Vintage Dirt Bike Q & A

Been working on the electrics on the MT and finally fitted the battery and... not much works... hmm...

Checked out the flasher unit and there were 3 wires and 3 connectors on the flasher, X, L and P. Ive read that X is the 12v feed from the battery, L is to the lamps and P is the pilot light in the clocks. so far so good...

But... when messing about with the flasher all i can get from it is when i connect the cables so that the flasher unit clicks all the time... then it gets very hot and blows the fuse...

So, what have i done wrong? anyone been down this route before?

Also.. is it possible to use a two prong flasher? I have one kicking around that is 6v but wouldnt know which wires i should use...

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MT250 with CR250 top end & Bassani pipe... almost fully restored.

See more of my motorbike builds at my Honda MT250 and Yamaha RD and RZ website, 2Smoked.com

If you like watches, check out my websites: DeskDivers.com & PloProf.com

I have never gotten a honda enduro from the 70's with a three prong flasher. I thought they came with two prong for a while but I do think I was wrong about that. If yours is constantly blinking its drawing too much current. I would check the wiring diagram and make sure you have it hooked up right. There is a diagram on this site you can look at.

the control lamp is not connected to the flasher unit, look at the wiring diagramm, it´s connected between the front flashers.
as i know:
X=+ (49 or B)
L= switch (49a)
P=ground (31 or E)

you can also use a two point flasher, there´s no ground needed.

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80 CR250Ra
80 CR250Ra
78 CR250R
80 CR80
82 Bultaco Sherpa 340
78 Bultaco Pursang 250 MK12
76 Bultaco Frontera 370 MK10
76 Bultaco Alpina 250
73 Bultaco Lobito 125 MK6
76 Suzuki RM125A
90 Kawasaki KX250

Thanks guys, I took on board what was said, grabbed the manual (Clymer) and also looked at the online shop manual and the owners manual and rewired the front light connections and the flasher unit and it now doesnt flash at all, none of the flasher bulbs come on, even the dash. I rewired the headlight unit again with a whole new front loom that i had in case the wiring had been crushed and something was broken, but its the same.

I tried 4 different flasher units... I didnt know i had some many 6v units! LOL. nothing helped...

Im really stumped with this. The taillight (in all headlight light positions), the brake light and the neutral light and horn all work perfectly now ive rewired the front end and the flasher no longer freaks out of course.

So... sitting here im thinking the only thing it can be is the main loom, dead flasher unit, or is it something i didnt check like a blown bulb?

Anything else you guys can think of?

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MT250 with CR250 top end & Bassani pipe... almost fully restored.

See more of my motorbike builds at my Honda MT250 and Yamaha RD and RZ website, 2Smoked.com

If you like watches, check out my websites: DeskDivers.com & PloProf.com

The 3-wire flasher is shown in the schematic, but isn't really indicated that middle (green) wire actually connects to anything. It is possible that the green wire, which is a ground, only connects to to case of the flasher?? Maybe some safety idea, in case of internal shorts. Maybe this is why your flasher gets hot (but you have tried different flashers)... or you have a short in the wiring, except it would be unusual to have both sides shorted after the turn signal switch. Or an internally shorted turn signal switch.

Do you have Black, Green, and Gray wires at your flasher?
Do your turn signals flash at all, before the fuse blows?
If you disconnect the flasher and momentarily connect the black and gray together, with the turn signal switch either Right or Left, does the corresponding turn signal light, along with the cluster indicator? Or do you get a BIG spark, and no light(s)?

These circuits are rather simple and a 2-wire flasher should be just as usable. The cluster indicator is wired between the two feeds to the right and left lights. Whichever turn signal bulb (side) isn't lit serves as the ground for the indicator.

It is probably best to isolate and test each turn signal light individually, to verify that they function. By unplugging circuits, checking continuity, and also checking for shorts, you should be able to pinpoint the problem.

You do have a multimeter, I assume... yes/no?
What types of flashers are you trying? Part numbers?
Check this page and see if any of the flashers are what you have:
http://autolumination.com/equalizers.htm

Is your flasher P X L or P + L?
Sounds like you may have an electro-mechanical type flasher and not sure if it would work on 6-volt.
Seem to be variations for either LED or incandesent lighting also.

