Forum

[Matt]

So, I've just bought a Yamaha TW125 to go on the back of the camper van. It's a kind of hybrid trail bike. I bought it for £200 which seems to be a magic number for me. It's a non runner. The guy had lost the key. I've hot wired it in no time at all and all the electrics work which is great. However, between the HT lead and the cylinder head (earth) I only get one spark the first time that I press the electric start button then the engine is spinning and no more sparks. When I release the button and press it again I get another spark and the again nothing. Weird. I'm wondering if it could be the HT coil? What are your thoughts? What would you check next? Thanks guys.

[jaffa90]

Have you a wiring diagram?You may have two feeds for the spark,one through the starter circuit and another running one through a magneto? Does it have a kick start?

[Alan R]

Hello again MATT--------- my, you're a busy lad !! Is this the beasty ?? ------- http://www.motorcyclenews.com/MCN/biker ... 999-2004-/ -------------------- I'm wondering if that "Hot-Wiring" has by-passed something ?? In the wiring diagram have a look for a Ballast Resistor for cold starting..If there IS one fitted then the ign. key will have to be involved as it's designed to cut-out the resistor for starting , then connect-in for normal running....I had one on my GL1000 Goldwing----took me yonks to diagnose the fault---- It's a very L-----O------N-------G shot, but you never know???...Personally I'd have bought an old Honda CG125 (unburstable!!) or a Suzuki VanVan.....http://suzukivanvan.forumandco.com/ ----------------.

[Matt]

Thanks. No kick start as standard. I do hav a wiring diagram on PDF but I can't really make sense of it. To hot wire it I disconnected all four wires heading to the ignition and then shorted them out (intended trial and error until I got some results.) As it happened the first two I connected together turned everything on, lights, horn and starter motor. Could it be something to do with the other wires that are now just hanging loose? Good point. Suggested trail and error or could I damage something? (Blown fuse worst case scenario?)

[Matt]

Thanks Alan. That's the one. Awful reviews in general. It's basically the same as the VanVan though as far as I can tell. I've had a CG125 but I like a bit of trail ridding which this Yamaha seems much better for. Also, for £200 I couldn't resist. Here she is.

[Matt]

UPDATE. I just earthed another of the loose the wires from my "hot wire" procedure and now I'm getting loads of good sparks. I'm going to see if she starts now.

[Matt]

She's alive. She started really easily and runs well. Great tick over. HOWEVER she smokes when she revs high. White smoke. Could be rings? Worst case a re-bore and new piston. If that's the case I might make it bigger. 150cc? Maybe there's a kit available to do this?
Could the smoke be anything else?

[jaffa90]

White smoke could be steam off condensation,water.

[Matt]

That's what I thought... It does seem to evaporate off into the atmosphere as well... It doesn't linger. It's not cleared though. It's been running until hot for about 5-10mins.

[Riggers]

Nah. It just means the new Pope's been elected.....