So Close!...
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Thank you, this is the good stuff that I need to know. I have another 3 wire servo that opens & closes much (3x slower, I thought the motor was fubar) slower than the one I’ve fitted to my 88. I’m going to try fitting it and see if it opens at something useful to me. I remember reading that some open as late as 8K+ (tzr) & some as low as 6-7…
I noticed no performance difference between the MB & BN heads either, at all. The 3bn was actually a lower CC (measured with liquid) than the MB which would make it higher compression! Go figure
…wrote on 7 Feb 2023, 20:39 last edited by@SpookDog This geezer seemed to have differing opinions.
https://yamahaclub.com/forums/topic/20583-de-restricting-my-dt125r/?page=6
And noted his 3MB head made more compression measured with a guage than the 3BN. I know others also remarked at how they noticed more mid-range.
Years ago when I was a wee lad and I went from a restricted CDI to green & black wire earthed and eventually to a Zeeltronic ignition system, I noticed no performance increase. It was only when I went back to stock ignition when my CDI developed a fault that I really appreciated how good the Zeeltronic was, then earthed the Green & Black wire to be surprised at what a difference it made.
The thing is, the difference might be quite small and hard to detect, it's not like slapping on the 170 kit and increasing the displacement by 30%+
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@SpookDog This geezer seemed to have differing opinions.
https://yamahaclub.com/forums/topic/20583-de-restricting-my-dt125r/?page=6
And noted his 3MB head made more compression measured with a guage than the 3BN. I know others also remarked at how they noticed more mid-range.
Years ago when I was a wee lad and I went from a restricted CDI to green & black wire earthed and eventually to a Zeeltronic ignition system, I noticed no performance increase. It was only when I went back to stock ignition when my CDI developed a fault that I really appreciated how good the Zeeltronic was, then earthed the Green & Black wire to be surprised at what a difference it made.
The thing is, the difference might be quite small and hard to detect, it's not like slapping on the 170 kit and increasing the displacement by 30%+
wrote on 8 Feb 2023, 16:43 last edited by SpookDog 2 Sept 2023, 10:19What’s your take on the Romeu Henrique pipe (or any stainless steel pipe) Do you get a ringing/humming at certain revs or speeds? Like a cross between ‘blowing across a open bottle top’ & one of those weird metal bowls that ring when you rub around the rim…
PS, on the MB v BN front, I don’t think there’s any real difference between them, not enough to call one ‘performance’ and the other ‘restrictive’ or to even argue about anyways. I think maybe it (the 3bn) seemed like a good idea at the time, but didn’t stand the test
Either way, I’d always pick the 3mb head if given the choice!
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What’s your take on the Romeu Henrique pipe (or any stainless steel pipe) Do you get a ringing/humming at certain revs or speeds? Like a cross between ‘blowing across a open bottle top’ & one of those weird metal bowls that ring when you rub around the rim…
PS, on the MB v BN front, I don’t think there’s any real difference between them, not enough to call one ‘performance’ and the other ‘restrictive’ or to even argue about anyways. I think maybe it (the 3bn) seemed like a good idea at the time, but didn’t stand the test
Either way, I’d always pick the 3mb head if given the choice! …wrote on 9 Feb 2023, 22:49 last edited bySweet! New thing!…
Speedo has stopped working, happened all of a sudden. Cable is good, stuck a small screwdriver in the bottom of the speedo and spun it and the needle goes up, so I’m guessing it’s the impossible to find gear at the wheel. What are the chances of it failing all of a sudden with no warning? I would of expected slow failure as the cogs teeth gave up the ghost? Strange thing is the speedo bulb went at the same time
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Sweet! New thing!…
Speedo has stopped working, happened all of a sudden. Cable is good, stuck a small screwdriver in the bottom of the speedo and spun it and the needle goes up, so I’m guessing it’s the impossible to find gear at the wheel. What are the chances of it failing all of a sudden with no warning? I would of expected slow failure as the cogs teeth gave up the ghost? Strange thing is the speedo bulb went at the same time
…wrote on 10 Feb 2023, 10:40 last edited by@SpookDog the speedo drive at the wheel is quite a common failure on these. With the cable removed from the clocks you can spin the wheel and check if the inner moves. They are still available new from Fowlers for about £50. Strange that the bulb stopped working same time but surely that has to be a coincidence?
