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914World.com _ 914World Garage _ Engine question

Posted by: MattR Nov 15 2005, 06:45 PM

It looks like my 2.0 cylinders were bored too big. My ring gap is .028", which isnt right for my 96mm KB pistons. I do have another set of 1.8 cylinders laying around. Are they dimensionally the same as a set of 2.0 cylinders? Can I just bore out the 1.8 cylinders to the proper size for my 96 pistons?

Posted by: SLITS Nov 15 2005, 06:50 PM

93mm vs 94mm

Maybe you should ask Santa for a set of 2.0

Posted by: Mark Henry Nov 15 2005, 06:55 PM

Yes

Posted by: Tom Perso Nov 15 2005, 07:17 PM

Yup, you betcha. Bore 'em esp if they are stock German metal. They'll hold tolerance better.

Tom

Posted by: Jake Raby Nov 15 2005, 07:25 PM

Yep-

Your best bet is to send me those for cores and buy my 96mm set based on bored cylinders. When boring cylinders they must be done in a torque plate and things like skirt clearance and cylinder roughnessaverages can add guesswork and increase the chaces of having a bad experience...

Posted by: Thorshammer Nov 15 2005, 07:49 PM

He's right! The only proper way to do it. Thats why I made the plate for my six cylinder engine. The only way. Everything else is just not acceptable.

Erik

Posted by: Tom Perso Nov 15 2005, 08:40 PM

I sent Jake a set of 94's, my pistons and rings.

They came back perfectly matched. Those slipper skirt 96's were a PERFECT fit and that thing ran GREAT. Good work, quick turnaround, and I knew the job was done by someone who really cared about the product, not the receipt of payment.

Tom

Posted by: Jake Raby Nov 15 2005, 08:44 PM

Thanks Tom....

And that was what, 4 years ago???

I have the process down to a science- it took a while to get it there too...

And yes- That plateau finish on the cylinder wall ROCKS!

Posted by: Cap'n Krusty Nov 15 2005, 08:46 PM

QUOTE (Jake Raby @ Nov 15 2005, 05:25 PM)
Yep-

Your best bet is to send me those for cores and buy my 96mm set based on bored cylinders. When boring cylinders they must be done in a torque plate and things like skirt clearance and cylinder roughnessaverages can add guesswork and increase the chaces of having a bad experience...

Here we agree. Machinists familiar and set up for motorcycle work might be able to do it, but they're few and far between. The Cap'n

Posted by: lagunero Nov 15 2005, 08:52 PM

Is it possible to send a set to a machine shop, say Rimco and simply give them the size that you'd like them bored to (96mm KB) and assume they will work or did I just ruin my cylinders too?

Posted by: Aaron Cox Nov 15 2005, 08:55 PM

like jake said, and like twystd1 explained to me....

they needed to be under a torque plate when honed/bored.

imagine the change of shape they take from set on a table, to torqued in a motor.

they may look out of round etc when all alone, but when torqued up, could be perfect....

Posted by: Jake Raby Nov 15 2005, 09:00 PM

If they don't ask for your piston go ahead and hang up the phone on them... Here tenths of thousandths of and inch can make or break the results...

How do you KNOW the size that you want them bored to?? Are you guessing?? Is it 3.7785 or 3.7790 or 3.7815???? There is much more to it than just saying "Ummn, I have these 96mm pistons and I need these cylinders bored to 96mm.." what about running clearance?? What about the hone specifics??

Can Rimco do it- Yes... They have done it for me before, years ago.. BUT That was years ago-

Only you will know if they ruin the cylinders, when you have an issue.

It amazes me just how much people will try NOT to do things the proven, tested and smartest way- You guys must TRY to make things hard for yourselves!

JEEZ! Hell I think its time to put the OLD AVATAR back up- thats the way I feel after doing all this homework for guys to TRY and make things hard and expensive for themselves!

Posted by: MattR Nov 15 2005, 09:32 PM

Jake, they went to rimco. I talked to Todd and used your name with your specs with pistons in my hand. I did my homework almost a year and a half ago and had this engine assembled with all the machine work done by rimco. Now, with 20 minutes on the engine, its all fucked up.

I have a machinist i TRUST in there now looking at everything. I'm doing my research so I dont have to be a wide eyed kid in his shop. I'm doing my homework on the board. Ive spent countless hours searching here and STF and talking with the machinist and people I trust about engines.

Posted by: Twystd1 Nov 15 2005, 09:39 PM

Yea... What they said

Twystd1

Posted by: Jake Raby Nov 15 2005, 09:42 PM

Matt, what happened to the engine??

Rimco's work is not what it used to be..

Posted by: MattR Nov 15 2005, 09:43 PM

QUOTE (Jake Raby @ Nov 15 2005, 07:42 PM)
Matt, what happened to the engine??

Rimco's work is not what it used to be..

I dont really want to bash them on a public forum... I'll send you a PM about it.

Posted by: Jake Raby Nov 15 2005, 09:45 PM

Hell, just call me 706 219 4874 I am by the phone doing DAMN PAPERWORK all night tonight... (literally)