TD1B / Ascot YDS3CM Cast Iron Cylinders

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Yamanatic
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TD1B / Ascot YDS3CM Cast Iron Cylinders

Postby Yamanatic » Wed May 04, 2016 7:09 pm

An interesting bit of Yamamystery has befallen the TD1 shop; a small lot of obscure NOS Genuine Yamaha cylinders. By all dimensions, porting, and the castings themselves, they are TD1B cylinders. Except they are Cast Iron. Side by side with a set of chrome-bore alloy "B" cylinders, they are spot on identical in every respect. It even looks like the same mold was used to make them.

Without baiting any suggestions, best guess is they were made for YDS3CM Ascot? After wondering why Yamaha offered TD1B oversize pistons when replacement cylinders were all standard bore, these cylinders may be the missing piece to the puzzle. Since Ascots have TD1 motors, these would be ideal since they could be over-bored and re-used if they sucked sand; life in the dirt is not where chrome cylinders would be expected (especially back in he 1960's), but Scrambles/FT racers would not care given the versatility. Road racers would just buy new cylinders given they were cheap back in the day - also the extra weight of iron would be shunned.

Another thought is they were produced to satisfy the privateer tuner. They could be ported and immediately tested without concerns of having them replated after each modification. They could also be welded and cut to different shapes such as "D" ports. Any home mechanic could be his own R&D team without a heliarc welder and plating tank.

No reference to Iron race cylinders can be found in any parts or repair manuals, and for all intent and purposes, the seem to never have existed. They would not be YDS1R cylinders since they have the later bolt spacing, and not likely GYT-kit since they have AMAL/Mikuni flange type carb mounts unlike YDS3 spigots, but at best, these are only guesses. Any ideas ??

Warren

ambike

Re: TD1B / Ascot YDS3CM Cast Iron Cylinders

Postby ambike » Thu May 05, 2016 10:33 am

I don't know, but a while back I ran across the following listing and had similar questions.

http://www.ebay.com/itm/NOS-Yamaha-TD1A ... Sw5dNWs-hq

Yamanatic
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Re: TD1B / Ascot YDS3CM Cast Iron Cylinders

Postby Yamanatic » Thu May 05, 2016 10:49 pm

On a similar note, I sold a set of alloy TD1B cylinders to a gent in Australia a few years back, and when they arrived the NOS pistons he had wouldn't go down the hole; when he measured, they were just under .25mm too big. 1st OS. His answer was the pistons were to allow a bad seizure or broken ring damage to be machined out and the cylinder could still be replated. Made sense at the time.

byland
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Re: TD1B / Ascot YDS3CM Cast Iron Cylinders

Postby byland » Tue Feb 06, 2018 5:50 pm

Hello
Do you still have a pair of cast iron cylinders?
I am the original owner of Ascot scrambler I bought in 1966. Motor # D6-16486. Over the years and many moves all was lost except complete motor and tachometer.
My stock cylinders are on the second over with a bad scuff mark in one cylinder.
I would like to find my old frame and expansion chambers.
Thanks in advance
Tim

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Re: TD1B / Ascot YDS3CM Cast Iron Cylinders

Postby Yamanatic » Thu Feb 08, 2018 2:35 pm

Hi Tim,

Cool! Just sold my last Ascot last fall. Your numbers are spot on; 3CM Ascots are all in the 163xxx/164xxx range. I was wondering if anyone else had experience with those cast iron TD1 style cylinders. Those casters I had went to another early Yamaguy, but he may still have a pair (there were several sets). I'll let you know if he still has them - just sent a message his way.

Regards,
Warren

byland
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Re: TD1B / Ascot YDS3CM Cast Iron Cylinders

Postby byland » Tue Feb 13, 2018 2:09 am

Hi Warren
Thanks for looking into that for me. My Ascot was purchased in April 1966. Must be a mistake on my title it's called a YDS1M. Did your frame start with Y14xxxxx.
The cast iron cylinders with the same porting as a TD1B are for the Ascot. The Ascot piston has two rings not one like the TD1B.
Any ideas on where Yamaha got the pistons for the Ascot. Are they YDS3?
When I got the Ascot it was the fastest thing going at my local 1/4 mile short tracks in Ohio.
In March 1967 I raced at Daytona 200 250cc sportsman class, didn't finish burnt a piston.
Tim

Yamanatic
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Re: TD1B / Ascot YDS3CM Cast Iron Cylinders

Postby Yamanatic » Tue Feb 13, 2018 5:52 pm

Hi Tim,

Yes, your prefix is correct for an Ascot 3CM. I try to ignore what old titles say - they just mess you up!
The YDS3 2 ring pistons were the option for going oversize mainly because the single ring .25 O.S are so rare - most racers just ran one ring on the YDS3 pistons. There is a cutout on the race pistons to alter the exhaust timing. You could cut the ramp in the street bike pistons.

I talked to my friend with the cylinders; he still has them. They are NOS standard bore cast iron that have the exact profile and porting as the TD1B and the Alloy Ascot cylinders. If you eMail my home addy, I can forward you what he wants for them and send his contact info if you want to go forward:
war_bar@hotmail.com

Warren

.

TD250
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Re: TD1B / Ascot YDS3CM Cast Iron Cylinders

Postby TD250 » Wed Feb 14, 2018 12:35 am

I may have some of those pistons and rings available.

I have often wondered what model's they were used on; now I know. Thank you.


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