Finally got her apart

[Tom M]

I have Mike Rich pistons and I'm happy with them.  If you go that route I would suggest that you send your cylinders to him too so he can check piston & ring fit and prepare the cylinder walls.  I didn't do that and had ring seating problems even though I thought I followed Mike's cylinder prep and break-in instructions correctly.  I know of another forum member who had the same problem.  IMO it's best to let Mike prep the cylinders.

[MikexG]

Tom - that is good advice. I have done some digging and there is no consistent answer on nikasil. Some say hone and some say leave it alone. I have a set if cylinders I bought off eBay and they look great with good cross-hatch visible. Not sure it's enought for new rings to seal. Sending them to Mike may be the best thing.

[gstallons]

Well , you could use Scotchbrite to hone the cylinder(s) moving up and down the cylinder bore quickly to get a cross hatch pattern and use brake cleaner to remove any foreign matter then lubricate the cylinder and pistons when reassembling .

[Lucky Phil]

Well , you could use Scotchbrite to hone the cylinder(s) moving up and down the cylinder bore quickly to get a cross hatch pattern and use brake cleaner to remove any foreign matter then lubricate the cylinder and pistons when reassembling .

Scotchbright wont touch a Nikasil cylinder. Take them to your nearest engine reco place and get them to run a "flexhone" through them. Its like a bottle brush with stones on the ends and is commonly used after the final hone to finish cylinders.

Wont remove any material to speak of and will give a nice finish for new rings. Will do that while you wait, takes all of 5 min. 

Make sure you clean the bores with warm soapy water and a brush after they are done then let them dry and wipe some engine oil into the cylinders with your hand then wipe it all out with a paper towel. Lube the gudgeon pin and rod fit the pistons and start it up.

Rods straightness? why would they be bent? Cant see the reason for that.

[dangerous]

to be honest with chrome or  Nikasil bores I thought it was inpossable to hone or bore, the hole idea of it... just hiff the new rings in???

[pete roper]

As Phil says, stick a boron ball hone through 'em, stones and scotch brite won't touch Nicasil.

 

While the pics are a bit hard to see the skirt look like they have seized. With compression of 80 and 120 with the throttle wide open you know they are f*cked. New barrels and pistons are the way to go, Mike Rich's stuff works well.

 

What is important though is to find out WHY it seized in the first place? Its damn near impossible to seize a piston in Nicasil. Something must be seriously out of whack with the tuning to make it run that lean!

 

Pete

[gstallons]

There are facilities that replace the nickasil coating in cylinders . You have to send the pistons w/the cylinders so they can hone to match the piston / wall clearance .

[MikexG]

Pete - I bought this thing with Bubs pipes and a power comander. I don't think it ever ran right that way. I put stick pipes back on and took out the power commander. Ran better - but compression was off. I am at a loss here. I have a feeling it was apart at some time and not put together right. The nicks on the piston make me suspect an improperly installed oil ring. It broke as I took it off - I think it was already cracked.

 

So here are my dilemmas - first - they no longer make the stock pistons . So I may need to go with Mike Rich's. But once I decide on pistons - I want to out this thing together ONCE and ride it. Here are my options I think:

 

Option 1: Harpers can have the cylinders I bought replated. - around $400. That and new pistons/rings seems like safe bet - but more money .

 

Option 2: Hone the cylinders with a Boron ball hone with new pistons/rings.

 

Option 3: new pistons and rings in the cylinders without honing. Remember the set I bought looks clean and hone marks look good.

 

I appreciate the insight

 

MG

[dangerous]

hey ok so... IMO and what I have found with my engine rebuilds and remember 90% were two strokes... If I saw scratchs like that on a piston and bore Id say tempory seizing

 

 

While the pics are a bit hard to see the skirt look like they have seized. 

 

What is important though is to find out WHY it seized in the first place? 

hey I thought that a page back, had no comments tho... great minds n all that shit aye pete LOL

serious leaning out maybe? could be fuel mix, timing or a air leak some were?

[MikexG]

So here is an update. Heads are done - needed 4 new valves and guides. Stock pistons are nowhere to be found. So I am sending my cylinders to Mike Rich to have honed to go with a new set of pistons. It all comes together next week.

[luhbo]

... Stock pistons are nowhere to be found. ...

Not a real problem. Take Breva ones in combination with Breva rods. Better than stock, albeit the rods cost extra, of course.

 

Hubert

[GuzziMoto]

The Mike Rich pistons are also better than stock. And likely better then the Breva pistons as Mike puts in the effort to make the squish area tighter.