T500 piston mods

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dbc105
On the street
Posts: 20
Joined: Thu Mar 26, 2015 12:06 pm
Country: USA
Suzuki 2-Strokes: T500

T500 piston mods

Post by dbc105 »

I've bought a set of Zookie Stage II barrels from a fellow in Ca. that never installed them. He also had a set of pistons that had been modified only thing was it looked like factory cast pistons were use and I run forged pistons in my bike. I'm trying to find out what the mods are so I can make the same mods to my new Wisecos. He said they were modified on the top and I wondered if the dome was rounded more in order to add to the transfer and the exhaust timing duration. Can anyone help me out? Then also how much would that drop the cylinder pressure?

Thanks,
DC
Zunspec4
Expert racer
Posts: 1087
Joined: Tue Dec 16, 2008 11:37 am
Country: UK
Suzuki 2-Strokes: T500R, SV1000S, TS125, Seeley T500
Location: Trowbridge UK

Re: T500 piston mods

Post by Zunspec4 »

Hi DC,

Altering the dome of the piston will make no difference to the port timings* but the PO may have done this to set the squish clearance. On my race engines one uses Weisco and the other Wossner and the combustion chamber is profiled to match their particular piston domes.

Cheers Geoff

* - Unless the dome is lowered solely in line with the transfer port opening which is effectively raising the transfers.
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tz375
Moto GP
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Joined: Mon Nov 03, 2008 10:47 am
Location: Illinois

Re: T500 piston mods

Post by tz375 »

It's not unheard of to modify the crown of a 2 stroke piston, but it is unusual. Do you have any pictures so we can see how different they look to stock or to the WISECOs?

BTW, for the street, cast are arguably more suitable. And they are cheaper. But if you already have the Wiseco's it's a moot point.
dbc105
On the street
Posts: 20
Joined: Thu Mar 26, 2015 12:06 pm
Country: USA
Suzuki 2-Strokes: T500

Re: T500 piston mods

Post by dbc105 »

No, I don't have any pics or measurements. I've read of where a two stroke piston is modded either on the crown at the locations of the exhaust and transfer ports and it said not to get any closer to the top of the top ring groove than 2mm.

As to the cast pistons, it is not a street bike it is one of my race bikes and everything I've read has said don't turn cast pistons to higher rpm due to skirt problems. So it is just as easy to run forged.

As to the squish, he didn't have squish heads, he just had stock heads which have no squish. i wish I had a set. I save a little money I want to sent a set of heads to RK Tek and get them done.

I was hoping someone here was familiar enough with Zookie's work and would know. I looked at his profile and it didn't look like he has been here in some time and so asking him looks to be a stretch. These barrels look good and he did a fantastic job on them and I'm glad I was able to get them. Always good to be able to depend on someone else's experience that has had good success.

As a side note, looking to get it on the track next weekend at Roebling if all goes well.

DC
diamondj
Road race school
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Joined: Tue Oct 14, 2008 11:00 pm
Location: Wharton, NJ USA

Re: T500 piston mods

Post by diamondj »

Hey - it's possible the skirts were modified for timing, or they could be balanced so the piston weights are similar, or it could just be the cylinders are bored to match the cast pistons. The most likely mod is the skirt edges are chamfered to not catch on the porting. You realize your piston to cylinder clearance will be wrong (ie too tight) if you switch to the Wisecos, right?
D&D CHASSIS
Around the block
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Country: usa
Suzuki 2-Strokes: GT750 dragbike
Location: Vicksburg, MI

Re: T500 piston mods

Post by D&D CHASSIS »

I have heard RKTek is highly over rated....... according to quite a few performance sled guys......
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