So Close!...
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Does anyone else with an early bike 88~96 have issues with the headlight dimming when the brake light comes on? It’s been bugging me forever since getting the bike! The headlight runs off of a/c directly from the stator coil, but the brake light is run off of the battery, it shouldn’t affect it! The only thing I can think of is that they share an earth?! I’ve just rigged up an earth to the frame straight from the battery. I’m gonna see if that helps any. The neutral light looks stronger anyways, as is the PV on the key
…Fixed the indicators (& intermittent speedo bulb). Six new bullet connectors behind the headlight!! (& 1 bulb) The last couple years have been hard on the loom! Everything looks brighter on the battery now
…Almost forgot: This may sound stupid, but: 2T oil from the exhaust ‘filming over’ the battery top, could it diminish the output amp/voltage? Mine was coated and the power valve & neutral light had gotten ‘sluggish’. It’s better since cleaning, but I’m not sure if it was this or a poor earth to the battery? I guess I’ll try not connecting the earth, later after night testing…
I wish I knew a motor cycle electrician/Wizard
️…wrote on 13 Aug 2023, 15:46 last edited by SpookDogHeadlight dimming when brake light is on: I really would like to know if other people with early 3 coil stator all have this problem. If I know it’s just my bike I can go about tracking it down and fixing the problem…
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Headlight dimming when brake light is on: I really would like to know if other people with early 3 coil stator all have this problem. If I know it’s just my bike I can go about tracking it down and fixing the problem…
wrote on 13 Aug 2023, 18:39 last edited by HOTSHOT III@SpookDog Lights dimming with brake lights/indicators/horn is not really a problem as such, we discussed this back in March IIRC. All the early DTRs I've owned have done this, the combined AC/DC electrical system is unique to the DTR:
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Headlight dimming when brake light is on: I really would like to know if other people with early 3 coil stator all have this problem. If I know it’s just my bike I can go about tracking it down and fixing the problem…
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@SpookDog Lights dimming with brake lights/indicators/horn is not really a problem as such, we discussed this back in March IIRC. All the early DTRs I've owned have done this, the combined AC/DC electrical system is unique to the DTR:
wrote on 13 Aug 2023, 19:48 last edited by SpookDogCheers bud! Mine dips regardless of revs. Tickover I could deal with…
@HOTSHOT-III
I can remember bringing it up but not if it got resolved in any way. It’s just gotten more noticeable the last couple nights I’ve ridden. Plus my electricals have gotten gremlins the last couple days…Oh yeah! My brake light just blew…
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wrote on 14 Aug 2023, 10:09 last edited by
Presumably they don't dim once the RPMs are up?
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wrote on 15 Aug 2023, 09:11 last edited by
Unbelievable! Half way on a commute I’ve lost all power to the indicators, dash lights, ect. The AC to the headlight, tail light and dial lights is still there. If it was the battery I’d still have working indicators, ect, when the engines running wouldn’t I?…
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wrote on 15 Aug 2023, 09:36 last edited by
Yeah, that doesn't sound good! Have you blown the fuse?
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Unbelievable! Half way on a commute I’ve lost all power to the indicators, dash lights, ect. The AC to the headlight, tail light and dial lights is still there. If it was the battery I’d still have working indicators, ect, when the engines running wouldn’t I?…
wrote on 15 Aug 2023, 10:35 last edited by SpookDogWow! It was just the fuse, only had a 5a fitted. I didn’t realise that the battery carried 90% of the load for ancillaries! Makes me wonder even more about why it takes power away from the headlight!?! I need to try a different RR…
I think it might be a weak earth. There was this ‘trick’ we used to do when water cooling PCs. The 12v fans were too loud so we would wire +12v to the fans positive and wire +5v to the negative. This would run the fan at 7v so it was quieter. Maybe something along these lines is happening?…
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Wow! It was just the fuse, only had a 5a fitted. I didn’t realise that the battery carried 90% of the load for ancillaries! Makes me wonder even more about why it takes power away from the headlight!?! I need to try a different RR…
I think it might be a weak earth. There was this ‘trick’ we used to do when water cooling PCs. The 12v fans were too loud so we would wire +12v to the fans positive and wire +5v to the negative. This would run the fan at 7v so it was quieter. Maybe something along these lines is happening?…
wrote on 16 Aug 2023, 12:23 last edited byBlown again! Could a ‘sticky’ power valve cause it to blow? The PV runs off of the battery, yes?
I used some non Castrol 2T oil and it leaves gum on the power valve… -
Blown again! Could a ‘sticky’ power valve cause it to blow? The PV runs off of the battery, yes?
I used some non Castrol 2T oil and it leaves gum on the power valve…wrote on 16 Aug 2023, 15:07 last edited byTa Daa! For today’s drama! We have a snapped PV cable that appears to have been stuck together by the inner lining and kinda still operating!
