DT125R FORUM

@Calum I have to think things through quite carefully to avoid the jobs piling up. For example, where I live is right on the edge of where the Purbeck sand/gravel ends and the Salisbury Plain chalk downland starts so for most of the year I head in the Purbeck general direction. It trashes drivetrains as you can imagine but makes for easier cleaning as all the mud brushes off even in winter. And having several bikes means it's essential to clean the one I've ridden before going out on one of the others.

Whereas out on the chalk it's great in summer but with even light rain you get that tacky cake mix style mud which sticks to everything meaning bikes need to actually be washed; more time-consuming and a leading cause of knackered suspension forks. RockShox seem slightly more prone to this than Fox which is rather annoying as IMO the ride quality is slightly better due to the independently adjustable positive and negative air chambers. I ended up robbing parts from four different sets of U-Turn Revelations to build one good one, some of them looked immaculate on the outside but it just depends how much they've been jet washed.

@Calum Thanks bud, I liked the look of the On One build you posted up on here a while ago. In fact after getting this Stumpjumper, to save time/cleaning I put the eXotic fork back in my hardtail and put it back to rim brakes so I had something easier to live with that I could just hop on and ride in the meantime. Seemed counter-intuitive to take on yet another project but that only took me a few days and meant I could then concentrate on the Stumpjumper build. Had a few nice road rides in the summer heatwave as well

Here are some pics of my 2007 Stumpjumper FSR Comp (large) which I've just rebuilt.

I’ve called this bike “The Time Capsule” because when I saw it advertised on eBay it was completely original right down to the tyres; even the rear had no discernible wear. Well worth a 300-mile round trip to Wales to collect it whereupon the seller informed me he bought it new 18 years ago, rode it home from the shop and it never left his garage again!

5 weeks on it’s now had a full recommission which includes:

Brand new wheelset built using new Shimano Deore XT M756 rear hub, original Specialized Stout front with new SKF 6001 2RS bearings, NukeProof Dolos rims and Sapim Race double butted spokes with coloured alloy nipples. Spoke nipple washers can't be seen in the pics but spread the load around the spoke holes in non-eyeletted rims and make truing easier.

Original Fox Float 120 fork fully serviced with Fox genuine parts and SKF green dust seals. Travel kicked out to 140mm during the service by removing the plastic spacer underneath the air piston whilst they were apart (this is literally Poor Man’s TALAS travel adjustment as some of the higher-end 2007s were supplied with the TALAS (Travel Adjustable Linear Air Spring) fork where you can adjust the travel externally on-the-fly; pretty cool when new but 18 years on these Floats are simpler and easier to service).

OEM Triad shock fully serviced likewise using Fox genuine parts, a nitrogen needle kit and RockShox shock pump to inflate the chamber behind the IFP.

Every chassis bearing has been replaced with full complement bearings; these have no cage and are packed with balls to take higher loads in low-speed applications. New headset bearings but the OEM Cane Creek cups and crown race were fine so I didn't disturb them.

Shimano Deore XT T8100 brakes; these deliver XT quality without the fiddly servo-wave levers. 180 front/160 rear rotors.

3 x 9 transmission with Shimano 73mm external BB and 2-piece crankset (these are a modern take on the old Hollowtech II cranks). Deore Shadow rear derailleur with ballraced jockey wheels as these do make a difference to shifting performance. Interestingly the Altus shifters are Shimano’s cheapest 3 x 9 offering, yet the only ones that allow me to put the dropper post lever where I can actually reach it (it’s actually a left lever but by installing it upside down on the right handlebar, the 3 x 9 Luddite (i.e me) can also enjoy the wonders of dropper seatposts).

New 2007 FSR pivot bolt kit I was lucky enough to find on eBay; the seller thoroughly cross-examined me before allowing me to pay because he’d had so many people buy the wrong kit for their bike and then argue with him and click Return This Item. 2007 isn't all that long ago so Specialized should really still supply pivot bolt kits for these, and try and help people rebuilding older bikes a little more by providing the info on their website.

NukeProof bars, Thomson Elite X4 40mm stem (gives exactly the same seat-to-bars length as my 2007 medium running a 70mm X4 stem) and No Logo external dropper post. Magnesium platform pedals, inline cable oilers and weirdly humungous RSP bar ends; for any half-decent UK MTB ride you’ll need these for the asphalt hills. Frame downtube protector made from the original front tyre as I didn’t trust the 18-year-old Kevlar bead; I once had a rock dent the downtube on a bike <6 months old riding in the Quantock Hills which is a great way to ruin one’s day and rather upsetting.

