What_a_teezer Posted July 28, 2021 Share Posted July 28, 2021 (edited) Hi everyone, i've just bought an early model tzr 125 and while i may also soon be posting asking for help on obscure knowledge for how to get it running perfectly, it should be manageable... (im going to regret saying that) So in short im wondering if anyone remembers the best ways to squeeze reliable power out of the 2rk (i need to check exact engine codes tomorrow) motor and if there are any reliable specialists still about. Also a more specific question i have about my new purchase; do the later model (4dl etc) servo motors for the ypvs valves fit straight onto the earlier models? As i have a U.K restricted model i assume making the YPVS work as intended is one of the best places to start looking to increase power? Any information on good parts to fit on an early model TZR 125 and how to get the YPVS working is greatly appreciated, cheers everyone! Edited July 28, 2021 by What_a_teezer Link to comment Share on other sites More sharing options...
jcr Posted July 28, 2021 Share Posted July 28, 2021 my first and favourite bike was a little TZR125. my advice would be leave it in its restricted state. i eventually bought the ypvs motor for mine, and while it makes the bike a lot faster, it wears the top end out alarmingly quick. derestrict it, and you will be doing regular top end rebuilds. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted July 28, 2021 Moderator Share Posted July 28, 2021 Agree with the above, also. Being of a suitable vintage myself i was one of the spotty yobs getting their hands on these at 17 , well there were a few earlier RDZ125s that had powervalve motors about that we cut our teeth on. Much as many folk went out chasing units to power up the servo, the slightly more budget option, better than just opening the valve as without the servo drive it self closes over a few days was far simpler and cheaper. We used to get hold of a lhs powervalve assembly from a 350 (10 a penny at the time) and then use a choke cable from a car, anything works, cortinas and escorts at the time as they were in the breakers but you get my drift. Fit that to the bars somehow, bingo, adjustable power. You will need either 2 cables or a locking choke cable and a return spring. You do need to use a de restricted exhaust and rejet the carb to full power spec or you will destroy the piston (if you need to ask...) Link to comment Share on other sites More sharing options...
jcr Posted July 29, 2021 Share Posted July 29, 2021 you can take the power valve out and rotate it 180 degrees to get a feel for the top end rush. you will lose all bottom end power, then the engine will suddenly go bonkers in the upper rev range. fun to try, but not to live with. Link to comment Share on other sites More sharing options...
What_a_teezer Posted July 31, 2021 Author Share Posted July 31, 2021 Thanks for the replies already everyone! Well this is going to be a fun weekend bike, garaged 9 months of the year most likely, and im already going to have to rebuild the top end anyway it seems so im still inclined to hook-up the servo considering ill struggle to break 1k miles in the year and the engine will be freshly re-built (and run in!). From what i've heard a big bore kit will cause catastrophic bottom end failure eventually, can anyone confirm? i'm looking at the 120 quid Giannelli exhausts that still seem to be everywhere for the tzr's and then jet the mikuni vm26 that the bike already has on it, hope the carb wont restrict power after tuning? As for the ypvs servo i'm assuming 'cynic' was talking about like a mechanical alternative to matching one specifically for the tzr's which is a great idea and could work great but there is someone with 4 ypvs valves for sale from like the 4dl and up which i think means they have the control modules in the servo too, so instead of having to find a control box as well as servo then splice the box into the cdi you just splice the servo wires straight into the cdi and away you go? If this is true wouldn't that be the easier (and potentially cheaper too) way to go? Link to comment Share on other sites More sharing options...
Moderator Cynic Posted July 31, 2021 Moderator Share Posted July 31, 2021 They are 2 different systems, the servos may be the same, they actually use the servos in tdr250, the rd's all the way up to 500 as well as the vmax believe it or not. As to the control, they are 2 different systems, you either have the cdi and the control box that lives in the tail (early) or the later unit where it is all in the cdi, shooters choice on that one, or, junk the whole sorry unreliable mess and upgrade to a zeeltronic ZEELTRONIC - HOME unit that controls ignition and allows you to set up the powervalve to your preference. As to the bigbore, yes an athena big bore makes these into serious 100+mph motorcycles but the gearbox cannot handle the torque, lacking thrust bearings and positive lubrication so it dies. Considering how good and well rounded a sweet tzr motor is you don't need a bigbore. One thing that is utterly unescapable on yam liquid cooled 2 strokes, genuine or athena head gaskets ONLY, anything else WILL fail. 2 Link to comment Share on other sites More sharing options...
