Top end rebuild

[pod35]

Hi Tamaco,
I bought genuine Yamaha gaskets in the end. Henri was kind enough to ship a top end gasket set from Partshark in the U.S. where they cost a lot less - ( all top end except for valve guide seals for less than the price of a head gasket in the U.K.) I had to buy some more gaskets/seals for the bottom end and just the valve guide seals, left and right cover gaskets cost more than the top end set from the U.S. including shipping.

Justin

[Tamaco]

Sorry to be a pain and ask another question. For the piston rings - did you use a piston compressor or did you do it by hand or is there another way?

Thanks

[edfmaniac]

I think this is the one I used. http://www.autozone.com/autozone/access ... 31921_0_0_

[Srinath]

I've heard atleast for those 4 cyl bikes where the stroke is pretty short and cyl spacing is tight these - http://www.autozone.com/autozone/access ... id=2922818 - work good.

Basically the compressor band is pretty thin. That's the big advantage. On a cyl the size of a coffee can, and un-encumbered access ... everything works I guess.

Cool.
Srinath.

[Tamaco]

Excellent, thanks for the answers and options guys.

Space won't be an issue, the engines coming out and onto the bench.

[Srinath]

Excellent, thanks for the answers and options guys.

Space won't be an issue, the engines coming out and onto the bench.

Even so the cyl studs get in the way in a 4 cyl ...
I remember on my eli the guy used his hands to get em in ...
Wont work on a newer 4 cyl sport bike, the stroke is so short and the studs are in the way.

Cool.
Srinath.

[edfmaniac]

There are no studs in this engine. Both the cylinder and head are held in place by hex head bolts. The ones for the cylinder are countersunk below the plane of the head gasket.

[Srinath]

There are no studs in this engine. Both the cylinder and head are held in place by hex head bolts. The ones for the cylinder are countersunk below the plane of the head gasket.

Yea, I was mainly talking about 4 cyl sport bikes ... especially GSXRs. Old air cooled GSXRs in fact have the studs exposed between the fins. They want to have those studs not come out of the lower cases. Its a pain, but supposedly you're not unscrewing the thing from the cases and thereby making it last longer ... yes if you take your cyls off every other week, it will make a huge difference ...

Cool.
Srinath.

[samandkimberly]

Use your fingers - they work as well as any compressor. If you're really worried, have a second set of hands available to move the barrel around as you move the piston, but is really isn't necessary. Squeeze the first ring in with your finger tips and wiggle the piston back and forth to rock it into the bore as you lower the cylinder onto the piston. Then, orient the 2nd and do the same, then the third. You need very little force if you're doing it right, they just compress themselves on the taper going into the bore.

Sam

[zippy49]

Haven't tried this yet on the Skorp, but on my Velocettes I use Total Seal rings that have a really tight oil ringset. I put the cylinder (with one circlip installed) on the bench upside down, insert the piston and work the rings into the bore with my fingertips. I stop with the piston pin hole still exposed. Then I place the assembly over the rod and insert the pin and second clip. A few rags around the rod will avoid the inevitable dropped clip going into the cases. Push the cylinder down and Bob's your mo's bro...

[Srinath]

Haven't tried this yet on the Skorp, but on my Velocettes I use Total Seal rings that have a really tight oil ringset. I put the cylinder (with one circlip installed) on the bench upside down, insert the piston and work the rings into the bore with my fingertips. I stop with the piston pin hole still exposed. Then I place the assembly over the rod and insert the pin and second clip. A few rags around the rod will avoid the inevitable dropped clip going into the cases. Push the cylinder down and Bob's your mo's bro...

Oh total seal has tight oil rings ? My old friend - I mean he is a older guy, like about 70 now, he says he would put old oil rings if they were OK over new oil rings. The oil slipping past them apparently helps lube the top and second ring better he would say.
If total seal oil rings are specially tight, maybe he was almost completely backwards - which he has been on ocassion, I've ended up disproving some things he has told me.

Cool.
Srinath.

[edfmaniac]

Sounds like your old friend was pulling some knowledge out of his rear end. If you want an engine that uses oil and doesn't make full compression, use your old rings. If you want an engine that's going to last, hone the cylinder, put new rings and do a break in on the new top end. All the oil that you need to lube the cylinder should be left behind in the tiny grooves of the remaining hone marks after break in. It's not much, just a layer that is a few molecules thick. Here's a link to the break in procedure that I used and a brief explanation of the method. http://www.ntnoa.org/enginebreakin.htm

cylwall.gif (3.65 KiB) Viewed 9147 times

Now that I've reread the posts, y'all were referring specifically to oil rings. I wouldn't think that anyone's oil rings would scrape enough oil off of the cylinder walls to negatively effect cooling and lubrication, but I'm no expert by any means. I just know that oil rings are very thin and weakly sprung compared to compression rings.

[Srinath]

That was his theory, it lets oil through and helps the other 2 rings.
He also had other theories like the valve stem top where the tappet makes contact, it should be slightly concave so it will catch and keep oil etc etc. Like to reference recent memory on this bike the cams are sitting in a pool of oil. Well similar idea. Oil to be used as a cushion for every bearing surface ...
Cool.
Srinath.