DT125R FORUM

Yeah, if you want originality, then try and source an engine that's correct for the period of bike you're trying to build.

Those crank cases and internals can be used, but you'll need to swap out a few parts and the engine numbers won't match the year for your build. Doesn't bother me with that sort of thing but your mileage may vary.

My servo do t seem to be getting any power it's not doing a cycle all the wires look good connections has me stopped myn is a 4 wore plug witha separate yellow wire it has me stupped

@StanKn

Mine was like it when I first sussed out it was removable. It was caked in what looked like cement dust!
I’m glad you got it running sweet again 😜

First gear, back brake on. I use a half inch socket with a slide bar, apply pressure to take up the ‘slack’ then a sharp tap with a rubber mallet usually does it…

Thanks for all the info sounds absolutely perfect for me, I'll definitely buy!

@erioni123

Like Callum said, use a flywheel puller to push the crank in and separate the cases. DO NOT use a screwdriver or chisel, please!…

A rubber mallet is usually enough for me…

@SpookDog

Ok i will try everything ……… I will find it 😂🤣

@Hark_Ptooie

Kinda pisses you off when your recently ‘rebored’ piston used to rattle back and forwards in the barrel, doesn’t it?! I had the same experience buying a REBORED barrel & piston.
I’m very particular about who does my rebores now…

Classic, well they say nothing last forever.

I'd change it at the recommend service interval, if nothing else, restores lost power.

Did you see my Cagiva Raptor. Nothing wrong with that engine on the face of it. Started on the button and ran really well. Last year I decided to do the service interval.

Turned out the piston had a hairline crack in on top of the piston crown and down the gudgeon locator...ticking time bomb.

I had a barrel replated, new piston/rings and the bike was utterly night and day in terms of performance. The thing absolutely flew.

Then a few weeks later it was really struggling to run. I went on an overseas trip and came back when the temperature had drops some, then the engine just died.

I haven't stripped it enough to figure it out yet, but at 30 PSI, prognosis is not good. I whipped the cylinder head off and the piston/bore are in good shape. My guess is the crankshaft seals have given up. The restored new power was just too much for them and they've let go.

Another one for another time

@Stevie-Wonder They're ace, they'll sell you a GPX TSE250R engine which bolts straight in, and other stuff like a cone-shaped shim which fits on a DTR crankshaft under the flywheel to enable running it in a DTRe bottom end.

Oh that's cool, though my brother ran a 38mm Keihin on his 2001 DTR. Just heated up the rubber and stretched it over.

https://www.youtube.com/shorts/bOGAEzTaBgI

There has to be somewhere in Europe that ships to Bosnia?

@HOTSHOT-III

Absolutely! The low to mid range is really quite something. I’m cruising at 55 @ 5K rpm so nicely, I’ve just got a new 18T front sprocket to try. I’m hoping it’ll make me rev it more. I’m riding it like a 4/ single at the moment!
I’ve upped the oil to just about 2.5%. I’ve been limp mode riding before now. I’ve just gotten over a spell of the pilot jet and main jet being partially blocked! (I thought the new CDI was failing!) it seems the paper-like filter was shedding micro fibres!
New tap, new pipe, new filter!…

Now that I can say it’s running properly! I’m going to get the auto lube refreshed and put back on…

Thanks for the info! Priceless!! 👍 …

@SpookDog Do you still have plain bolts and copper washers in your carb warmer hose connections? If so this could be the culprit. The official Yamaha procedure for bleeding the cooling system is to remove the carb warmer hose where it joins the thermostat housing (i.e above the actual thermostat), then fill the rad whilst watching for coolant to come out of the tube with no bubbles, then refit the tube and fill the radiator to the brim with the bike vertical. If your carb warmer circuit isn't operating you'll have a small air pocket below the thermostat until it opens.

I'm not a huge fan of the carb warmer circuit as IMO it's not really cold enough to warrant it in the UK and it makes getting the carb off a right PITA if you like experimenting with jetting, float heights etc. But it has another useful function which is to make the cooling system self-bleeding by allowing it to bypass the thermostat during refilling (this is why bikes like the 350LC without a carb warmer circuit have bleed bolts on the sides of the cylinders). So the best compromise I found was to just run a single hose directly from one banjo to the other, retaining the self-bleeding and not having to disturb the cooling system if/when taking the carb off.

I've never primed the expansion tank circuit and I'm not sure it would be necessary because as the coolant expands in use and travels down the tube, it would probably expel any air present anyway. But I guess you could by filling the tank, then putting a long tube over the filler hole to avoid ingesting any antifreeze and blowing through it until coolant comes back out the tube and fills the rad to the brim, then sticking the rad cap on quick and topping up the expansion tank. And definitely fill the rad slowly as @OllieDTR said.

TBH I'd try refitting the carb warmer banjos first and see if you're still getting an air gap in the rad. When I sold Greta the other day Liam asked to see the coolant level as I mentioned I'd replaced the head gasket when I bought the bike, so we took off the rad cap to look and the coolant was right to the brim after being ridden a few thousand miles (including getting quite hot off-road a few times) and being in my living room for over two years.

DTRE/X are the same as the DTR except they came with an electric start instead of a kicker. The stator and cranks are therefore different but everything else about the engine is the same.

It's only the 4GW TZRs and 4DL TDRs that came with the 4FU cylinders to my knowledge. There may have been other designations that came with 4FUs but none in DTR configuration.

I always wanted to try it out myself and a few units back in the day. Never did though, I am happy to park DTR development for the time being, happy enough with the Athena 170 kit for the moment.

@HOTSHOT-III

Bud, thank you! I can get the PV working on the tizzer now for not to much money. The length of those (impossible to find!) cables wouldn’t of last a winter without lube ports at the highest point! Plus stainless cables! 🙂 …

@Vcelicka

Happy for you bud! 👍 …

If you can afford it get a NGK rubber (red) ‘racing’ cap and an NGK Iridium spark plug. They are the Bogs Dollox! 😜 …

@OllieDTR No? Jetting is normally easy as pi.

But apparently, as I found out on a recent dyno session, my entire setup is jank 🤣 Not terribly convinced. They sent me home on a completely broken/dangerous bike...

@OllieDTR Not sure of the thickness but along with the cylinder base nuts and studs, these are fasteners worth buying genuine from Fowlers.

It's a good question, 70 sounds about right for the coolant temperature, not sure about temperature at the spark plug.