philhill

Hi, have tried a new plug and 2 old ones but still no spark, have put the old coil back on.... no spark. Checked kill switch as I regularly forget and can't remember which way it should go, with 'OFF' written in the ON (up)position. I checked electrical continuity with switch UP, showing the red square at the bottom and its passing current through. So I must be right, Yes? Anyway what do I check next? Hope its not the CDI gone wrong as just checked and they are £180!!!!!! HELP haven't ridden a bike for 5 weeks and getting withdrawal symptoms. Phil

Hi, Granbys sell original i believe but only to limited number of oversizes. Yambits sell patern in more oversizes and they seem ok to me though i have melted holes in a few and had one seize couple of months back but causes were more likely to be my fault ie wrong jets and ? lubrication failure. (I dont appear to be having much luck recently!) Good luck with your choice. Phil

Hi, can anyone help, DT was running fine then went on holiday and when i got back i tried to get it going and it wont start. Previously a good starter, now no spark. Have tried a new 'cheap' coil they sold me down the local bike shop for 20 quid which doesn't fit properly and a new spark plug, checked the connections, earth connector wire to the metal frame of the coil was chaffed and rubbing on the frame, but I presume this doesnt matter as its the earth, repaired anyway. Connected a meter set to voltage, to the input and earth and it sends the digits wizzing when i push the kick starter, but don't know what it read! Bit stuck now, electrics not my thing. Anyone know what to try next? Neither of my bikes are working at the moment and want to get back out on the road! Thanks Phil

Hi, have just got my DT175MX running again, see previous threads, and I keep feeling for a bigger gear when riding in top. As far as I know I am on standard chain sprockets for a 125. Is the 175 different and if not which way do I go, bigger front sprocket or smaller rear. Anyone know, done it before? Thanks Phil

Hi Cynic, Great thread, having just done this myself twice I wish you had posted a couple of weeks previous! Anyway just to let you know, as you gave me some helpful advice, my DT175 was finished yesterday and has run perfect from Mansfield to the Stafford show and back without any problems. Spark plug chocolate brown again! There was a hell of a lot of metal bits in the crank case chamber though, I don't think much went out the exhaust! Thanks Phil

Thanks Cynic, i will have a look at the timing when the rest is fixed but to be truthful i have no idea where to start with it as the timing is pre set with the CDI. The coil plate is fixed as previous with marks on the plate lined up with line on the crank case. There is a potential risk of the flywheel moving i suppose as I had probs tightening the flywheel onto the crank taper so will check this later. Thanks Phil

Thanks for the reply Cynic, I am wanting to use the DT as a road bike mainly to get to work over the winter, its great for town work but the bypass is part of my route as well and though there is a speed restriction of 50 it is tempting to stretch that out a little to see what the bike will do. You have warned in the past that the DT is not a bike for the bypass but in my teens I used to travel to and from Sheffield to Merseyside to see my parents whilst I was training, on a DT125 and about half that journey was on the motorway and didn't have any problem except for a blown exhaust once that was very painful on the ears! I would love to use the DT off road and there is a place called the 'Desert' just half a mile from me but it is illegal to use and has become too risky as police patrol and neighbours complain. If I could find a 'stealth' exhaust though I would have a go, shame no one makes one. With the previous carb set up ie none holing 4th from the top needle groove the engine made a loud clatter on a trailing throttle in low gears, low speeds, and loads of clatter and noise pulling away in 1st gear. This was reduced on the leaner mixture. If I go up 5 on the main but down to 3rd groove on the needle can I get the best of both? You seemed to suggest not? Would a cooler plug help and where can I find out more about the mods you describe? Thanks Phil

Hi, help wanted. Have been a bit unlucky or un-careful recently as I have managed to hole two pistons on my bike. I had just finished rebuilding the DT as a 175 (previously 125 which holed a piston sparking off the 175 conversion) and it had been running fine except that when I checked the spark plug it was a bit sooty (dark brown) so I went one grove down on the needle, from 4 from the top down to 3. Took it down the bypass to see what it would do and holed the piston again this afternoon!! Oh BUGGER !!! The advice wanted is, do I need to strip the whole thing down again? Is it possible/safe to remove the barrel etc and turn the engine upside down and spray engine cleaner, WD40, high pressure water or whatever into the crankcase chamber to remove the shrapnel instead of a full strip down which I have just done previous on last hole? Then when I have rebuilt where do I start with the carb set up. The carb is a VM24SS 2H500 but set up like a 3U500 with a 1.5 Slide cutaway a 4J6 needle and 170 (instead of a 160) main jet. The 170 jet was to compensate for a Fresco exhaust and K&N type filter. Any help/commiserations welcome

