Overboring, Replating Cylinders..... How Much Is Too Much ?

[Ductape]

After seeing other discussions here on big bore kits, woods ports , race builds, etc, it seems that there is plenty more to be had from stock, pro-grade saws. I realize stock cranks, rods, bearings and cases all have their limitations, but is the cost of boring and replating a cylinder the biggest reason very few people are running oversized pistons? At some point, crankcase volume comes into play, but at what point? I'd like to more about the possibilities here............ thoughts ?

 

[mdavlee]

I think it's around $200 to have a cylinder redone so it's a big expense and more than the BB kits out there. On some cylinders like husky 2100 there's no new to be found so it's the only choice to keep one running if you need a cylinder and have a scored one.

 

[Bob Wright]

Not to be stupid but who does that work? I thought i had a link but i can't find it. Thanks...Bob

 

[Boleclimber]

Past discussion on this subject indicate there are no companies which will replate a chainsaw cylinder as is. There is said to be a company that will do cylinders which have had the head cut off, like race saws.

I have read boring a chainsaw cylinder requires rework of the transfer port curves. As a the cylinder is widened it changes upper and lower transfer curves by bringing the bore closer to the tunnel.

The application of doing all this work is best for race applications.

 

[Ductape]

This 090 suffered a burned up top end because of a crack in a fuel line of all things.

If it had not been for AS member Teddy.Scout this saw would still be in a box under the bench. He was kind enough to help out with a very nice OEM piston, rings, and clips. He also provided two clutch shoes and an exhaust deflector.

Thanks Matt!!!!!

The original jug was sent to US Chrome to be replated with Nicasil. They did a damn fine job too!!!!

Here you can see the shoes that are missing their lining.

Matt warned me that replacing the springs was a chore. We figured out an easy way to get that done though. Jon, my son-in-law and right hand man, thought this trick up.

The saw got a carb kit, new fuel line and vent line. Aside from that it was in very good shape.

Apparently, US Chrome will do Chainsaw cylinders.

 

[rwoods]

Now who makes oversized pistons for saws that came with chrome lined cylinders? I'm not talking about pistons from a larger model nor oversized pistons that are common for cast iron liners. I'm talking one-off made to spec pistons. Thanks, Ron

 

[Ductape]

Here's, a trick on 372 or 2171 saws. Everybody has a junk china 52mm big bore kit. Send it to US Chrome and bore it to 54mm and replate with the good stuff. Buy a new 2083 Jonsered 54mm one ring piston. Cut the top of the piston .050,come in .450 from the edge of the piston. Set the squish at .020 you will have around 220-230 psi. Alittle over a 5cu. saw in a 4.3 cu. The carb, needs to be drilled on the low side for more fuel. Now, you guy's may be using a bigger piston.

066stihl

Bole, I hadn't thought about the transfer work, but above is the type of mod I was thinking of when I started this thread. I don't see many talked about like the one 066stihl describes. Perhaps its just too expensive for most?

Past discussion on this subject indicate there are no companies which will replate a chainsaw cylinder as is. There is said to be a company that will do cylinders which have had the head cut off, like race saws.

I have read boring a chainsaw cylinder requires rework of the transfer port curves. As a the cylinder is widened it changes upper and lower transfer curves by bringing the bore closer to the tunnel.

The application of doing all this work is best for race applications.

 

[chopperfreak2k1]

now this is my kind of thread!!

sorry, i have no input. it just excites me.

i peed a little.

 

[Roanoker494]

I currently have a email out to US Chrome to see if they can help me out on a Homelite 750 cylinder, I will let you know what they say. Boring and plating a cylinder should not be a issue but finding a over sized piston may cause some troubles.

 

[Boleclimber]

I suspect the re-plating company may want the over-sized piston as a reference for finish bore measurements. The pin to crown height and skirt length would be an issue.

A good machinist can make a their own piston. There is one chainsaw modifyer who has the skills and has made his own pistons in the past.

That 090 is interesting, I had read that companies didn't have the machines for blind cylinders.

 

[Roanoker494]

I have just gotten a email from Scott Reath at US Chrome stating they can do blind bore plating as long as your cylinder is closed port. He has asked me for pictures before he will quote a estimate, so I should have a round about price in the next few days.

 

[lfnh]

Wonder why closed port and not open port ?

 

[Nitroman]

I was watching "How It's Made", they showed how Wiseco made thier slugs: slap them in a lathe and let'er rip. Well, it was a $250k machining center but it was a lathe. And if you need one, you can send the old piston to them, they will make you a new one OEM or with any mods you ask for.

 

[one.man.band]

there is a coating company called Swain Tech in new york state that can build up piston skirts. (would not do this unless the ring lands are true to size in a used piston), and do not know the maximum total thickness of build up. have sent lots of motorcycle pistons for ceramic top coat and side skirt lubricating coating. they cannot build up a cylinder wall, but can do the combustion chamber and ports as well. nascar teams send stuff there. reasonable prices (i think).

will post a pic of an m/c piston.

hope it helps.

 

[4cyl2vy]

Wonder why closed port and not open port ?

Too hard to bore/clean the old cylinder lining out?

 

[Roanoker494]

Wonder why closed port and not open port ?

I did not investigate it further since my cylinder is closed port, but I will ask.


US Chrome has emailed me back, after I sent the picture, and the price is $198 plus all shipping. They require you send them the cylinder completely stripped off all hardware, the piston, your specs for piston to cylinder clearance and turn around time is 2 weeks.

 

[one.man.band]

good info Roanoker..thx for sharing!

 

[lfnh]

I did not investigate it further since my cylinder is closed port, but I will ask.


US Chrome has emailed me back, after I sent the picture, and the price is $198 plus all shipping. They require you send them the cylinder completely stripped off all hardware, the piston, your specs for piston to cylinder clearance and turn around time is 2 weeks.

Thanks Roanoker. Appreciate the research, will be very handy.

 

[Roanoker494]

On a side note my quote is for restoring my cylinder to factory specs. One issue that comes to mind, if wanting to bore a cylinder out, would be the transfer ports. There is very little "meat" there to be boring on and you would likely punch through or weaken the cylinder to the point that it would fail in no time. Then there is the issue of getting a piston and the $200 to chrome the cylinder.

 

[Boleclimber]

Did they say if the finish was chrome or Nikasil?