low rpm stumble

[gamorg02]

hey guys

did a couple hundred miles this weekend and noticed an issue, which i think is carbs. around say 2.3krpms - 3k rpms with low accel to WOT (not at cruise) the bike stumbles a bit. from what i know (which aint much) it almost feels like its going lean. turning the choke on helps, so that makes sense. However since i ride vboost always on, turning that off also helps but not as much! And turning the vboost off leans it out, right?

so coupled with two symptoms that are saying different things, i was thinking about it and remembered one of my carb -> intake manifold boots had a crack in it. I'm wondering if that couldn't be causing the issue? creating a lean condition, and then when i shut off vboost it limits it to one cylinder instead of 2?


i have wicked limited time lately with the wife, baby, etc, so just looking for a consensus on a game plan. I'm not ruling out doing the simple carb cleaning steps (shotgun/peashooter) but i could. i've tried running some seafoam thru too without much help.

after a highway run, it seems to calm down for a bit as well (wonder if its the rubber expanding and closing off the 'crack'?). i have some 'start your engines' which i was thinking about trying too.

that range is right about the pilot -> needle transition, yea?

 

[drdrewdown]

cracked boots are not cool bro!

spray some sort of starting fluid or similar near the crack & see if the motor speed changes. if so thats probably your issue

 

[gamorg02]

that was my plan... i'll have to try to find some time to do it.

that'd be an easy fix. plus i don't let my bike sit around and if it does for over a few days i make sure the float bowls are full so i realy don't think it was a gummed up issue.

 

[tugla]

just started ? how cold out there garrett? just past idle circuit so could be needle that might help it a bit but id go thru the cleaning first and then go from there.

 

[gamorg02]

just started ? how cold out there garrett? just past idle circuit so could be needle that might help it a bit but id go thru the cleaning first and then go from there.

it seems to happen at any temp, from 50 to 80. and its been going on for maybe a month but haven't rode that much and wanted to give some seafoam a chance.

 

[dannymax]

Do the propane test Garrett, you must have a cylinder around....no?

 

[sdt354]

QUOTE]
I'm thinking intake leak Garrett. Boots always suspect when you have one.
Steve

 

[gamorg02]

Do the propane test Garrett, you must have a cylinder around....no?

just one from the grill. starter fluid/carb cleaner should work the same eh?

QUOTE]
I'm thinking intake leak Garrett. Boots always suspect when you have one.
Steve

yea i agree with you steve.

 

[GREEN light BLITZ]

+1 carb cleaner test. Crack kills,kids! its possible your recent reduced riding time allowed the boots time to dry up and crack a bit more.

 

[gamorg02]

will do... maybe tomorrow evening.

 

[gamorg02]

let the bike warm up a bit. not fully warm but did the test while she was warming up and didn't see any signs of leaks except for the airbox boots (very slight) which i can fix some other time. i don't think that'd be causing it though because that air still gets 'mixturized' yea? i gotta imagine intake leaks AFTER the carbs can be deadlier...

whats this 'propane' test danny?

 

[tugla]

take a plumbers propane torch do not light it, just let the gas flow, and point it at various parts on the carb area and if there is a leak it will suck the propane up and increase idle like the carb cleaner method.

 

[gamorg02]

take a plumbers propane torch do not light it, just let the gas flow, and point it at various parts on the carb area and if there is a leak it will suck the propane up and increase idle like the carb cleaner method.

that sounds easy.

and wicked dangerous, haha. i'll be careful.

you think if the rubber is cracked somewhere its more likely to show when warmed up or cold?

 

[tugla]

cold if you can get the bike to idle constant at reg idle speed. otherwise warm is best, your splitting hairs if only works cold and no issues warm, for sure got leaks

 

[gamorg02]

got it. thanks ro. i'll report back probably this weekend.

 

[tugla]

got any new visitors yet hanging out at ur place??

 

[gamorg02]

got any new visitors yet hanging out at ur place??

nah no little monkeys. i'll definitely let you guys know!

Ro, send me a PM with that stuff you wanted? u needed the shift light link and the pants thing right?

 

[gamorg02]

so my carb to airbox boots were loose. i tightened them down and my 2.5k rpm stumble got a bit better. now my off idle is funky. needs more throttle than it should not to stall and keep going...

i still need to synch but also if i turn off vboost or put it to stock (i usually run it always on) it fixes ALL the issues. that sounds like i'm running too rich eh? maybe a turn in on the a/f screws? I wonder what would have caused it to act up all of a sudden?

 

[gamorg02]

is my next step to try some propane? any idea what could have caused this? i still should try a synch

 

[dannymax]

is my next step to try some propane? any idea what could have caused this? i still should try a synch

Pretty odd Garrett....if you didn't turn the A/F screws to create the stumble then you shouldn't have to turn them to make it go away.

The propane isn't dangerous....well, long as you don't have any plug wire arcing........:angry flame devil: :rofl_200:

Rovic....are you sure about that "Don't light the propane torch thing???" :hihi: