DT125R FORUM

This is a bit of a tee off from my power valve cable thread, however after confirming there is no big issue with my cables I thought it was better to continue the discussion in a more relevant thread of it's own.

So for people that didn't see my PV cable thread, I own what was and should be a full power 1993 french import DT125R. Back when I first got this bike it would happily sit with the clocks maxed out about 80/85mph. But I left it sitting under a cover for a while and unforunately it got a crankcase full of water and needed a rebuild.

So I pulled the engine. Fitted a Top Racing complete crankshaft with new crank bearings, upgraded small end bearing, Japanese Mitaka piston and a full Athena gasket and oil seal set. Then stripped the carb completely and made sure there was no corrosion or old full blocking anything, putting it back together with the original 240 main jet.

First test ride. Bike started nicely warmed up and seemed to ride okay at low rpm down my street, but as soon as I opened it up once it got to about 7k rpm it felt like I was hitting a hard rev limit. If it feathered the throttle down hill I could get it to rev past 7k, but under full throttle it just killed all power when I hit it. So took it home and pulled the plug which was looking very rich even though it was on the stock jets for an import. Decided to tryt a 220 main jet in it and this actually helped a little. Plug colour improved and it would now rev to 8k not 7k before doing the same. So took a guess the coil was breaking up under high rpm and fitted a new "racing" coil from square motorcycles, put a fresh plug in it and put it back on the 240 main.

Now the bike is much better. Pulls better, plug colour looks good and it revs all the way around to 11k. Well all the way to 11k in the first few gears anyway because it still won't go over 60mph.

Crank, Rod, Piston, Bearings, Seals = new
Carb clean and stock jetting
Coil, Plug = new
Power Vavle is set up and working correctly as per my previous thread.
Air filter is clean

Running out of ideas, where would you guys recommend looking next?

So took it for a ride today with the PV pinned and all that happened was I lost all the bottom end power under about 6 to 7K. Top end once it came onto power was the same as before. So seems my PV is working fine even with the kink in the cables. Still going to do the bike cable mod though will post back in this thread when I do. But for now I'll start a new, more relevant thread to do with the lack of power.

Thanks for all the replies everyone. Maybe I do just have a set of pattern cables on then. Got the bike back together with the PV pinned for now ready to try in the morning. If the top end pulls the same with it pinned and I know it's not a PV issue I've got then I might go ahead and do the MTB cable conversion HOTSHOT posted about. Really like that inline oiler setup and would be nice to get the kink out just to take the strain off the servo.

Hi, I've been reading this forum for years as it seems to be the best place to get advice on anything related to DTs but this is my first post.

This is my french import 1993 DT125R I picked up from Unit 5 some years back. It's my second DT, with my first being an early 2000's blue supermoto when I was in my 20s. 15 years later I decided to try and recapture my youth by picking up another and got this Pinky.

However it sat around for a few years now and unfortunatly it spent a lot of time outdoors (under a cover) and ended up with a crankcase full of water and needed an engine rebuild.
So a few months ago I took everything apart and put a new crank, bearings, rod and piston in it. Anyway I've finally got everything back together, but I'm not conviniced I've got the power valve right.

Mostly I'm just looking to see if everyones bike looks like this or if I've done something wrong?

As you can see from the photo below the adjuster on the left is wound almost all the way out putting a big kink in the cable and making the servo work harder. I can't imagine this is how it's supposed to be but it seems to be the only way I can get the two pin holes to line up on the cam and case. As far as the cables I've got 1 going to 2 and 2 going to 1, fairly sure this is correct. With the exhaust back off and my fingers up the port the edge of the power valve feels flush with the top of the exhaust port and the pin holes line up after cycling the ignition. When I put the ignition on the cam turns clockwise about 45 degrees and then back to lined up. Also if it makes a difference I have the diamond power valve with square hole in cam.

Note the reason I'm looking into this isn't just because it looks wrong but also because the bike doesn't seem to be making the same power it was a few years ago. I'm sure before the rebuild I could get it off the clocks at about 80mph+ (130kph), but although in lower gears it will rev right round to about 11k, in top it won't pull more than 60mph (100kph).

Any feedback appreciated.