low rpm stumble

[tugla]

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:

only depends on the size of the insurance policy :rofl_200:

 

[sdt354]

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?

Speaking of cracked rubber. I'm in the process of changing all of my v-boost boots and clamps. It was hard to tell how bad they really were under the clamps, which hid a lot of the boot. Should be riding this afternoon if all goes well. The sun just came out. Got to get back at it. I like my little butane pencel torch for leak detection. It gets in there good.
Steve

 

[gamorg02]

yea i gotta get the propane torch on it soon. hopefully when u come up. if i don't play rugby this weekend maybe we can work something out.

 

[gamorg02]

just thinking out loud and revisiting this. had the vmax out for about a week now and no real issue to speak of. filled her up last night and the issue kinda came back. wondering if the 93 octane is too much (was running a non-stock curve). so was thinking of putting the curve back to stock and dropping the octane. maybe the gas around here is crap and sits a long time at that high.

never found any air leaks to speak of. weird thing as i said before both putting the choke on (richening it up) or turning off vboost full time (leaning it) helps the issue.

 

[tugla]

could just be the quality of fuel/ethanol blend crap.........try midgrade and seafoam or which ever brand to help treat the fuel.

main thing that is confusing me is.......how do you ever get a low rpm stumble? aren't you like idle to wide open all the time:rofl_200::rofl_200:

 

[gamorg02]

thats the point. when i go from 2k rpms cruise to between 1/2 throttle -> WOT it sputters for a bit heh

 

[gamorg02]

shotgunned the bike. much better now!

 

[gamorg02]

this issue comes back when it gets hot and humid out, so i'm pretty sure its actually a rich condition as shutting vboost back to normal operation cleans it up. i notice it under a few conditions:

1. crusing from 2k - 2.75k and giving it 3/4 - WOT. it doesn't stumble but gets a little jerky. kind of bogging.

2. from a stop, i need like 2.5k+ of rpms to make it go smooth. so i think i need to lean it out somewhere.

3. weird one - when its warm out i get backfiring when starting. but once started it still needs the choke slightly to idle just like normal.

what is this, is this the upper end of the a/fs or the very low end of needle? I'm thinking the a/fs.

altho i might just turn vboost to tboost for the time being.

 

[tugla]

Check the a/f screws pull them out and visual insp on them damage.
Also maybe. Clip or shim to drop needle a bit,lean it out......how's the wide open cut test look along with your a/f meter at wot.....
Sure no vacuume leaks......back to the old propane aka get the leafs at BRC shop test lol

 

[jfeagins]

this issue comes back when it gets hot and humid out, so i'm pretty sure its actually a rich condition as shutting vboost back to normal operation cleans it up. i notice it under a few conditions:

1. crusing from 2k - 2.75k and giving it 3/4 - WOT. it doesn't stumble but gets a little jerky. kind of bogging.

2. from a stop, i need like 2.5k+ of rpms to make it go smooth. so i think i need to lean it out somewhere.

3. weird one - when its warm out i get backfiring when starting. but once started it still needs the choke slightly to idle just like normal.

what is this, is this the upper end of the a/fs or the very low end of needle? I'm thinking the a/fs.

altho i might just turn vboost to tboost for the time being.

Maybe two problems happening at once? Cause part of those symtoms sound a bit like the ole' hot misfire bad charging sydrome. The CDI box will stumble and do chit when under 2.5K rpms. Just thinking out loud here..

 

[gamorg02]

Check the a/f screws pull them out and visual insp on them damage.
Also maybe. Clip or shim to drop needle a bit,lean it out......how's the wide open cut test look along with your a/f meter at wot.....
Sure no vacuume leaks......back to the old propane aka get the leafs at BRC shop test lol

screws are fine, shotgunned helped her last year. the a/f meter is my brothers and i haven't had a chance to slap it on the bike yet.

thinking about it more wondering if the valve adjust threw the a/f adjustments out. if i could get his maybe its just re-doing the a/f screws and bobs your uncle.

Maybe two problems happening at once? Cause part of those symtoms sound a bit like the ole' hot misfire bad charging sydrome. The CDI box will stumble and do chit when under 2.5K rpms. Just thinking out loud here..

i doubt it as i have a dyna and the temp and humidity effect it a lot.

 

[tugla]

ya worth tinkering with the screws but there is a point you are off that circuit and wont effect it as much...

 

[m-cman]

I think if the valves were changed by your adjustment, you need to sync again.

 

[gamorg02]

ya worth tinkering with the screws but there is a point you are off that circuit and wont effect it as much...

yea i hear ya, trying to figure out where that spot is.

I think if the valves were changed by your adjustment, you need to sync again.

sync was done quite a few times.

 

[jwood]

I just did a stage 7 jet kit, now having a low rpm hesitation/stumble/bucking going on, if I close the vboost it is gone.. With the vboost open and unplugged the bucking starts under 2000 rpm... Any ideas.. Sync is good... I thought bucking was a result of a lean condition? Open vboost should cause a rich condition? Going to turn the af screws in tonight...

Sent from my Galaxy Nexus using Tapatalk 2

 

[tugla]

think might be the compromise.....open vboost good mid to top closed good low rpm ........you try leaving it hooked up and let it open normally the vboost.....yami got it set up pretty good. I know the idle sounds cooler with it open but balance in life I guess

 

[gamorg02]

i would say you're too rich then, right? vboost makes it richer. try adding choke, altho that made mine better too, even with vboost open.

the thing is mine worked fine for about a year, then started up with these schenanigans.

 

[gamorg02]

think might be the compromise.....open vboost good mid to top closed good low rpm ........you try leaving it hooked up and let it open normally the vboost.....yami got it set up pretty good. I know the idle sounds cooler with it open but balance in life I guess

damnit rovic, we're thinking too much alike

changed my zboost from on -off - stock to on -off -3k and ran it on 3k this morning, it loved it, esp since my midrange is tuned for vboost on.

 

[jwood]

think might be the compromise.....open vboost good mid to top closed good low rpm ........you try leaving it hooked up and let it open normally the vboost.....yami got it set up pretty good. I know the idle sounds cooler with it open but balance in life I guess

Maybe I will try unplugging the VBOOST at half way, in stead of full open!!:biglaugh:

 

[tugla]

For sure I will give ya that balance lol