Source for XT350 piston

[jester_parks]

Took some shots of the pistons to give a first idea:
Honda piston comlete with pin and rings =329gr, Yamaha XT350 =369gr

[xwhatsit]

Oh! So the RS piston is the higher crowned one? I thought Muzz said he trimmed out stuff for the valves to have clearance? Interesting. Then again, he did it with an XL250S, which is lower compression than the RS.

Nevertheless, that's good, looks like it'll be fairly low-compression, so nice and flat and grunty.

[xwhatsit]

I spoke to a guy in Mt Wellington yesterday, a bloke at a place called Wade Automotive. Was just passing by but I saw their sign and it seemed an old-school sort of place. Popped in and wasn't disappointed.

The guy said they can have a crowd in Christchurch make one-off cast-iron sleeves for them, then they machine them etc. About $200-$250 to get one made, so probably just buy that sleeve if I can still get hold of it when the money comes through and have it machined to suit. He seemed quite interested and enthusiastic about it actually, which is a good sign, he was worried about taking 6mm both sides out of the cylinder itself (worried about getting to close to the fins/camchain tunnel and it turning to cardboard), but then again it's been done before.

About conrods and bottom end strength to deal with the extra piston weight; I take it there's nothing that can be done to strengthen the conrod? Other than very expensive and specialised work I suppose. Is it possible to lighten a piston? Take meat off the skirt? I would guess the best way of keeping the conrod in one piece is simply to keep the revs down; suits my plan of using just a 33mm CR33 carb and keeping the valve sizes as standard.

[Kickaha]

The guy said they can have a crowd in Christchurch make one-off cast-iron sleeves for them,

Cliff Bond in Ferry road, I've talked to them about making a one off for a big bore GN125

I take it there's nothing that can be done to strengthen the conrod?

Get a rod made for it ,

you could have it shot peened which will supposedly help

[Motu]

I spoke to a guy in Mt Wellington yesterday, a bloke at a place called Wade Automotive. Was just passing by but I saw their sign and it seemed an old-school sort of place. Popped in and wasn't disappointed.

Behind Johnson Piston Rings.Wadey does good work and I've used him a few times when my guy closer was too busy.His brother used to be the bass player in Billy T James band,a renowned bass player....but was an upholsterer by trade.He upholstered the seat on the C50 for me......just to connect all the dots.

[Ixion]

About conrods and bottom end strength to deal with the extra piston weight; I take it there's nothing that can be done to strengthen the conrod? Other than very expensive and specialised work I suppose. .

Best thing is to polish and smooth it. Stress builds up in scratches and sharp edges. carefully smooth all edges, remove any flash, polish scratches out.

[pete376403]

If you know the rod dimensions, length between centres, big and small end diameters, etc, go and have a look here.\
The rod would probably end up being worth more than the rest of the bike, but you'd never break it. Ever.

http://www.carrilloind.com/Powerspor...3/Default.aspx

[jester_parks]

200 - 300 Dollars.....this is freaking lot of money for a sleeve....rather wait until I can send you one!
Carillo conrod is the premium way to go....but haven`t got a rod around to take the measurements....who has?

[xwhatsit]

I've got a couple of cranks sitting out of the engine, could take measurements if necessary -- one thing though, how would you get the bastard off? I think it's all one piece.

@Ixion: this is what shot peening does then? By smoothing it all over like that this is a poor man's shot peening?

The way I see it, the conrod would be the weakest part of this whole equation. Well, there's always the gearbox, clutch etc. You don't hear of many pre-RFVC engines exploding the bottom end, it's all valves, holed pistons, slow gearbox deterioration.

Right well I'll nab that sleeve on eBay. One thing, it says: `The castings used in the manufacture of these sleeves are made from an alloy of carbon chrome, and molybdenum of 200 brinell hardness which insures ease of installation, trouble-free boring and dependable long engine life.' Does that mean it's going to be a prick to shorten and machine?

I'm curious how much a Wiseco piston would be lighter. The std bore one I'm looking at (4674M08600 is the number) says it's forged, and says it's lighter weight. Would be nice to quantify that.

[Ixion]

No. If possible shot peen AND polish. Shot peening releases local stress left in the metal from the forging process. Sort of like a metallic massage. Polishing removes local stress point concentrations. Both are good, but polishing is free (except for your time).

Sleeve won't be too hard to machine, but it will need a competent machine shop.

[pete376403]

I've got a couple of cranks sitting out of the engine, could take measurements if necessary -- one thing though, how would you get the bastard off? I think it's all one piece..

If its a one piece rod then the crank must be a built up unit - crank pin pressed into the flywheels (like just about every two stroke ever built)
If you have access to a press you can push the crank pin out of one of the flywheels and then remove the rod and bearings, otherwise any shop competent in repair of motocross bikes should be able to do it.
If you do have the rod shot peened make sure the bearing surfaces are protected.

[jester_parks]

I`ve ordered the Wiseco in the US and it should be well on its way - will tell you the weight as soon as I`ve got it.
Valves will be made in China to size - sending the samples this week and wait for the quote!

[jester_parks]

....and will give you an idea, what size sleeve I could give to you: the sleeves I`ve got are all oversize (bored once or twice), so all you have to do ist to get hold of a Wiseco-o/s-piston of 87 or 88 mm....still cheaper than spending lots of Dollars for a custom-made-one.
Check ebay-USA for those pistons - I`ve got a good deal over there.

[jester_parks]

or else:

check here:

http://cgi.ebay.com/ebaymotors/Cylin...116#ht_781wt_0

[xwhatsit]

Right, saved up some money and ordered that eBay sleeve. Shame the NZ dollar has taken such a dive compared to the US dollar, makes $US120 + shipping for the Wiseco piston actually relatively high. I'll see if I can get it cheaper locally -- where do people think is cheapest to get Wiseco bits and pieces?

There's a $40 new std OEM piston on eBay, but no rings or gudgeon pin -- and did the Wiseco piston turn out to be lighter in the end, Jester?