I've wanted one of these in a large for a while as I’m right between a medium and a large according to the sizing charts of the day due to my height (5’11”). My medium (last pic in green/red) has shorter wheelbase and runs narrower rims and 2.1” tyres (this is running 2.3”s) which should mean it’s more agile than this bike but the large should have the edge in stability.

First ride on this on Tuesday and it went very well so looking forward to comparing them directly!

@SpookDog Thermostat definitely worth a look as @Calum said. Also the rad could have a blockage, it's not unheard of. I've had some success on cars blocking off the ends, filling them half full of Gunk/Jizer and giving them a good shake before rinsing with a garden hose. I like doing this on the outside of radiators as well, get loads of degreaser in the fins and it's amazing how much crap you can hose out. And I'd still take a look at the fins particulalrly on the back of the rad as they're prone to being folded over by people doing plug changes etc. which can considerably reduce flow through them. It can be quite relaxing to take a thin screwdriver and straighten every single fin and this can make DTRs run a bit cooler.

Also have you taken a look at the waterpump? Being a plastic impeller moulded onto a steel shaft it's possible this could have separated meaning it's no longer making the coolant circulate. TBH I've never known this to happen on the DTR but worth checking on a high mileage bike.

@OllieDTR Has Liam got any wheels for sale? Would be a fairly local solution...

@Corswolds89DTR It sounds like someone has put a later electrical system (and possibly engine) in your bike as to my knowledge all 1989 DTRs are either 3MB or 3NC electrical platform, both of which use the 3-wire servo.

It's a fairly common mod as the later engines are mechanically identical to the '89 onwards and some of the earlier bikes have had their wiring looms butchered over the years, 3-wire servos dying etc.

The electrical platform that ran the 5-wire servo came along in around 1999, I don't know very much about these having never owned one but if your Haynes manual is the type that covers all DTRs from 1988 to 2007 this is the model/wiring diagram you need to refer to. If your manual only covers the earlier models take a look here:

https://www.ebay.co.uk/itm/394118631267?_skw=dt125r+haynes+manual&itmmeta=01JYTRX3H7E124JNTSMMTBR2C3&hash=item5bc34d0f63:g:eEwAAOSwGXxiq26m&itmprp=enc%3AAQAKAAAA0FkggFvd1GGDu0w3yXCmi1eIah29XoGpBsiWtwJAV9MgEd61gI5Ej6kO5ykBg6ydLxdXW3P8b%2BI0B5u2Q1%2FVqwTdHslAHfiDHUTVZVRd0nEwB%2B3EyEt%2Fqn4nT3bShgiNTKLI4r%2BlwHGHSpqcBqiXi0OaUIzdE4bJuiN7ZaCKMO5%2BpxH2J%2FJeZcxY0yPrgdH2ztTJWsOGRLEAhte%2Fgd6%2FUvLi5uhZhjPtnJ8JooVoKvyNAgnWzF2UBpO6SrrdRQnNiFB%2B9nJBpQ7br0gmifIETpg%3D|tkp%3ABlBMUP649Nj2ZQ

@SpookDog Hey bud, hope you're feeling better. I did wonder what had happened to you.

Good to hear you've sorted the rear suspension

Try Salisbury Wheel Builders over in Ringwood: https://salisbury-wheel-builders.ueniweb.com/ 01202 081994

@Calum Is that a DT200R 3ET swingarm? Very nice, I bought one from Japan and it weighed literally half as much as the DT125R steel version.

However the plastic mud flap that protects the rear shock wears the (basically priceless) alloy swingarm away at the rear of the linkage bearing over time so it can be helpful to install something to prevent this. A lot of people with modern Huskies, KTMs etc. JB Weld a coin to the surface of the arm as they're prone to it as well.

I considered all that mud and chain lube floating about to be quite a harsh environment in which to try and glue two pieces of metal together so on my 250EXC I used the plastic sleeve which you get inside one of those boxes of sticky labels they sell in the Post Office cut open and cable tied on. Worked very well and I reasoned when it wears out you can easily make another one, but you might want to come up with a slightly more elegant solution for a road bike lol.

@RikuRo Try some of the DTR Facebook groups, doing this to the DT125Re is quite a popular modification and some of the sellers will supply you a kit with everything you need.

