reboot Posted May 29, 2012 Share Posted May 29, 2012 Hi, does anybody know how to derestrict a 12w 1982 DT 125 LC. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted May 29, 2012 Moderator Share Posted May 29, 2012 Why, if by some slim chance its still restricted you will ruin it. Link to comment Share on other sites More sharing options...
reboot Posted May 29, 2012 Author Share Posted May 29, 2012 Thanks for replying Cynic. I just got the bike and I'm susing it out. It will do about 60 mph flat out in 5th but bogs down in 6th. From what I've read that indicates it's restricted. I'm only just getting back on the road due to back problems so need a light bike, the Guzzi's out of the question. A little bit more speed would help keeping up with traffic. I understood it was restricted only for the UK learner market. If the unrestricted 10v ( full power ? )version works OK and I can get it to that spec, why would that ruin it? From what I can gather so far the exhausts got a restrictor plate and I would need to increase the main jet. Any help gratefully received. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted May 29, 2012 Moderator Share Posted May 29, 2012 Its just at the moment its a genuine 30 year old classic. Seems a shame for a few mph you will never get to. Stop and think for a moment, could your car get to its max rpm in top and on a big hill would it pull you up. I have the 175 and know your pain on the speed issue as i would love another 10mph, but i'd only want another 10 afterwards. Link to comment Share on other sites More sharing options...
reboot Posted May 29, 2012 Author Share Posted May 29, 2012 If it's straight forward to do - exhaust and jet - and only makes it the full power version, as Yamaha originally designed it, whats the downside? According to the Haynes manual the restricted version makes 12 bhp at 7500 rpm and the unrestricted makes 21 bhp at 9500 rpm. Thats going to make a big difference. Now I'm not sure if this applies to the Mk 1 but I hope so. Link to comment Share on other sites More sharing options...
Moderator Cynic Posted May 30, 2012 Moderator Share Posted May 30, 2012 You won't get 9hp from an exhaust and a re jet. Maybe 3 or 4 and you will lose it from somewhere else, robing peter to pay paul. I would expect the euro motor to have differences in the piston and barrel, possibly the head and reed block too, not to mention the cdi. Getting close to double the HP from just an exhaust would have made it a legend back in the day, and from what i can remember it wasn't. They were out in the cold till they got the powervalve motor that the RD got first. Link to comment Share on other sites More sharing options...
YPVS TONE Posted May 30, 2012 Share Posted May 30, 2012 Just been reading an old Yamaha Technical Service Information Bulletin that was sent out to dealers regarding the power output of the DT125LC MK1. It says that the 12W ( Restricted) and 10V (Unrestricted) are basically similar but utilize different exhaust systems to alter the power output. 12W = 9.0Kw uses 12W-14610-00 Exhaust 10V = 11.9Kw uses 10V-14610-01 Exhaust Tony Link to comment Share on other sites More sharing options...
Moderator Cynic Posted May 30, 2012 Moderator Share Posted May 30, 2012 I can't believe its that simple, the ones i rode in the stone age were all peaky with a pipe on them. Made them horrible to ride, bloody things wanted to whelie everywhere, if you wanted to or not. Link to comment Share on other sites More sharing options...
YPVS TONE Posted May 30, 2012 Share Posted May 30, 2012 Found this conversion chart which the 10V unrestricted version works out at 15.95 HP http://www.aqua-calc...t-to-horsepower reboot Just out of interest could you see what the id mark of your carb is which is usually on the RH side of the carb stamped just above the oil inlet nozzle of the carb. The only reason I ask is that I have a Yamaha Service Data book that lists the same carb data for the 12W and 10V models i.e Carb Type / Manufacture / I.D Mark = VM24SS / Mikuni / 10V00 Main Jet = #80 Jet Needle / Clip Position = 4J13 / 4 Needle Jet = P-2 Cutaway = 2.0 Pilot Jet = #20 Air Screw = 1 1/2 Turns Out Float Height = 21mm + or - 1mm Link to comment Share on other sites More sharing options...
Moderator Cynic Posted May 30, 2012 Moderator Share Posted May 30, 2012 LOL, so the pipe is worth around 3-4 hp, thought so. Link to comment Share on other sites More sharing options...
reboot Posted May 30, 2012 Author Share Posted May 30, 2012 Hi guys, thanks for the info. I'm on a bit of a learning curve here. I made a mistake with the 21 bhp, it's for the rd 125 lc, 12 bhp for restricted model. Carb is 10v00. It appears the restricted model has a plate welded in the exhaust where it bolts to the engine. It needs painting so I'll check it out then, seems all I have to do is remove it, or would I have to rejet? Link to comment Share on other sites More sharing options...
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