TY250 E Piston

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TY250 E Piston

Postby Stanm » Mon Feb 28, 2011 11:00 pm

Hi Folks
I have my TY250 E apart and I am looking to get and oversized piston.

I can source oversize original piston via ebay but will an after market perform much better and late as long? I want a good quality long lasting piston kit. Say 32 years would be good ( like last one the E was on the original piston !!! ) Some suggestions on brands and suppliers would be great.

I have also contacted redlizard co UK who sell Heptolite pistons. They said the don't supply TY ones. But the do supply DT ones. So is the DT 250 piston exactly the same? If so I would appreciate some advice / numbers /year so I can source the right piston.

Cheers

Stanm
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Re: TY250 E Piston

Postby TriCub » Mon Feb 28, 2011 11:24 pm

Not familiar with a TY250E(What year is it) but if it was me I would get the original if the price wasn't to bad. If you had an MX machine or some sort of race bike you would probably think about a Wiseco or a Wossner both of which are forgings. The original is very well made casting that if looked after will give you a very long life. The forged pistons are stronger but quite often a little heavier and need more clearence as the metal has a higher expansion rate causing them to rattle more.
If one of my customers asks for a piston to be supplied when I bore there cylinder, I will only get an aftermarket piston if the genuine is not available or in most cases double the price.
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Re: TY250 E Piston

Postby Stanm » Tue Mar 01, 2011 9:13 pm

Hi TriCub
The E is a 1978 twinshock pretty much the same as the B-D. It had a very strong stock motor when I got it several years ago. In fact I think the motor had very little use. I am very keen also to know the difference between these models. Particularly the A and E. I have and "A" piston barrel and head and the "E" piston looks the same to me. Is it in the crank space??? I will do some measurements and post them for comment.
I tried Wossner and they don't have any 0.25 or 0.5 oversize pistons.
Have you bored Ty's before? Are you in Melbourne? Can you advise what is the recommend bore clearance for the standard?
Do you think their is any performance benefit the after market ones?

Thanks for the advice

Stan
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Re: TY250 E Piston

Postby TriCub » Tue Mar 01, 2011 9:33 pm

I can't tell you what is different between the models but if the piston looks the same as the A model then a DT250 piston will work ok. I think I have done a bore on a TY250 before ,but after doing this for over 20 years the memory is a bit shaky. I'm in Brisbane. The stock clearance is around .05mm from memory. There is no performance advantage using aftermarket pistons although the Wossner has a teflon coating which is meant to reduce friction. I have not noticed any difference myself. I would still stick with a Yamaha piston if you can get one. The other chance is a Pro-x piston, I'll have a look in their catalouge later.
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Re: TY250 E Piston

Postby TriCub » Tue Mar 01, 2011 9:58 pm

Who did you try for the Wossner? The catalogue I have list oversizes starting at .5mm.
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Re: TY250 E Piston

Postby David Lahey » Tue Mar 01, 2011 10:09 pm

Tricub, you rebored my TY250B about 10 years ago and used a Wiseco DT250 piston and it has been very good for durability.
A local motorcycle mechanic rebored my TY250D motor (the one in the Majesty) and also used a Wiseco DT250 piston and it has also gone very well but that was only 2 years ago.
The Yamaha DT250 piston is the same in all the important dimensions as the Yamaha TY250 piston. Yes the TY250ABCDE can all use the Wiseco DT250 piston. From memory the windows are a slightly different shape in the DT piston, and this can be fixed by reshaping them. I don't remember how close in shape and position the Wiseco rear windows are to the Yamaha TY250 piston windows, but I remember that I didn't reshape them before use.
The TY250E barrel is the same design as the C and D models
The internal design of the B model cylinder is the same as the CDE models but is quite different externally to the CDE models.
The A model cylinder is different externally to all the others, and I have never had to pull my A model head or barrel off so I don't yet know how different it is inside to the others.
As good as the Wiseco pistons have been that I have used, I would still prefer to use original Yamaha pistons because they are quieter from a cold start and have proven themselves to be incredibly long-lasting and reliable.
David
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Re: TY250 E Piston

Postby Stanm » Tue Mar 01, 2011 10:10 pm

Hi
I got the lead for the Wossner piston on ebay. Actually never hear of them before but their spiel sounded good.
http://stores.ebay.com.au/firefoxracinguk
Advice re other suppliers and Pro X appreciated
Stan
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Re: TY250 E Piston

Postby Stanm » Tue Mar 01, 2011 10:41 pm

Hi David & Tricub
As you guys have both suggested I am now keen to go for the original.

My bore 70mm and have measured it at about 70.03-70.05 with a few cratches. The local guy I spoke to about a rebore suggested I got to 70.5 (skipping the .25 o/s) as he was no confident to get a clean rebore. ( without looking at It) Would this be your recommendation Tricub??

So now come the bit that is confuses me re the Original piston.

My E manual 2nd o/s - 438-11636-01 Rings 434-11610-02 and the A & B manual is the same.

I have seen some DT250 rings with the same number but piston is different. Any idea on the cross referencing on DT and TY original pistons. Or suggestion on the year of DT250.
Good to hear your opinion David and I will compare the TY head and barrel and head and let you know what I find. Have you ever researched the crank volumes of the different models?