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@SpookDog the speedo drive at the wheel is quite a common failure on these. With the cable removed from the clocks you can spin the wheel and check if the inner moves. They are still available new from Fowlers for about £50. Strange that the bulb stopped working same time but surely that has to be a coincidence?
wrote on 10 Feb 2023, 18:19 last edited by SpookDog 2 Oct 2023, 18:20@markus-w
Yeah, the hub drive has failed, it did have a bit of a needle wobble at 50-55 before for a while, as I’ve now remembered! My bad memory is the main reason I document so much info in this thread. I used to rite it down on bits of cardboard (aka my work bench) and pads, but I was always loosing them or forgetting to date them…
I checked the cable was sound then removed the speedo, put a bit of tape on the end of the top inner and checked to see if it was spinning, alas it was just sat there, useless as me
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@markus-w
Yeah, the hub drive has failed, it did have a bit of a needle wobble at 50-55 before for a while, as I’ve now remembered! My bad memory is the main reason I document so much info in this thread. I used to rite it down on bits of cardboard (aka my work bench) and pads, but I was always loosing them or forgetting to date them…
I checked the cable was sound then removed the speedo, put a bit of tape on the end of the top inner and checked to see if it was spinning, alas it was just sat there, useless as me
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@SpookDog tell me about it bud, I've mislaid a note book with so much Important information in it. Nightmare.
wrote on 10 Feb 2023, 20:44 last edited by SpookDog 2 Oct 2023, 22:05There’s a tiny pin that holds the brass insert into the gear housing (that the speedo cable screws onto). Has anyone ever taken the worm drive out? I can’t see if it’s a tiny Allen grub screw or a press pin that needs to be drilled out? Anyone help?…
The worm drive has seized on mine and I want to take it out and free it off…
The worm drive (that the cable fits into @ the hub) has seized solid, the ring gear is intact, but the 3 tabbed/pronged ring has had the tabs bent down on it. If I can dismantle the worm gear and get it turning again I can save the unit. It’s just getting out the pin/grub screw thing so I can remove the brass threaded cap (that the speedo cable screws to) and get to the worm drive/shaft… -
There’s a tiny pin that holds the brass insert into the gear housing (that the speedo cable screws onto). Has anyone ever taken the worm drive out? I can’t see if it’s a tiny Allen grub screw or a press pin that needs to be drilled out? Anyone help?…
The worm drive has seized on mine and I want to take it out and free it off…
The worm drive (that the cable fits into @ the hub) has seized solid, the ring gear is intact, but the 3 tabbed/pronged ring has had the tabs bent down on it. If I can dismantle the worm gear and get it turning again I can save the unit. It’s just getting out the pin/grub screw thing so I can remove the brass threaded cap (that the speedo cable screws to) and get to the worm drive/shaft…wrote on 11 Feb 2023, 06:58 last edited by HOTSHOT III 2 Nov 2023, 07:00@SpookDog It's a hollow roll pin that holds the worm drive into the speedo drive housing. I've repaired a couple of plastic ones, IIRC I drilled a small hole into the housing from the inside enabling me to tap out the pin (I think I might have even made something smaller in diameter than my smallest punch to do this). Then once I got it all apart and freed off I used a split pin to keep it all together on reassembly. Also bought a load of shims the correct ID/OD as the worm drive eats into the plastic as it rotates. And you can get the seal where the unit fits onto the wheel hub from a bearing shop, I think Ashley Bearings in Poole are pretty good. Well worth replacing as they leak sometimes, and you can get ones with a garter spring (better than OEM) meaning you can really pack the unit with grease once it's fixed.
An aluminium one might be more difficult as there's potential for the roll pin to seize into the housing so maybe a bit of heat after you've drilled it?
