Lets beat the dead horse... again

[65fury]

Okay.. i just got my carbs back from Fargo, BTW Thanks Fargo for all the work!!!unk: Carbs are officially clean, and the floats set correctly, jet blocks not loose, and new gaskets!

Anyways for the bad news, i still have a mid range stumble... basically as bad as it was MONTHS ago when i started another thread about it. I got 177.5 mains and they kinda helped... heres a list of whats happened(btw vboost is on a switch)

-177.5 PAJ2s, bike stumbles in mid range at WOT with vboost closed
-177.5PAJ2s, bike stumbles harder and WOT with vboost open infact it falls on its face so hard it slows the bike down almost like its killing it
-stock PAJ2s(170s) bike is completely gutless above 5k and WOT will just about kill the motor with or without the vboost open, i could never get past 5k with 170 PAJ2s

I dont even know what to do now??

Jason

 

[gamorg02]

paj's don't do as much as mains and needles at 5k and above.

is it possible the 160 is too fat?

 

[KJShover]

I'm around 440' here, I dropped my mains to 150's and had no issues with the stock airbox ("Y" shimmed 3/8") and Kerker. I kept them in when I went to the Morley kit. Maybe 150 or even 147.5's (went with these when I ran trapps) might help.

Here is my current setup, if that helps any.
Altitide: 440 Feet
Exhaust: Kerker 4-2-1, Carbon fiber can (12") 2" comp baffle/turned down tip
Stock carbs: Morley Muscle Kit (slides not drilled)
Mains: 150 Mikuni
PAJ 1: 90 Mikuni
PAJ 2: 177.5 Mikuni
Needles: Stage 7 (clip 4th from the blunt end)
Springs: Stage 7
A/F: Varies from cyl to cyl, 3-3.25 turns out.
Vboost: Stock

 

[COP RUNNER]

i MAYBE ITS YOUR IGNITION BOX GOING BAD ! .. :confused2:

 

[65fury]

Oooops i need to change my mods list, im down to 152.5 mains, guess ill try my 150s again and maybe 147.5s after that, whats weird is before the problem was the same but it would atleast studder and stumble its way thru the mid range till 6.5k and then be fine... now it straight falls on its face at WOT, i have to nurse the throttle to get up to 65mph!

Should i shim my needles?? im not sure if im rich or lean... i know i need an A/F sniffer but havent gotten one yet. Sorry im just so frustrated with this bike!! ive had it for almost a year and it hasnt run right since a month after i bought it!!:bang head::bang head::bang head:

Jason

 

[KJShover]

was it sync'd correctly?

 

[65fury]

was it sync'd correctly?

Well as good as i can get it with my two vacuum gauges, it worked before.... i sync with my vacuum gauges then went to the motorcycle shop in town and used there sync gauge and i wasnt to far off..... i ordered a morgan carb tune 2 but its shiopping from the UK so itll be a while before i get it.

Jason

 

[Rusty McNeil]

I'd put it back to stock and then start working the mains down leaner???

Although what your describing sounds like once it gets fully "on the mains
" it''s OK, it's the transition from mid range to mains that's the problem...... which would be the needle, PAJ2 and clip position, and slide spring strength..

Sure your diaphragms don't have any holes????

Are the o-rings in place on the little hole behind the slide covers?:ummm:

 

[Saml01]

Put in 175 mains. Problem solved.

Trust me.

My bike ran like shit with anything lower than 165 and Kerker 4-1. Put in the 175 and the bike runs like a bat outta hell. With a 152 you are starving the needle jet at 5k.

Want to be certain? Bring the bike up to where it stumbles and engage the choke. If it runs better, then im right.

 

[65fury]

I'd put it back to stock and then start working the mains down leaner???

Although what your describing sounds like once it gets fully "on the mains
" it''s OK, it's the transition from mid range to mains that's the problem...... which would be the needle, PAJ2 and clip position, and slide spring strength..

Sure your diaphragms don't have any holes????

Are the o-rings in place on the little hole behind the sldie cover?:ummm:

No holes in diaphragms, my carbs were recently cleaned and rebuilt by Fargo so they are in good shape, i just gotta figure out how to tune them

Well im currently at stock settings, minus the 177.5 PAJ2s. And ive run all the way down to 150 mains and still never had any luck or difference. And thats correct my top end is fine...... if i can get there.