Time to strip & clean the PV!…
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Ta Daa! For today’s drama! We have a snapped PV cable that appears to have been stuck together by the inner lining and kinda still operating!
Time to strip & clean the PV!…
wrote on 16 Aug 2023, 15:18 last edited by SpookDogLuckily I was able to purchase one of these that came with a 3mb-p barrel head & piston for £130!
Bless that fleabay vendor 
I hate spending time off the road when it’s not my choice!…
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Luckily I was able to purchase one of these that came with a 3mb-p barrel head & piston for £130!
Bless that fleabay vendor
I hate spending time off the road when it’s not my choice!…
wrote on 16 Aug 2023, 15:41 last edited byI have two 3 wire servos, one is marked: 3MB -00 27 U
The other is: 3MB -00 87 #
The ‘#’ is illegible…Can anyone please give me information on which should be fitted the the Dtr?…
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Luckily I was able to purchase one of these that came with a 3mb-p barrel head & piston for £130!
Bless that fleabay vendor
I hate spending time off the road when it’s not my choice!…
wrote on 16 Aug 2023, 19:19 last edited by@SpookDog Glad to hear you have a spare servo and cables, but maybe time for some home made PV cables you can lube in situ?
https://dt125r.co.uk/post/28693
The trouble with YPVS is, on most bikes equipped with it the PV cables are too short and vertical to retain lube for any length of time. Plus to lube the stock cables you have to take them off then refit and readjust them so usually they just never get done and eventually break.
There is only one 3MB servo as far as I'm aware, the part number is 3MB-85820-00, I think the other numbers on them just refer to batch numbers used during manufacture. In fact I bought some brand new 3MB servos from Germany with KTM part numbers (originally destined for the KTM LC2 125, a kind of DTR-engined KTM 125 trail bike) and they also had the above part number on the packaging as well as having 3MB stamped on the actual servo and Yamaha moulded into the case. Fitted one to my '93 during the frame-off rebuild and performance was identical. Exactly the same part, and the LC2 also runs a 3MB CDI unit (I bought a used one and it worked on my '98 DTRe).
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@SpookDog Glad to hear you have a spare servo and cables, but maybe time for some home made PV cables you can lube in situ?
https://dt125r.co.uk/post/28693
The trouble with YPVS is, on most bikes equipped with it the PV cables are too short and vertical to retain lube for any length of time. Plus to lube the stock cables you have to take them off then refit and readjust them so usually they just never get done and eventually break.
There is only one 3MB servo as far as I'm aware, the part number is 3MB-85820-00, I think the other numbers on them just refer to batch numbers used during manufacture. In fact I bought some brand new 3MB servos from Germany with KTM part numbers (originally destined for the KTM LC2 125, a kind of DTR-engined KTM 125 trail bike) and they also had the above part number on the packaging as well as having 3MB stamped on the actual servo and Yamaha moulded into the case. Fitted one to my '93 during the frame-off rebuild and performance was identical. Exactly the same part, and the LC2 also runs a 3MB CDI unit (I bought a used one and it worked on my '98 DTRe).
wrote on 17 Aug 2023, 10:46 last edited by SpookDogCheers bud, I was worried that the controller board inside would have it cutting in at a different range, or some such. The spare one came with a P barrel with moto morrini marked on the power valve housing. So I thought it may be different if it’s for a Tzr…
Cleaned the power valve to within an inch of its life and lubed it. You can turn it by blowing on it now
lubed the cables too…But the fuse has blown again! The tail & brake light stopped working as well! Replaced a bullet connector on the brake wire and the tail light fixed itself
35 year old wiring syndrome. Vibration takes its toll over time on the connectors. I believe it’s why connections are crimped, rather than a ‘hard joint’ solder…All this started when I repaired a lot of worn connectors behind the headlight. The only thing I changed is putting an earth directly from the battery to the frame. I’ve got a RR off of a later Dtr that I’m going to try fitting. It’s got to be better than the OEM replacement that the previous owner fitted…
Hopefully it’ll put my electrical gremlins down long enough that i can get to trying to make a new loom… -
Cheers bud, I was worried that the controller board inside would have it cutting in at a different range, or some such. The spare one came with a P barrel with moto morrini marked on the power valve housing. So I thought it may be different if it’s for a Tzr…
Cleaned the power valve to within an inch of its life and lubed it. You can turn it by blowing on it now
lubed the cables too…But the fuse has blown again! The tail & brake light stopped working as well! Replaced a bullet connector on the brake wire and the tail light fixed itself
35 year old wiring syndrome. Vibration takes its toll over time on the connectors. I believe it’s why connections are crimped, rather than a ‘hard joint’ solder…All this started when I repaired a lot of worn connectors behind the headlight. The only thing I changed is putting an earth directly from the battery to the frame. I’ve got a RR off of a later Dtr that I’m going to try fitting. It’s got to be better than the OEM replacement that the previous owner fitted…
Hopefully it’ll put my electrical gremlins down long enough that i can get to trying to make a new loom…wrote on 17 Aug 2023, 11:26 last edited by@SpookDog All sounds good
Interesting mod running an earth directly to the frame; the main earth is on the coil mounting so I guess you've probably checked/cleaned that already. Worth looking at though as lots of people get their frame painted, then don't scrape off the paint here before refitting the coil. Also the earth on the taillight sometimes gives trouble as it's in the form of a spade connector on the back of the actual bulb holder and so rarely gets any attention as it's hidden between the light and rear mudguard.
