Benjersey

Plot thickens further guys, the reproduction cylinder barrel although looking well made has a different bolt spacing and size inlet port, new spacing is 70mmx52mm which is the same as a DT250 so I’ve managed to find a reed cage and carb boot from a DT250. Should be here this week and the fun can start. Can anyone shed any light or advice on if the different reed cage/inlet port size will change the required specifications for the carb. I am attempting to stick with the original VM22 still using the specs posted above by Cynic. Thanks, Ben

Love a good bits box! Happy to transfer money for postage and a box of beers to say thanks. Really appreciate it. Ben

Cynic I am happy to take your advice and stick with the 22mm it's a 4J300, do you think it would need any increase in jetting for the extra 50cc? Main Jet - 130 Main Air Jet - 0.5 Jet Needle - 4h16 Clip position - 2nd Needle Jet - 0-2 TS Cutaway - 2.5 Pilot Jet - 22.5 Pilot air screw turns - 1 1/4 Starter Jet - 20 Thanks as always, Ben

Quick update from me, not much has happened i'm still waiting on a piston to come down but have all the other parts ready. I'm still torn on whether to buy a new VM24 Mikuni rather than try to use the VM22(4J300) currently on the bike, this will involve drilling on oil injection port as it seems modern reincarnations do not come with them and originals are rare as hens teeth. Fingers crossed the postman comes this week so I can get cracking this weekend and give you an update with more substance. Ben

Fab thanks Cynic sounds like we are on, I know mine isn’t points so that rules out that option. I will build up with the existing CDI and see how she runs. Will take a gamble on the carb and just adjust the jetting as best I can to get the mixture correct. If not I’ll purchase a 175 CDI and mag if still not running right.

So before I embark on a conversion to a 175 top end I have a couple of questions that I would greatly appreciate help with. Firstly I cannot seem to get a definitative answer as to what the standard carb on the DT125MX was some places I look say VM24 and some say VM26 can anyone shed any light please or a way to check. Second question besides the head, barrel, piston, rings, small end bearing and new gasket set is there anything else that needs changing? would I for example need a 175 CDI this is assuming the carb is in fact a VM26 which is the same as what the 175's came with. Thanks as always Ben

Yep she's in pretty good nick Airhead, thanks for the compliment.

Nice one thanks very much to you both for the recommendation. Will give them a ring for a chat tomorrow. Bore on the cylinder is like a mirror so doesn't need any work, am thinking about building it back up as a 175 , stay tuned Cheers, Ben

Evening all, Noticed the DT was running rough on the way home from work, vibrations and a worrying rumbling noise lead me to believe it was worth taking a closer look. Pulled the head and barrel off and found lateral left to right play in the conrod caused I'm guessing by a knackered big end bearing. I'll split the case and get the crank sent off to have the bearing replaced. Can anyone recommend somewhere that would do a good job of this? no where in jersey can do it so it will be sent to the UK anyhow. Thanks, Ben

Hi I got it from my local tools supply place it's a Sealey one and can lift 140kgs of there abouts. Was about £120 if I remember rightly, it's useful as I can put it under the bench when not in use.

Hi all, I've been a lurker for a while so thought I should say hello, I'm currently in my purgatory year on a 125 before being able to ride something larger. The new 125's left me a little cold so after a bit of research I settled on a DT125MX and found one that needed a few little things finishing off. Plan was always to get shot of it but have decided to keep it, silencer hanger bolt thought 50mph was a good speed to fail and sent the silencer skipping down the road at the weekend but I guess that comes with the territory! Thanks, Ben