Custom Big Bore HT Bicycle Engine?

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sketchman

New Member

Mar 23, 2011

168

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WV, USA

Jun 2, 2011

• #1

You know there are 49mm pistons with 10mm wrist pins available for cheap? Made for a stihl chainsaw. One could take one and hone out a stock jug and have quite the upgrade I would think. I saw them too late or I would have tried it, but I'll be happy with my cag I think.

Just something to think about for those with bad jugs that might wanna try it.
Piston Kit fit STIHL TS400 TS 400 (49MM) chainsaw *NEW* | eBay

 

Mike B

New Member

Mar 23, 2011

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Central CA

Jun 2, 2011

• #2

Re: Custom Big Bore HT?

Don't forget to re-chrome it.

 

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sketchman

New Member

Mar 23, 2011

168

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WV, USA

Jun 2, 2011

• #3

Re: Custom Big Bore HT?

Ooh, forgot about that. Would that cost much for you guys with shops close by that do work like that? I couldn't, but I know not everybody lives in the middle of nowhere.

 

flybytaco

Metal Molding Madman

Oct 17, 2009

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seekonk MASS

Jun 4, 2011

• #4

Re: Custom Big Bore HT?

all i know is everytime i send milenium technologies my dirt bike jugs for replating it costs me 150 dealer cost.

 

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sketchman

New Member

Mar 23, 2011

168

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WV, USA

Jun 4, 2011

• #5

Re: Custom Big Bore HT?

For how many? That sounds crazy.

 

thatsdax

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Feb 22, 2008

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www.thatsdax.com

Jun 4, 2011

• #6

Re: Custom Big Bore HT?

Yes.. Do not take out your Chrome or Flame Spray lining. Also.. Check wrist pin position , skirt length and shape as well. All critical functions.

 

rohmell

Active Member

Jun 2, 2010

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New York

Jun 5, 2011

• #7

Re: Custom Big Bore HT?

Couldn't you do the chrome job yourself with one of these kits?
Plating Kits Chrome Plating Kits Aluminum Anodizing Kits Electroplating Kits - Caswell Inc.

 

Mike B

New Member

Mar 23, 2011

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Central CA

Jun 5, 2011

• #8

Re: Custom Big Bore HT?

Hard chrome is a different process than electroplate.

 

DaveC

Member

Jul 14, 2010

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Boise, ID

Jun 8, 2011

• #9

Re: Custom Big Bore HT?

Only way to bore these motors is to find a replacement jug, piston, rings and head as a kit from like treatland. Finding just the right kit is the problem. The transfer ports have to be close enough of a match so maybe portmatching would be all you'd have to do. Welding in some metal to grind away to the right shape is an option, too. The key would be the right rod length so the piston isn't shoved against the head or interfere with the bottom dead center clearances.

 

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sketchman

New Member

Mar 23, 2011

168

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WV, USA

Jun 8, 2011

• #10

Re: Custom Big Bore HT?

If you're gonna go far enough to actually bore it with a hone, I don't see why you couldn't trim the piston where it needs to be to fit how you want. The chrome thing is a bummer though. I didn't think about that.

Maybe some backyard engineered sleeves from steel shim stock sheet. Hmm. Ideas.

 

Last edited: Jun 8, 2011

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coryc

New Member

Jun 17, 2011

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bullhead city,AZ

Aug 13, 2011

• #11

Re: Custom Big Bore HT?

how much bigger of a bore is that stihl 49mm piston than the stock 66cc piston. i know theres not alot of meat to take off thesecylinder walls/jugs and the metal they're made out of is probably pretty cheap/weak. can you take enough out w/out strip perforating the wall or weakening it to the point of distortion at high temp? otherwise, i would think if it uses the same rod you could trim the skirt if needs be and it should work.i have a spare jug i've thought of trying this but not sure what the next size up would be that it could handle or size range/scale of piston kits out there. anybody?