TZR500 Race bike

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Helmers
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Re: TZR500 Race bike

#76 Post by Helmers » Sun Jan 17, 2016 11:03 am

Thanks Gary! As you see from the dyno chart above Alexander, it made 111 rwhp at 10.400rpm with a waterleak into one cylinder present. The new cylinder adapter plates solves the problem, and increases crankcase volume in addition with longer rods.

The TZ cylinders and exhaust should make most power at 11.700-11.800 rpm, so I'm hoping to get +130 rwhp ;)


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alexander
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Re: TZR500 Race bike

#77 Post by alexander » Mon Jan 18, 2016 8:35 am

Nice. What size connecting rods are you using? What about pistons? I think you should be making more power with the leak fixed. Nice idea. I know the cylinders are not cheap.

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Re: TZR500 Race bike

#78 Post by Helmers » Mon Jan 18, 2016 3:25 pm

Hi! Originally, I used standard RD500 cranks and rods. Since I needed to make new adapter plates anyway, I made them 10mm thicker and bought Krauser 500 rods which have the same dimentions as RD, only 10mm longer.

Foreward Pistons are Yamaha TZ250 4DP. They fit right in. Rear pistons are Yamaha TZ250 1RK. The thing is that the TZ pistons wrist pin is about 1 or 2mm offset towards rotational direction. (Std tz crank rotation is anti clockwise, and wrist pin hole is 1-2mm in forward direction) Both RD crankshaft rotates anti clockwise. Because of this, you cannot only rotate the rear pistons 180 degrees. In addition to this, the piston skirt cut out must face towards the transfer boost port.

Therefor, for rear pistons, I have used 1RK pistons with no cut out as standard. I have machined off the piston ring lock pin, and drilled a new hole at the opposite side, for the ring gap to face inlet side, and made a cut out in the piston skirt.

You got it ;) Sounds difficult, but not so hard to do in reality.

I have also made a "cylindrical weight" to fit inside the rear piston wrist pins to mach the forward piston weight!


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Re: TZR500 Race bike

#79 Post by Helmers » Mon Jan 18, 2016 3:35 pm

ImageImageImage


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Re: TZR500 Race bike

#80 Post by WVWRZ500N » Mon Jan 18, 2016 3:51 pm

Helmers,

I wouldn't install the weight in the wrist pin. Had a similar discussion on a private tuners board. The fact is the transfer of mass from + to - tends to dislodge anything inside the wrist pins.

If it were me I'd try and lighten the other assembly somehow.

Regards,
Bill Wilson
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Regards,
Bill Wilson
Wilson Performance
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http://www.wilsonperformance.net" onclick="window.open(this.href);return false;
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Re: TZR500 Race bike

#81 Post by Helmers » Mon Jan 18, 2016 4:05 pm

Hi Bill! Thanks for the feedback. I don't remember exactly the weight differance, but I think it was 12-13 grams. I'm not sure if the forward pistons can be lightened this much by only removing aluminium from "non important areas". I'll have another look.

However, they are pressed in by force and glued with epoxy, but if the ever should come out...


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Re: TZR500 Race bike

#82 Post by Helmers » Mon Jan 18, 2016 4:28 pm

Forgot to mention Alexander, but the rear 1RK pistons where also machined to have a flat top like the forward pistons.


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Re: TZR500 Race bike

#83 Post by WVWRZ500N » Mon Jan 18, 2016 4:33 pm

m
Last edited by WVWRZ500N on Mon Jan 18, 2016 5:32 pm, edited 1 time in total.
Regards,
Bill Wilson
Wilson Performance
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http://www.wilsonperformance.net" onclick="window.open(this.href);return false;
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Re: TZR500 Race bike

#84 Post by WVWRZ500N » Mon Jan 18, 2016 4:34 pm

Helmer,

You might looking at a different wrist pin all together. It looks as though those are the same ID all the way through. Wiseco pins are tapered back on the ID and thinner in most cases.

Image

What is the big difference between the upper and lower top end?

Regards,
Bill Wilson
Wilson Performance
Lee's Summit, MO
http://www.wilsonperformance.net" onclick="window.open(this.href);return false;
Member RZ500 Owners Group #573
816-377-3185
WVWRZ500N@aol.com
Regards,
Bill Wilson
Wilson Performance
Lee's Summit, MO
http://www.wilsonperformance.net" onclick="window.open(this.href);return false;
Member RZ500 Owners Group #573
816-377-3185
WVWRZ500N@aol.com

Helmers
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Re: TZR500 Race bike

#85 Post by Helmers » Mon Jan 18, 2016 4:53 pm

Thanks for the advice! Piston wrist pin off-set is the reason for the custom rear piston set-up. Both cylinder banks has the off-set towards the rotational direction. The TZ4DP lower pistons also have a standard cut-out towards the inlet side. If you where to use the TZ4DP pistons at the rear bank, (and ofcourse rotate the piston ring 180 degrees to get the wrist pin off-set correct) the piston skirt cut-out will make an opening to the exhaust duct at TDC, if I understood you're question.


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Rick Lance
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Re: TZR500 Race bike

#86 Post by Rick Lance » Mon Jan 18, 2016 5:29 pm

In my opinion, the motor wouldn't care less about a 15 gr difference between front and rear piston and crank assemblies. It would probably perform better without the extra weight added just from being lighter overall (splitting hairs here). Pistons on the same crank, that's another matter. If they are pressed in, there's no clearance for epoxy between the parts, only on the end of the plug. Hard to say what combustion temperatures will do to press fit clearance with dissimilar expansion rates of the pin and plug. Engine vibration could give it a reason to move.
Helmers wrote:Hi Bill! Thanks for the feedback. I don't remember exactly the weight differance, but I think it was 12-13 grams. I'm not sure if the forward pistons can be lightened this much by only removing aluminium from "non important areas". I'll have another look.

However, they are pressed in by force and glued with epoxy, but if the ever should come out...


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Re: TZR500 Race bike

#87 Post by Helmers » Mon Jan 18, 2016 6:34 pm

Thanks for the input Rick! The feedback I get from all of you is highly valued!! O though the engine project looks good in general, I'm far from an expert, just a two-stroke addicted with high ambitions ;)


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Re: TZR500 Race bike

#88 Post by pstamper » Mon Jan 18, 2016 10:56 pm

You guys are way over my head on this. This is why major mechanical work is left to you. I am trying to figure out how to mount my gauges. And on the lighter side.

Thanks Solo 2
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Re: TZR500 Race bike

#89 Post by Smoker » Mon Jan 18, 2016 11:11 pm

I was wondering why a plug in the wristpin that might come loose?

Isn't it easier to machine a heavier (thick wall) wristpin? :smt017

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Re: TZR500 Race bike

#90 Post by Helmers » Tue Jan 19, 2016 3:42 am

Hi Smoker! Bill recommended the wiseco wrist pin which seem heavier. I'll look into that option!


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