Cylinder Liner fit to crankcases

[Chrish]

Hi,

I have new crankcases that measure correctly at the cylinder mouths, what fit should there be between the crankcase and cylinder liner? i.e. how tight the cylinder liner in the cases?

If the liners are not tight in the cases then what will be the ongoing problems?

Thanks,

Chris

 

[Comet Rider]

Hi Chris,

There are 2 schools of thought here;

1/ sliding fit when the c/case bolts are tight
2/ maybe a thou' or so of squeeze, in that the liner will slide in when the bolts are loose.

My personal preference is for No. 2

HTH
Neil

 

[nkt267]

If you buy a new liner then it will most likely fit with enough clearance that it can be tossed across the room into the cylinder mouth.
I was shocked to find that an original barrel and liner that I had to replace and was a snug fit was replaced by a liner that could be dropped over the bolts and find it's own way in..John

 

[Chrish]

Hi Chris,

There are 2 schools of thought here;

1/ sliding fit when the c/case bolts are tight
2/ maybe a thou' or so of squeeze, in that the liner will slide in when the bolts are loose.

My personal preference is for No. 2

HTH
Neil

Hi Neil,

I also thought that a tight sliding fit of the liners was about right but these new liners fall in.

 

[Chrish]

If you buy a new liner then it will most likely fit with enough clearance that it can be tossed across the room into the cylinder mouth.
I was shocked to find that an original barrel and liner that I had to replace and was a snug fit was replaced by a liner that could be dropped over the bolts and find it's own way in..John

Thanks John, I thought it was just me! I'm not sure another new set will be any better.

Chris

 

[vibrac]

When I sleeved my Racing Comet 600 back to a 500 (the things we do to get points!) I used a top hat bush (by Clever Trevor) sliding into the bored crankcase and also to the liner. bearing in mind the only thing really clamped was the top hat to the crankcase (I suppose some clamp distortion might have passed through the walls) we have run a good season with no ill effects
NB it was a 90 bore as a 600

 

[Bill Thomas]

If it's too tight you will Nip!! the piston, Cheers Bill.

 

[Howard]

Hi Chris, I'm sure there's a long thread on this forum about liner clearance, posted this year.

H

 

[Big Sid]

I like them to be a snug slide in with just a rap or two from your fist . Be sure you have the nuts loose on the left side of the cases when sliding them in , or when removing . Then retighten . Sid .

 

[davidd]

I prefer to have nothing to cause a change in bore size if I can avoid it.

If you have bored out cases and you choose to go back to 500 per cylinder, you can also use an aluminum sleeve that has been coated with Nikasil. As long as you run the correct rings for Nikasil they are very durable. Any old muff except the early series D die cast ones will do as the intereference fit does not need to be as high as the "tight" ductile iron liners. Carleton Palmer has run his cylinders this way for years. I have run the thin walled version for stock cases. Neither of us has found a difference in performance between the two.

David