DT125R FORUM

PLEASE NOTE THESE ARE BASICALLY MY NOTES FOR THE TIME BEING BUT MAY AS WELL GO ON HERE IN CASE ITS USEFUL. AS I SAY BELOW, ILL GET ROUND TO TYPING IT UP NICELY WITH PHOTOS/VIDEOS ONCE IM DONE

So I'm about to undertake my first full DT125R engine rebuild. I suppose its testament to the little powerhouses that I've never had to do it before but this one has main bearings that sound like 2 cheese grates shagging.

So I started with this video as a guide. I'm sure the Haynes manual would also be useful but I find videos a lot easier to follow. I will try to make my own with commentary and more close ups etc but this one is now split so too late.

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

Tips along the way.

1. The alluminium to lock the gears was very useful. I used a bit from a CPU heatsink from a computer that i chopped up with an angle grinder. What a mess that made!

2. I couldn't get enough leverage on the nut with a breaker bar and resorted to an impact gun. I've got a Clarke mains powered one. They are about £60 and worth their weight in gold!

3. Before you start, make sure you have pots and labels and a notepad to make notes of things you'll need to buy. Stuff comes off in excitement and its possible to forget woodruff keys. But if you keep them in pots you'll notice if you miss something.

4. Order your parts before or as soon as you take it apart. You dont want to be putting it together and realise you forgot to order a tab washer or bearing. DONT RE USE THEM......ITS NOT EXACTLY QUICK TO TAKE APART AGAIN!

5. Change all the bearings and all the seals. If you think about the extra cost you'd be happy to pay it if it was an extra little insurance policy on the engine. Dont go cheap. Koyo bearings at a minimum and Athena gaskets at a minimum. Any other head gasket will pop!

6. If the barrel needs reboring passed 2mm then you may need the powervalve reworking. In this case it may even be worth finding a different barrel but personal choice.

7. make sure you have the right barrel. There are slight difference between 3bn and 3mb. If you can get a 3mb head its worth doing at the same time.

8. Whilst the piston and head are off, give the crown (top) of the piston and the combustion area of the head a polish with some metal polish and toothbrush then a bit of rag. It will stop carbon deposits and improve airflow. Its worthing doing whilst you have easy access to both parts.

9. Maybe one of the most important tips is to work out why you are rebuilding. If there is an issue, are you resolving it by rebuilding. If you dont know why the engine is being rebuilt then try and work it out first so you dont end up with the same situation after all your hard work.

I'm at the point where my cases are split and i need to remove the gearbox bearings so ill update once thats done and I'll keep updating this as i go along and eventually add photos etc to accompany the words.

note: It's worthing getting a bearing slide hammer set to remove the gearbox bearings.

Costings:

Crank Rebuild £42 PJME
ConRod kit £43-55 PJME (depedning on Long or moto RRT)
Barrel Rebore £36 PJME
Athena Full Gasket Set £28 PJME
Mitaka Piston Kit £47 PJME
Athena Oil seal kit £25
Gearbox Bearings £22.50 Simply Bearings
Threebond 1084 case sealant £9 ebay
3 x tab washers(gen yam) £10

Note: needle roller bearings are generally not replaced. They dont seem to be available from bearing stockists so gen yam seems to be the only option. About £14 for the one ive checked.

WASHER, LOCK
90215-20283

WASHER, LOCK
90215-12271

WASHER, LOCK
90215-12272

Welcome to the forum neil! Great condition bike, you've done well there.

You can get a speedo converter that changes form kph to mph. Just screws into the back of the speedo. about £30 i think.

I've always wanted a bigger adventure / enduro style bike. A friend had an xt660z a few years ago that actually got stolen but i loved the idea of it. The money was a big thing though. His was worth about 12 times what i paid for mine! Recently he's bought an XT600R and has been kitting it out again for big trips. I was jealous to say the least but short on funds as they were all tied up in my Rd350LC project, 4DL series 1 project and other DT parts that were filling my garage.

