Topic: new cylinder block arrived damaged!!! help!!

[CB750R]

Hey all, I just recieved my much anticipated 67mm pistons and machined head, and one of the sleeves has a flat spot on the bottom of it and the piston won't slide through.  I understand that this is well below where the rings will travel, so is this repairable?  the sleeves are larger than stock in outer and inner diameter so are very thin.  I paid a LOT of dough for this on ebay, and the seller says he's willing to pay for the repair, (to what extant that means I don't know).  I need some advice here fellas, I'm really choked at the moment and want to get this bloddy bike rolling again!! Help!!

Grant

[Tim.]

If I were you, I'd probably get yourself a refund and start over (unless you got a REALLY good deal on this set).

You should take it into a reputable machine shop and get an estimate.  I don't know how you get a flat spot in a cylinder, and repairing it might take you beyond your 67mm piston size.

BTW - 67mm sounds awfully big - aren't stock 750 pistons only 61mm - is this an 836 kit or something like that?  Link to the auction so we know what we're talking about?

[cb750_chris]

That sucker must have been dropped ??

[CHUNG]

That's 888cc I don't know why it's called an 895 Kit???
If the sleeve it banged hard then it might need replaced. At the very least, the whole Cyl Block needs to be Miic'ed by someone that can view "the big picture"
If it's only at the very bottom then you might just have a hone run through it at the damaged area. The skirt travels pretty close to the bottom of the sleeve and although it's much cooler down there, you must keep the proper piston to bore clearance throughout the stroke.

[CB750R]

yeah it definatly got hit on the bottom, so far I'm dealing with the seller and it was a consignment deal from a dude who had a whole bunch of oversized sohc and some drag performance parts, so far the seller is being co-operative, I prolly have to get it resleeved, from the sound of things because the cast iron sleeve is quite thin at this bore.  I hope to get some pics soon

[MRieck]

Cast iron is brittle too- dropping or striking it could cause a crack which can't be seen with the eye. bLA Sleeve or Advanced sleeve should have the right one- I'd replace it. I saw that auction....you paid good money for those pieces.

[CB750R]

Yes, Yes I did pay a healthy amount, its funny what a guy will pay for when his bike is in pieces....

however, it is about 200cdn a hole for boring here, plus pistons, so.... the math aint that far off.  I was sold consignment by a reputable ebayer, so I believe all should work out, because I doubt a big ebayer would like a #$%*ty review, for someone elses part!!

I did hear from the machine shop that the cast sleeve is brittle, and that was my main reason for suggesting that I either get my money back or get it resleaved.  The crappy part is I don't know whats going to happen yet so I can't call up Cometic to get the gaskets!!!

I knew that custom building a 27 year old bike would have its ups and downs but holy schmoly I just wanna go ride!!!

[oldbiker]

If you feel the eBayer is reputable and he has a consignment of these parts, perhaps he will exchange the block you have for an undamaged one!

[kghost]

Aha. I see the problem. 27 yr old bike and you want to go ride?

Buy a restored one or a new one. Or restore yours and then ride it. Half way doesn't work well.
Recommend a beater bike while you restore.

[Tim.]

...it is about 200cdn a hole for boring here, plus pistons, so....

$200 a hole for boring?  I just had my 550 bored 0.5mm over and it's about $50 a hole here in Toronto for the bore and hone.  Am I missing something?

[MRieck]

200.00 does seem little high for 1 hole. Keep in mind though the existing sleeve has to be removed, the new sleeve installed and it has to be bored out. It is a fair amount of work.