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Changed head gasket, lost spark

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Had a leaky head gasket on my 2005 TTR 125 with BBR 150 big bore.  I took the motor out, replaced the gasket, re-set the timing, and put it all back together.  Now I have no spark.  I have cleaned all the connections, added dielectric grease, ensured good ground contact, and put in a new spark plug. 

 

Now I'm at a total loss.  If I re-set the timing incorrectly, that wouldn't cause me to lose spark would it?  Other possible causes?

Edited by dpop24

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"The timing" refers to valve timing through cam chain links i assume? As that would have no effect, but spark timing would, though i doubt there is adjustment for that on this bike.

Perhaps you knocked the coil or something and busted a wire. If you checked what you said you did thoroughly and put it together correctly there shouldn't be a problem with the electrics.

You said you took the motor out? Did it get dropped or bumped while it was out? May have damaged the generator coil?

I know you said you checked ground, but try a direct method, touch a multimeter to the spark plug electrode and ground, see if there is a connection.

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"The timing" refers to valve timing through cam chain links i assume? As that would have no effect, but spark timing would, though i doubt there is adjustment for that on this bike.

Perhaps you knocked the coil or something and busted a wire. If you checked what you said you did thoroughly and put it together correctly there shouldn't be a problem with the electrics.

You said you took the motor out? Did it get dropped or bumped while it was out? May have damaged the generator coil?

I know you said you checked ground, but try a direct method, touch a multimeter to the spark plug electrode and ground, see if there is a connection.

 

Yes, I am referring to valve timing by re-setting the cam chain. The motor came out and got placed on my workbench.  To my knowledge, it didn't get bumped around at all and definitely not dropped.  I'll try touching my multimeter to the spark plug and ground - I'm assuming I'm just checking for continuity?

 

Thanks for the tips!

Edited by dpop24

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Does this bike have clutch and neutral position switches?  If so, did you get those hooked up correctly?  Have you checked that they are in the correct states?  You'd need a shop manual to know for sure when the switches should be opened or closed.  If it's like my 230, the neutral switch should be closed to get spark.

 

Also check the main switch and engine kill switch (if you have both).

Edited by Punkinhead

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I always forget about safety switches. Yeah, i would say they may be the cause. Considering this query had me stumped.

Make sure you hook the engine up to the bike loom entirely before trying to start it, i made this mistake with my 250.

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hey guys.  i'm a friend of dpop and love working on this kind of stuff.  i asked him to give me a crack at it.  so tonight i checked the safety switches and they appear to be working fine.  but i have a question...don't the safety switches really only decide to engage the starter or not?  the neutral switch should have nothing to do with spark.  if it did, wouldn't the bike die the minute you switched gears?  I believe this is the case, but either way I believe the switches are working properly.  and just to be sure, i manually bypassed them both and there is still no spark.  luckily dpop has a manual and he's going to bring it in so i can get a look at the schematics.  my guess at this point is either the coil, bad ground/connection, or cdi in that order.  wish me luck....and if you have other ideas or think i'm wrong PLEASE let me know.  thanks

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Hey Folks...just an update.

 

I swapped out the ingnition coil and no luck.  I double checked all the switches and they are all working as the manual states.  I took the wiring harness completely apart and checked for continuity from one end to the other and nothing.  I find it hard to believe that one of the main electrical components has failed considering that it was running fine before the repair and now has no spark, but anything is possible.

 

I have a question though.  Lets suppose that the timing is off which it could be.  That would change when the spark happens, but it should still spark, right?  Just trying anything I can think of.

 

My other guess at this point is that either a wire got pinched or wiggled loose or that there is a bad ground somewhere.

 

Any help is appreciated.  I'll keep digging as well.

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Hey Guys.  Final update!

 

Well, I have spark!  It ended up being a pinched wire coming out of the motor from the stator.  The wire was caught between the exhaust mount nut and the frame.  Soldered the wires back together, some heat shrink, and we're back in business.

 

The lesson I learned yet again (and hope it sticks this time) is to check all wires and connection before I start throwing parts at it!

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