Author Topic: It just wont start.  (Read 754 times)

snosk8er

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It just wont start.
« on: March 21, 2003, 07:32:28 PM »
I have just had the pleasure of replacing the crankshaft conecting rod bearings etc and now the motor is back in my machine it will not start.
It turns over fine, carbies are ok ( I can see fuel when i give the accelarator a squeeze down thru main body.) and it has a strong strong spark.
Every now again it has big backfire, this happens while not turing the motor over only when sitting with ignition on, or when ignition is first turned on.
I followed the timing proceedure to a Tee from Haynes manual but I am stumped as to what else it could be.
Hope someone may have some advice, to help put me out of my misery.
Thanks
Jim  

bikeseamus

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Re: It just wont start.
« Reply #1 on: March 21, 2003, 11:36:56 PM »
 Jim   I had the exact problem. I replaced the ignition relay, and was then OK. I think others in this forum could explain why better than I, but it did work for me. Make sure the resistance checks out in your relays for a start. If you haven't upgraded to modern bayonet fuses, you probably should. Loose connections throw too many jokers into the deck. Let us know what you found. OK Bub

Dave T.

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Re: It just wont start.
« Reply #2 on: March 22, 2003, 04:05:06 AM »
The TCI will fire the spark plugs (take away 12V primary power) if the crank isn't spinning after a few seconds. The V has "wasted" spark. Both plugs fire every revolution.

I re-did my top end and had the rear not firing. I figured out that I went by the timing marks on the timing gears and not the camshaft itself so the timing was a "tooth" off (17 degrees??). Remember it's a 70 degree twin, so TDC should be 290 degrees off each cylinder.
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Lucky

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Re: It just wont start.
« Reply #3 on: March 22, 2003, 04:17:57 AM »
The backfire (some times muffled, correct?) is normal for the bike.  when the ignition is turned off the TCI will sometimes fire. Leather describes this phenominom on his page as a self test.

If it is also backfiring while your trying to crank the bike then probably the pilot settings, carb sync or both are probably off..  Did you make adjustments somehow to the carbs since the last time you started the bike?

also, try disconnecting the starting safety circut from the
TCI.  remove or cutting the black wire with the white stripe at the TCI 6 wire connector  also the yellow/black wire in the same TCI plug goes to the rev limiter in the Tach.  if the rev limiter is malfunctioning, then it will cut out the front cylinder.  this can also make it hard if not impossable to start the bike, so at least as a test, pull this wire too.   if your careful, with a pin wou can remove these wires from the connector without cutting them.

and of course, double and tripple check all your connections, make sure everything is clean & shinny.

good luck & keep us posted... --Lucky
1982/3 XZ550 Touring Vison, Gold on Black

RobTx

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Re: It just wont start.
« Reply #4 on: March 22, 2003, 07:20:32 AM »
Try using jumper cables to start the bike if the battery is run down in the least.  The TCI won't make a spark below a certain voltage.  When you crank the engine, the battery voltage may drop below this threshold.  You said it would fire sometimes when you turn the key on, but not while cranking, is that right?  If you have the tools, check the compression to make sure the cams are timed right, although it's unlikely both of them are and the Vision will run on one cylinder.
Rob