Wish I was there to help, as remote troubleshooting always has it's difficulties.
I keep re-reading your issue.
Does the flasher start flashing/clicking as soon as you connect it, even with the turn signal switch centered?
I suspect a short circuit before the turn signal switch or in the switch itself.

Thanks so much for your input, I spent some more time today with the bike...

I did have a dead short... that's why the flasher would just start up as soon as the ignition switch was switched to 'on'. I fixed that and what i got then was that only the right rear would flash, nothing else.... the flasher unit was fine and didnt overheat. getting there.....

I tested the rear flashers and they both worked properly direct from the a battery, upon reconnection the flashers worked fine, but the I realised the back flashers were bright and the fronts were dim... but the dash bulb worked and it was kinda like christmas! haha.... I felt pretty elated... it was 'close'....

....but it was going to be short lived.... I changed the fronts to 6v8w like the rears and for about 2mins i had working flashers... and then it went bad again...

....all i had was the right rear flashing, no matter weather i indicated to turn right or left.

I manipulated the loom a bit near the headstock plug and there was obviously some breaks in it, i could switch off the whole front end doing that, ie no neutral light or horn.

I cut the wires back from the plug and added a better front end of the main loom from a spare loom i had and i thought that would do it, but...

...now i have the right rear working again, but it even works with the left rear when indicating left... hmm... cool hazard lights, but no good for what i want LOL!

I did find that by adding or removing bulbs from the front indicators would give me different effects, i guess its due to some voltage drop or something... this may well be key to working out what the real issue is perhaps?

So... i think i need to play with this some more, but would welcome any input anyone would have, it seems the flasher unit works well when you have 2x 8w plus the 3w dash bulb so my original problem is fixed in that i do seem to have that right, i just need to work out why my indicators do strange things, it could be them earthing or there could be more loom issues i guess... hmm....

All and any help gratefully received... Thanks!

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MT250 with CR250 top end & Bassani pipe... almost fully restored.

See more of my motorbike builds at my Honda MT250 and Yamaha RD and RZ website, 2Smoked.com

If you like watches, check out my websites: DeskDivers.com & PloProf.com

Jon,

If this were my bike, I would either run a continuity check on every single wire (if the loom appeared in excellent shape), or better yet, replace the loom with a known-good (or at least known-better) one. eBay has a bunch of used ones, probably more than just these:

http://www.ebay.com/sch/i.html?_from=R4 ... Categories

If you think you're having fun now, wait till the ignition-related wiring starts cutting out 20 miles from home. I think you're having sufficient mystery problems at this point to safely assume that several wires / switches / connectors are compromised - perhaps the entire bundle! - and it's surprisingly easy to spend days "fixing" this and that minor problem, when all you've really done is move the loom around to a different position where it works for a while.

At the very least, I'd completely remove the existing harness for a thorough visual inspection and continuity check. I pulled my buddy's harness off last week, it took about 15 minutes (getting it back on will surely take longer ).

Ray

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'74 CR125M (175cc), '75 MR175, '82 RM250Z, '08 YZ250F, '14 Zero FX electric, '14 Zero MX electric, '18 Alta MXR electric

Ray, of course you're quite right. I may just buy some wire and make my own, its not exactly a very difficult loom to redo if i am honest, and i could reuse the connector blocks with new spades of course. I will check it out, i do have another loom which i could have used, but whilst the front end was good the middle was cut up, or i would have just used it. hmm, maybe i should have done that anyway :/

_________________
MT250 with CR250 top end & Bassani pipe... almost fully restored.

See more of my motorbike builds at my Honda MT250 and Yamaha RD and RZ website, 2Smoked.com

If you like watches, check out my websites: DeskDivers.com & PloProf.com

Ok, an update....

Whilst i always tell anyone who is messing with an electrical problem to check their earths, i obviously dont take my own advice LOL!

So, the issue with the front indicators making the rears do strange things was that they were earthing thru the dash bulb i think. the bracket that hols the indicators on was powdercoated and was not making a contact with the headlight bolts, hence no earth...(these units i fitted have no separate earth wire. A clean up and now the bracket is earthed to the headlight bolts and im fixed.

(obviously the main loom fix worked fine... hmm... we'll see...)

_________________
MT250 with CR250 top end & Bassani pipe... almost fully restored.

See more of my motorbike builds at my Honda MT250 and Yamaha RD and RZ website, 2Smoked.com

If you like watches, check out my websites: DeskDivers.com & PloProf.com