350 YPVS into a TZR 250 1KT?

Technical questions and answers

350 YPVS into a TZR 250 1KT?

Postby nick_b » Wed Feb 17, 2016 1:55 pm

I want to fit a 350 YPVS into my TZR 250 (1KT). Has anyone here done this conversion? What is involved?

Cheers,

Nick
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Re: 350 YPVS into a TZR 250 1KT?

Postby Higgsy » Wed Feb 17, 2016 9:28 pm

A few have done it with mixed results, YPMer paul Toland has a 350 engined TZR race bike he's developing. Biggest problem with the the conversion is the length of the 350 motor, it makes radiator and pipes quite tight for space.
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Re: 350 YPVS into a TZR 250 1KT?

Postby nick_b » Sat Feb 20, 2016 1:40 pm

Thanks for the reply and the links.
Not so straight forward then!

Cheers,

Nick
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Re: 350 YPVS into a TZR 250 1KT?

Postby Higgsy » Mon Feb 22, 2016 4:45 am

There is one on ebay that keeps turning up, won't sell at the money the shop wants for it although i've seen the bike in the past and it's nicely done. As conversions go it isn't bad, just the length of the motor, so you need to get it as far back in the frame as possible. I did consider doing it at one point with an Athena top end, i doubt you would be able to keep the front wheel down :lol:
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Re: 350 YPVS into a TZR 250 1KT?

Postby Mikkel » Mon May 23, 2016 10:21 am

I am building one at the moment... :mrgreen:

I bought a frame and subframe that Was allready prepared - so now I have started rebuilding the 350 engine ;)

The plan is to use the existing cdi and wire harness from the TZR (HEARD its possible :roll: )

I Can send a few pictures IF you are interested?


And does anybody know, IF the TZR cdi and harness Will work with the rd350 engine/Stator/rotor???
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Re: 350 YPVS into a TZR 250 1KT?

Postby Higgsy » Mon May 23, 2016 4:29 pm

The TZR shares it's stator with the the F2 powervalve, so working on that theory the two should work together. I would use the F2 cdi myself I think, It's probably better suited to the 350 motor. The earlier 31K type stator and flywheel are very different and won't work with the later cdi. i don't know anybody who's tried using a TZR cdi, it might work but the advance curve would be a bit wrong i would have though. Wiring should be near enough, some of the colours will be wrong, but Yamaha are pretty standard in their colours and you only need the red/green/brown stator wires, the pickup is the same at red/white and green/white. The regulator wires are the same thee phase white. The plugs are different though, so you'll have to rewire them
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Re: 350 YPVS into a TZR 250 1KT?

Postby Mikkel » Tue May 24, 2016 7:37 am

Higgsy - thanks for the reply. This is very interesting!

I do have both rotor/stator from 31k and 1ua... I Will look into what to use ;)

Its for a trackbike - standard 1ua (64,50) cylinders, and Microns that more or less fits the frame... I would like it to rev as "much as possible" (11.000 max? I KNOW its hard on the crank - but I believe it Will make it easy to race :twisted: ).

My understanding is, that the 1ua cdi is very retarded - and Thats why I want to try the TZR cdi...
Only info I Can find about this is on bdk's site - so testing TZR cdi first. Next step MAY be zeeltronic ;)
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Re: 350 YPVS into a TZR 250 1KT?

Postby Higgsy » Tue May 24, 2016 7:17 pm

The F1 52y-50 cdi (F1/F2) is the one to use. The 1UA Cdi isn't really restricted, the curve has less advance all over i believe. I gained 4 hp everywhere when I swopped to the 52Y-50. If you are going to rev it that hard i would strongly suggest rebuilding the crank with TZ type flat cage bearings, the stock big ends won't take those revs.

Those Microns are horrible, you will gain a lot more power with a decent set of proper race pipes.

Everytime i've set up a Zeeltronic I've ended up on a curve similar to the 52Y-50, Yamaha got it right with that one. No matter what i did it wouldn't improve the peak power, I could custom curve around that base but it was only minimal gains. They work far better on an lc as the ignition curve is flat on those with no advance.

A 350 is all about torque. Torque gives you drive out of the corners which in turn makes the bike fast.

Watch this vid as an example https://www.youtube.com/watch?v=aO0keMiR9L0

Half way through Matt (2015 YPM champion who's bike were are on) catches Rik riding my 350YPVS LC, the drive he gets out of the corners compared to the TZR is what makes him fast. If we could find away of taming the slightly wayward handeling and actually stopping the bike, he'd have cleared off i think.

Stock 1UA cylinders are OK, some work on the transfers and optimising the squish, about 1mm is spot on, will pay big dividends
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Re: 350 YPVS into a TZR 250 1KT?

Postby Mikkel » Wed May 25, 2016 10:02 am

I allready have built a Rgv framed RD-engined hybrid. It actually runs the 52y-50 cdi, jolly moto's and 35mm pwk's.
It runs GREAT!
But the Rgv frame is not allowed in 1980-1987 (max 600 cc 4-stroke or 400 cc 2-stroke) class, where I want to race next year :| :mrgreen:
Thats why I am building the TZR 350!!! :twisted: (And I promise - IF I get the TZR 350 to run Well, Then I Will look into better piges ;) )

And that video is GREAT!!!! It shows very Well the Breaking and handling of the TZR - and the power of the RD !!!
Best video I have seen so far - thanks for that link! ;)


Back to the cdi's...
I can find information about 31k and 1ua cdi curves on the internet. All in degrees.
But the only information about TZR 2ma cdi curves I Can find - is on the bdk site, and suddently i mm...?! :?: :shock:
I havent Got enough knowledge to relate to that - so do you know where I Can find more 2ma cdi information? Just so I Can compare to the RD cdi...
(Other wise, I can only rely on my "Butt-dyno"... :oops: :mrgreen: )


I dont Think I Will do any porting on my 1ua cylinders - but skimmed heads are on Their Way from the machine shop 8-)
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Re: 350 YPVS into a TZR 250 1KT?

Postby Higgsy » Wed May 25, 2016 10:15 pm

Never really found any proper information on the TZr cdi's, I guess somebody more clever than me could work it out.

What series do you race in and which country?
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