puzzling problem

[naughtyG]

So overnight, out of nowhere, the bike goes from idling perfectly at 1000 rpm to idling at 750-800 rpm, sounding a bit like it's running on 3 cylinders :ummm:

Also, at times it still 'sneezes' at low revs, has been doing that forever even before and after the carbs rebuild. But now, I'm also getting odd backfiring explosions - today I accelerated in the second gear, then shut the throttle and slowed down and then 'bang'! Happened a couple of times just like that.

Also, at one time today, having switched the bike off while hot, I went back to it, and when I turned the ignition on I got a 'carb fart' - it was like some built-up pressure just went 'pooof' and exited.

Please note that while all of this is happening, the bike is otherwise running absolutely fine. It runs smoothly, and when I twist the throttle it goes just great. No flat spots or anything - pulling as strong as it's ever done.

The only other trouble I have is I suspect a weak battery, as sometimes when it's hot and the fan is going it struggles to crank if it's only been off for a minute or two. I also just did a carb sync about 3 days ago - was pretty much bang on so only made very minor adjustments.

WTF is going on!?! :ummm::ummm::ummm:

 

[richwrench]

What's your battery voltage at idle G ? I had a low voltage issue with my 'Max when I first got it - would barely crank when hot, even though it was great 15 minutes earlier when cold. I ran an extra wire from my r/r to the battery + and cured it. I also had a number of corroded connectors on my bike when I got it ( you saw it was a little on the rough side at the bike-fest ) & I packed all my connectors with di-electric grease - now I'm running about 14.4 volts at idle & no more probs ! It can't be your carbs - we all saw your posts - you have the cleanest carbs in town ! :eusa_dance:

 

[RagingMain]

If you are checking the voltage to the battery make sure you disconnect the output of the r/r so battery voltage doesnt interfere with your reading.

Also I had an issue once like this and it was my ignitor. It finally went out on me, when I replaced it all the symptoms went away.

Cheers

 

[ssnsltd]

if it is a voltage issue, you could maybe upgrade the stator to one of the venture ones, they (at least some ) put out an extra 50w.

 

[maxout1200]

If you are getting back firing issues check all your exhaust joints for leaks especially the head pipes where they bolt to the head. I would also put in a new set of spark plugs to rule that out as a possible cause.

 

[Hatter]

Sounds like bad gas to me.

 

[maxout1200]

Good suggestion Hatter! Start with the simple things first!

 

[naughtyG]

Well I refilled the tank since but have not observed any improvement yet, so I guess that rules that one out :confused2:

 

[maleko89]

So overnight, out of nowhere, the bike goes from idling perfectly at 1000 rpm to idling at 750-800 rpm, sounding a bit like it's running on 3 cylinders :ummm:

Also, at times it still 'sneezes' at low revs, has been doing that forever even before and after the carbs rebuild. But now, I'm also getting odd backfiring explosions - today I accelerated in the second gear, then shut the throttle and slowed down and then 'bang'! Happened a couple of times just like that.

Also, at one time today, having switched the bike off while hot, I went back to it, and when I turned the ignition on I got a 'carb fart' - it was like some built-up pressure just went 'pooof' and exited.

Please note that while all of this is happening, the bike is otherwise running absolutely fine. It runs smoothly, and when I twist the throttle it goes just great. No flat spots or anything - pulling as strong as it's ever done.

The only other trouble I have is I suspect a weak battery, as sometimes when it's hot and the fan is going it struggles to crank if it's only been off for a minute or two. I also just did a carb sync about 3 days ago - was pretty much bang on so only made very minor adjustments.

WTF is going on!?! :ummm::ummm::ummm:

G, how do the plugs look? I had the same problem a year or so ago and it was due to the gap being near zero. I dropped it and didn't re-check the gap.

Since you downloaded the charging system guide I would go through that step-by-step.

 

[Hatter]

Well I refilled the tank since but have not observed any improvement yet, so I guess that rules that one out

I had the same symtoms on mine last spring. It took about 2 weeks for it to clear up.

Seafoam?

 

[naughtyG]

G, how do the plugs look? I had the same problem a year or so ago and it was due to the gap being near zero. I dropped it and didn't re-check the gap.

Last I checked the plugs (2 weeks ago) all the gaps were perfect. They also looked pretty good in the middle, but a wee bit sooty on the edges (the ring where the thread ends).

Since you downloaded the charging system guide I would go through that step-by-step.

Having fully charged the battery, done the crimp fix, and also fixed the negative wire connection from R/R to battery, I started the step by step guide.

Checked my voltage at the battery with engine running - pretty constant 13.79 Volts no matter what rpm. According to the guide this means everything's fine..

 

[maxout1200]

Well I refilled the tank since but have not observed any improvement yet, so I guess that rules that one out :confused2:

Did you drain the carbs. Water can collect in the float bowls and still be sitting in the bottom of the bowls even with a fresh tank of gas.

Open each carb drain screw and let some fuel drain in to a clear container. Check for water fuel separation the water will settle to the bottom.