Paul_R Posted March 11, 2010 Posted March 11, 2010 Hi, Can anyone give me some advice? My bike has been de-restricted and I can open the power valve manually, but this obviously loses power low down. So I want to fit a power valve servo to it. It's a 1988 TZR 125. What parts do I need and how do I retro fit it? Can I use the parts off of another bike or does it need to be a TZR125 from 87-89? Cheers, Paul.
Guest MaD.VeZ Posted March 11, 2010 Posted March 11, 2010 Minimum you will need is the servo and relevant cables. But with the bike being 88, I don't think you will have the right cdi, the cdi should have a 4 pin(iirc) block connector not connected to anything. If you haven't got the right one then you will probably need to replace the cdi and maybe the wiring loom(or part of it at least), with one from a later model (post 97 with the DTR so maybe the same for TZR). There could also be issues with the stator plate assembly im not sure about that though. You could replace the whole electrical system with one from a newer TZR with a PV system on. Its theoretical, but the electrical system from the DTR may fit, but that would be quite a challenge imo. Im just a DTR fan but they are very similar apart from rolling chassis. Maybe some else can give you a clearer answer. Vez
Paul_R Posted March 11, 2010 Author Posted March 11, 2010 Minimum you will need is the servo and relevant cables. But with the bike being 88, I don't think you will have the right cdi, the cdi should have a 4 pin(iirc) block connector not connected to anything. If you haven't got the right one then you will probably need to replace the cdi and maybe the wiring loom(or part of it at least), with one from a later model (post 97 with the DTR so maybe the same for TZR). There could also be issues with the stator plate assembly im not sure about that though. You could replace the whole electrical system with one from a newer TZR with a PV system on. Its theoretical, but the electrical system from the DTR may fit, but that would be quite a challenge imo. Im just a DTR fan but they are very similar apart from rolling chassis. Maybe some else can give you a clearer answer. Vez OK, Thanks for the reply. I'm new to bikes (this is my first one) So I dont know what a bike with the servo looks like and if mine would be compatable. How does the one off of the DTR work? Paul.
Guest MaD.VeZ Posted March 11, 2010 Posted March 11, 2010 It turns the power valve depending on the revs to keep the power flowing smoothly from low revs to high. As the power valve turns it changes the shape of the exhaust port. It opens the port fully, allowing more gases to flow through at higher revs, while at lower revs it closes, making the port smaller to stop the fresh gases escaping as the engine scavenges the mixture from the exhaust. (anyone else wants to put it better feel free). The TZR has the same engine as the DTR, apart from small differences with the cylinder head and gearing. The engine is also used in other bikes like the sachs xtc-n125. If you go for parts from a newer TZR, it is possible to put a PV system on your bike, there were only removed due to learner restrictions in the UK back then. Getting funny looks from my tutor, back to work for me Vez.
Paul_R Posted March 11, 2010 Author Posted March 11, 2010 It turns the power valve depending on the revs to keep the power flowing smoothly from low revs to high. As the power valve turns it changes the shape of the exhaust port. It opens the port fully, allowing more gases to flow through at higher revs, while at lower revs it closes, making the port smaller to stop the fresh gases escaping as the engine scavenges the mixture from the exhaust. (anyone else wants to put it better feel free). The TZR has the same engine as the DTR, apart from small differences with the cylinder head and gearing. The engine is also used in other bikes like the sachs xtc-n125. If you go for parts from a newer TZR, it is possible to put a PV system on your bike, there were only removed due to learner restrictions in the UK back then. Getting funny looks from my tutor, back to work for me Vez. Sorry, I know how the powervalve works....I meant how does the electrical system work over the servo with a cdi? Cheers, Paul.
Guest MaD.VeZ Posted March 11, 2010 Posted March 11, 2010 The cdi (Capacity Discharge Ignition) controls the ignition timing of the bike and tells the servo what position the PV needs to be for the revs at any given RPM. I'm not exactly sure what would stop you putting a cdi and pv from a DTR on a TZR, but it would be less trail and error with another TZR electrical system and PV imo. The cdi's from DTR's/TZR's have changed with the different years/models. I think the ideal years to aim for with a DTR is between 98-02(not 100% as CDI's are a messy topic for DTR's) as this seems to be the time they introduced the PV to the DTR in the UK and it had less restrictions built into the electrics/cdi. At that time Yamaha used mechanical restrictions (exhaust, inlet manifold etc) which are reversible relatively easily compared to the electrical restrictions from later models. Sorry for the waffle but i don't have Internet at home atm, so i'm trying to give as much info as i can before i leave college for the weekend. There are a few DTR gurus on here that should be able to help with some more info (or correct me where im wrong). Anyway hope this helps, Vez.
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