Hi Cynic, in the end i omitted the thick washer to enable the nut to be fully tightened, as it tightened it receded into the flywheel threaded area allowing less purchase with socket wrench and so perhaps there was some benefit in the nut protruding? I checked multiple times that the woodruff key was insitu, as best as you can without being able to see it and I feel sure it is in the right place. The magnetism in the flywheel did have a tendency to pull it out of place at times but I believe/hope it is seated properly now. I have put 100 miles on it now with no problem but will keep checking. One problem that has arisen since is that the old exhaust keeps cracking near the U bend i have had it welded but as soon as one crack is repaired an other appears. I think I may get a plate welded over the top of the existing metal but am also considering a new exhaust. Any suggestions on make, sound reduction is more important than extra power as the noise gets wearing after a while. Phil

Hi, another question regarding the rebuild. I have nearly completed the rebuild but had a couple of problems along the way that i will just mention first. I didn't get a gudgeon pin or small end bearing with the stuff i bought for my 175cc conversion. Just so others are aware you need a new pin and bearing as these will need to be longer and wider. I assumed I could use the 125's and this created 2 extra trips to Granbys which is an hours round trip each time for me, so loads of time wasted on Saturday getting these bits. Also I have got a standard 175 pin and bearing and my piston is 1.5mm oversize so there is till some lateral movement of the bearing on the pin and I'm hoping this won't have any detremental effect when I get it running? Anyway what i really want to know is why the nut on the crank, flywheel side won't do up all the way and protrudes a few mm from the treaded shaft. I'm fairly sure it was all the way on when I took it of. The nut has been properly torqued to 70 Newton/meters and there is minimal gap between the flywheel and the base plate and I have taken it off and put it back on about 5 times but it still won't do up ?? The flywheel appears to be well up against the taper with no wobble so can't understand what has happened ?!! Should I just swap the thick washer for a smaller one and hope its ok?. yours perplexed. Phil

Thanks for explaining that Cynic, I now know what to do. The crank and bearings are in the freezer! Phil

ps, have got new mounting bushes from Granbys for £30 which is still expensive but not as bad as you quoted as decided to do it properly in the end. Also the crank bearings from Granbys where only £5+ each and they have confirmed they are the right ones, so not too expensive in the end. Thanks Phil

Hi, have used a heat gun and mallet and got the crank and bearing out, bearing still attached to crank. I am going to have to buy a tool to remove the bearing! When done i presume I put the new bearing in the casing first heating the case to get it in, then heat the bearing so I can get the crank to fit through it? Just to confirm the lettering on the bearing will be facing out away from the crank, will it? Help to confirm would be great so I don't balls it up. Thanks Phil

Thanks Cynic, i'll get my rubber mallet out again then and give it hell with a bit of heat. Bushes look like shit and are mangled and misshaped so will try to get them out. If they tun out to be too expensive then i will get my mate to turn me something solid out of ally to replace them as I also can't see what they do if you are going to tighten up the other too solid fixings to the frame. Thanks Phil

Hi, eventually got round to stripping the rest of the engine. Have split the cases though this took some time and excessive rubber mallet and WD40 treatment as the rear large dowel was clinging hard to the cases! The rubber/steel rear engine mount inserts in both cases are seized in and need replacing any suggestions how to remove. I have soaked in WD40 type stuff and then whacked with a screw driver and rubber mallet but still refusing to budge!! Considering a drill next but does anyone have any other ideas? Also the crank is still in place in the left hand case but I am wanting to get it out so I can clean in there and replace the bearings and seals. The Clymer manual states that I need to take it to a Yam dealer to get it removed but can't I just whack it out with my trusty rubber mallet? Also the crank oil seal on the right case looks like its the wrong way round i.e. the metal spring round the seal lip is facing outwards away from the crank. Is this right? its the other way round on the left and not shown this way in the manual. Has someone put it in the wrong way? Any help gratefully received. Thanks Phil

