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DT175MX Still Running Poor After MOT & Ride About


XR650-R
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Bike passed her MOT today and she is all set ready to go but now she won't start from the kick starter and is reluctant to bump start, when she does run she is poorly at mid range but ticks over fine....?.

Removed the coil tonight and primary is spot on 1.0 ohm but secondary is 12k ohm rather than 5.9k ohms as per book ? I did have the plug cap in place whilst testing....is that wrong...

Anyway messing tonight I do seem to lose the spark from time to time which might explain the poor running and the more lately non starting problems, I have un-tapped the wires below the coil as when I was trying to bump her she did fire slightly when messing about in this area; however I have found no external wires damaged within the loom. Are the coils know to fail ?, might be the original item which is 35 years old:)

Bit of a bummer as she is tax'd, MOT'd and insured now just won't run :(

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If you had the cap on you would have measured the 4k ohms in the cap too.

Please tell me you have tried a new plug.

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Yes plug was new but tried another just in case will test coil this morning without the cap....least the bike not starting now should help find the fault and with luck the poor running.....

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Small update spent a couple of hours this morning testing wires etc, nothing broken on the actual wiring but the source charge coil is only showing 201ohms rather than book 300ohms ?....the pulse pickup coil is OK at 9.8ohms book is 10.0ohms +/1 10%

I have tested the ignition coil with a power supply and I get a nice spark when dropping 7 volts on to the coil...so that seems fine along with the plug....

So it's either the low source charge coil or the CDI is borked ?.....any thought anyone ?

Hmm my log book says its a 2K4 frame and according to the manual it should have a Source high speed value of 13.6ohms across the red & black wires....my bike doesn't have a red wire from the generator ?.....which would match up with the "All other models" part of the manual ?....which state Not Applicable ?

My generator has the following wires which all match up to my loom and plugs etc...

Green/White

Yellow

Brown

White/Red

Black

Confused now

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OK removed the fly wheel and the source coil...

DSC06642.jpg

As you can see the reading is 206 measured directly at the coil...

DSC06643.jpg

Just looking for a replacement, I have see the pattern ones on ebay and have asked my local Yamaha dealer to quote....

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OK what would the effect of a low resistance coil be ?, bad/no spark as that's my symptoms really hoping to nail this problem once and for all, Yamaha should reply tomorrow if their prices are not to sky high I will get a new 1 from there. I read your post on the electrex coli's and having to modify the slot so they fit ?....I don't mind going down that route if I have to there are some cheap coils on ebay which say they fit the DT's...

http://www.ebay.co.uk/itm/321674846549?_trksid=p2060778.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Anyone tried 1 of these ?

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I have already asked about the resistance values and will let you know their reply....going back to my bike and it's current 206ohms would you suggest all my problems are related to the poor values ?, even when the bike ran it was running poorly like something was breaking down electrically ?...source coil in particular as everything else checks out OK not done anything with the CDI unit.

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Dont forget a coil can have leakage to earth as well whice can lose voltage . Salt crud moisture etc can also reduce voltage to earth if varnish is low insulation . If you know electrician with a megger get him to do leakage test.

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Shame I used to have a tester which could do 250v,500v & 1000v :)....I will unwrap the coil tomorrow and have a look inside got nothing to lose and might even try a rewind. Thanks for all the advice guys as mentioned really want to get the bike sorted as a dead bike is no good to anyone...does my head in having a bike it bits...not short of something to ride mind you...

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