G Digger

Hi guys it’s me again. i’m just trying to find out what the correct length of the clutch springs are for my 1978 dt250mx. my Haynes manual suggest 36.4mm. my manual I downloaded suggests 34.9mm. the ones I got from yambits are 34.7mm. ones for sale on autodoc suggest 36mm thanks in advance

Thanks for that. I think the best thing for me to do is post this on ebay specifying its to fit a dt250 1M1 spec. Cheers Digger

Hi everyone I have a barrel, piston and head off a 1M1. I know its off a dt250 but was wondering what the difference was between the 1M1 and the 1R7 engine. It is a spare so I am going to put on ebay once i am sure what bike its off. When researched it says its off a dt250f 1979. The 1R7 it says is off a dt250 1977-1980, hence the confusion. Thanks in advance for any helpful info. Digger Hi a quick update, apparently the 1R7 is european/UK spec and 1M1 is US spec. Next question are they inter changeable? T.I.A Digger

Hi everyone I have just reinstalled a oil pump on my dt after years of premix. It appears to be smoking a lot more. Do I remove a shim or add one to lesson the oil/fuel mix. I’m thinking add so it lessens the stroke of the pump. Am I right or wrong. T.I.A Digger

Hi sorry for late responce. bike back together all gears shifting nicely, neutral abit hard to find but manageable. read somewhere if chain a bit tight can cause this issue so i will loosen chain to see if improves. Thanks for everybody's help so far, cheers Graham

Hi I looked into the welded part and apparently the later models came with this part welded. Must have been a mod due to problems before. the teeth aren’t tight so that’s 2 things off the tick list although I am changing the shaft for the one I’ve bought as this one is slightly bent (about.5mm) Thanks for all your help will let you know how it is when it’s running

Hi Snakebite I've had a look. You are quite observant there is a nick in the change shaft but I think it’s how it’s made for clearance to stop it fouling on the drum. Have cleaned the drum now. Have put it together again tonight and it went through all the gears ok (WHAT !!!). Didn’t do anything different. Had to disassemble it to fit new shaft when it arrives so hopefully it will work .

Hi The top picture where you can see the worn bits on the spider, I'm not sure if that's just some bits of the file I used. I think the selector actually connects with the dowels behind that plate. see 2nd picture. The spider like thing I think that is just a way of securing the dowels in situe, i.e bent over them to secure in place. As for the nick on the lever I will have a look at that, I have just bought a second hand replacement for that. Anyway thanks for your help. Will let you know what I find

Hi Neo l have had a look, interesting but would help more with pictures. mine has not got clutch built up and not filled with oil yet. just making sure gears engage before rest of build.

Hi Neo have tried on every tooth tonight and it doesn’t move the drum. I think the movement when using the file is because it is radial so it’s moving it using 2 pins (top and bottom)but when using the selector it’s a push or pull movement on one of the pins. I think the selector drum has to be addressed so the change is lighter and smoother so I think it’s cases split and further internal investigation. will keep you informed. cheers mate and thanks again

Hi thanks Neo. I’ve had a look. It appears to link one tooth different to how I have it. I think I have tried it all ways but I will have a go in the morning. I have changed the internal selector drum, selector forks plus shafts. they looked ok but I thought there must be a reason why the shaft was bent! they are used but I thought I’d try them. internally I think it’s all good because when I use the file to rotate the selector it works through all the gears. Thanks again Graham will let you know tomorrow Yes got a Haynes manual but very vague description. Does look similar to how I’ve done it. Also I downloaded a manual off emanual but again a bit vague

Hi I’m having problems with my gearbox after strip down. I believe the problem was already there before as it was a non runner and when stripping I noticed the gear change shaft was bent about 2mm. I have straightened it now to about .5mm. When I try to change gear when gear selector is built up I get nothing but if I use a flattened file as a selector it changes ok. see photos Any advice would be great cheers Graham

Hi Neo all sorted now had to adjust spring length but all working good now. Cheers Graham