A forum for owners of Yamaha TTR250 trail and enduro bikes!

Nige Taylor · Senior Member

Possible Electrical fault help

Cubber · Super Guru

I presume it's a UK model, since you're from Plymouth. confuse

I would guess it's an intermittent short in your system so IMO you'd better start looking at the wiring loom, component connections and check for broken wires.

Bad earths are common, since a TTR tends to be ridden and used in damp, muddy places just for fun. hmm

Inspect the obvious areas of exposed wiring harness found around the handlebars, headlamp and headstock areas for trapped or chaffed wires/loose connections.

Copious spraying (and praying) with WD40 on dismantled (and then replaced) connectors would help.

Try narrowing down the symptoms like when they occur - any cause for it? puddles? splashes? bumps? confuse confuse

Good luck.

Martyn

TT-R250M · Super Guru

Hello Nige, sorry to hear you are having trouble.

Things to rule out-

The fuel breather hose and cap as this can cause it to stop but usually not abruptly. It should splutter and die and then repeat it's vicious cycle. In this case choke usually helps but this is unlikely to be the problem by the way you described the problem.

List of possible causes and cures-

First of all I would check that you have a good main earth connection and also that the trigger circuit is grounded correctly to the ignition coil. To do this- remove the bolt from the regulator/rectifier and make sure the bolt and connector is rust free and clean. You should then do the same to the trigger/earth wire that bolts to the ignition coil.

Faulty spark plug- replace

Check the spark plug cap for the specified resistance i.e. 10k at 20 degrees Celsius. You may need to unscrew the ignition lead (secondary) from the cap and cut it off (to renew the wire inside)and twist it back on.

If it only happens when it heats up, the ignition coil may be at fault. They usually start to break down once the bike has warmed up and make the bike run constantly rough though. Check the ignition coil resistance, it should be- Primary :0.36~0.48k at 20 degrees Celsius and Secondary: 5.44~7.36 k at 20 degrees Celsius (spark plug lead-spark plug lead).

There may be an ignition power wire that is grounded to the frame or an earth in the harness. Check the entire ignition circuit for cuts or burnt wires.

The On/Off switch or ignition switch may be sticking. Hard to tell in this situation without dismantling them and checking the operation of it. For the main switch you can check the continuity between red and brown and for the On/Off/engine stop switch check the continuity between red and white. However, I hardly think this will work in your case.

The exciter/pulser/pick-up coil coil may be at fault. Check the resistance of this and compare it to the manuals specification i.e. 190~230 at 20 degrees Celsius.

The CDi may be at fault. This would be a hard one to test and replacing it (as a last resort) may be the only way to find out for sure.

If you have trouble with any of this, refer to your manual under the ''trouble shooting'' section or ask if unsure.

Jarrah

P.S if you have a friend nearby that owns a TTR250 that is willing to swap ignition parts to help diagnose the problem, it would be VERY helpful!

TT-R250M · Super Guru

Nige Taylor wrote:
Also on the odd occasion the bike will not start on the button and it is completely dead when this happens, although again all the lights come on and work as normal.
Thanks, Nige

On the intermittent starter motor issue-

Provided that your battery is charging as you seem to verify in your post, the list of things to check would be-

Battery leads are tight.

The fuse to make sure it has a good connection.

The starter relay high tension leads are tight and corrosion/rust free.

The starter relay is in bolted in tight and not touching the frame.

Start button has a good connection.

The battery earth lead that leads from the battery to the earth at the starter motor bolt is tight and corrosion/rust free.

Solenoid/starter relay.

Starter motor bushes.

Here is a thread that you may find useful - http://ttr250.activeboard.com/t49344651/starter-motor-removing-and-replacing-a-starter-motor-plus-ch/?w_r=1387231995

Testing switches-

You can test switches by disconnecting the switch from the harness and (1.) Use a multimeter that has a continuity function and testing the continuity between the power feed end and the receiving end of the switch OR (2.) Run 12-V power through the start switch (using a battery) and test the voltage with a multimeter. The purpose of this would see if the voltage remains the same voltage as the battery used and is not the current is not intermittent. You would need to run the 12v through the power feed wire and test the receiving wire to use the second method mentioned. Keep in mind that with a start switch you would have to press the button while testing (obviously).

Hope that helps, any questions- ask!

Jarrah

Nige Taylor · Senior Member

Thanks very much for your help everyone, that gives me something to go on to try and solve the problem!

Nige

TTRfan · Super Guru

If all else fails then I can help swap parts Nige.

My bet is that it's the combined starter/stop switch or its connections.

Brian

TT-R250M · Super Guru

TTRfan wrote:
If all else fails then I can help swap parts Nige.
My bet is that it's the combined starter/stop switch or its connections.
Brian

Very nice of you Brian

If you are talking about the intermittent starter motor issue I think that you are correct. However, if you are talking about the intermittent spark issue i.e. ''cuts out very very briefly and then continues to run'', the start switch has nothing to do with this!

Jarrah

TTRfan · Super Guru

TT-R250M wrote:

TTRfan wrote:
If all else fails then I can help swap parts Nige.
My bet is that it's the combined starter/stop switch or its connections.
Brian
Very nice of you Brian
If you are talking about the intermittent starter motor issue I think that you are correct. However, if you are talking about the intermittent spark issue i.e. ''cuts out very very briefly and then continues to run'', the start switch has nothing to do with this!
Jarrah

There could be a temporary occasional short on the "stop" switch circuit of the switch?

TT-R250M · Super Guru

TTRfan wrote:

There could be a temporary occasional short on the "stop" switch circuit of the combined starter/stop switch?

Yes, or the ignition switch, but NOT the start switch. The start switch only controls the starter motor and has nothing to do with the ignition in that regard. Unless the AC start switch wires are touching the DC wires (highly unlikely or wires would burn instantaneously and cause more problems than just intermittent spark), the start switch cannot interfere with the ignition circuit.

Jarrah

Nige Taylor · Senior Member

Not had chance to look at anything yet, but thanks Brian, very kind of you.