PICTURE_MAN36

Will it not work if I just jet the carb up with a bigger jet? Just had a quick look on good ole ebay and there's no carbs to be had!

Great ! You've just answered my 2nd question. Dug the airbox out, and the air box cover is on the left. The battery sits on the right. I bought the bike from someone who had used it as a field bike, and the airbox and oil tank were missing. Thought I'd bought the wrong airbox as the carb inlet from the airbox seems to be very tight. Will use a bit of fairy liquid to get them to fit together. The carb is a mikuni, and '4J3 00' stamped into it. Have fitted the 160 jet so hopefully this should be enough in its '175' guise. I've bought the carb repair kit but it looks like I've bought the wrong one. The rubber O rings in the kit look nothing like the carb I have assuming that I should get a float chamber gasket with the kit. Just refurbed the genuine headlamp I bought on EBAY.... next job the front forks. Thanks for your response.

I need to dig the airbox out. Its sat in a stacker box awaiting cleaning etc.. I'm a bit concerned now as I wasn't aware that there were different airboxes. I bought the bike as a field bike, and the air box, 2 stroke tank etc where all missing. I've managed to pick the bits I need up, but it would just be my luck that I have the wrong one... will check tonight when I get home. # Thank you

You've got me thinking now. I think mine had access from the right, so a 160 will be OK. I couldn't read the number on the original jet very well, but it looked like a 140 to me. Ok will give it a go with the 160. Thanks for your response. Cheers

If Yambits or Yuniparts don't have them try your local Yamaha Dealer. I am restoring a DT125MX and you will be surprised how many bits are still available.

I have a DT125LC mk 2, which I am in the process of restoring. Its on a 'C' / 1985/6 plate. It is the 1st DT model to come with the power valve blank, but without the servo etc. I understand from my local dealer who is quite knowledgeable on early Yamaha's that the UK did not receive the full power versions BUT that at the time a kit was available to enable the powervalve, and came with the servo & cables etc. Appreciate that the bike is now close to 25 years old, and that anything like this is likely to be long gone. However, I recently purchased some new old stock panels from a retired Yamaha Dealer, and we got onto this subject, and he told me that the DT125LC mk2 shared the same engine as the 1st TZR125 and that he thought that the TZR powervalve kit would fit. Has anyone ever attempted to fit a powervalve to an early DT125LC Mk2 or 3, and is this correct? I did own a DTR125 a long time ago, and I know that this engine is totall different, and the powervalve from the DTR does not fit the DT. Would appreciate a response from anyone who has done this mod. Thanks & Regards

I am currently in the process of restoring an 1981 'X' Plate DT125MX. I have opted to change the piston, barrel & head with a DT175MX, and have rebuilt the engine, and reinstated the 2 stroke autolube with a DT175MX oil pump, shaft etc. I am now ready to refurb the carb, which is currently dismantled for cleaning. I understand that I need to change the main jet in the carb as it will now run as a '175', and the '125' jet will not be sufficient and may cause the engine to run lean, and seize. The main jain in the carb is currently a 140. I've checked the good old Haynes manual, as well as the part manual, but can't make a lot of sense. The Haynes manual refers to anything from a 150 to a 200 jet. I intend to keep the stock airfilter box, and air filter. I went to the local bike shop in the village, and the guy at the shop suggested a 160 to start with, and if needs be switch to a 180. Does sound correct and what size jet would have been fitted to a DT175MX when it left the factory. Appreciate it can differ for different countries and climates, but I am referring to a UK spec model. Look forward to hearing from anyone who can help. Thank you

Update..... 13/10/11 Got there in the end. Engine now back together and crated up in the stacker box. Next job frame! The barrel does fit straight on to the 125 bottom end no problem. Note that the 175 barrel has 6 head studs not 4... thought I'd dropped a bollock but it works along as you have the 175 head for the barrel. Had the barrel and head vapour blasted, looks good. At the same time, I have reinstated the 2 stroke autolube pump. The bike had been run on premix and when I took the pump off it was easy to see why. The drive gear in the pump was totally wasted. The pump is lubricated by the 2 stroke oil, and I'm guessing that at some point the 2 stroke tank was ditched and the pump consequently seized. Bought a second hand pump from a DT175MX, thinking it was a straight swap, BUT this is not the case. PLEASE NOTE! The 175 pump is geared differently to the 125 pump, and you need to swap the pump if you're swapping the barrel!. This is OK if you have a complete pump and shaft, but mine came as a pump only as the shaft had been sold seperately. I thought my 125 oil pump shaft would fit the pump, but it did not, and 48 hrs and a few calls to the local Yamaha Dealer, and it became apparent that the part numbers were different. I had a quick look on EBAY, and there were no shafts in the country. I ended up buying a new shaft through the local Yamaha Dealer, which came from Japan at a cost of £ 20! Bargain! Sadly during the rebuild, the pump shaft collar became lost, so another weeks wait, and finally shaft, collar, pump, and casing all came together followed by the engine cases which have been freshly painted and now I have a motor that looks like its just left the factory. Next job Frame! I am hoping that all the work done to convert the engine to a 175 will be all worth while. I don't expect to have the DT on the road until next spring, but I'm looking forward to running it in, and pottering around the village, and lanes surrounding where I live.

