Strange problem..Dyna S ????YES !!!!!!!!

Wife and kids gone for the week, so I've been forced to have extra time to ride;) 350 plus mile this week.
The bike has been running GREAT !!
Last night went over a couple of towns, got only .658 gallons of gas as I don't want to be too low on gas, I like to be full when out of town just in case...
Rode around for maybe five minutes and left to head home. Cranked on it some as I left town, up to about 90+ - miles and hour, nothing over 8 grand. AND THEN.. the bike started cutting out, bucking, backfiring through the pipes, bogging on and off. Once in a while it felt like it shut off then came back on. I clutched it and it reved up fine MOST of the time, but under a load.. the same crap:( the next time under a load it ran fine W T F@$#%*?!!!?? I made it the twenty miles home, one mile no problems, the next mile the above mentioned problems.
I don't really feel it was the gas..seemed almost like an electrical problem.. but I'm no pro on this. If I was it would be fixed now.
I checked the plugs all looked good except # 1 that I have had a problem with running too rich.
I dumped a bottle of HEAT into it just as a "fingers crossed" fix. But I haven't rode it since. It starts fine. Just afraid to ride it and break down on me with nobody @ home to come get me.
So point a old man in the right direction if you would PLEASE.
1974 900 Z1 - DYNA COILS, NEW DYNA WIRES, NEW DYNA S IGNITION, W/G 28 CARBS, NEW CARB BOOTS, K&N PODS, FRESH ( LAST YEAR ) RINGS/ HONE AND VALVE JOB, NEW CAM CHAIN.
Thanks, Pat

Post edited by: patmann, at: 2006/07/03 10:05

Sounds like an issue with fuel line blockage somewhere. If you have a fuel filter, might want to check that it isn't plugged. If not, there may be gunk of one sort or another playing games in your petcock or standpipe. Might be a good idea to drain, pull and inspect the tank and associated plumbing...

Hope that helps...

I was going to head that way tonight. I'm going at lunch to pick up new fuel filters, even though the new late last year clear ones "look good". All it takes is one tank or batch of bad gas to cause good to go bad..
Keep the ideas coming

Thanks Pat

Not much to go on with the available info. First thing you will want to do to diagnose the issue is that when it recurs, spray some water on the pipes. If the water vaporizes, that cylinder is firing. If the water seems hot but doesn't vaporize; it rolls down off the pipe, that cylinder isn't firing. It sure sounds like you are running on two or perhaps three cylinders. When you have incomplete combustion, this makes a plug look like you have been running rich. Three things can cause lack of combsustion... no gas, no spark, no compression... that simple.

The least likely is the no gas. Open the drain screw of the carbs that are not firing. IF you have dry bowls, then troubleshooting should be pointed at the fuel system. The problem COULD be no spark. Depending on WHICH plugs are not firing (spray test), you can swap wire from the same coil to narrow down the possible causes. Say #1 isn't firing. If you swap it with four and the problem moves, then the problem likely isn't the spark plug, ignition or coil but more likely connection of the wire to the coil or the wire or cap. If the problem doesn't move, it is either compression or the plug. Compression is generally a valve clearance issue on an engine that has not been recently repaired.

If you drain the tank and add fresh gas it will rule out the bad gas factor, it seems the more we pay for gas the more bad gas comes out of the pump, I don't go to the pump for the bikes when I don't have to, I use a 5 gal clear can and fill it from there, got a whole tank full last fall, the bike was doing what you were describing, changed the gas bike straightend out shortly after

Check to make sure you did not blow one of the vaccum covers on the carb boots off. I had this happen and it did something similar.

Also make sure all wiring to your dyna setup is plugged together securely and the wiring to the coils is plugged in fully and not corroded. I had this on one of my KZ650s.
Also on one of my KZ1000s I had basically the same thing happen when for some odd reason one of the carbs decided to somehow turn to crap on a 5000 mile trip. That time I sprayed tons of gumout in the air intake while revving the engine and it cleared up.

RonKZ650 wrote:

Also make sure all wiring to your dyna setup is plugged together securely and the wiring to the coils is plugged in fully and not corroded. I had this on one of my KZ650s.
Also on one of my KZ1000s I had basically the same thing happen when for some odd reason one of the carbs decided to somehow turn to crap on a 5000 mile trip. That time I sprayed tons of gumout in the air intake while revving the engine and it cleared up.

I am curious. It is my opinion that any cleaner sprayed into the intake will only enter the intake air. It would clean the intake and possibly the valves.
How would the cleaner enter the carburator fuel system?.

Most problems in carb goo come in the pilot circuit. If you spray carb cleaner into the AIR jet on the intake venturi edge, it will go through the pilot circuit and come out the small hole in front of the needle jet in the base of the venturi. It MAY not go through the pilot jets themselves but should get through all the other internal passageways. It is unlikely that a running bike will develop a block of the main jet which also is where fuel for the jet needle is picked up. It would be a good idea to spray carb cleaner into the venturi edge air jet that leads to the main jet because if it is obstructed, the bike will not run decently at lower speeds when the slide is mostly closed and this air jet is what is bringing air into the main circuit (and jet needle circuit). Just spraying carb cleaner into the main venturi won't have much effect on anything as far as the carb goes. The stuff is shot directly into the combstion chamber. It MIGHT remove some carbon deposits if the bike is run with the stuff in there but there are better and safer products for that purpose (Yamaha Ring Free or Seafoam).

It could be as simple as the gas cap vent is plugged.

Well.. I finally got around to starting the bike as the wife and kids are home now.( translated= NO TIME ) It started fine with only the standard cold blooded popping and bogging the first few minutes. Then it ran fine in the shop. I took it out for a short ride ( 4 miles total ) and it ran fine.
I sprayed water on the exhaust, all of it evaporated the second it hit the pipes. No run off .
I hope to pull the tank and petcock and filters this weekend if I can get an hour or so of that rare thing called free time:P But then again I have to replace the outbuild's well pump handle and hardware too :pinch: ( read dig a six foot hole three feet across )so the wife can water her garden And we all know what project comes first if I want to stay married:whistle:
Thanks for all the words of wisdom and ideas!!!
I'll let you know what if anything I find out.
Pat

Post edited by: patmann, at: 2006/06/21 11:13

Post edited by: patmann, at: 2006/06/26 11:03

Cleaned the tank ..nothing, cleaned the petcock..nothing,changed the fuel filters, replaced the gas. Bike started and ran fine. Went for a short ride, ran fine, went for a longer ride three miles into it it started again:angry: :dry: . Got it home sprayed water on the pipes ( thanks WG ) #1 HOT #2 warm #3 warm #4 HOT.
So now I know for sure it's electical:pinch: . I had found that my #1 & 4 coil was NOT bolted down, it was just sitting in the holes. I'm real sure that was the coil my 12 year old was to bolt down last Winter.. I had hoped it was that.. NOPE. I checked all wires I could for loose or something / anything I could find. Nothing.
I didn't get a chance to change coils and see if it's the coils. Maybe later this week as the wife and kids are heading to Wisconsin early this week and I will be single for a couple of days;)
Thanks for ALL your help!
Pat

Post edited by: patmann, at: 2006/06/26 11:07

Post edited by: patmann, at: 2006/06/27 09:45