sputter, loss of power

grasshopper864 · New Member Joined: May 03, 2009 Posts: 7

hope someone can help me!! last week while riding my xs i noticed a slite sputter. i thought it was the carb. it kinda came and went so i rode the bike a couple of times after i noticed it. i took the carbs off and cleaned them very good. rode again and same sputter, and was getting worse the more i rode. i was a long way from home when the bike lost so much power it felt and sounded like it was only firing(running) in one cylinder.i could barely take off from a red light it was so bad! took carbs apart again, still the same. i have checked the plugs, plug wires, all other wiring,and battery and all are fine. i have compression, but not sure if it is right because i cant get a tester gauge till tomorrow. the sputter prior to the complete loss of power seemed to be at cruising speeds and felt like it was running out of gas or carb dirty. both exhaust pipes have pressure coming out the ends. help me!!

pumps · Posted: May 3, 2009, 6:12 am Post subject: Re: sputter, loss of power

Do you have filters in your fuel lines? Is your tank clean and free of crud?

Retiredgentleman · Posted: May 3, 2009, 12:31 pm Post subject: Re: sputter, loss of power

Inspect and clean the following: ignition switch, kill switch, all fuses.
If you still have an original fuse panel (glass fuses), you need to get rid of it and replace it with inline automotive blade type fuses.

Corroded, high resistance components in the electrics will cause no end of grief.

grasshopper864 · New Member Joined: May 03, 2009 Posts: 7

i read on here about timing, coils, etc. could it be any of this? i'll be working on the bike here shortly, so i have to be back to you all on what i find.

yamaman · Posted: May 3, 2009, 1:00 pm Post subject: Re: sputter, loss of power

Do whats not going to cost you first! You've had the carbs apart, how's the float level?
As mentioned above, pull all your connections & clean them up!

Check charging voltage

Good luck!

grasshopper864 · New Member Joined: May 03, 2009 Posts: 7

ok, i have checked all fuses wiring and connections, all seem to be in fine working order. the temp of the exhaust coming out of one of the pipes is very very hot, but the temp of the other is not....what is that all about??

Jake68 · 650Rider Supporter Joined: Mar 23, 2007 Posts: 841

I would say making sure you have hi quality fuel filters fitted inline is the first thing to do. Fit them then re-clean your carbs.

Go through the ignition system making sure your points are working properly..If you have a healthy spark and your timing good enough to run one cylinder well then....

Then look at the compression.

In my experience this is still most likely to be being caused by crap in your fuel.

TeeCat · Posted: May 3, 2009, 5:28 pm Post subject: Re: sputter, loss of power

And grasshopper, once you reconnect your fuel lines to the tank, undo them at the carbs and let some fuel run into a white margarine tub or the like... make sure the fuel is clean. I do this every so often out of habit and change my fuel filters more often than necessary.

grasshopper864 · New Member Joined: May 03, 2009 Posts: 7

ok all this trouble and it seems like the cylinder is fouling plugs. it had NGK R plugs in it. when i changed them they were some autolight cross referenced kind.(didnt want them but that was all that was in stock). anyway i am running air pods instead of the factory air boxes along with the factory carbs. i'm assuming i need to adjust for all the extra air coming in now. is there a mixture screw that i dont know about, or do i need to rejet??

gordo · Posted: May 3, 2009, 10:12 pm Post subject: Re: sputter, loss of power

grasshopper, what year is the machine?Make's a difference, on the type of carb's you'll have & the associated problem's with the different type's(BS 38 vs.BS34).At mikesxs.com,use his ID chart for positive I.D. on the carb's. On BS34's, the float seat has a screen on top of it to keep crap out, you should remove it. Then set the float's to the spec's given for your carb's. Too much fuel will foul plug's.Google jayel here & check out his maintenance list, he cover's just about everything needed to do .Good luck,,, Gordo

grasshopper864 · New Member Joined: May 03, 2009 Posts: 7

THANKS!! WILL CHECK IT OUT ASAP!!

Jake68 · 650Rider Supporter Joined: Mar 23, 2007 Posts: 841

It sounds more like a sticking needle to me..

But you must fit inline filters as well. Its a must. A bit of crap could stop the needle from closing. You clean it, but a new bit of crap drops in. It happened to me over and over until I got decent filters. Briggs and Stratton (yep) 30Micron. highly recommended.

But Gordo is right.. know what year it is would be good.

Would also be nice to know that compression on cylinder in question is normal..

As for jetting, one or two sizes up on mains. Leave Pilots alone in my experience.

If anything pods would lean out the mix. Unless....they got WET!

So you could try running without for a very short time..

heibar · New Member Joined: Oct 16, 2007 Posts: 5

Just a wild guess;

I had symptoms like you are describing.
Could it be the grounding of the ignition;
Take off the tank and look at the head motor mount. (4 bolts)
Are any bolts loose?
One of those bolts also tightens down the ground for the ignition, at least on my model. (1977 D model)
If it is loose, the ignition gets ground sometimes and sometimes not (stutter and hesitates)

Try it, you never know......
Heimir Bardason

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