Thanks. Spoke with my local Yamaha dealer in the UK, and the part I need is still available from Yamaha central stores in Japan. I was trying not to pay the dealer price, but it looks like I have no choice. I've spoken with a company locally who do new old stock, and they're comming back to me. I should have realised that the 175 barrel will need more oil; I'm trying to mate a 175 top end with a 125 bottom end to give me a few more horse power. I've had the carb rejetted, and just want to get the engone back together and crated up. Thanks for your response. Cheers

Finally a conclusive answer to the question. Spoke with the local dealer, and the DT125MX & DT175MX have different pumps and drive shafts. Suppose its logical; bigger barrel = more 2 stroke oil! If anyone is looking to put the 175 barrel on a 125 bottom end, you will need the 175 pump, and shaft! Now the hard part; unless I can source a 2nd hand shaft to go with the pump, its a trip to the local dealer, and £26 from the wallet!

Just looked on EBAY roughly around the same time and the shaft, and drive gear were sold for a few quid seperately, and from the photo the worm gear appears to be different to mine. It looks like the gear on the shaft which went with this pump is a lot coarser thread, and mine is finer. Guess that this means that the 175 pump is geared different to the 125. I'm a bit stuffed now. The pump that came with my bike had seized, and the driver gear in my pump has lost some teeth. The replacement pump works fine, but won't match with the fine thread on the worm gear on the 125 shaft... Happy days.... Many thanks for your response.

Thanks. That's what I thought but the seller sold this item seperately so I guess I am up the creek without a paddle. Just had a look on EBAY for a pump, and there is nothing to be seen. I guess its a call to the local Yamaha dealer tomorrow, and a trawl through new old stock lists. I've contacted him but had no response yet. I thought it was me. I guess that the worm gear on the 125 & 175 different. Thank you

Hello. Appreciate its an old bike, but I'd be appreciative if anyone can help with my problem. I am in the process of restoring an '83 / Y plate Yamaha DT125MX. I have taken the clutch cover off to flat it and paint it, and have disconnected the oil pump. Whilst it was off, I checked the pump and found the reason why the previous owner had run it on premix. The oil pump was seized. I bought another oil pump from a DT175MX on EBAY. The seller said that it was also for the DT125MX. Having painted the panel, I am now in the process of putting the pump back in the casing, and putting the casing back on. I have checked the new pump, and it is not seized, and the gear rotates with my finger. I have put my shaft from the 125, into the pump, and it is as if the worm gear on my shaft does not match with the gear wheel in the pump. If I put the collar in the pump the shaft locks up completely, and the pump will not go anywhere near the casing. I've taken chunks out of my fingers, and I am in danger of knackering the casing I've just painted, so I have come away for the evening. Does anyone know if the worm gear is different on the 125 & 175 AND if I do have to match up a '175' shaft with my '175' pump, will this work with my 125 (Which incidently now has a 175 barrel and head on it any way. Any help you can offer would be appreciated. Thank you

Did anyone ever respond to your mail? I have the same problem. I have a DT125LCII which I am currently restoring, and it also has the powervalve fitted. I've seen some threads that refer to using the servo unit from a RD350 Powervalve. Speaking with our local bike shop, the guy there told me that we never got the full power version, and he'd never seen one, although I see that some did come here are often advertised on EBAY. For sure, the DTR servo does not fit. Its a different shape, and its on the right hand side of the barrel, not the left. Also, you have to get the servo to work with the CDI. Apparently the CDI controls the powervalve, and when it rotates. I'd be interested to know if you ever got yours to work. Cheers

Thanks... I'll also look at these threads. To be honest my first port of call was the local Yamaha Dealer, and he said that he'd never seen the full power kit for a DT. I'd seen a few DTR servo's on EBAY, and was going to have a go with a DTR one, but they look totally different. The local bike shop guy was pretty clued up on them, and said that even if you get the servo fitted, you've got to get the CDI activate the servo. I think I'm going to struggle with a 25 year old bike, so will be happy to do a full restoration and leave standard... If anyone has spare plastics, I'd be interested. Thank you

Thanks for your response. I've just had a quick look at the bike on EBAY, and it has the same decals as mine. I notice he's got the wrong colour radiator cover. Its a red one, and should be white. Mine is the red version of this, and has the drum brake at the front also. I couldn't quite see whether it shows powervalve. As far as I am aware, the DT125LC was had a 6 volt electrical system, and the LCII got a 12 volt system, and blanked off power valve. The LC has no rev counter, but the LCII and LCIII have. I had an '88 E plate DTR and this looked very similar to the LC II & III albeit it stood a lot taller, and it went like stink! The clocks on my early DTR appear to be the same as the LCII so I'm hoping to pick some up to fit. I'm missing both side panels. but will keep hunting. Know what you mean about the powervalve.... I'm in my 40's now, and carrying a few more pounds that I used to do... I spoke with a local bike shop, and the guy has restored a few DT's and he said that full powered LCII did not come into the UK, and at the time, you could get one or the kit if you passed your test. He said that it was controlled by the CDI. I've be interested in your headlamp and surround, and I'd be very appreciative if you could email me a copy of the parts list. My email address is [email protected] Cheers

