350 YPVS into a TZR 250 1KT?

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Re: 350 YPVS into a TZR 250 1KT?

Postby Yatsushiro » Thu May 26, 2016 8:02 am

Stroke, conrod length & a bit of trigonometry will get you the curve in degrees...
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Re: 350 YPVS into a TZR 250 1KT?

Postby Yatsushiro » Thu May 26, 2016 9:48 am

With a ø50mm stroke, and a 105mm conrod length:

0.5mm = 10.32°
1mm = 14.52°
1.2mm = 16.03°
1.6mm = 18.55°
1.8mm = 19.69°
2mm = 20.77°
2.5mm = 23.27°
3mm = 25.55°

So the target for peak power is 1.051mm BTDC at the revs where your pipes peak.

You then need to take into account the +/-5° tolerance that Yamaha (Nippon Denso) seem to have built into their CDIs...
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Re: 350 YPVS into a TZR 250 1KT?

Postby Mikkel » Thu May 26, 2016 12:11 pm

Yatsushiro - This is very interesting! You are giving some good hints to work with here! Thanks! ;)


Regarding TZR cdi curves - then this id what I found so far:

BDK race eng. - in mm:
http://www.bdkraceeng.co.uk/Bike2.html

A very interesting hybrid build (see 2nd last picture at the very bottom of page):
http://tzrchronicles.blogspot.dk/


So far it looks as IF the TZR cdi COULD be a good race cdi for the RD! :twisted: :mrgreen:


Higgsy:
I am based in Copenhagen, Denmark. I am going to race the scandinavian "modern" classic series, 1980-1987, 0-600cc 4 strokes (mainly CBR600 F1), and 0-400cc 2 strokes (mainly nothing - but have seen a RD350 here).
Besides that. I am going to race my rgv vj21 in the scandinavian 250 GP class (I will certanly struggle against the TZ and RS REAL race bikes :mrgreen: ) - but mainly I train/race trackdays on my various 2 strokes...

Hope it's OK that I am "spamming" the ypmrc forum - only doing it, because I find A LOT of interesting TZR/RD information here! ;)
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Re: 350 YPVS into a TZR 250 1KT?

Postby Higgsy » Fri May 27, 2016 8:03 am

Hope it's OK that I am "spamming" the ypmrc forum - only doing it, because I find A LOT of interesting TZR/RD information here! ;)


No you are fine Mikkel, we have friends of the YPMRC all over the world, anybody racing a Yamaha two stroke is cool by us :-)


Yatsushiro - This is very interesting! You are giving some good hints to work with here! Thanks!


See I said somebody more clever than me would know the maths :lol:

Two strokes in general are quite rare in Scandinavia are they not?
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Re: 350 YPVS into a TZR 250 1KT?

Postby Mikkel » Tue May 31, 2016 8:05 am

We did have quite a few rd350's "back in the days". It seems as IF they are all crashed now :D

I believe Denmark Got less than 20 rg500 imported - and probably a similar number with rd500...
Kr1s, Rgv and the aprilia rs250 were imported - but rediciolusly expensive!

That all adds up to the fact, that they a kind of rare to see now - and People dont really Care about Them here, so when they come for sale, they are often in terrible and negleceted condition... And priced thereafter...
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Re: 350 YPVS into a TZR 250 1KT?

Postby Mikkel » Sun Aug 28, 2016 3:09 pm

Higgsy... In an other thread I read that you worked on static advance on the 1ua cdi:

"The curve on the 1UA actually looks smoother so there may be some advantage in adding static advance on the 1UA, experimentation still in progress."

What did you find out? Is the 1ua cdi ok when advancing it 3-4 degrees??
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Re: 350 YPVS into a TZR 250 1KT?

Postby Mac1 » Fri Jan 06, 2017 7:06 pm

DSC009552.jpg
DSC009552.jpg
I made this one last year from an SZR 660
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