So I was on ebay and found this xt600e 1994 model and it was cheap. It had no MOT but was in a 'runs and rides' state.

I negotiated a price with the seller and went and bought it. The rear tyre wasnt sitting right and there was a small dent in the rim but it didnt seem relevant to the tyre. There was some place in the suspension linkage ( my pet hate). It had been resprayed all over in blue which I wasnt keen on but it probably looked better than it did before!

After i got it home and had a check over in the garage I thought I'd book it in for an mot and see whats what. I stuck a jerry can of petrol in that had been sitting in my garage and away i went. It was running like a dog. lump, back firing and even cutting out! What? Oh well, get it through the mot and then see, i thought, its probably just old fuel from that can.

It failed on the rear tyre not seating properly and the suspension linkage, surprisingly ....which was a relief really. I knew I wasnt going to be able to do it within the 10 days but I also was annoyed at the mot place as I know them and they said they would just blow the tyre back on the rim and they didnt even try...

So I ordered a set of Continental Escapes as recommended by my friend with the 660.

I found a 2nd hand linkage on ebay that "had no play". When it turned up it came still attached to the swing arm and shock! Great!!!

...Oh... it does have play in. I tried a straight swap with my parts and the play was about the same. I swapped around various bits to make one good linkage out of the two. It got rid of a lot of the play but still not what i felt would be good enough for an mot.

I ordered some brand new parts from Fowlers which again made a difference but were only the solid bushes and not the nylon collars that sit inside the relay arm as the cost for all of those was really adding up and i wasn't 100% sure which one/s was/were the issue. I moved on for the time being whilst deciding what to do.

Along with the linkage/arm and from the same guy I got a new airbox as mine was missing the top section and snorkel. He wouldnt sell it seperatly and it was about £30 so fine...

...when i went to fit it I realised that what had been stuff in place of the snorkel was a DNA air filter! with a stock one in place. So I cleaned up the DNA but noticed it's missing its sealing edge. I still need to sort that but a nice find!

Next I started looking at the carbs. Took em off and the bowl was full of bits! Thats probably why it was running lumpy and kept cutting out on the way to the MOT!

I cleaned it all up and thought I'd check the float needle condition and make sure the floats weren't holding fuel. Thats where it went bad! the part of the carb body where the float pivot pin goes into was broken! Damnit!

At this point I was getting excited and looking at all sorts of modifications I could do to improve it and heard about the oversized Acerbis petrol tanks made from plastic. They were about £260 but for my model bike they are no longer available. DAMNIT!

Then by chance I saw an XT600 listed up on ebay about £750 as an import from Norway with no paper. Kicks over fine but doesn't start and is missing some parts. But wait...the tank on it is one of these elusive Acerbis 90-94 20L plastic Tanks!

I messaged the buyer to try and buy the tank and a few other parts but it wasn't happening! He wanted it gone as complete bike. I negotiated it down to £450 and arranged a courier for £105. So all up it owes me £550. I'll take the parts I want/need and break the rest of it.

This also gave me another chance to play with the suspension linkage and carbs. So i swapped and changed and got even better on the linkage side of things. I swapped the shock and clevis across and I now feel comfortable with that. I think there is a minute amount still there and may well rebuild a new lnkage relay arm over this year incase the play gets worse again.

Whilst I was trying to sort the Sus linkage I noticed that the chain was dead, like you could almost lift it off the back of the rear sprocket! Apparently this wasn't a problem on the mot. For various reasons I won't be going back to that mot tester (other issues) but this was pretty bad too!

Ordered a new DID chain and either JT or sunstar sprocket kit from Wemoto along with some other bits like oil filter, carb repair kit, magnetic sump plug. I had to buy a Chain tool and went for a draper. Got the hang of it after some youtube videos and it seems to have done the job. Not sure if the riveter pin has faired too well but ill find out next time. It's a lot of pressure needed to flare the rivets which I've never done before. Always dealt with the clip link type.