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@SpookDog It's a hollow roll pin that holds the worm drive into the speedo drive housing. I've repaired a couple of plastic ones, IIRC I drilled a small hole into the housing from the inside enabling me to tap out the pin (I think I might have even made something smaller in diameter than my smallest punch to do this). Then once I got it all apart and freed off I used a split pin to keep it all together on reassembly. Also bought a load of shims the correct ID/OD as the worm drive eats into the plastic as it rotates. And you can get the seal where the unit fits onto the wheel hub from a bearing shop, I think Ashley Bearings in Poole are pretty good. Well worth replacing as they leak sometimes, and you can get ones with a garter spring (better than OEM) meaning you can really pack the unit with grease once it's fixed.
An aluminium one might be more difficult as there's potential for the roll pin to seize into the housing so maybe a bit of heat after you've drilled it?
wrote on 11 Feb 2023, 15:41 last edited by SpookDog 2 Nov 2023, 15:43Ashley bearings, in parkstone sill going? I wish I’d known that before. Cheers bud…
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Ashley bearings, in parkstone sill going? I wish I’d known that before. Cheers bud…
wrote on 11 Feb 2023, 17:17 last edited by@SpookDog Yes mate but they've moved, just off Holes Bay Road now
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Ashley bearings, in parkstone sill going? I wish I’d known that before. Cheers bud…
wrote on 11 Feb 2023, 23:44 last edited by SpookDog 2 Nov 2023, 23:46This is the pin holding in the brass threaded coupling
You can see it’s possible to drill from the rear but it’s such a small diameter. If I do drill it from the rear I could use what’s left of the pin and drift it in with a micro punch afterwards…
I would rather mend & resurrect the original part just because I’m a mean, stubborn git! Besides these genuine aluminium parts are going for fucking ridiculous prices! Some people have no (or @ least less than me) shame! I’ve seen nearly £120 asked for
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This is the pin holding in the brass threaded coupling
You can see it’s possible to drill from the rear but it’s such a small diameter. If I do drill it from the rear I could use what’s left of the pin and drift it in with a micro punch afterwards…
I would rather mend & resurrect the original part just because I’m a mean, stubborn git! Besides these genuine aluminium parts are going for fucking ridiculous prices! Some people have no (or @ least less than me) shame! I’ve seen nearly £120 asked for
…wrote on 11 Feb 2023, 23:48 last edited by SpookDog 2 Nov 2023, 23:55I’m assuming that the brass coupling has a groove in it that the pin ‘bites’ into?…
PS: no input on the stainless steel pipe? I hope I haven’t caused offence! I know that I can be quite abrasive sometimes when I drink the Brew. Please, just don’t take it personally. I’m tetchy with the World in general, not specifically
not on purpose, anyways 
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I’m assuming that the brass coupling has a groove in it that the pin ‘bites’ into?…
PS: no input on the stainless steel pipe? I hope I haven’t caused offence! I know that I can be quite abrasive sometimes when I drink the Brew. Please, just don’t take it personally. I’m tetchy with the World in general, not specifically
not on purpose, anyways …wrote on 12 Feb 2023, 08:09 last edited by@SpookDog Yes there's a groove in the brass coupling for the pin to retain it. If you can get the roll pin out intact it would be perfectly in order to re-use it IMO, although it might not fit as tightly as when installed by the factory hence my decision to use a split pin the same size.
