Cylinder work: Bore Oversize or Nickasil Coating?

[9hondas]

Guys,

Just a refresher here, the previous dishonest owner (rsxjosh) who sold me the bike being in excellent condition had actually had the chain come off and blow out his cases around the cs sprocket. I found out after the purchase. Its been a long legal process and he won the initial round, but it ain't over yet.

The bike is an '05 in excellent shape otherwise and I don't want to install some junkyard motor with unkown miles or condition. If I do the motor work myself I will know it was done right, assuming I take the time to do so.

Anyway, I got a set of cases for my bike to swap the rest of the internals into. I noticed some scoring in the bores and would like the opinions of some of you experienced motor builders.

I originally thought I might be able to just have the bores lightly honed and then put in new pistons & rings.

To investigate that, I took the cases down to Fastline Cycles in Fremont, CA and talked to Alex there. From what I was told Honda uses a high-silicone aluminum alloy and the cylinders are not Nikasil. Some sort of special honing stone must be used for example. He said my options were either bore and hone 25mm oversize for $325 or have the bores cut slightly then nikasil back to standard size for $435.

Pictures of the scoring are below. They don't feel very deep and barely catch a fingernail. I haven't had a chance to mic out the cyls to see if they're worn, but there's absolutely no ridge to be felt from ring wear at the top of the bores.

Thanks in advance for the replies! Hopefully this condition had been addressed by someone already. The cases are in good shape otherwise.

http://www.speedzilla.com/forums/att...d=12245501 47

http://www.speedzilla.com/forums/att...d=12245501 58

[jracer]

i had my rc cylinders bored and re nikisiled buy them and they had trouble getting it to "stick " they re did them three times before they finally sent them back to me.. while many guys have had great results with millenium.. i had some issues .. put it this way it blew up the second time i raced it..seemes the piston seized to the cyclinder.. i think the coating ( nikisil ) came of and it was aluminum on alminum after that and poof !!
just my two cents.. this was in 2001 so maybe they figured it out now...they did tell me they never had done it before on a rc51...seems the rc51 cylinders go egg shape after awhile..i talked to bob H at BVH about it.. he agreed..he really told me just get new cases.. well he knows his stuff and i should have listend !!..i did build the first motor before with the same pistons ,crank, heads ect..and it lasted all year.. then it was time to feshin it up ..thats when we found the wornout egg cylinders...thats when we tryed the millenium thing..didnt seem to work out..
i. good luck !! hope it works out for you...
some of my rc51 pics....this bike was built in 2000 when there was no parts avalible at the time .. so i made everything..like my home made front rads ?? hahahah.. used old dirt bike rads chopped up.. worked great !!!
its alittle beat up but it was race for three years....
MySpace.com - John rc51


***just my experance.. i have been told millenium has it figured out mow and have done many.. so i am told......

[jracer]

seems alot of rc engines get those marks on the cylinders...

[eye-p]

I have an engine in excellent condition with just over 4800 miles on it. $600 + shipping if you are interested.

[whitw wings]

That would be a great deal from a stand up member, give it some SERIOUS thought or possibley waste a HELL of a lot more trying to have someone work out your engine issue. One bad review is enough for me!

[sparkyz]

If you decide to go the replating route, US chrome is highly recommended in the motocross world, so I would guess they can also do an excellent job on streetbike cylinders.

[RVTMAVERICK]

WHOLEY CRAP!... How'd you lose man?

I thought you be taken care of,... I mean The dude clearly miss represented whatTF he was selling!

[gpz11]

Well, since it is this far apart, I'd get them replated.

You might as well do it right and you know it's correct.

It's a shame that you had to go through all this BS.

[9hondas]

Originally Posted by gpz11

Well, since it is this far apart, I'd get them replated.

You might as well do it right and you know it's correct.

It's a shame that you had to go through all this BS.

Thanks for the opinions, and the offer for the motor. Right now I want to investigate doing the motor I have here. Maybe that will change.

Any recommendations on having who do the plating work?

So far I've found

Millennium Technologies mt-llc.com

U.S. Chrome usnicom.com

[Redstar]

Go with millenium tech. My

[irishaggression]

My custom cut pistons are at millenium and so are my cases right now. They are doing custom hone to match the pistons and nikisil

[9hondas]

Originally Posted by irishaggression

My custom cut pistons are at millenium and so are my cases right now. They are doing custom hone to match the pistons and nikisil

Thanks for the input. I'll be building my motor for the street, probably going with stock pistons.

What piston clearance should I specify when I send it all in?

The manual says to allow .015-.055 mm piston clearance with .2mm being the service limit. I'm curious if having a nikasil job done affects the desired clearance.

In other words should I shoot for a tighter fit or looser piston fit with a plated cylinder?

Just off the top of my head I would think I'd want a slightly looser fit since the plated cylinder won't be wearing, and there's no sense having such a tight clearance.

Thanks again for the help guys!

[gpz11]

I used Mill. Tech. and was happy with their work. Send them the poistons you are going to use and they will work out the clearances.

Make sure you package the parts up very well. They will get bounced around.

[irishaggression]

Originally Posted by gpz11

Make sure you package the parts up very well. They will get bounced around.

this just cant be said enough