Camshaft Top End Rattle

The cylinders have quite a large surface area that bears on the crankcase so wouldn't a gasket made by myself work OK. Where would the oil get through? How would the gasket fail?

Typically the failure would be from the gasket shifting or squeezing out. I like to install them bone dry with clean surfaces both sides. The tendency varies with different gasket materials......Billy

Hey Don, I know its hard to find good gasket material. I saw this stuff on the net and wondered if this is what you have, looks decent to me, probably better than what my auto part store carries......Billy.....http://www.amazon.com/Mr-Gasket-9614...=pd_sim_auto_3

Billy I bought a roll of gasket material from the auto parts store last week, it is .8mm thick and I specifically asked the guy if it was oil resistant and he said it was.

What are my other options? I don't have any.

Someone said that there was a company in the US that could make a custom gasket to my specifications.
EDIT: A custom height base-gasket from cometic was the suggestion.

Is that true. Are there any other suggestions?

The cylinders have quite a large surface area that bears on the crankcase so wouldn't a gasket made by myself work OK. Where would the oil get through? How would the gasket fail?

Hey there Don, although you seem to be on the right track, I am going to have to agree with Ed. If you are going to make your own gasket, I would be real careful about what type of material you use. Most of the stuff we have locally here in the parts store is crap.....Do you have any options ???.....Billy

Hey Don, nice work measuring the clearance...BTW, how much is there?

After my experiences with base gasket failure with the Athena gasket material I'd be leery of cutting my own gasket for that application unless you can be assured you have the proper stuff. Sorry to be negative, and let me know if I can help you in any way - shipping you a gasket for example.

Sorry Ed I forgot to put the most obvious detail in the post didn't I. Had a long day, getting very tired.

When measuring the compressed solder I came up with .026" on one end and .028" on the other end. So I could average it out at .027" or go with .028" to allow a bit more clearance for a margin of safety.

So if I can make my own gasket from the .031" (.8mm) sheet of gasket material I bought to replace the .020" OEM gasket I should end up with .039" clearance between the piston swish band and the head surface. The ideal apparently is between .035" and .040" so this puts me in the correct range and should eliminate any chance of the piston kissing the head. Just in case that was my knocking noise in the motor previously.

BTW from what I have read quench is non-existent past .060", so I would still be well below this figure at .039".

[Nessism]

Hey Don, nice work measuring the clearance...BTW, how much is there?

After my experiences with base gasket failure with the Athena gasket material I'd be leery of cutting my own gasket for that application unless you can be assured you have the proper stuff. Sorry to be negative, and let me know if I can help you in any way - shipping you a gasket for example.

OK so I have bitten the bullet and decided to do a proper internal measurement of the deck height rather than guessing how much gaskets will compress etc.

This is what I did with the original factory base gasket in place and the cylinders fitted.


1. I cut two pieces of resin core solder about an inch long with my stanley knife which I glued with crankcase sealer to the top of the #1 piston running directly above the wrist pin.



2. I pushed the square ends of the solder against the cylinder walls and placed the piston a couple of mm before top dead centre.



3. I then fitted the old head gasket, did not want to ruin the new one by crushing it down.




4. I then fitted the cylinder head and torqued it to specification.


5. I then turned the piston past TDC so the solder would crush to the required space between swish band on the piston and head surface. This is view through #1 plug hole.




6. Then I removed the head and removed the pieces of solder and took the measurements.










Project not finished yet. I have to do the maths on the new deck height measurement and determine which size thickness base gasket material I will need to use and purchase some stout hole punch tools to do a reasonable job on making a new base gasket.

BTW I used the original base gasket that I had in there previously so I could compare measurements between the solder method and the vernier caliper method.

.

I'm not sure why you need a dial gauge, but you could measure piston height to deck with a good mic. Hampshire explained what Billy meant about measuring at the wrist pin.

[hampshirehog]

Billy could you explain in detail how to do the dial gauge measurements, I don't understand the bit about the wrist pin. I can't get to the wrist pin with the cylinders in place.

Don, if the carb and exhaust are at 6 and 12 o'clock measure the clearance at 3 or 9 o'clock. You will have some,albeit small, movement of your piston at the front and back but not at the sides - i.e. above the wrist pin.

Hey there Don. You didn't mention how thick the current base gasket is. I'm guessing it's probably .020" to .022" thick. If you make a gasket out of the .031" material, and leave out the other gasket (one gasket is preferred for better sealing), that should give you around .038" clearance on the piston. This would be a much better number than 50 something........Do you have a dial indicator ???...This needs to be measured accurately before and after. Take your measurement directly above the wrist pin as the piston can rock in the bore....Is shipping real costly from a place like Bike Bandit ???...They have base gaskets for around 11 dollars US......Billy

OK Guys I have measured the 650 OEM base gasket and head gasket again. The head gaskets, both new and used (the one I pulled off the motor with only 100 miles on it) measured .048". The OEM base gasket (new OEM) measured at .020". So if I replace the OEM base gasket with my home made .031" base gasket, I will pick up .011" extra clearance. Which should push the clearance at deck height from .028" to .039". So everything should be OK. Thoughts.

Billy could you explain in detail how to do the dial gauge measurements, I don't understand the bit about the wrist pin. I can't get to the wrist pin with the cylinders in place.

As far as freight from the US goes, the costs have gone way over the top in the last 12 months or so. As an example I was going to buy a 2" volt meter to mount on my instrument panel to monitor the rectifier output. The gauge cost $12.50 and the freight was $42.

Thanks again guys for your help.

OK. Billy is right, you could just cut yourself a new base gasket out of the gasket material and be close to the right height. It will compress a bit, too, though. You'll be very close to .035".
That said, cometic can cut you a gasket to varying thicknesses.
I think a good micrometer can give you the measurements you need, not sure why a dial gauge is necessary. IMO, all you need to know here is distance from shoulder to head.

Hey there Don. You didn't mention how thick the current base gasket is. I'm guessing it's probably .020" to .022" thick. If you make a gasket out of the .031" material, and leave out the other gasket (one gasket is preferred for better sealing), that should give you around .038" clearance on the piston. This would be a much better number than 50 something........Do you have a dial indicator ???...This needs to be measured accurately before and after. Take your measurement directly above the wrist pin as the piston can rock in the bore....Is shipping real costly from a place like Bike Bandit ???...They have base gaskets for around 11 dollars US......Billy

Nursing a bit of a hangover. Will do math and give my recommendation in a few, Don.

Hey Don, Mlinder is correct. The target clearance is .040" ......035" is absolute bare minimum.....Billy

Guys thanks for the replies. Would you believe there is not a single cylinder base gasket for the 650 motor in this country. You guys in the US don't know how lucky you are. So I've been up to Pep's Auto and bought a roll of oil resistant gasket material to make one of my own. It is .8mm thick.

So I need your advice on the swish band parameters.

The head gasket is .050" thick and the .8mm base gasket will equate to .031" minus .004" for the head gasket squashing up equals .077" then minus the .020" average that the piston swish band is above the cylinder deck equals a distance of .057" (hope my maths is right).

You guys are suggesting .035" minimum or preferably .040" as ideal. As my calcs end up at .057" will that be acceptable or will it affect the swish/quench issue and reduce performance in any way.


So my choice seems to be .057" with an extra gasket or .028" with only a single base gasket.

What are your thoughts on this?

Thanks

BadBilly is probably correct, for the least amount of work to get it running correctly now, etc.
But I'm weird. I'd still do the shoulder work. The quench would be the same, and the squish band appears to be really mild, though I'll have a closer look at it tonight.