DT125R FORUM

fitted the new base gasket, the old one was soggy and leaking under the exhaust manifold into the barrel. Still pushing out white smoke! i went back on some of my threads from 18 months ago when i built the bottom end and found out that i'd used hermatite red instead of silicone RTV to seal the crank casings. I think it's failedwhere the coolant flows from the barrel to the block.
I'm gonna have to split the casings and use proper RTV...
At least i kno2w why it was running hot. Also learned not to use mismatched casings. Mr Yamaha obviously used different castings for various iterations...

tzr pipe?

No body know when 4BL,s were about?

@mbmO8

Head’s still leaking bud. It’s probably best to replace the base/barrel gasket as well.
Myself, I remove the studs from the barrel an lap the top in with a square of plate glass and some 240-ish wet and dry sand paper. Then do the same with the cylinder head. Just to remove the crap.
Doing up the head nuts really needs a little 1/4 in drive torque wrench to get it right. I do it in three stages…

I know that it’s no consolation but I’ve just had to put a newly rebored barrel and head on and had to go through all the fuxin hassle of it myself 🫤 …

It’s starting with JYA4BL

I don’t know if it’s a Dtr or a DtrE

Ta!…

@mbmO8
Sorry for late reply.

It’s since you did the top end build I’m thinking about, not before.
It can take a while for sludge to build up.

Is it loosing coolant from the radiator? Check the level …

Have you checked the thermostat?
Is the coolant in the radiator staying at the same level, or are you constantly topping it up?
The only reason for the expansion tank to be full and overflowing is if the head gasket has blown and is pressuring the coolant system, which results in loss of coolant through the expansion tank.

P.S. yes the expansion tank is connected to that part of the frame by a small rubber tube. it lives up behind the side panel above the rear wheel. there's a min & max level about halfway up the tank. Check it out to see if it's full to the top...

Any decent fan kits to mount to the radiator? Adjustable thermo activated switch, shrouded to pull air through from the rear of the radiator?…

I’ve got some work to do first, there was oil scum in the radiator and I guess all the way through the thermostat, pump and system. (I’m wondering if the stat is all gummed up) The pump rotor and seals were replaced when I rebuilt the bottom end…

It’s not the head gasket blowing though, it’s not pushing coolant into the expansion tank or noticeably lowering the level in the radiator.
I had problems with a slight step in the casings at the rear of the barrel which I thought I had fixed. There’s a ‘wet line’ between the barrel and inlet manifold that seems to support my theory.

I’m waiting on a new genuine base gasket, thermostat and some Loctite VHT copper RTV sealant, as well as the thermostat and gasket…

@Calum

It’s a shame that they’re shite, because I think the radiator is the main problem. If it was the thermostat I’d of thought that it would overheat from the start, but it keeps cool enough for a while depending on how hot it is and how slow I’m going (less air flow over the radiator). The radiator is well hot to the touch!

I’m waiting on a new stat and gasket from PJME and I’m going to flush the radiator that’s on the bike with a hose in the meantime. The fins on the back are better than my other radiator, which is originally pristine in every way apart from the rear fins being the worst I’ve personally seen

@Corswolds89DTR

It won’t be a 1989 diagram you need. Look through the other years models till you find one that looks familiar…

Cheers guys!...

I've got a half decent rad i bought a while back. alot better than the used stuff you normally see on fleabay. i'm gonna flush that and leak test it, as well as checking for decent flowrate. Ill order a new thermostat and do them both together...

Has anyone looked at the replacement rads on fleabay? there's a chinese one for £90 and a chek one for £114. i'm leaning towards the chinese one just because the quality of the TIG weld looks to a much better standard.

Still going well mechanically, just looks like a dog

Cheers for the link bud!…

I really need some hubs if anyone knows of any for sale? Back one is way more urgent than the front!

Only issue is it seems to be running a bit hot. I removed the plastic cover from the radiator and it was an improvement, but not great. I’m wondering if being stood up and hardly ridden since last winter has let the radiator clog up? The radiator was well hot when I checked it. Like it’s not shedding the heat. The ‘fins’ look clear, so I’m wondering if it’s an internal obstruction?