What puzzles me was how the bike was setup when i first got it... stock headers with supertrapp slip ons and 165main(mikuni) with drilled slides and this thing was FAST!!! ive tried the 165s again but didnt notice much difference, although ive never gone bigger than those... maybe ill throw my 170s in... hell ive tried going lower and never had any luck... maybe i need to go bigger!

JASON

 

[Rusty McNeil]

Want to be certain? Bring the bike up to where it stumbles and engage the choke. If it runs better, then im right.

That IS a good test methodunk:..Do it slowly...


I run a wideband a/f guage and anything above 165 DJ's or 155 mikuni's showed mine way too rich...like 11:1 rich...but every bike is different, generally most Maxes are rich to begin with, my bike ran pretty damn good with stock jetting and a header. then again every bike is different...

Look up factory pro cv tuning, it'll outline pretty well how to work through them, starting with the mains and working down ............ in my opinion, if it get's "to the mains" and is doing well, then the mains aren't the problem, although they could be "part" of the problem...

 

[65fury]

Well ive tried the choke method too.... didnt really seem to change anything though. Also my vboost is on a switch so i can run it open or closed. And to my knowledge(what ive been told) with vboost open it runs richer.... is that true? or is it leaner? cause so far opening vboost just kilss my midrange completely and with it closed my midrange still sucks but i can slowly nurse the throttle to almost top end... it worked once but i havent been able to get ti up there since. even running without the "Y" doesnt seem to change much either... makes it run a little worse i think.

Side note ive tried 150s, 165s, 152.5s, 155s, and 160s(which i think were DJs) and my topend always ran fine with all those mains.. some made it pull harder(the 165s and 155s) and the others not so much.... ive shimmed my needles and still nothing.. only thing i havent tried is a main larger than 165... so i just installed some 170s... should be interesting to see what happens now


Jason

 

[gamorg02]

its at this point that i'd go to a dyno with a sniffer.

 

[65fury]

its at this point that i'd go to a dyno with a sniffer.

im kinda a cheap bastard right now:bang head: so if i dont have any head way or change in the way it runs with 170mains...... ill go dyno it i guess... or buy a sniffer... probably buy a sniffer first?

well i didnt get it tuned/synced last night cause one of my stupid A/F screws lost the tip!!!:damn angry: i have no idea how, but after swapping main jets i start the bike to sync the carbs and my #1 cylinder aint firing at idle.... so in the process of the p shooter and shotgun methods i find out the damn needle tip of the A/F screw is now missing!! luckily my local hole in the wall bike shop had oneunk:, so ill continue working on it tonight and see what results i get.

Jason

 

[65fury]

THATS IT IM DONE!!!!
who wants my vmax??? any takers??? FREE!!!!

my midrange hasnt changed a bit!! but if it get it up to 6k it rips!!!!!! even with 170 mains bottom end good, top end good..... i know the slides effect the mids more than the mains.... but really!!! i so sick of tuning these carbs:bang head::bang head: nothing i do ever makes any change(atleast no change thats worth noting) i havent shimmed the needles yet... but i did in the past with all kinds of different main jet sizes and still NEVER saw a notable change.

Why is it with the vboost open my bike will literally cutout and SLOW me down at WOT around 4k, but with vboost closed it sometimes will stumble thru the mid range at WOT and finally at 6k it rips!

I know i need to go on a dyno and see whats happening.... but really?? no change has happened from 150mains to 170 mains and everything inbetween the two??? shimmed the needles and still nothing, 177.5 PAJ2s or 170PAJ2s and no difference...... stock needles, slides slightly drilled(even tried them with stock hole size) no difference

Swapped over to COPS(thinking maybe my coils werent up to snuff, and cause i wanted to) still no difference, ive considered my ignition module being bad... but then it should be able to pull the higher rpms right??

Also noticed on my test ride.... only in 3rd gear(no second gear on my bike:damn angry will it actually stumble and pull thru the mid range rpms and reach 6k, but in 4th gear i can nurse it up to about 5k... but any more throttle and it straight dies.....

