DT125R FORUM

@calum Good point, I could start by checking the voltage at the PV. It's a '95.

Hi.
Have anyone disassebled the PV servo and maybe oiled/greased it? If it's possible, I will give it a go. Mine seems to sound like it's struggling a little more than it should, and don't turn the valve back and forth as fast as I see in videos. It's not the cables/valve, I checked this when I reassembled the bike after rebuilding the engine, the servo still sounds 'unhappy' even without the cables on.

Merry Christmas from Denmark!

@calum Hi Calum, i've seen the FMF mentioned af couple of times here on the forum, do they actually make an bolt-on exhaust for the DT? I can't seem to find one myself at any dealers, nor on FMF's own homepage.

Hi..
Have anyone tried to swap out the springs in the stock forks out with some progressive from Wilbers, Wirth, Hyperpro etc? If so, I would like to hear som experiences with them. I'm looking to stiffen up the front end (giggity) without doing a complete fork swap.

Hi..
Can anybody tell me if a rear shock from a TT600 will fit my '95 DT 125R?

@Ads123 said in Overpressure in cooling system:

Head gasket has gone mate 100% ha he that and all will be sorted

Yep, it sure was the head gasket

@Calum said in Overpressure in cooling system:

Yeah that's the usual suspect on these bikes. I dismissed it because you said you had used an Athena gasket. I would love to build an engine with those cheap gaskets and NOT have it fail.

They are notoriously bad!

I really believed I did use Athena gaskets, my mistake - won't do that again, that's for sure.

Sooo, time for an update.

Turns out it WASN'T Athena gaskets I fitted, rather some chinese noname ones - I had the top end gasket kit laying around for ages (can't remember where I bought it from) and didn't look much at the package when I fitted the new parts, but now I have done the light skim of the head and barrel, fitted Athena gaskets and guess what - no more overpressure in the radiator And it feels like the compression has increased quite a lot too (duh).

@andrewj1680 said in Overpressure in cooling system:

Looks like too much pressure to me and like calum mentions I'd say the mating surfaces need skimming, guessing you used a decent gasket?

Yes, used a Athena gasket kit when refitting the top end.

Well, I'll order another gasket kit and get to it as soon as possible, hope this solves the issue, if you guys have any other thoughts, please let me know.

@Mightyman said in Overpressure in cooling system:

Man that engine does sound sweet! You shouldn't really remove that cap when the bike is warmed up as there is always going to be some sort of pressure in the system. I don't actually know if your video shows TOO much pressure though. Anyone else?

Yeah, I know there are supposed to be some pressure, but this is definetly too much, i've filled the system a number of times by now, and i've never noticed anything like this before

@Calum said in Overpressure in cooling system:

As the coolant heats it expands hence pressure.

The radiator cap is supposed to handle some sort of pressure, replacing that can sometimes fix the problem.

If the pressure is massively undue then it is likely to be a headgasket.

The head and barrel needs to be skimmed. They are both ally and both warp.

Might be the cap yes, but this wasn't an issue a month ago, before I changed the piston, so I doubt it helps changing the cap - it's more likely the head that maybe is warped yes, I didn't really check it since it seemed to be in a very good condition.

Hi guys,

Well, it seems everytime I solve an issue with my DT, along comes another. I just replaced the piston because I struggled with piston slap - turned out to be the piston fitted when the barrel was rebored was too small - while I was at it, I fitted another 3MB head a had laying around in mint condition, moved the thermostat and housing over etc. Fired the bike up, sounds great, no weird noises anymore - however, when filling the cooling system I discovered that somehow the pressure in the system is way too high - with the cap off the radiator at squirts a large amount of coolant right out, everytime I give it some throttle, this happens from cold start and continues when the engine is hot, if I fit the radiator cap it just comes out from the coolant resorvoir instead.

Any ideas why this happens? Only thing I can think off is a bad bottom or head gasket, but this seems unlikely as it would have to be very leaky to make this kind of issue, and I was very thorough as always.

https://www.youtube.com/watch?v=iwrBbsG8YN4

Happy new year lads, here's a little "end of season" vid from my streetbike crew, located in the northern part of Jutland (Denmark) https://www.youtube.com/watch?v=451ZGBBZMEA - also a little bit of me riding my DT 125 R in there

Link to our other vids:

Season 1 https://www.youtube.com/watch?v=-n8USrV1m7w
Season 2 https://www.youtube.com/watch?v=W4zDvHaFuPc

Let me know what you think

@britshgigolo Nope, nothing - I will probably investigate it further after christmas, i'm pretty busy atm - if I find a solution, I will of course share it here - in the meantime, if someone have a suggestion to a possible cause/solution, please let me know!

@CYBER-NINJA Sorry for the late response, haven't had much spare time this past week. I've made a deal with a guy from our machineshop at work, he'll make some for me for free, so i'll have to decline your offer - thanks for your help, and sorry for the trouble!

@CYBER-NINJA Sounds fair, though I just realised that the link you posted is for 2005- onwards, do you know if they fit my '95 DT 125 R?

It's quite annoying, yes. I'm starting to wonder if it could be pistol slap - though it doesn't make sense on a freshly rebuilt top end. I've been watching videos on YouTube, and some DT's seem to have the exactly same noise - hmm.

Hi..
Just about done with my DT 125 R, and one of the minor details (at least I hope it is, lol) is starting to bug me out - the engine have been completely rebuild with rebored barrel to new wössner piston, crank rebuilt, all bearings in engine and gearbox, waterpump and clutch kit.

Check out my video: https://www.youtube.com/watch?v=F31U322ZwD4&feature=youtu.be

This ticking/rattle noise have been there since the rebuild. Off course I investigated right after the first test ride, removed the top end and everything looked fine, so I refitted it and have now done about 500 km since rebuild, and the bike is running strong, no issues at all.

Can any of you recognize the sound? If yes, should I be worried?

@CYBER-NINJA Sounds good, please do so, and let me know

@Darty Thanks again!

@Darty said in Making your own "lowering-dogbones"? '95 DT 125 R:

@MDN91
https://dt125r.co.uk/post/1752
I had some made a while ago

https://www.dropbox.com/s/6aropyq2sjczw0z/Tie Bar 130mm x 6mm 1.dxf?dl=0

https://www.dropbox.com/s/0bj1uprutg8im74/TIE BAR 120mm x 6 Reform1.DXF?dl=0

Standard Drop links - Tie bars.. Dogbones... for the DT were like 110?mm

Hope that helps.

Nice, thanks a lot! Do you remember what the diameter of the holes is?

@CYBER-NINJA said in Making your own "lowering-dogbones"? '95 DT 125 R:

@MDN91 I have a pair of Lust Racing -50mm dogbones I could sell to you for a decent price bud.

Interesting, though I don't know if it makes sense with shipment to Denmark? I suppose they are too heavy to send as a letter, and a parcel will be pricey, I think.