What_a_teezer Posted July 31, 2021 Author Share Posted July 31, 2021 Ok i seem to have found a fairly well priced full athena gasket set, this might be a stupid question but if it turns out the engine we're building is screwed can i re-use the gaskets for the top end when i re-fit a rebored barrel? The zeeltronic stuff looks great, im assuming since it supports dt125's it also supports the tzr125? Because it doesnt mention compatibility with the tzr125 specifically. I'm guessing what you mean with the ypvs stuff is that if i can find a 2rk/rh/rm etc etc valve and box it should work just fine but if i use the later ones for 4dl etc etc id need a 4dl cdi unit too? Wondering if the cdi unit for the 4dl would work on my 2rk... OR i could some zeeltronic stuff but the site kind of confuses me, if their stuff is even compatible with the 2rk tzr125 do you know what products i would need to do what i want and how much the parts would be? Thanks again for the reply! Link to comment Share on other sites More sharing options...
Moderator Cynic Posted July 31, 2021 Moderator Share Posted July 31, 2021 2 hours ago, What_a_teezer said: 1 Ok i seem to have found a fairly well priced full athena gasket set, this might be a stupid question but if it turns out the engine we're building is screwed can i re-use the gaskets for the top end when i re-fit a rebored barrel? 2 The zeeltronic stuff looks great, im assuming since it supports dt125's it also supports the tzr125? Because it doesnt mention compatibility with the tzr125 specifically. 3 I'm guessing what you mean with the ypvs stuff is that if i can find a 2rk/rh/rm etc etc valve and box it should work just fine but if i use the later ones for 4dl etc etc id need a 4dl cdi unit too? Wondering if the cdi unit for the 4dl would work on my 2rk... OR i could some zeeltronic stuff but the site kind of confuses me, if their stuff is even compatible with the 2rk tzr125 do you know what products i would need to do what i want and how much the parts would be? Thanks again for the reply! 1 I wouldn't. 2 Best to speak to them. From the tdr forums I use the zeeltronics units are the goto upgrade as cdi's for TDR's and TZR'S are getting harder to find and more expensive not to mention guaranteeing its working. 3 Yes. The earlier bikes have different cdi's that won't swap. Whatever bike you have will dictate the cdi you use. Often the cdi needs the corresponding flywheel and mag combination too so beware of what your changing and why. You could end up chasing down very rare parts. That's why the zeeltronics is such a tempting option. 2 Link to comment Share on other sites More sharing options...
What_a_teezer Posted July 31, 2021 Author Share Posted July 31, 2021 So what you're saying is the 4dl servo with the control unit inside wont work if spliced into a 2rh cdi unit (even if its a 3 wire 4dl servo) and it would be instead a case of 4dl servo needing a 4dl cdi, which would also need the 4dl flywheel and mag / whole engine in order for the cdi to work? ill give them a call at some point but is there any rough price i might be looking at? I can't find any prices or even ways to buy any zeeltronic stuff from their site... I've got a mikuni that has "26" stamped on the air filter intake end, im assuming this is a stock carb and is also known as the VM22? Also again does anyone know if the giannelli exhausts are any good on the tzr125? link: https://www.ebay.co.uk/itm/113678185449?epid=2109577761&hash=item1a77bf73e9:g:6yQAAOSwiZhcgksl Link to comment Share on other sites More sharing options...
Moderator Cynic Posted August 1, 2021 Moderator Share Posted August 1, 2021 The gianelli pipes were always regarded as a better pipe that gave better mid range at the expense of a little bit of top end power. Microns on the other hand gave you every ounce of top end go but if your engine was not 100%... They got a bit of a rep as engine killers because of it. Not fair really, not a new thing kids blaming others eh? All I know about the actual servos for certain is they are very reliable and some have more wires than others. But yes if you have a 4dl the safest route is all 4dl parts. Link to comment Share on other sites More sharing options...
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