No leaks, i sprayed carb cleaner everywhere, stock airbox with stock filter(clean) ive tried removing the "Y" and that made zero difference either... even tried running no filter... NOTHING WTF!!
Sorry for the long write... i just felt i should try to include everything ive done/tried for everyones better understanding


Jason

 

[KJShover]

What kind of springs are you running? Maybe they're allowing your slides to move and the needle to come on the main too quickly and your going rich untill it catches up (6k+ it starts to recover and fly right?)

I think the reason you start to stumble when the Vboost opens your now feeding a cyl with two carbs fattening the mixture up. When closed it's still one carb one cyl.



[SIZE=+1]Midrange (full throttle /5k-7k)[/SIZE]

[SIZE=+1]Select best needle clip position[/SIZE] ​

• To get the best power at full throttle / 5k-7k rpm, adjust the needle height, after you have already selected the best main jet.
  • If the engine pulls better or is smoother at full throttle/5k-7k in a full throttle roll-on starting at <3k when cool but soft and/or rough when at full operating temperature, it is too rich in the midrange and the needle should be lowered.
  • If the engine pulls better when fully warmed up but still not great between 5k-7k, try raising the needle to richen 5k-7k.
  • If the engine pulls equally well between 5k-7k when cooler as compared to fully warmed up, the needle height is probably properly set.

NOTE: Do not pay too much attention to the low-end richness when you are changing needle clip positions - you still need to be using the clip position that produces the best full throttle / 5k-7k power in conjunction with the main jets (Step 1) that produce the best power at high rpm.

 

[06VMAXIMUS]

well i didnt get it tuned/synced last night cause one of my stupid A/F screws lost the tip!!!:damn angry: i have no idea how, but after swapping main jets i start the bike to sync the carbs and my #1 cylinder aint firing at idle.... so in the process of the p shooter and shotgun methods i find out the damn needle tip of the A/F screw is now missing!!

Jason

How does the "tip"of your A/F screw come up missing??? Didn't you just send these out and have them cleaned/soda blasted?:ummm:

 

[65fury]

What kind of springs are you running? Maybe they're allowing your slides to move and the needle to come on the main too quickly and your going rich untill it catches up (6k+ it starts to recover and fly right?)

I think the reason you start to stumble when the Vboost opens your now feeding a cyl with two carbs fattening the mixture up. When closed it's still one carb one cyl.



Well my slide springs are stock(just bought a stock set from Morely) my needles are also stock so no setting adjustment(until now, i just borrowed some DJ needles to try) Also i was told vboost leans it out too?? since opening it alos allows air from the other carb in too:confused2:

Today i borrowed a sync gauge, needles, and DJ springs to put in and see if i cant get some change in my mids.

So i synced the carbs up and it idles smoother, ill take it for a spin and post back.

 

[65fury]

How does the "tip"of your A/F screw come up missing??? Didn't you just send these out and have them cleaned/soda blasted?:ummm:

Not sure:ummm: that cylinder idled fine until after changing my main jets and then it wouldnt idle, its possible i tightened the A/F scew in too much and broke the needle tip:confused2: and yes they were sent out and cleaned, no problems there since after getting them back and syncing the carbs the bike idled fine so somewhere in my tinkering i may back buggered it up... oh well, i got a new one so it idles good nowunk:

Jason

 

[KJShover]

i was told vboost leans it out too?? since opening it alos allows air from the other carb in too:confused2:

Today i borrowed a sync gauge, needles, and DJ springs to put in and see if i cant get some change in my mids.

So i synced the carbs up and it idles smoother, ill take it for a spin and post back.

Nahh, you think you were told wrong. Think of the carbs w/Vboost as a big 4bbl carb with vacuum secondaries. The reason why Vboost makes the power is the introduction of more fuel. Same with turbo's, Superchargers, Nitrous. The addition of more fuel with the proper amount of air (nitrous is the oxidizer when it's used) creates a bigger combustion that equals more power.

If you are already running too rich (or lean) with the carbs, once Vboost opens up another rich or lean carb enters the picture on that cyl. Thats going to make things worse.

You said you've already tried the choke test and you didn't feel anything, makes me think your on the rich side of the street. Have you pulled your plugs to have a look? If you can, pull your plugs and post a picture of them. You can get alot of info on the way they look

The main thing is, shit happens and we'll get you through this and riding in no time. unk: