Yamaha Dt200r no spark situation

[joc57]

Hi all i have a no spark situation with my dt 200r i have checked the kill switch and it appears to work as in when the kill switch is pressed i get continuity. i have also checked the coil and get a 2.5ohm reading on the primary side and a 15,000ohm reading on the secondary side (no sure if this is to spec) i am at a loss as to where to check next i would greatly appreciated it if some one on here had some advice on this. BTW i only use it for off road riding all of its accessories have been remove lights blinker ect. any help is much appreciated. cheers
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Josh

[jaffa90]

Have you a low tension voltage pulse going to the coil when kicking the engine over?

[TbirdX]

My DT125 had a loose solder connection on the stator, would cause loss of spark intermittantly.
After much wailing I tracked it down, resoldered it and it never failed to start again.

Have you a workshop manual?
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VFR800X - TTR250

[joc57]

Thanks for the reply guys, jaffa90 how would i go about testing for this what equipment do i need? between cdi and coil? excuse my ignorance im new at bike mechanics. i will be testing the stator coils this week as im waiting on a flywheel puller to get at the stator. cheers guys.
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Josh

[jaffa90]

Your coil will have a thin feed wire, this should have a pulse voltage feed up to 12 volts. Set the multimeter on volts dc and with the red probe safely in this feed and the black probe earthing on the bike frame and the coil mounting body as well.

[Robby]

In addition to the test jaffa has proposed (which is a good test to do), was it previously running with all of the lights etc removed? Did you also remove the battery?

[joc57]

hi robby i bought the bike not working the guy i bought it off said there is no spark so i have gone through and tested the kill switch which appears to function as it should the coil give the correct resistance on both primary and secondary side of it. the cdi is questionable as i dont think there is a test to do on it. i have just tested the coil on the stator and its resistance appears to be out of spec with the manual, so im going to replace the coil on the stator and see what happens. if any of you guys know where i can get my hands on a service manual that would be awesome as im currently using a manual i found online. Cheers guys
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Josh

[Easy-X]

I would imagine there wouldn't be more than magneto > CDI > coil > sparkplug with a wire running off the CDI to the kill switch and ignition. If you can find this wire just check it toggles between ground and open circuit when you toggle the switch/ignition.

After that move along the chain and check each stage is chucking out some voltage.
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[joc57]

Thanks for the reply easy-x i am working my way through the ignition system checking each component. i have two questions at the moment the ignition coil according to the manual should be 0.7 - 1.1 ohms on the primary side the one i have is reading 4.5 ohms is this too far out of spec? and the second question is does anyone know what the ignition control unit does or how to test it, or is it needed for the bike to run?
Thanks guys.
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Josh

[Easy-X]

When you get to such low ohms it's easy to gain a tiny bit of resistance through dirt and minor corrosion. The main thing it's not massively high resistance which would imply the coil's burnt out and not close to zero resistance which would imply the coil's shorted out. I'd peg it as a "maybe" for now.

The "black box" is variously called a CDI, TDI, Ignitor, etc. depending on the design and how the manufacturer's feeling at the time This controls when the angry electrical piskies are released. Old bikes would have the points system where mechanical rotation effectively closes a switch near top-dead-centre of the piston travel. The black box on newer bikes picks up this rotation from the electrical pulses from the magneto and through a circuit of capacitors and transistors emulates what the mechanical points would have done...

Unfortunately this "black box" is not as easy to test as the other components and is best categorised as "it works or it doesn't"
After that it's there's the chunky high tension lead from the coil, the plug cap and the spark plug itself.

I take it if you touch the spark plug to any patch of unpainted engine or frame you're getting nothing when you turn it over? (Worth doing in the shade in case you're getting a very weak spark.)
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[jaffa90]

UR, U no answer Questions.

[bikenut]

Check out Rex Speed Shop....

Get a red neon plug cap that fits into the plug and the or plug cap fits into, you may need to make an adaptor...

You have a wiring diagram ?

This will tell you if your system needs a battery for your system to work...
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nuts about bikes

[joc57]

Hi Guys this is the schematic for my dt200r can anyone tell me whether the ignition system requires a battery to run? My understanding of this schematic is that the battery is just there for the lights,blinkers, gauges ect(which I have removed from the bike) The only part of the ignition system that is hooked up to the battery on the negative rail is the rectifier for and I can only surmise that it’s turning the ac wave form coming from the stator to dc for the the lights and gauges is this correct or am I missing something? I appreciate all the responses guys.
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Josh

[bikenut]

Gosh Josh, could you post a clearer picture, it's fuzzy and a bit difficult to see on my phone, no computer this end.

Servo motor ?
Ign control unit etc...

Are you sure this is the exact diagram for your bike ?
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nuts about bikes

[joc57]

Sorry mate thats the best my phone could do i am pretty sure thats the manual for my bike it says dt 200rw for Oceania, after a day of re wiring i finally have spark when tested against the bike frame but the bike still doesn't run anyone have any suggestions where to look? cheers guys.
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Josh

[bikenut]

So you now have a spark, but at the right time ?

