Intermittent stalling

[N2TekAndrew]

Ok you experts - this is a tough one...are you sure you are up to the task??
Ok I have had my bike (2000 Kat 750) for two years. I added a stage 3 myself along with K&N. Finally works great. Jump ahead a year or so...
Starts right up and I make it to work on the usual E-Ticket ride about 10 miles. Park it. At lunch I usually go home. I usually use choak for initial 30sec-1min start then off it comes. I found it reduces the warm-up time. Ride it out of the parking lot to the light then 100yards doen the road it dies...like no spark or no gas. When I hear it starting to 'act' funny I tried to switch over to PRI still nothing won't keep running.
The 2 times in the past year it has done it to me before - each time 3-4 months apart - I can push it started again. Starter just seems to crank till the bat is dead. Starts rough - like fouled plugs - then I head home. but the time I am home running fine again.
This last time I actually made it home with it running rough. Dissassembled and looked immediately at the plugs. None are fouled but look a little black and maybe wet...Cleaned and reinstalled.
Found throttle cable bracket loose w/o screw and fixed that.
I'm thinking some intermitment electrical issue. I has hoping to see one plug fouled so I could concentrate on that side, but nada.
So for intermittent problems like this what's the best approach? I have a service manual but tesing the coils you need a special spark adapter.
I'll try simply holding the plugs to ground to see if I have spark, but with it being so intermitent not sure if I'll get very far.

[elsueco]

I just went through a similar thing on my bike (1995 Kat 750). After 6 weeks in the shop and a top end rebuild, the problem turned out to be a couple frayed wires and a melted electrical connection. Bike runs beautifully now, though I wish I'd thought to inspect the wires before having all that work done. Good luck!

[joseph2027]

o k iva had that prob too. i found that my fuel filter was cloged.

[N2TekAndrew]

Intermittent stalling - More info

Ok spent a little time this weekend exploring this issue.
Replaced fuel filter - no change.
I wanted to rule out either electronics or fuel, so I pulled plugs recleaned and reinstalled - marked each one so I knew which one was which. Ran the bike in the garage for ~10 min. Pulled plugs and found that cyl 2 and maybe 4 was dirtier than the other 2. Hummm.
Tested I took an auto timing light to each plug wire while reving the engine. Strangely enough cyl #2 flashed just fine till you got to higher RPM's then would almost stop flashing! Same with #4 cyl, where 1 and 3 the light flashed as expected.
So I'm now thinking the left coil is flakey - but only at high RPM's - What The? I verified the connections just in case and they look good at the coils. I put a meter on the incoming wires and the voltage seemed to pulse accordingly - kinda tough to be sure but both sides were roughly the same. Oh BTW when the RPM's are up - 6K ish - and the coil cut's out then I can begin to hear backfires in the exhaust - which makes sence if #2 and #4 are not firing.
Correct me if I am wrong but for it to be just the one side - not both coils acting up then to me it rules out issues with connections / components up to this coil. i.e. not batery, switches, ignitor and especially the signal generator. - Right?
Now this does not rule out carb issues - but for now this seems like the initial issue. Hope this helps others with a similar issue. Keep ya posted.

[Court93kat]

This was just discussed in another thread, but I'm pretty sure the left coil (as sitting on bike) is supposed to run cylinders 1&4 and the right coil runs cylinders 2&3. The way you wrote it it sounds like you have the left coil running 2&4. Plug wires on the wrong plugs would definately cause some freaky stuff to happen, but I would think it would run crappy at all rpm's not just up high. Could you clarify which coil is running which spark plug?

[N2TekAndrew]

Yes my bad.
Left coil cyl's 1 & 4. Right 2 and 3.

Additional note - tonight I am going to unbolt and swap them, and if the plug wires are long enough, I should see the same happening but now on the other two cyl's. Reason for this - to rule out any bad wires or connections. If the same cyl's are showing bad then coil may be OK.
Anything else I'm not thinking of which I could test?

[rexazz2]

DO NOT clean plugs
IMHO it not worth it
I had problems friday nite , seems it was a fuel issue (water)
I would have bet money that I lost ignition to two cylinders
huge bogg , and afterfire blue flame out exhaust at 7K rpm
Idle and just stall , start right up again???
I put in new plugs , PIA and I was not going back in there for them again
Drain the fuel bowls , new air filter and 1/2 a can of Seafoam in the fuel tank

I was back and forth with Astro4X4 and he ran threw the same problems and it turned out to be fuel also

A guy I work with ( bike mechanic) had the same thing happen on his HD and he trailered it home , he was ****ed to find water in the fuel
He told me the same thing , he thought a coil died

[md86]

I have a service manual but tesing the coils you need a special spark adapter.

No yu don't , you just need a multimeter .

DO NOT clean plugs
IMHO it not worth it d

I disagree . I have MANY times on the roadside , and got home just fine . Depends on how bad the plugs are ....

[N2TekAndrew]

Quote..."No yu don't , you just need a multimeter ."

- agreed and it tested OK BUT...the trouble here is it is intermittent. Works fine at idle, but fails at higher RPM's.

On a similar note...didn't get around to do much testing last night...hooked it all back up just to verify the issue. All cyl's working now except #1 - which I believe was working fine before??...again only fails at high RPM's (same plugs in the same holes). So 1/2 of a coil not working? I guess this is possible and most likely the reason the multimeter test shows OK. So now what...the??

[md86]

Coils don't "half-fail" as I understand it from some of the experts .....

[ICEG]

ok it may be the spark plug boots
i had the same problems

on a random thought ......the little o-ring thats inside the petcock that seals it might
have slipped off ......it happened to me and the bike turned off

when i turned the petcock valve i guess it slipped back on and caused the same issue

[N2TekAndrew]

Wow interesting thought...Petcock. Humm...I take a peek as I have noticed a bit of gas leaking on occasion but it seems to go away.

My bike is a 2000 750 and I am trying to find a rebuild kit - I thought CyberPoet had them on his site, but I don't seem them any more and individual parts are hard to find.

I bought a used coil just to test it against the others to rule out anything else. Doing the valve adj right now - since all is ripped apart anyhoo, then back to this issue.

[Kreylyn]

Wow interesting thought...Petcock. Humm...I take a peek as I have noticed a bit of gas leaking on occasion but it seems to go away.

My bike is a 2000 750 and I am trying to find a rebuild kit - I thought CyberPoet had them on his site, but I don't seem them any more and individual parts are hard to find.

I bought a used coil just to test it against the others to rule out anything else. Doing the valve adj right now - since all is ripped apart anyhoo, then back to this issue.

There isn't a rebuild kit for the post kats specifically. The pre rebuild kits will work if you reuse the springs inside your petcock. It's normally just the diaphram and o-ring that needs replaced anyways, and they match.

There is a thread from someone who did just this and took pics.

Krey