1150 coughing and spuddering

[Carter Turk]

I have a new frustrating problem I can't figure out.

Even when my charging system was completely shot, my bike revved clean to redline.

Smooth carburetion above 3000 rpm to redline was the norm.

Now all of a sudden its couging and spuddering about 10 miles into a ride.

I thought it might be fuel starvation or inline fuel filter clogging or vacuum lock in the tank.

I just returned from a horrible 80 mile ride where I had the fuel filter on, then stopped at Schucks, removed the fuel filter and rode out the parking lot. Still spuddering, I pulled over took the gas cap completely off, and rode same thing.

I've covered just about all the wiring on the bike and replaced many shoddy connectors etc.

The bike recently had a Dyna S installed and timed with a gun, the rectifier has been replaced a new used stator installed, fresh plugs.

It feel like its running out of gas, like the floats are emptying. If I back out of the throttle it seems to clear out momentarily, but then if I maintain steady throttle in 4 or 5th it begins to hesitate and feels as if its running on 2 cylinders. If I close the throttle completely for a moment and then introduce it again it feels like its running on all four.

Anything beyond 1/4 throttle openings eventually it starts cutting out. I can't quite tell if its electrical or carburetion.

The bike has 3ohm dyna coils, ngk caps. The tank does have some rust in it, that's why I had the filter on. The petcock is a Pingel with no vacuum line. Carbs are off a 90 GSXR 11 36mm. I've been running the setup for 5 years with no issues after getting the mixtures right. I'm stumped on where to look next. Thanks for any theories.

 

[Carter Turk]

Nobody out there have any words of wisdom?

 

[Gravity Tester]

Before I give you my thoughts, Ride it again only this time when it starts to sputer ever so slowly start turning on the choke. see if the problem goes away.
Pat

 

[Carter Turk]

I've tryed that with other troubleshooting, but failed to try it this time.

The carbs are off at the moment, so I'll have a look in there first.

 

[earlfor]

You said you have some rust in the tank and that is why the inline fuel filter.
Removing the filter does not help the situation. I will bet you 5 cents to a tenspot that the sediment in the tank is being drawn over the screen or into the petcock and restricting fuel flow. when you shut down the engine and remove the fuel line, fuel flows easily. As soon as there is draw from the engine, it pulls the sediment back into place to clog it back up. I would remove the petcock, clean it out and clean the screen. I would also slosh some gas around in the tank with the petcock removed and let it wash/drain all the sediment out.

Earl

Nobody out there have any words of wisdom?

 

[MinnesotaTim]

What about running some SeaFoam or Berryman's B12 through with the next tank of gas, just in case there is a deposit in the carbs? Can't hurt, right?

 

[Carter Turk]

I was thinking about removing the petcock as removing the fuel filter did nothing for flow. I thought maybe the rust deposited enough on the filter to cause flow problems.

Earl I'll let you know if you're correct

Never heard of the foam or B12. What is it and where do I find it?

Thanks for the help

 

[Road_Clam]

Rust debris is the #1 cause for ill acceleration from clogged carbs. The debris is most likely all clogged in your fuel petcock. The debris also most commonly plugs the pilot jets. How does the engine idle?

 

[flyingace]

The assumption is you're running out of gas. What do your plugs look like when the engine misfires? If they are black/sooty, fuel starvation isn't your problem.

 

[jhw84]

Yea, you mention this wonderful ignition, but what about new plugs?

 

[Carter Turk]

The plugs look fine, no black soot. And I did mention new plugs in the first post.

 

[earlfor]

B-12 can be found at Walmart. Its intended for varnish build up. I dont think it would do a thing for blockage due to rust sediment.

Earl

I was thinking about removing the petcock as removing the fuel filter did nothing for flow. I thought maybe the rust deposited enough on the filter to cause flow problems.

Earl I'll let you know if you're correct

Never heard of the foam or B12. What is it and where do I find it?

Thanks for the help

 

[Carter Turk]

Well, the Pingel petcock looked pretty darn clean. No noticable blockage apparent.

Could my Dyna coils that I bought in 96 be functioning intermitently?

I have this feeling I'll putting everything back on, not finding anything obvious and the same symptoms will be there.

I'm just getting into the carbs, they look clean so far.

 

[earlfor]

If the Pingel is clean and the Dyna S is about new, then I would suspect coils. The first thing I would check is voltage to the coils. If thats OK, then I would check the coils.
I have had coils that checked good for specs and broke down once warmed up though.

Earl

Well, the Pingel petcock looked pretty darn clean. No noticable blockage apparent.

Could my Dyna coils that I bought in 96 be functioning intermitently?

I have this feeling I'll putting everything back on, not finding anything obvious and the same symptoms will be there.

I'm just getting into the carbs, they look clean so far.

 

[minutemen]

The dyna coils don't last forever. I just replaced mine [bought new in 1990] with the 23 year old stock coils and now the bike rips.I was having a intermittant miss at 7000-9000 rpms. Also check the wires going to the coil from the harness they have a tendency to short out on the frame if you are using the stock coil mounts.Tony

 

[Carter Turk]

As suspected, the bike exhibited the same symptoms. It took about 7 miles for it to start cutting out.

I did even try the choke when it was cutting out, and it continued to stutter, and backfire.

I drained the gas tank, cleaned the petcock, disassembled the gas cap, removed the floats, and pilots, pulled the slides all to net nothing. I'm hoping there's still hope.

I guess my coils are likely the problem.

I have a stock set I could try, does it matter which coil goes to 1,4 or 2,3?

Or should I check the voltage first. Is there really anything else besides the coils that would cause this assuming the Dyna -S is almost new?

Should I not trust aftermarket coils or is 10 years a good run?

I did use the original O/W wire going to the switched 12V. If I were to bypass this and wire directly to the coils isn't there another O/W wire going to the starter button or run switch?

As always, thanks for the advice

 

[Rick]

I would start running down the ignition system as it seems you've covered the carb side of it...check the voltage going to the coils...how much voltage drop? if that is suspect you can jumper a lead directly from the battery as the system supplies the ground to fire the coils...no it doesn't matter 1-4 or 2-3 just as long as the correct ground wire matches the correct coil..the hot doesn't matter...remember the hot line going to the coils snakes its way round and round and to the run switch and I've found this stupid switch to be a pain in the a**..
What about those stupid screw-in wires to the plug caps?...or are those wires you have a 'better' style. Could they have been disturbed?...I found one once that the cap just fell off from corrosion at the connection...made for a very maddening symptom hunt....just some thoughts..
____________________________________________Rick.........

 

[Carter Turk]

I've nipped the ends of the wire inside the cap. They are NGK, but still have the screw in deal

 

[Carter Turk]

I just called Dynatek and they said if my coils were bad they'd replace them for $70 bucks. That sounds better than paying $155.

 

[raypen4]

Sea Foam and B12 (Berryman's) can both be found at ant good auto parts store. I know for a fact that AutoZone carries both items and they are both very good cleaners.