Author Topic: Aprilia TZRS 125 hybrid...  (Read 2777 times)

Martin77

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Re: Aprilia TZRS 125 hybrid...
« Reply #30 on: May 12, 2017, 07:51:37 PM »
Nice curve that Andy :)

So you're going the 170 route too? I think you'll like it.. just remember to jet up a bit, and double check the pv cable setting. On mine with the pulley lined up with the mark, it was only about 3/4 open. Only when I looked up the port did I spot why it felt so flat initially!

I also went to a 23mm stinger, just to be safe..


Martin77

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Re: Aprilia TZRS 125 hybrid...
« Reply #31 on: April 06, 2018, 09:11:45 PM »
Thought I'd do a little update on the mighty Pipsqueek..it's only been a year or so since the last one!

I had a spare Brembo caliper from a Ducati, and in a flash of inspiration thought I'll see if I can fit it with a mounting bracket. A bit of playing with cardboard, eyeing it up.. it looked feasible. So, couple of spacers, drilling and tapping and hacksawing..it fitted!



What a difference, bit of experimenting with the lever ratio and it's really nice, plenty of feel and lots of power..

The suspension was always a bit firm over our bumpy lanes, so I've been trying to soften off the damping whilst maintaining the tautness. So, I thought I'd try putting a cartridge in one side.. I had some old ZX-something forks Alison had found in a skip, and a used RS fork for 30. Three days of oily hands and machining later...






I figured the ZX fork damping was set for a 200kg bike, and the RS is sub 100... so one ought to be close. for the compression damping control I just drilled a small bleed hole in the side of the cartridge. Some thin 2.5 fork oil.. some juggling with springs to match the rate as the stock springs (the space for a spring was less, so I couldn't use the stock spring, and shortening it made it much too firm). Anyway.... quite a bit of work, but the rebound adjuster worked great, going from too much damping to none, so plenty of scope for tuning. And.... it works! much more progressive, more natural feel on the brakes (I like a bit of dive), and no feeling of squishiness with the rebound dialled in.. perfect!

Which then showed up the firmness of the shock still, so that came apart again for some shim juggling. My home made spring compressor in action..(bit nervous doing this part)..



So swapped some shims about to spread the stack, and a couple off the rebound too. Bung it back together, pump it up with a hypodermic needle wedged in the end of a bicycle pump, up to 80psi.. (should use hydrogen, but I don't have any to hand). Feels plusher... just have to wind up the rebound a couple of clicks, but so far so good.. overall it's much nicer and feels more like a back lane scratcher.

Latest mod has been to fine tune the ignition timing, backing it off a couple of degrees at the top end gave it an extra 750rpm or so and a much longer overrev. And then I splashed out on a Yamaha Blaster Quad V force 4 reed block. Looking at the engine specs in a modelling simulator showed the ports were well matched after my tuning, but the intake was too small, so the V force with it's extra area should help match the intake to the rest of the engine. Some changes to the mounting holes and cutting off the manifold ears had it fitted;



This, with the retarded timing has given it a big increase in top end, so I guess it really was intake restricted... but still very useable, pulling from less than 3000 and overrevving to 11000, with no flatspots. Just wish I had a local dyno to see what it's putting out now..

And, the one mod I have lined up sometime is fitting a TMX35 carb as opposed to the stock 28 carb still on it. I found an old 2RH manifold gave the right angle for it, and once the carb end had been turned down and the manifold enlarged, it fitted fine. Even the splitter allowed full throttle.. only test fitted it so far though, will get around to it sometime soon...



Skimming the carb end..no going back now!


ybk

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Re: Aprilia TZRS 125 hybrid...
« Reply #32 on: April 06, 2018, 10:05:44 PM »
You make it look easy, nice to have the tools and skills to be able to do all that. 8) (-P)

Martin77

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Re: Aprilia TZRS 125 hybrid...
« Reply #33 on: April 06, 2018, 10:22:29 PM »
Reading it back, it makes me look like I know what I'm doing... I just like mucking about with things to see what happens :))

Louis

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Re: Aprilia TZRS 125 hybrid...
« Reply #34 on: April 07, 2018, 06:43:11 PM »
Hello Martin,

Looking good :) your project is going better then mine at the moment ::)

Having a flashback at your rotating carb, done mine exactly the same (-P)
King off all twostrokes ''TZR250 3MA''

Martin77

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Re: Aprilia TZRS 125 hybrid...
« Reply #35 on: April 07, 2018, 09:21:20 PM »
Thanks Louis.. a lot of the work was done over winter, and only now it's a bit warmer and I have some spare time have I actually fitted the parts to the bike..

Cutting the carb is always a bit nerve wracking, I don't want it to grab and fly across the workshop!