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I’m assuming that the brass coupling has a groove in it that the pin ‘bites’ into?…
PS: no input on the stainless steel pipe? I hope I haven’t caused offence! I know that I can be quite abrasive sometimes when I drink the Brew. Please, just don’t take it personally. I’m tetchy with the World in general, not specifically
not on purpose, anyways …wrote on 12 Feb 2023, 10:42 last edited by@SpookDog Like this, looks neat enough but it can always be taken apart again if necessary. In hindsight I could've used an M3 CSK screw from the RC car box but that would have meant countersinking the housing to match and being plastic, I wanted to disturb/mutilate it as little as possible
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@SpookDog Like this, looks neat enough but it can always be taken apart again if necessary. In hindsight I could've used an M3 CSK screw from the RC car box but that would have meant countersinking the housing to match and being plastic, I wanted to disturb/mutilate it as little as possible
wrote on 12 Feb 2023, 12:57 last edited byWow, so that’s what a clean one looks like?! Cool, when you said it was plastic and you drilled from the inside, I thought something else…
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Wow, so that’s what a clean one looks like?! Cool, when you said it was plastic and you drilled from the inside, I thought something else…
wrote on 12 Feb 2023, 15:34 last edited by SpookDog 2 Dec 2023, 15:55I don’t know if it shows in the pic’s very well but my locator ring is proper bowed out to a saucer!…
It’s proper curvy. The worm gear has seized solid in the brass fitting and caused the ring drive to stop turning, forcing it against the wheels rotation, which in turn bent up the tabs…
I’m lucky it just pushed the tabs up and didn’t tear them up, or off completely!…
I’m guessing that the 3 prong locator ring should be fla …PS does the locator ring need to be a tight fit onto the ring gear, or does the curclip hold it in place?…
If you’re not sure I guess I’ll just tweak the clip to grip the ring gear. It was well tight when I dismantled it but I assumed it was cause it was so deformed… -
I don’t know if it shows in the pic’s very well but my locator ring is proper bowed out to a saucer!…
It’s proper curvy. The worm gear has seized solid in the brass fitting and caused the ring drive to stop turning, forcing it against the wheels rotation, which in turn bent up the tabs…
I’m lucky it just pushed the tabs up and didn’t tear them up, or off completely!…
I’m guessing that the 3 prong locator ring should be fla …PS does the locator ring need to be a tight fit onto the ring gear, or does the curclip hold it in place?…
If you’re not sure I guess I’ll just tweak the clip to grip the ring gear. It was well tight when I dismantled it but I assumed it was cause it was so deformed…wrote on 12 Feb 2023, 19:30 last edited bySuss this one out…
I actually cut the whole bit off after I drilled it out and it still wouldn’t come out…
You can see the groove where the pin fitted! It still will not let grip of the brass insert!!
although the insert turns freely!! WTF?!!Have a link to a cheap copy replacement, anyone?
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I don’t know if it shows in the pic’s very well but my locator ring is proper bowed out to a saucer!…
It’s proper curvy. The worm gear has seized solid in the brass fitting and caused the ring drive to stop turning, forcing it against the wheels rotation, which in turn bent up the tabs…
I’m lucky it just pushed the tabs up and didn’t tear them up, or off completely!…
I’m guessing that the 3 prong locator ring should be fla …PS does the locator ring need to be a tight fit onto the ring gear, or does the curclip hold it in place?…
If you’re not sure I guess I’ll just tweak the clip to grip the ring gear. It was well tight when I dismantled it but I assumed it was cause it was so deformed…wrote on 13 Feb 2023, 08:34 last edited by@SpookDog said in So Close!...:
I don’t know if it shows in the pic’s very well but my locator ring is proper bowed out to a saucer!…
It’s proper curvy. The worm gear has seized solid in the brass fitting and caused the ring drive to stop turning, forcing it against the wheels rotation, which in turn bent up the tabs…
I’m lucky it just pushed the tabs up and didn’t tear them up, or off completely!…
I’m guessing that the 3 prong locator ring should be fla …PS does the locator ring need to be a tight fit onto the ring gear, or does the curclip hold it in place?…
If you’re not sure I guess I’ll just tweak the clip to grip the ring gear. It was well tight when I dismantled it but I assumed it was cause it was so deformed…@SpookDog IIRC the ring with the 3 tabs is supposed to be flat yes. It also has 2 flats on its ID which correspond with flats on the ring gear and should locate over these so the gear drives it. And there should also be two shims, one underneath the ring gear and one between the 3 tab ring and circlip.
Shame you had to do that to get the pin out but if you're really determined to save the unit I guess you could get someone to build it up with ally weld and re-machine it, whereupon you could decide exactly how you want to retain the brass insert using a nut and bolt or similar, might be a cool project which moves the DTR community forward as those speedo drives are difficult to get hold of secondhand.
