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Bike lost spark at speed - dead as a hammer

  • Thread starter Thread starter Fishman
  • Start date Start date
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Fishman

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I am beginning to think my bike has an evil gremlin hiding somewhere in it. I synched the replacement carbs today and sure enough, they were way off. Bike sounded sweet at idle and on up through the rpm range in 1 and 2. Higher gears encountered a big dead zone that the bike didn't want to rev past . . . from 6k on. I think this is likely due to the 110 jets in the rebuilt carbs. The manual specs 92.5, whatever those numbers refer to. But with a stock airbox and exhaust, it's probably too much.

So I was messing around during my ride on the way home to make sure I had a good handle on what was going on. I planned to pull the carbs and put the standard jets from my old carbs in it when I got back. As I was giving full throttle and noting the response the bike just quit. It acted like the key had been switched off. I managed to coast a little way and pulled off to the side of the road. The bike was just dead, although the lights all worked. Two and a half miles later (I watched the odometer) and three hills, I was home, but half dead or felt like it.

This is exactly what my original 550t did in 1992 when I was riding it to a buddies house to deliver it after selling it to him. Riding along and then "wham" no go. He told me later it was the voltage regulator, but I'm not sure he had the whole story. He sold it within a few weeks for a tidy profit.:mad:

Just venting a little, but some guidance would be appreciated. Would an ignitor go out just like that? What other likely places might I look? The charging system was operating correctly when tested three weeks ago.
 
The basics, fuel, spark, compression.
compression won't up and go away.
fuel usually sputters/bogs then dies.
but spark can go away. kill switch bad, blown fuse, bad connection ect...
 
Check for spark. I'm betting you don't have any.

Does the bike still turn over but just not fire?

If so, i'd bet my paycheck on the ignitor. It can cut out just like that.
 
The two wire/prong plug from the signal generator that plugs into the igniter on my bike was corroded something awful. Check yours to make sure.
 
Mine too.

Mine too.

I have had the same issue on my 81 450. On the way home one night it just died. It sat for a few then started and then repeated itself. The situation got progressively worse until it just would not start.
I have checked the coils and got 6 ohm's which is in range. I also checked the generator which is good. I have an ignitor on the way and i am keeping my fingers crossed on it. Good luck.
 
fuse

fuse

First, check the fuses. If the ignition fuse blew, you'd have to find out why. But that's one sure reason that it can just quit. If the fuse is ok , then you start looking at things like the igniter box, signal generator and connections. Most of the other stuff will make it run bad, but not just drop dead in the middle of a run.
 
Thanks very much to all who responded, I see some good advice in there. I won't be able to get to work on the bike until tomorrow evening because of real work needing me.:o Thought about it a bit and the first thing I'm going to check (after making sure there isn't any spark) is the kill switch since that is on the throttle grip which is the last thing I was operating before it died. Also going to check the fuses. If those check good, then I'm going to pull the ignitor and check for corrosion/heat indications. I'll post back what I find, hopefully Wed.

rlong74, post back here what you find, that will be interesting.

In the meantime, anybody know where to get an ignitor? I haven't seen one on Ebay and I think the 550t is fairly specific. I know I can cross-ref with the part number to see what other bikes might use it, but I was just wondering if someone had a source for one already.
 
Well i got the enw ignitor in today and she fired right up. I was freaking elated! i went around the block then the same old **** happened. I am pulling out the carbs tomorrow. Sorry that wasn't any better.
 
Hi rlong 74,
If a bike dies suddenly most likely it's an elecric problem, not the carbs. Save yourself the hassle of going trough the carbs, and concentrate on the electrics. Check all the connectors first, then the switches.
Succes,
Ed
 
I had the same problem with my GS750, riding to work one day the motor just stopped. Coasted to a halt, everything dead. After a few minutes cursing, tried the starter and she fired up. Ran great a few more miles then the same thing. Turned out to be a badly corroded connection to the ignition switch. Like Ed suggested, I`d check out the connectors on the ignition circuit first of all, I`m inclined to think thats where the problem lies.
 
Listen to these guys . . .

Listen to these guys . . .

Check your electrics first. I pulled the sidepanel to get to my fuse box and "wtf!" one of the fuses was popped out and forward! No way, how did that happen! Put it back in and the bike fired right up. This is after a 2.5 mile push.:oops:

I am inclined to replace the fuse box, which no longer has a cover, with a new one using blade fuses. I've seen that conversion on here and some look right nice.

Thanks everyone. I feel stupid though.:o
 
Already got the carb headache. Those things are clean as a whistle now. Thanks for the advice. i will go through everything electric.
Thanks again.
 
ignition coils

ignition coils

I checked all wires i could see. No corrosion anywhere. I replaced a fuse that looked a little worn. I also jiggled the spark plug wires. After i jiggled the wires she fired up and idled nicely with none of the dying off when i gave it any throttle. That lasted until i dropped it down and moved it then it started bogging down again. Does anyone know if those coil wires replaceable or are they all one unit? 81 450t.
 
You can likely unscrew the plug caps and trim the ends of the plug wires to ensure good connection. Hold the wire tightly and turn the boot counterclockwise. I did this a while back but it did not solve the problems I had at the time.

Since yours is a twin (right?), loss of one plug could cause your symptoms. Do you know your coils are good?
 
I got 6 ohm resistance on the primary but i can't test the secondary. a shop nearby wanted to charge me $100 to test them. I will try with the boots though or at least look at them. I might also say there was a couple of spots where the wires are rubbing almost to the insulation.
I'll keep looking. Thanks.
Trimmed the plug wires, de-bent? any bent wires crossed my fingers and she fired up.Looks like i'm back on the road. :D
Thanks to everyone and your advice. Makes me proud to own a GS. Even a little one.
 
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