Stopped riding for about six months cause of old git health problems, only just renewed my CBT again!
Took me over a year to fit the new bearings and bushes into the rear suspension linkage! Didn’t realise how big of a faff it was going to be to get them pressed in straight and to the depth that’s needed for the seals! Done though. Nice and tight on the ass end! No more ‘snatchy chain’ feel when pulling away

Is HotShot still around? I need some info on wheel builders in Dorset. I can’t find the old post recommending a particular one. My back wheel is a bit up and down, as well as being a bit side to side…

Unless anyone has a decent straight rear wheel for sale?…
Ta!…

Hi! What’s the best way of removing the twin short bronze bushes from the rear suspension linkage, also the ones on the swingarm? One gets in the way of the other so I can’t press them out. I’ve tried heat and ‘hammer & screwdriver’ approach, so as to get to the other, but to no joy…
Cheers for any help, advice. I couldn’t find sh!t on the search engine…

@Calum

I remember you having a Li-ion bonfire
but the thing I’m most interested in is the old AC/DC bikes that have three coils on the stator. The ignition coil is horizontal on the top of the stator. The lighting and charging coils are at a V at the bottom of the stator.
I don’t claim to understand it but the lighting & charging coils are both numbered the same in the Haynes manual and seem to be connected, unlike the ignition coil which seems to be more isolated.
It would seem to have something to do with my investigation into why my headlight dims badly (when I have a FUBAR battery) when I use the brake lights, horn or indicators.
I’m hoping that the short life of my battery’s is down to the Reg/Rec being of the oriental OEM variety that’s always been on the bike since I got it. Like the lighting coil being burnt out. It’s the last gremlin on the bike since I got it as a basket case back when the pandemic started. Unfortunately my multi metre chose this time to die, just when I want to check the coils….

The later DC only bikes (anything with more than 3coils) don’t apply to me, unfortunately ….

On average I need a new battery once a year. If I don’t replace it I start to get the headlight dim when I use the brake lights, or even horn sometimes. I’ve tried 5amp, gel, they all die a bit over a year…

I’ve always had a Chinese replacement Rectifier/Regulator that came with the bike. It has its own short cable loom (2~3in) The original block connector that is connected to the loom has a melt mark on the connector block. The new~used R/R is marked bn with a load of numbers after it. The lighting coil was FUBAR when I got the bike as well. It looked like the block connector rested against the exhaust and earthed out the lighting coil, the previous owner replaced the R/R with the cheap and nasty that’s currently on there. I have the new~used R/R to go on and a new battery coming…

So my question remains: how often do you have to replace your battery? This only applies to 1988~96 bikes. As I remember they went from 3 coils (A/C lighting) to being totally DC so the headlight ran from the battery and the ‘R/R’ had no provision for A/C for the ‘old fashioned’ headlight on the early bikes…

@HOTSHOT-III
I thought that it’d do the same thing but without having to ‘fight’ it’s way through the two little holes in the bolts. The one I took apart and degreased last night had ‘scorch’ marks either end. That was with me having the original bush with the two holes as well. I think this would be a better ‘delivery system’ without having to drill the long centre bushes.
I’ve got an old swingarm that has a grease nipple either side in the middle of each part the swingarm bolt runs through…
I want to ‘up my game’ since finding the scorch marks on the ‘dogbone’ long bush…

Cheers bud, I thought you were using red rubber grease which is excellent for certain applications, but I thought too sticky, with no ‘travel’ if that makes any sense? I was thinking of CV booot grease just because it moves so freely and might be easier when using the Grease Gun…
Lithium general purpose is tried and tested through. Cheers for the input, it’s given me a lot of confidence …
Richy…

@HOTSHOT-III

Did you ever manage to get any of them drilled?
It might be easier to fit a nipple to the linkage and the swingarm (centre of) the rear dogbone join? At least the grease would be going where it should (like the frame mount with roller bearings). Not trying to work it’s way out of the centre of the 2mm holes in the 2 dog bone bolts and then through the full length bush, that’s if they even have holes…

Does that make sense, Or has my dementia catching up on me?! ‍

PS what grease to use. Normal,l lithium, red~rubber or CV joint black grease. Or am I missing something? There’s so little movement really…

Just found the allballs kit picks and everything I’ve got looks right except the full length bronze ‘tubes’ (x2) for the dog bones and the single tube (roller bearings) the fits inside the link that attaches to the frame. Any idea where I can get those 3 full length bushes?…
Cheers peeps, sorry for any confusion …

Damn the ones recommended last year are the wrong size. The long dog bone bolts sit in a single long bush. Mine are 2 per bolt and too big. Not sure about the roller bearings but the look was too big for the bolt that joins the frame. More like swingarm size…

Anywhere do a complete kit bolts and all?…