On the carb front by now I had bought a Ultrasonic Cleaner. Its a 6 litre model and is a lot smaller than i expected. You only get like 4-4.5 litre in it as there is a max fill line but it does what I need now so im happy. (£85 on ebay IIRC).

So i took the carbs off the donor bike and put them in the US cleaner. After a good clean up they ended up being more viable as they were, rather than trying to combine the 2 sets. That was suprising considering they were spray painted black...yes...the carbs were spray painted black!

Back on the bike and it wont even start now!

Balls....

After killing the battery a number of times and having to wait for it to charge (it was very cold) I eventually found that the HT lead wasn't clipping on well enough on top of the spark plug...sounds silly now i type it but it was a right hassle at the time. By the time i found that, id killed the battery again. After a charge on the optimate over night i went out, battery on, choke on, press the button and pop pop pop, first press!

http://s1228.photobucket.com/user/andyyam1/media/Xt600E build plus Xt600k/IMG_0045_zpsl6ay7w2j.mp4.html

I warmed it up and the tried to adjust the pilot screw but even with it screwed all the way in it wasn't making much difference. So I'm sure I need to mess about with it a bit more soon but its running nicely which is good!

This was all done with the plastic tank just sitting loosely on the bike. When i finally tried to fit it securely I found that there is supposed to be a mounting kit with the tank that...you guessed it...I dont appear to have.

After contacting the guy who is regarded as the UK expert on XT's (and believe me he is!) I found out what they look like but also that they don't make them anymore. He says they do come up on ebay occasionally but also mentioned that he doesn't have enough to go with the tanks he has, so competition will be stiff when they do come up.

So I've got a guy who knows a guy who knows a guy who owns a favour, who might be able to make me something up that'll work. I managed to get technical drawings of them online from Germany so i guess people are making them up themselves.

So with that tank out of action until I get the mounting kit I thought, no problem, ill put the original metal one back on. I thought i better check the fuel coming out of it and it turns out its full of rust!

ARGHHHHHHHHH!!!!!!

Quick google and everything points towards sealing the tank or replacing. Fuel filters wont block much and cleaning them wont be a long term solution. I decided to give it a go. I bought about 3-4 litres of distilled vinegar and after a long soak and shaking with the old chain inside, theres lots of loose stuff coming out and the colour is...well...i think i invented a new colour.

I then rinsed it with half the contents of my water butt and them some petrol. The output gradually got cleaner and cleaner and there appeared to be none of the red globules of rust that was the initial concern. Once i was happy (enough) with the cleanliness of what was coming out I put it back on the bike, fitted an in line fuel filter and connected it back up. It seems to be running well so hopefully that will get me through the mot and until I can secure the Acerbis tank properly.

I still need to bleed the brakes, maybe refresh the fluid, but other than that it's pretty much ready for an MOT.

So that's the back story...and here's where I'm at now:

I've got some larger footpegs on their way. Cheap at £16 but steel. They'll mean I can lift it on the Eazy Rizer better, by using the footpeg mounts to lift it. Yeah that sounds weird? Check out Eazy Rizer bike lifts!

I'm planning to swap all the black plastics across from the donor bike.

I'm also planning on fitting the kickstart from the donor. It's an XT600K (K for kick start) and mine is an XT600E ( E for electric start) and you can fit the kicker across similar to the old DT125RE mod. A decompression lever is needed which is attached to the kick start and operates at the same time.

I didn't yet mention but the bike came with a spare engine which turns out to be the original one for the bike and matches the frame. So i expect ill rebuild that over time and re fit it in it's rightful place.

I have plenty of other plans for it including:

• -remodelling the seat and making it more comfy
  -replacing the imitation renthals with real ones
  -fitting some nice hand guards
  -fitting a better sump guard
  -finding a rack. (ive bought one from ebay that says its for a 94 but im not convinced. awaiting delivery.
  -Getting some soft luggage for the sides.
  -installing some better LED spot lights
  -upgrading the gear lever and brake lever
  -rebuilding caliper ( rear appears to be the same as a DT125R as are a few other parts)

Welcome to the forum. As Cal says, im sure we can work out the year from photos and engine numbers etc. Just dont show us any more photos of Citroens or dirty 4 strokes

@Jens-Eskildsen Yeah I know what you mean and I'm sure you are right. I suppose it's just an area where companys can make extra profit knowning how people feel about "more money meaning better quality".