There's a guy on the web somewhere called Badfoot Customs who does exactly this kind of work, he's saved smashed MX bike crankcases by welding in extra replacement sections and stuff like that.
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@SpookDog said in So Close!...:
I don’t know if it shows in the pic’s very well but my locator ring is proper bowed out to a saucer!…
It’s proper curvy. The worm gear has seized solid in the brass fitting and caused the ring drive to stop turning, forcing it against the wheels rotation, which in turn bent up the tabs…
I’m lucky it just pushed the tabs up and didn’t tear them up, or off completely!…
I’m guessing that the 3 prong locator ring should be fla …PS does the locator ring need to be a tight fit onto the ring gear, or does the curclip hold it in place?…
If you’re not sure I guess I’ll just tweak the clip to grip the ring gear. It was well tight when I dismantled it but I assumed it was cause it was so deformed…@SpookDog IIRC the ring with the 3 tabs is supposed to be flat yes. It also has 2 flats on its ID which correspond with flats on the ring gear and should locate over these so the gear drives it. And there should also be two shims, one underneath the ring gear and one between the 3 tab ring and circlip.
Shame you had to do that to get the pin out but if you're really determined to save the unit I guess you could get someone to build it up with ally weld and re-machine it, whereupon you could decide exactly how you want to retain the brass insert using a nut and bolt or similar, might be a cool project which moves the DTR community forward as those speedo drives are difficult to get hold of secondhand.
There's a guy on the web somewhere called Badfoot Customs who does exactly this kind of work, he's saved smashed MX bike crankcases by welding in extra replacement sections and stuff like that.
wrote on 13 Feb 2023, 08:37 last edited by@HOTSHOT-III I follow badfoot customs on Facebook. They do some amazing work.
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@SpookDog said in So Close!...:
I don’t know if it shows in the pic’s very well but my locator ring is proper bowed out to a saucer!…
It’s proper curvy. The worm gear has seized solid in the brass fitting and caused the ring drive to stop turning, forcing it against the wheels rotation, which in turn bent up the tabs…
I’m lucky it just pushed the tabs up and didn’t tear them up, or off completely!…
I’m guessing that the 3 prong locator ring should be fla …PS does the locator ring need to be a tight fit onto the ring gear, or does the curclip hold it in place?…
If you’re not sure I guess I’ll just tweak the clip to grip the ring gear. It was well tight when I dismantled it but I assumed it was cause it was so deformed…@SpookDog IIRC the ring with the 3 tabs is supposed to be flat yes. It also has 2 flats on its ID which correspond with flats on the ring gear and should locate over these so the gear drives it. And there should also be two shims, one underneath the ring gear and one between the 3 tab ring and circlip.
Shame you had to do that to get the pin out but if you're really determined to save the unit I guess you could get someone to build it up with ally weld and re-machine it, whereupon you could decide exactly how you want to retain the brass insert using a nut and bolt or similar, might be a cool project which moves the DTR community forward as those speedo drives are difficult to get hold of secondhand.
There's a guy on the web somewhere called Badfoot Customs who does exactly this kind of work, he's saved smashed MX bike crankcases by welding in extra replacement sections and stuff like that.
wrote on 13 Feb 2023, 15:56 last edited by SpookDogI’m gutted as well. It still wouldn’t come out after drilling the pin out with a 1.5, then 2mm drill, so I was using a 3mm bit and it snapped the casing apart. The brass bit still wouldn’t come out so I started trimming back the sharp bits to get at whatever was stopping the brass coming out. Things got out of hand as I got more irate. The brass fitting turns in the casing but will not pull out. I’ve put it in a vice and pulled on the thing with no outward movement. It has to come out cause the worm drive is bent and needs straightening as well as clean & lube…
Some of the XT drives look similar, they use the same speedo I think, as well as a 21in wheel. Still not cheap, but cheaper than the ‘dtr tax’
If anyone has an original part (preferably) or even a known working copy, please let me know
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