@Bilbo9000 Outstanding, I never thought of doing that! Well done Sir

@Bilbo9000 Sorry to tell you what you really don't want to hear but that spacer fits between the cases and the lower rear engine mount bolt passes through it (items 5 and 6):

https://www.fowlersparts.co.uk/parts/4105067/dt125r-3rm5-1993-999-a/crankcase

Not sure what would happen if you leave this out; it has a rubber vibration damper either side of it (Yambits sell those or item 4) so I think this is to stop the inner parts of the vibration dampers being pulled towards one another when you tighten the bolt. It could potentially also pull the frame mount out of line as without the spacer present, there's nothing to stop you just tightening the bolt more and more. End of the day Yamaha put it there for a reason so I'd bite the bullet and get on and do it.

If you've just assembled your cases this will test your Anglo-Saxon vocabulary to its absolute limit (as it would mine) but you're not the first and won't be the last mate; archaeologists have found rectangular boulders of the same stone used to build Stonehenge (these were quarried in South Wales) at the bottom of the Bristol Channel so imagine how that guy felt...

@Marillionado Hi, welcome to the Forum!

Not very familiar with the 3RM but on the earlier 3NC and 3MB bikes you do need to remove the powder coat where the coil attaches to the frame for a really good earth connection. It's also where the loom earths to the frame (the black ring terminal) and IIRC this attaches at the rearmost (i.e nearest the shock) coil mount. Lastly, only one mounting point on some of the coils is an earth so it's important you mount the coil the correct way, it should look like this:

As title, Lidl have just got these in, cheaper than most but I've always been impressed with their tools. Useful for all the small stuff on the DTR like coolant drain bolt (10Nm), oil drain bolt (15Nm) and fork and handlebar clamps (23Nm). If your 1/4" drive socket set has a universal joint you can use it to do all all 5 cylinder head nuts with the engine in situ as well:

https://www.lidl.co.uk/p/crivit-bike-torque-wrench/p10026677

@Calum That kit looks ace, I've never seen one of those before.

Spare a thought for the man somewhere in Europe on one of the TDR250 Facebook pages who tried to make it 340cc using two Athena DTR 170 kits. Barrel stud locations slightly different on the TDR crankcases so he filed them out to match, and then he noticed they were too wide to mount side by side. His solution? Just machine off the offending water jackets from the inside of both cylinders, then plug the holes with a whole packet of JB Weld. This was a few years ago so not sure where that bike is now...

@SpookDog Yes you could install grease nipples on the swingarm and linkage, might be easier because all you'd really need is a set of M6 taps. It would work exactly the same as the one in the roller bearing bush as you say.

I never got any of those sleeves drilled as every time I did the rear linkage job on a DTR I always found the sleeves aren't very prone to wear, two or three times IIRC I measured the OEM ones that came out with a digital vernier, found them to be almost exactly 20mm OD and just re-used them and replaced the bushes.

I always just used NLGI2 Lithium grease off eBay, it's the same spec as Silkolene Pro RG2 but a lot cheaper (it's also the same colour which kind of points to where Silkolene get it from lol).

@SpookDog There is a complete linkage repair kit on eBay that reconditions all 3 pivots but this is the one I was saying you'll need to get the long tubes drilled in order to grease them externally. Apart from that it's excellent quality and fits very well:

https://www.ebay.co.uk/itm/273964244490?_skw=dt125r+linkage+repair+kit&itmmeta=01JNS8GP47RXBRY3388JTDD77P&hash=item3fc98a9e0a:g:QeIAAOSwejlmIRnp&itmprp=enc%3AAQAKAAABAFkggFvd1GGDu0w3yXCmi1ewok0zvqvvsjaaesI%2B3AqBrNzJsMtN%2ByfXZjyUIUUXfj6QoCMC13skvVzLiqG%2FH%2F9tbxdIjH%2B4atRlor7FzTWzGMpxOzPLgwpWCAZ%2BsYD23e%2FVBR3dWDx4fm4J8E8GmosgW9fdd67Bv%2BTCogYvcKlITQftiOe0zTVTJE1LT3aL5vS0qIojINIgvTN26rq%2FHC1mQgSUVuPxjHprHzZZZLrHBay7eg6unKoC1l1ZETeZwamUAwvHK0789UP%2FcuJuCq8d%2FeKNbtq%2Bu1J%2B%2BxqoY5EHFq87Q0cyo76L7apLVo80bDYNTtniwioOGYH0%2BlqLdDs%3D|tkp%3ABk9SR7jiwqiuZQ

Only other thing you might need is the bolt/nut where the linkage joins the frame; this is no longer available but as long as you can get it out it's solid enough to clean up. Just try to resist whacking it as there's a good chance it will knacker the thread, the studding method gets them out clean. Long linkage bolts are still available but special order from Japan:

https://www.fowlersparts.co.uk/parts/4163783/dt125r-3rmj-2000-050-a/rear-arm

@SpookDog Hey bud, didn't think I'd seen you on here for a while

You can remove the relay arm without taking the swingarm out, and at both ends of the dogbones there are just plain bushes (the needle roller bearings go where the relay arm attaches to the frame). However at the upper end of the dogbone the bushes are in the swingarm so if you have the time, I personally would take it out which will make the job a lot easier, and it's also a great time to replace the swingarm bearings and set the swingarm side clearance if you haven't done this already.