Thank you. I've seen that Yuni Parts are advertising a parts manual on EBAY. I've had another quick look at the bike and I'm sure that some of the bits for the early DTR are the same. I've picked up a headlamp bracket this morning, and I've seen an ad on the net for a new old stock head lamp surround. I've no switchgear, but again, I think they can be picked up new from somewhere like Yambits etc. Its the usual field bike, with lights, indicators etc missing, but the main bits I need are there. I've given up on the idea of getting the power valve working. Its a shame because I understand that it does make a difference. I had a TZR250 with the powervalve, and it went like stink! Bit flumoxed with the front end though. My Haynes shows the LC II with a disc front ent, but mine seems to have a drum. I had thought may be that I'd bought a LC and that someone had put a newer tank on with LCII graphics, only its definately an LCII engine with power valve, and Yamaha UK have confirmed it from their records. The frame number starts 35A. They very kindly supplied me with the registration number, although I note that DVLA now charge £ 25 for the priviledge! Cheers for the response.

Thank you. If you could let me know what bits you have I'd be appreciative. I need the usual stuff; clocks head light, tail light, head light surround, & 2 stroke tank (Why anyone would choose to premix rather than use the tank amazes me.) I had a long conversation with the guy at our local bike shop today. He's a source of info, and went through the differences between the LC Mk 1 & Mk 2 & Mk 3. I haven't actually been able to get my hands on the bike yet, as its still on its way to me, but should have it for the end of the week. I thought I'd sourced a servo kit for it today. Unfortunately the local bike guy informs me that the servo kit for the LC 2 & 3 is nothing like the DTR servo. I've a full licence anyway, but just wanted something retro to blast around our village on. Look forward to hearing from you. Thank you

Hello... I've recent bought a DT125LC Mk2 'field bike' which I intend to restore, and put back on the road. The seller says it is a 'B' or 'C' '85' or '86' DT125 LC Mk2. I won't actually see it until tomorrow as its an EBAY buy, but from what I have seen in the photo's there does not seem to be much difference between the Mk1 & Mk2, albeit I see that the radiator on the Mk2 has a small fairing in the right. As expected its missing the clocks, side panels, and the small fairing over the radiator. I know that early DT's are now like hens teeth (I've just started to restore an '83' plate DT125MX and it seemed that there are still plenty of parts for the 125/175MX). Does anyone know if the Mk2 & DTR share any common parts? Clocks, switches etc? I see that there are plenty of DTR's in the breakers yards.... I understand that the Mk2 was a cosmetic facelift of the Mk1 and that the Mk2 had a disc front end, but apart from that it was the basic 125 DT/RD engine. The Mk3 had the powervalve, and the DTR was the next in the series? Any comments would be appreciated... Thank you

Don't think that you'd quite get away with that one if plod stopped you... I know that a mate I did my YTS with ran a RD125DX with twin microns on, which did 85 mph ish.. I don't think my RD200DX did more than 90.. I think that a 125 doing the tonne might be a bit suspicious!! They were great bikes in their day, but were ultimately eclipsed by the 'LC's. I owned an '83 RD125LC which was good. Sadly I always wanted a 350 LC, but never had one, and don't think I could afford one now. I have a soft spot for 2 strokes... Cheers

I guess that you've done it the other way to make it learner legal? I am umming and rrring as to whether I want to re-register my 125 as a 175, or just leave it as it is on the V5. In the '80's when we were 16 we all had FS1E's RD50's Suzuki ER50's etc which had 60cc & 80cc kits on them, and I remember that some of the RD125MX's running about where in fact RD200MX's which were identical except for the electric start, which the 125 never had. I ran an RD200MX for a while with race pipes on, and I had a big job getting in MOT'ed as it was so loud.. I ran a HONDA MT5 when I was 16, and a local kid had a MT5 which rang rings round mine. It wasn't until I spoke with him one night when he was parked up at the local Tates shop that he confessed that he'd actually got a big bore kit on it, and it was in fact 60 kit... His did close to 55 mph, and mine did nearly 40 mph dependant whether it has just been decoked. Thanks for the info.. Happy days eh?

Thank you. I'm not sure of the state of the clutch so may opt to fit new friction plates. I've ridden the thing once, and it was running etc, but tatty. The exhaust gasket was leaking, and the gasket that joined the front and tail pipes was missing so needless to say it rode like a bag of sh*te... Looking forward to rebuilding the top end, and making the engine pretty. Thanks for the info with the front forks. It was something I was looking at in a perfect blue sky world. I planned to fit new shoes front and rear anyway, so it should stop, and to be fair it wont be thrashed anyway. I'm keeping the bike for me to re-live my youth on. It'll blast around our village with the odd run to town. Will let you know how I get on... Many thanks for your response. Cheers

Forgot to mention... I have a 'Y' plate / 83' DT125MX and its the last model they did with the mono shock rear end, before Yamaha went over to the DT125LC mark 1. Cheers