Yeh, you may be right there i think the output bearing/seal is leaking as the chain is always well oiled!! I will give Granbys a ring for prices. They have original stuff and are handy for me. Thanks for making me do the right thing. Phil

Hi, just wanting some advice before attempting a strip down of my DT 125 MX engine. I was enjoying the improved performance of the 125 after fitting a bigger carb purchased from Oldgit. I was experimenting with the jetting and was getting 10mph better than previous ie 70 when previous best was 60mph when I lost all power and a little later discovered I had holed the piston, fun whilst it lasted though!! Anyway this is now the opportunity to convert to 175. I have stripped the left hand side but before I strip the right side I wanted to check if it is possible to just remove the clutch basket before i split the crankcase. I just want to remove the crankshaft so I can clean the debris out of its housing. The manuals show the engine stripped with left side of the engine down and everything stripped from the right side of the engine. Does it matter if you do it the other way round, I was thinking this should save me some time but usually when i try to cut corners something goes wrong and i regret not being more thorough and following the instructions so can I or not. Anyone in the know can you please let me know! Thanks Phil

Hi, was just reading the other thread on 'new rings for DT175' and read that the clearance between the piston skirt and bore should be 0.035 - 0.04mm. I have just bought a rebored barrel, new piston, rings etc to convert my DT125MX and decided to check mine out. The bore 'appears' to be ok according to the new rings which when placed in the bore give the correct end gap but the new piston appears to rattle a little in the bore and I am able to get a 0.06mm feeler in between skirt and bore. The piston is made by MITAKA and i was wondering about the accuracy of manufacture and if this is a quality manufacturer or not ? ! Or is it more likely that the bore is not accurate. Thanks Phil

Hi, yep I'm interested, Does anyone want an 250LC carb that just needs correct needle and jets? Phil

Hi, thanks for the responses, this carb has a jet needle 4J13 and then 3or5 but is slightly bent and I think a 150 main jet, the slide cut out is 2, the carb is generally in good condition. I would do a swap if oldgitonabike wants it and has the right one to swap? More torque would also be good if you know where to start with the jetting for the VM22SS, torque is always better than power to my mind which is why my other bike is a Guzzi, when it got really twisty in the Pyrannies my mate on his brand new Tiger couldn't keep up and I left him for dead, and the Triumphs not short of torque! That said I also love the DT when it comes into the powerband and starts screaching !!!!

Sorry, more carb questions. I'm converting my DT125MX 1982 with the barrel, head, carb etc from a 1978 DT175MX. The bloke I bought them of swears that the carb is correct and original but I can't find it in the manuals! its a mikuni, stamped 4L100. The carb looks quite a bit bigger than the 125's and when I Googled the number it came up as a VM26. Right so here are my questions :- Have VM26's ever been fitted to the 175's ? Would they work on a 175 (overbored to + 1.50)? Could the 125 carb work on the 175 engine? Can I buy the correct carb anywhere if the answers to the above are negative? Also how do I check if it is a VM26 and confirm the Google info, I presume the '26' is a measurement in mm, but where is it measured? I got the lot for £51 so can't really complain if the carb is wrong, but don't want to wait 6 months for the correct one to turn up on ebay. Thanks Phil

tried to post image but couldn't get it to work.

p.s. If you need the decals I am getting some made up and could get extra, mine are the blue and white striped onto a red tank, i could get other colours made but would need a colour match. Phil

Hi, doing exactly the same with the same bike, same year and need the same part, you also must live nearby as I'm from Mansfield. I got some rear indicators for £9 they are ok but the quality isn't as good, but look the part. The rubber on one indicator arm split and I have repaired with rubber inner tube patch glue. There may be varying qualities available as some are more expensive than others. Granbys in Ilkeston are good for bits and I was in today and asked about the rear light but they are no longer available. I am just waiting for a 175 barrel, head, piston and carb to come through the post, got the lot for £51 !! So there are some bargins out there. Phil

Hi, my silencer is about the same size but has a different end cap and double hole fixing, only one used, and is not as shiney. I will look for some packing and perhaps try a 'big one' if I can find one at the right price. Any idea about the paint colour or where to look, I have got the decals sorted. Phil