It probably isnt any safer or less likely to have issues but it's the name and brand and the big boys on race bikes that have invested in branded companies like HEL that make us happy to pay for it.

Yeah on that offer it was 50% off all online orders. So it was £29.99 per set ( £60 for both) but then 50% off bringing the total order back down to £29.99 which was a total steal. Meant you can get HEL quality lines for less than the cost of unbranded. Now those are the deals I like!!

You seem like a very clued up guy so hope you don't feel like anyones putting you down for putting an opinion across. I personally value anyones educated opinions and experiences, i see it as the fundamentals of a progressive society, but hey lets not get too deep here, this is bikes!

@Jens-Eskildsen Have you used them before and know them to be good? A set of front and back brake lines for less than £30 from an unbranded company would worry me.

I ended up using a bit of alluminium between the gears and an impact gun on the nut. A bit pikey but it did it

Have you got a copy of the ebay listing we can see to offer advice? Sounds like you've just run into a complete tool. It happens. If the bike was in a similar condition I may be leaning towards taking it back to avoid further hassle but it sounds like he's monkied it about.

I would report it to the police now in case anything escalates. Keep all txts and communcations and copies of the ebay listing. You've done nothing wrong so just tell the police everything and if he has made any kind of threat or even the harrasment then i would tell them you're scared. They should at least go and speak to him about it.

The only concern is that he obviously knows where you live/work and regardless of the law he could still be a nasty bit of work. If you dont have CCTV then it might be worth considering just incase. I'm not trying to scare you, instead trying to pre empt the actions of some idiots, which this guy clearly is.

hey guys, not been around for a while again as ive not had a dt for a while and had lots of other stuff on. my commuter cbf125 has just failed in the big end bearing department. i was expecting it but it was still returning over 100 to the gallon. anyway it'll need a full rebuild but a friend had an 01 dt that also needs a rebuild so he sold it to me and thats gonna become the commuter. i may put a thread in the technical section for the rebuild but heres my hello again! peace

Plenty available on ebay or wemoto by searching for DT125R. Personally i'd stick to stock unless you've modified the bike in some other way to compensate for the difference. Yamaha made the DT125R...they know what they doin'!

1st off, great thread.

with regards to the exhaust im sure there is a slight difference between the 88-96 and 96-04 frames or at least the brackets. i remember swapping them over and they just didnt line up the same.

You can also try a Delorto VHSA32 which is a 32mm carb used on the TZR 4DL which shares the same engine as the DT125R.

Only putting it out there, if it were me, I'd go for a tm28ss which is standard on DT125R from 1991 as Darty says.

The jetting changed in around 1996 as well but that will depend on the conditions of where you ride so you'll have to experiment with that.

I've never actually looked at the setup of a non pulley version.

What's on the inner side of part 20 in the diagram. Looks like it's already fitted to the end of the end cap. Does it have a diamond shape that holds onto the end of the valve itself?

From the parts diagram it doesn't look like there is a separate pin so I would guess not. If it came apart then im sure Yamaha would have listed with it's own part number. So unless your end cap or part 20 is broken then it should all be fine. Try fit it all together and then put your finger up the barrel and try and move the valve.

Yeah true, I just find that a forum rebuild guide with photos and advice often encourages people to dive in compared to a haynes which can sometimes appear a little over complicated and lacking in detailed photos. I followed a youtube video for the strip down and case splitting which really spurred me on. They used a bit of alluminium the lock the gears which really proved useful. to be fair i didnt even check what haynes suggested.

Also a guide of what parts to buy and what not to buy might help. Your gearbox bearings post was great for me, but although I know not to use yambits engine oil seals and only Athena or gen head gasket, I might have been tempted.

I'll see how I go but watch this space