Cheers

Stan
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Re: TY250 E Piston

Postby TriCub » Tue Mar 01, 2011 11:41 pm

You can try "Bikes and bits Importers" in Perth or "Serco" in Brisbane both are Wossner dealers and Serco have the Wiseco. I'm sure if you Google you will find them.
The Wossners are German made and at the moment are a bit cheaper. They both use the same rings and both are forged with the Wossner being coated with Teflon.
Boring to .25 can be tricky and if I have to do it I would bore it to the honing size (.075mm under the finished size) before ordering the piston so that if it doesn't clean up you can go up to the next size. Your local guy may not want to do that because it takes more time. Going to .25 from the original bore should be ok but if it has already been bored it might not be square anymore and that can cause problems.
If you go with aftermarket you can't get .25 so the last paragraph was a waste of my one finger typing.

David. I remember now I think!
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Re: TY250 E Piston

Postby Guy53 » Wed Mar 02, 2011 2:12 am

Don't know why but my first reply did not '' travel '' to Australia. I have in the basement a ty ( 434 model ) and a dt ( I don't remenber the model but will post the number ). The DT is heavier than the TY and the '' corner '' of the sleeve are slightly shaved on the TY. I will post pictures tonight ( I am in Canada )

Guy
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Re: TY250 E Piston

Postby Guy53 » Wed Mar 02, 2011 11:06 am

Here are the pictures of the pistons,
DT on the left and the Ty on the right. Note that the corner of the skirt on the ty piston is slightly cut to clear the crankshaft.

Guy
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Re: TY250 E Piston

Postby TriCub » Wed Mar 02, 2011 2:20 pm

Just picked up a Wossner catalouge this morning and they list the same piston for DT2/3, DT250, MX250 and TY250. I Guess they would have the corners cut away making them universial. If you got a DT piston it would be easy to trim of the corners to suit.
Incidently while I was at Serco I checked and they have the .5mm Wossners in stock.
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Re: TY250 E Piston

Postby Stanm » Wed Mar 02, 2011 9:50 pm

Hi Tricub & Guy
Thanks for the info I think I may be able to source a genuine TY/DT Piston. But still interested in the DT piston code.
I looked at MX250 pistons on Ebay the original pistons only have one ring and the skirt on quite a few look cut away more on the pin sides. So the aftermarket may suit but original???
Tricub thanks for the info on rebore I will try another rebore shop tomorrow. Its on the original bore so sould be OK square wise.

Cheers

Stan
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Re: TY250 E Piston

Postby Guy53 » Thu Mar 03, 2011 2:21 am

Hey Stanm be carefull in choosing MX, YZ or other high reving motor pistons, they don't have the same shape ( high reving motor tend to heat up ) they will be loose and you won't like the sound of your motor , plus I prefer a 2 rings piston.

Guy
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Re: TY250 E Piston

Postby Stanm » Sat Mar 05, 2011 6:30 pm

Thanks guys for your comments. I got a original 0.25mm oversized piston from ebay and Phil at Dandenong Motorcycles said no problems to bore to that.

So some info on the A vs E model as promised. I am keen to know why they are so different in power

I have started with the piston and head

Pistons look the same and measure the same or close with measurements by vernia
I have an original E piston that weighed 288 gms and a 1.0 0/S A the weighed 311gm. So that about same for weight vs size.
I think the E and the A piston are the same

The Heads
I levelled the heads and added water and got the following

Both heads take 33ml . I measured to the plug and 1cm in and measurements close to the same so I think the same profile. I believe the E and the A head are the same.

If anyone can suggest a critical dimension i should check please advise.

I will investigate the Cylinder next and Post the results

Cheers

Stan
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Re: TY250 E Piston

Postby David Lahey » Sat Mar 05, 2011 7:26 pm

Stan please compare the distance from the top of the exhaust port to the top of the cylinder. I'm thinking the E distance might be greater than the A.
Please also have a look and see if the conrods look different. I remember reading that one of the improvements that came with the B model was a lighter conrod compared with the A. I think this might be right too because my B and D motors have much less motor frequency vibration than the A.
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Re: TY250 E Piston

Postby Stanm » Mon Mar 07, 2011 9:21 pm

Hi David
I measured up most dimensions on the A & E cylinder and taped off the transfer ports and measured their volume by filling with water. I have attached the scribble results. From results conclusion is from the outside they look different but inside they are quite similar. Will investigate the crank and crank case volume next.

Cheers

Stan
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Re: TY250 E Piston

Postby Stanm » Mon Mar 21, 2011 10:29 pm

Hi David
Finally got around to checkingthe bottom end of the A vs E

I have both with the cylinder off at the moment.

Filled both cranks with petrol and got close to 490ml in both so not a great difference there.
Crank wieghts on E may be very slight ly thicker but only by 1mm.

Con rod on the A has markin of '311" and is 8mm thick

Con rod on the E has "498" marking and is 6.5mm thick

I got an original piston from Ebay and I believe it is a DT piston. It is almost 30gms heavier than the original Piston.

I will let you know how it goes.

Cheers
Stan
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Re: TY250 E Piston

Postby David Lahey » Mon Mar 21, 2011 10:50 pm

Stan I'm amazed that the port timing was so close between your TY250A and TY250E cylinders. I'm wondering if your A model is of a later type to mine. My A model has a very low ID number so I think it is an early one.

The first photo shows the front of the cylinder on my TY250A. Does your A cylinder have the flat round bit above the exhaust pipe like this one, or does it look like the cylinder in the second photo (which I think is an early B model cylinder) with the fins going all the way across the front?
David
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Re: TY250 E Piston

Postby Guy53 » Tue Mar 22, 2011 11:45 am

David, I have 2 434 cylinder and none of them as that flat round above the exhaust.

Guy
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