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@SpookDog All sounds good
Interesting mod running an earth directly to the frame; the main earth is on the coil mounting so I guess you've probably checked/cleaned that already. Worth looking at though as lots of people get their frame painted, then don't scrape off the paint here before refitting the coil. Also the earth on the taillight sometimes gives trouble as it's in the form of a spade connector on the back of the actual bulb holder and so rarely gets any attention as it's hidden between the light and rear mudguard.
wrote on 17 Aug 2023, 12:41 last edited by SpookDogYep I always file them back to good metal. I think it was the spade connector jinking with the tail light
May sound silly but how many red wires connect to the battery positive +? 1 or 2?… -
Yep I always file them back to good metal. I think it was the spade connector jinking with the tail light
May sound silly but how many red wires connect to the battery positive +? 1 or 2?…wrote on 17 Aug 2023, 13:30 last edited byJust been studying the manual and even though the AC & DC share a common earth there are two distinct earth~circuits, one B black the other Br brown. They both go through the key barrel separately.
I’m thinking that either the previous owner or Me have ‘polluted’ the two circuits. Seeing how I’ve had this problem from day one I’m blaming them
Now I just have to find out where the brown and black have crossed…The brake switchs, indicator flasher, neutral light, horn use the brown curcuit. The split from single black to black & brown happens just after the RR…
Hopefully this will help me fix something that’s been bugging me for ages!
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Just been studying the manual and even though the AC & DC share a common earth there are two distinct earth~circuits, one B black the other Br brown. They both go through the key barrel separately.
I’m thinking that either the previous owner or Me have ‘polluted’ the two circuits. Seeing how I’ve had this problem from day one I’m blaming them
Now I just have to find out where the brown and black have crossed…The brake switchs, indicator flasher, neutral light, horn use the brown curcuit. The split from single black to black & brown happens just after the RR…
Hopefully this will help me fix something that’s been bugging me for ages!
…wrote on 17 Aug 2023, 15:43 last edited by SpookDogDamn, nothing! I really thought I was on to something. Oh well, RR is fitted and I’ll test it later on…
Can anyone tell me about the red 2T oil warning light? I seem to remember there’s a thing it does when you first turn on the ignition? Comes on regardless of oil and then goes out the first time you put it in gear, or the like?
Mine hasn’t been connected for a long while and I’ve totally forgotten …I ask because the black earth that is one of the three wires has a diode in it (one way valve for electricity?) I can’t suss out why…
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Damn, nothing! I really thought I was on to something. Oh well, RR is fitted and I’ll test it later on…
Can anyone tell me about the red 2T oil warning light? I seem to remember there’s a thing it does when you first turn on the ignition? Comes on regardless of oil and then goes out the first time you put it in gear, or the like?
Mine hasn’t been connected for a long while and I’ve totally forgotten …I ask because the black earth that is one of the three wires has a diode in it (one way valve for electricity?) I can’t suss out why…
wrote on 17 Aug 2023, 16:51 last edited by HOTSHOT III@SpookDog Looking at the 3NC wiring diagram there should only be one red wire coming off the battery +ve terminal.
The oil light should illuminate at the same time as the neutral light even with a full tank of two-stroke oil and go out when you put the bike in gear, it's just a visual check that the oil light works.
Light brown (Br on the diagram, not the same as dark brown for the left indicators which is marked Ch) is the main +ve feed from the ignition switch on all Yamahas from this era; it connects red to brown when you turn on the ignition, then as you say Br feeds the horn, brake light switches, indicator relay, temp gauge, neutral/oil lights and YPVS servo. So it helps to just consider it a continuation of the red wire. In fact if you remove your 3MB servo from the bike completely and apply battery voltage -ve to black and +ve to brown, it will perform its cleaning cycle like it does when you turn the ignition on.
Can't shed any light on why your black wire has a diode in it, only diode I can see is on the sky blue (Sb) wire near the oil level gauge.