This guarantees perfect chain/sprocket alignment and without the rear wheel/linkage fitted, you can get the arm to fall under its own weight with <1mm side-to-side play even with the swingarm pivot bolt fully tightened. A lot of the "specialist DTR restorers" on Facebook etc. miss this step but it makes a huge difference to the bike's handling and chain/sprocket life.

From memory I think I always just drifted the linkage bushes out with a hammer and punch, and pressed the new ones in in the vice using a socket. Same goes for the needle roller bearings except I pressed these out as well, and be sure to take out the grease nipple first otherwise the outer cage of the roller bearing will vandalise the protruding end of its thread as it goes past.

The linkage bolts with grease nipples shouldn't be worn at all because assuming they're done up tight with the linkage assembled correctly, they, the bearing sleeves and the dogbones form a rigid sub-assembly and so should never move relative to one another.

If you've bought the eBay linkage repair kit, unfortunately the long inner sleeves (i.e the tubes which fit between the linkage bolts and bushes) lack the 2mm holes necessary to allow greasing of the pivots via the grease nipples. It's well worth getting these drilled as it makes a massive difference to how long the bushes last if you keep re-greasing them. I say get them drilled because I think they're case-hardened; I once tried doing it myself on a pillar drill and even using a cobalt drill bit set that cost me 50 quid in Screwfix, I couldn't make any impression on them so this needs doing by some engineering firm somewhere.

If you have double-lipped seals from Simply Bearings etc., another hack you can do when assembling the linkage/relay arm is to flip the seals so the garter spring faces outwards away from the bearing; the lip without the spring is just a dust wiper so you can then cut small sections out of this with Swiss Army Knife scissors (best/sharpest scissors I've ever used) or one of those leather punches so when you re-lube the linkage bearings with a grease gun, the hydraulic pressure is less likely to force the seals out. The grease is free to pass through the gaps in the dust seal lip (now on the inside) and lift up the lip with the garter spring in its bid for freedom! The sprung lip then retracts, retaining enough grease inside the bearing and keeping dirt out.

If like me you're ham-fisted with the grease gun, it will still try and force out the seals so you can also hacksaw a section out of an M20 x 3mm washer and insert it in the gap between the tiebars and the arm during greasing to prevent this (with the linkage bolted together and the seals where they should be, you can actually move the tiebar/sleeve assembly 2-3mm side to side; useful after you've greased up everything as you can move it fully each way to make it splodge the excess grease away from the bearings/seals, then clean it all off thoroughly to prevent any getting on the rear tyre).

Lastly I'd also replace the lower rear shock bushing as this usually wears before any of the actual linkage bearings. It's held in the shock by two of those PITA C-clips and IIRC I destroyed a Lidl precision screwdriver set getting them out (mind your eyes as the speed one of mine flew out, I think explains why the Northern Lights were visible over Dorset that time). This one fits the DTR:

https://www.mandp.co.uk/products/29-5027-lower-rear-shock-bearing-kit-605946

All sounds like a lot of work I know but being able to externally grease up the rear suspension is one of the greatest features of the DTR, done like this you can just ride the bike week in week out, 10 minutes with the grease gun every week or two and you'll probably pass next year's MOT without even having to look at this again.

Happy New Year everyone, agreed it's important to keep the Forum alive as the DT125R is IMO one of Yamaha's greatest achievements, I'll be here in 2025!!

@Calum Merry Christmas and a Happy New Year!!

@Camugica No worries

The DT125R TM28SS uses a mixture screw instead of an air jet, it's the brass one on the left of the carb body just in front of the carb-to-airbox rubber (below the idle screw). Normal starting point with a healthy engine is around 1.5 turns out from fully screwed in. Screw it in further to richen the low-speed mixture or unscrew it more to make it leaner. There should also be a spring, washer and O-ring on the screw (in this order) so it's well worth checking this if you're having low-rpm running problems. The screw is prone to seizing on the DTR carb so whilst it's removed smear some copper grease on the threads.

Some other Yamahas use the TM28SS with an air jet instead of a mixture screw like the TZR/TDR250 and DT200R 3ET (I think).

@Camugica 15.5 - 16.5mm on the TM28SS.