Topic: Is 45 thousandths enough for sleeve thickness?

[jessezm]

Well howdy again folks!   I contacted another fellow who bought the same big-bore kit from China that i did off of ebay for my CB400f.  The pistons are 54.5 mm, and the kit does not come with sleeves, just the pistons, a gasket, pins, clips and rings.  The other guy seemed to know his stuff, and said the quality of the kit was very good--CNC-turned and exact dimensions.  But, he said he was not going to use it with the stock sleeves because it would only leave 45 thousandths of an inch left of the sleeves and he wasn't too comfortable with that.   Is someone here willing to make me comfortable with those tolerances or do I need to go another route?   Other than the pistons, I'm not planning any major engine mods, though I have been kicking around the thought of a webcam and performance springs.  The original cam is in really good shape, though and I kind of don't really want to mess with it.  Anyhow, any advice would be much appreciated!  Thanks,

jesse

[bucky katt]

i wouldnt be comfortable with it but thats me. some of the more experienced folks here need to chime in on this.

[NoXi]

at 1.1mm i'd imagine you'd encounter some serious problems, what are the stock sleeves?

[jessezm]

I've just measured the sleeves off another 400f and they are 3mm on my digital micrometer.  So yeah, that would be like removing 2/3 of the material...

Any engine experts out there want to chime in?

[bucky katt]

i would think that they wouldnt last long before cracking, alot like the old style of 92mm pistons/cylinders on air cooled beetles. too much compression or rpms and KABOOM! i have a wall with 7 or 8 cylinders hanging on it.

[bistromath]

They will be much more vulnerable to warping and ovalling. I wouldn't run them that thin.

[ttr400]

54mm was a common yoshi kit for the CB400F, these are no longer available. then they came out with a 54.5mm kit, these are still available.
54.5mm is the largest you can go with the stock sleeves.
The stock sleeve is 59mm on the main part and 57mm on the lower section. this will leave you with a wall thickness of 2.25mm main and 1.3mm on the lower section of the sleeve.

This will be no problem at all, I always try to have a minimum of a 2.0mm wall on the main part of the sleeve when I make custom sleeves for even bigger bores up to 57mm.

Kevin

[eurban]

In case you don't know who to believe. Go to Kevin's (ttr400) website.  He's well versed with the 400s to put it mildly . . . .

[jessezm]

Thanks you guys are the best!  I think you are all right, as it sounds like the numbers I gave were wrong in the first place.