the locking compound and then use an air impact wrench while holding the cam with the 22 mm wrench... Or at least this is what I had to do.  Yamaha definitely didn't want the cam gears coming loose. 

[RedBaron]

Thanks very much.

Art

[PwrManDan]

R.B. - just curious as to why you have to remove the sprockets?

[Jimustanguitar]

I had sprockets that just weren't removable. The bolts were either horribly over bathed in the red loctite, or something else was wrong. I wrenched and wrenched on them and couldn't get them off. Even used an impact wrench (while holding the cams stationary with a wrench so that I wasn't hammering on the chain) Finally, I figured out how to wiggle them just right and removed the whole cams from the heads with the sprockets still on.

I clamped the hex portion of the cams in a vice, used a torch (very carefully with the cam itself wrapped in a wet rag), and still couldn't make them budge. I didn't want to twist my cams or risk gouging them with the vice, so I just left them on. I tried hard enough that I was surprised that one of them didn't just shear off. All 4 of them were this way.

I figured that if I couldn't forcibly remove them, it was a safe bet that they wouldn't loosen up on their own :) I've rebuilt a few other Yammy's with this style of bolted cam gear and have never had trouble like this.

[RedBaron]

R.B. - just curious as to why you have to remove the sprockets?

The book indicates this step is necessary prior to removing the cams, chain and then heads.

[RedBaron]

I had sprockets that just weren't removable. The bolts were either horribly over bathed in the red loctite, or something else was wrong. I wrenched and wrenched on them and couldn't get them off. Even used an impact wrench (while holding the cams stationary with a wrench so that I wasn't hammering on the chain) Finally, I figured out how to wiggle them just right and removed the whole cams from the heads with the sprockets still on.

I clamped the hex portion of the cams in a vice, used a torch (very carefully with the cam itself wrapped in a wet rag), and still couldn't make them budge. I didn't want to twist my cams or risk gouging them with the vice, so I just left them on. I tried hard enough that I was surprised that one of them didn't just shear off. All 4 of them were this way.

I figured that if I couldn't forcibly remove them, it was a safe bet that they wouldn't loosen up on their own :) I've rebuilt a few other Yammy's with this style of bolted cam gear and have never had trouble like this.

So, you removed the caps and wiggled the cam sprockets off the chains and then reversed that on installation? Any more details would be appreciated. Were you doing a bottom teardown also?

[Jimustanguitar]

I haven't cracked the case and done anything to the lower end, I've only pulled off the heads and jugs.

There isn't really a special procedure or anything. Pretty much you remove the chain tensioner and chain guides that you can reach, take off the cam caps, remove the alignment dowels, and start wiggling the cams around until it comes out.

Be careful not to twist the cams or to lift them unevenly, you only want to lift them straight up or else you can gouge the bearing seat. You can rotate the cams to turn where the lobes are at, but it's risky tilting them.


After you get them out and the chain is loose, be very careful about turning the engine. The cam chains tend to bind up under the lower sprocket, and you don't want to damage either piece. It takes 3 hands to pull both sides of the chain taught and turn the crank (5 hands if you have both heads open).

[RedBaron]

Thanks all.

In my particular case I tried the heat gun and lacking an air wrench I was not successful, except in making a little smoke. I then went to plan B and carefully removed the caps and, starting on the side with the change tensioner, I was able to slip the chain off the cam sprocket and easily remove the cam and sprocket in one piece. I then found removing the back cam was extremely easy. Now the head is off which was the objective.

[RedBaron]

...and now the cylinders are both off revealing smooth surfaces and great looking 10k mile pistons. I have a set of gauges on order to measure everything.

It's good I took her apart as the back piston did have oil saturated mud, about a small thimble full, on the edge of one side and on top of the first ring, apparently added sometime since it last ran. I was afraid of that since the carbs were off when I purchased her sitting in the sellers yard and so the possibility of dirt working it's way past the intake valve was possible, perhaps added by a child in that family, but likely only for a short time since there is no rust. I also found the O-rings and gaskets very brittle and need replacing.

I am so pleased the cylinders are in great shape after 31 years! I'm tearing the whole thing down and cleaning everything, checking valves  and replacing all seals and polishing the outsides and doing a light hone and finally putting in the new rings purchased for this moment. After all, part of the reason for buying her was to gain experience in this rebuild. Another reason is to have a light bike for back road riding with a large tank for occasional touring.

[Fuzzlewump]

Just curious....where did you pick up rings? Standard size or oversize? How much did they cost ya?

[RedBaron]

Just curious....where did you pick up rings? Standard size or oversize? How much did they cost ya?

Standard size. On Ebay last December for 106 USD for 2 cylinders. I see them occasionally.

[Rick G]

Thats good information Red, I haven;t seen any source of Vision rings in quite a while.

[RedBaron]

I've written the seller asking if he has more. The price was actually 85 USD free shipping in looking at my ebay purchase history. I have also seen new carb floats for pretty reasonable and picked up two about six months ago. You just have to keep your eyes peeled. Course, not having a running bike is motivation for part hunting. Like me.

[PwrManDan]

http://www.ebay.com/itm/YAMAHA-XZ550-XZ550H-J-XZ550RH-RJ-Piston-Ring-Set-x2-4th-O-S-11H-11610-40-/200937027430?pt=AU_Motorcycle_Parts_Accessories&hash=item2ec8c7b766&vxp=mtr

[The Prophet of Doom]

Those rings are 4th oversize.  I don't think they will work happily on standard pistons

[Rick G]

They could be used , but you need the skills of an old time mechanic  to resize the rings . Most modern parts exchangers wont be able to do it.

[PwrManDan]

how about these?

http://www.ebay.com/itm/YAMAHA-XZ550-XZ550H-J-XZ550RH-RJ-Piston-Ring-Set-x2-2nd-O-S-11H-11610-20-/200948868881?pt=AU_Motorcycle_Parts_Accessories&hash=item2ec97c6711&vxp=mtr

[RedBaron]

These are fine for 2nd oversize and from what I gather, there are four sizes letting you rebuild the engine four times each time increasing the cylinder size to remove the cylinder wear and replacing the pistons and the matching rings with the next size up so they fit the larger size bore in the cylinder. You have Standard, 2nd oversize which are the ones you found without the required matching pistons, 3rd oversize and 4th oversize all requiring a larger size piston to match.

[The Prophet of Doom]

... and of course none of those pistons and rings are available from Yamaha

I've got a set of 2nd OS pistons and rings I am saving for the day the smoke out the rear end gets so much I can't pass the safety inspection.