The engine has compression, breathes ok and has fresh fuel in the carb

Saw an advert on TV last night, a chap getting a close shave via remote control using a mobile phone powered by EE, balonney ! Try that around here EE, the chap would have his throat cut !!!

Can't access CMSNL for the exploded views which would show me and you a lot, internet being a pita the last few days.

Anyways, do the timing marks line up on the flywheel for tdc etc..

A sheared flywheel key will allow the ignition system to work, but, at the incorrect time.

Get a red neon plug cap that flashes when they pass HT, they fit between plug and ie plug cap but you may have to make an adapter. Cheap and a quick real world HT tester......

You may have a spark with the plug out, but does the system create a spark when the plug is in ?

Good clean plug ?

I assume you have not seen or heard the engine running ?

Has the previous owner had the engine apart ? Chewed screws)bolts, new gaskets, sealer ouzzing out of joints/gasket faces....is the piston in the wrong way ( Kawasaki k100 many many many years ago, non starter, found piston fitted backwards, it had an arrow on the crown ffs !!!! ).
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nuts about bikes

[bikenut]

So you now have a spark, but at the right time ?

The engine has compression, breathes ok and has fresh fuel in the carb ?
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nuts about bikes

[Robby]

You have spark. We will assume it's happening at the right time and strong enough, and put that to one side. Next things you need are fuel and compression.

Compression can only be properly tested with a compression tester, comparing the figures against the workshop manual.

Which leaves fuel. Seeing as the bike doesn't seem to have fun for a while, I would assume the fuel you have is fairly old and may have some water in. The carb may also be full of crap as well, but let's not go down that road just yet - even a filthy carb will still often allow the engine to run, or at least try.

I would drain the fuel out of the tank and carb and refill with a gallon of fresh petrol. If it is running pre-mix, then mix it up. If not, make sure the oil tank has oil in it. Fresh petrol, full choke, kick it over and see if it will live.

In reality, kick it over many, many times. Eventually it will cough, and then run.

[joc57]

Thanks everyone for your reply's its been a big help, so i had the bike running it ran for about a minute then i gave it a bit of juice and got the revs up i heard a bang like a electrical bang and she died. So now im back to fault finding in the electrical system i currently have no spark again so im not sure if its the coil that went because when i measure the primary and secondary sides they measure with in spec the only thing i have noticed is that when i test for continuity the primary side has continuity and the secondary doesn't. i have measured the source coil on the stator and its with in spec and so is the pulser coil so the only items that i can see that have failed is either the secondary side of the ignition coil or the cdi what do you guys think.
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Josh

[jeffyjeff]

If you heard an 'electrical bang', that means the genie escaped. not good. Sometimes you can see where he got out, especially if he left a burn mark on exit. Other times you can use your nose. Usually, if there is an 'electrical bang', some evidence is left behind. Sharpen your senses and and examine your system carefully.
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History shows again and again how nature points out the folly of men - BOC

[joc57]

hi guys just an update with my dt 200 i have found out that the bang i heard was actually a misfire due to the fly wheel coming out of sink (so the timing was out) so on further inspection it appears when i removed the fly wheel last time when i put it back on i didn't tighten the nut enough and now have broken the key way on the crank shaft that slides into the flywheel. any of you guys out there know a way of fixing this with out replacing the crank? cheers guys.
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Josh

[jeffyjeff]

Contact a competent machine shop. A photograph will help the machinist understand the extent of the damage. It may be possible to have the damage welded and a new keyway cut. If you are very lucky, maybe even without removing the crank, but in all likelihood, the crank will need to come out.
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History shows again and again how nature points out the folly of men - BOC

[Robby]

If all you broke was the key, then replace the key.

If you fucked the crank, you're probably fucked.

[joc57]

Thanks again everyone for your time to reply to these questions, i have manged to fix the woodruff key buy simply removing the old/broken one and replacing it with a new one from yamaha it wasn't machined into the crank as i first though. know onto my next question does anyone know why the ypvs might be wired into the rear brake switch? seems a bit odd but according to the schematic the the center wire goes to the rear brake switch and my next question is does anyone know if the yvps requires the battery. Cheers again guys
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Josh

[Easy-X]

Worth mentioning for non-Yammie/2-stroke ppl that "YPVS" is the "Yamaha Power Valve System" (which is servo driven.)

As to why it's connected to the rear brake switch? The [probably] brown wire you're talking about is the switched power from the battery and it runs to lots of things on the bike

As far as I can tell the magneto is wired straight to the CDI and the other 3 wires on the CDI are "engine stop" "ground" and an output to the power valve controller - doesn't look like it needs the battery to start but it would need it to run well as the YPVS is on the switched battery circuit. Maybe it could just run from the power from the regulator but you'd need someone who has a DT125R/DT200R to tell you that.

<addendum> If the blurry picture hurts your eyes: https://www.manualslib.com/manual/1101765/Yamaha-Dt200r.html?page=115#manual
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter