Carb sync problem????

[65fury]

Okay fellas i got the sync tool(motionpro) and have been trying to get them sync'd but it seems like i just cant get tehm all to sync right, the four tubes with blue fluid are always bouncing up and down and after i get 2-3 carbs the sync'd(blue fluids bouncing at the same level) they change after idleing just a bit longer, or after i blip the throttle:bang head::bang head: why does the fluid bounce??? is that normal? and yes for those who may ask... the brass filters were installed correctly according to the manual i got, brass filters 3/8" in vaccum line, all lines are the same length, and the filter end of the line on the carb nipple, i sync'd the meter to the master carb and then started my sync process, engine warm at idle(1000rpms) sooo whats wrong? should the fluids be bouncing? or still? thanks

Jason

 

[naughtyG]

Is your Vboost set to be on all the time? Stage 7 installed? If so, it's a lot harder to do a sync.

If you can, make sure your vboost butterfly valves are closed while syncing.

Also, I'm not sure about 'brass filters'? The tool I use has restrictors in the vacuum tube, basically they make the inside diameter tiny and that helps regulating the vacuum and eliminates the bounce a lot. You could try getting a bit of coaxial cable (like the one that goes to your cable TV box, remove the metal core and insert about an inch of what's left in each vacuum tube.

 

[65fury]

Nope no mods of any kind yet, stock carbs and airbox. The vboost is connected and the brass filters were basically what you said, they have a tiny hole in them to regulate vaccum. Kinda like the t-valve I used on my trucks fuel pressure gauge, otherwise it would bounce all over, but even with the brass filters that motoin pro gave me the fluid levels are always bouncing so i dont get a good reading


jason

 

[65fury]

Well i have a vaccum gauge so i figured i try using that to see where my vaccum readings were on all cylinders, and then i set all my cylinders to basically the same vaccum gauge reading(not perfect, but damn close) all the cylinders were pulling about 8.5in hg, is that even the right amount of vaccum? anyways so after setting all the cylinders with the vaccum gauge i hooked my motion pro back up to see if they were close on that. but NOOO my #1 was high, then #2 was a step lower #3 was another step lower and #4 was the lowest, none were even close!! :bang head::bang head: what the heck? so i said screw it and went for a test ride to see how it ran, it seemed to run good up to 4-4.5k and had the stumble but all cruising rpms were smooth and strong(2k-4k) then when the bike cooled down a bit from riding(it got real warm idling while i tuned it) so after it cooled down a bit it stopped running as smooth and i started hearing low popping sounds at 2.5k in 3rd it didnt want to cruise smoothly at 4k either and didnt pull smoothly to 4.5k...... almost seemed to run better HOT than at normal operating temp.

Jason

 

[naughtyG]

Interesting, yet very frustrating I'm sure! Maybe Sean will have better suggestions..

Only other things I can think of:
- are your carbs clean? (i.e. have you tried the shotgun/peashooter cleaning methods?)
- have you checked all 4 diaphragms to be in good condition?
- are all your rubber boots above and below carbs in good condition and fitted perfectly?
- is your air box OEM too, no 'Y' removed, and tight into all 4 boots?

 

[satariel666]

Well i have a vaccum gauge so i figured i try using that to see where my vaccum readings were on all cylinders, and then i set all my cylinders to basically the same vaccum gauge reading(not perfect, but damn close) all the cylinders were pulling about 8.5in hg, is that even the right amount of vaccum? anyways so after setting all the cylinders with the vaccum gauge i hooked my motion pro back up to see if they were close on that. but NOOO my #1 was high, then #2 was a step lower #3 was another step lower and #4 was the lowest, none were even close!! :bang head::bang head: what the heck? so i said screw it and went for a test ride to see how it ran, it seemed to run good up to 4-4.5k and had the stumble but all cruising rpms were smooth and strong(2k-4k) then when the bike cooled down a bit from riding(it got real warm idling while i tuned it) so after it cooled down a bit it stopped running as smooth and i started hearing low popping sounds at 2.5k in 3rd it didnt want to cruise smoothly at 4k either and didnt pull smoothly to 4.5k...... almost seemed to run better HOT than at normal operating temp.

Jason

Vaccum should be 6,69 Hg with 0,79 Hm max diffrences.

Follow what NG said about symptoms, mosf defo smoethingw rong with carbs.
Oherhaul the carbs may ba a good idea.

 

[KJShover]

I'm thinking still some residual gunk in there from the last cleaning.

 

[dannymax]

I'm thinking still some residual gunk in there from the last cleaning.

+1 That's what it sounds like to me also.

 

[65fury]

Interesting, yet very frustrating I'm sure! Maybe Sean will have better suggestions..

Only other things I can think of:
- are your carbs clean? (i.e. have you tried the shotgun/peashooter cleaning methods?)
- have you checked all 4 diaphragms to be in good condition?
- are all your rubber boots above and below carbs in good condition and fitted perfectly?
- is your air box OEM too, no 'Y' removed, and tight into all 4 boots?

Yes very frustrating!! As for you suggestions ive done them all and checked them all.... im half tempted to pull the carbs today and go over them again to see if i missed something:bang head: Hell i need to check and see what my main jets are anyways.. guess ill go tear them apart again:damn angry: ill check back in an hr or so and let yall know what i find. Any ideas as to why my vaccum reading was so high? Thanks again everyone


Jason

 

[naughtyG]

Only other suggestion I have is that it's real easy to screw up the assembly of the sync screws, springs and related hardware. Double and triple-check, hope you get lucky!

 

[65fury]

Only other suggestion I have is that it's real easy to screw up the assembly of the sync screws, springs and related hardware. Double and triple-check, hope you get lucky!

Yeah i thopught about that, except when i pulled the carbs the first time i didnt touch th elinkage assembly at all, i kept each bank of carbs together and well.... to be honest i didnt completely pull them apart:hammer bash: but after cleaning my float bowls and such i figured since they were so clean why mess with the rest:ummm: ive learned my lesson so im taking them all the way apart right now ill post my jet sizes too. thanks

jason

 

[naughtyG]

You found my posts about the carbs rebuild right? The whole lot in pics

http://www.vmaxforum.net/showthread.php?t=5830

http://www.vmaxforum.net/showthread.php?t=5831

http://www.vmaxforum.net/showthread.php?t=5832

http://www.vmaxforum.net/showthread.php?t=5833

http://www.vmaxforum.net/showthread.php?t=5834

 

[65fury]

You found my posts about the carbs rebuild right? The whole lot in pics

http://www.vmaxforum.net/showthread.php?t=5830

http://www.vmaxforum.net/showthread.php?t=5831

http://www.vmaxforum.net/showthread.php?t=5832

http://www.vmaxforum.net/showthread.php?t=5833

http://www.vmaxforum.net/showthread.php?t=5834

Yeah........ but i guess i would be okay to skip a few steps... not this time! im going to thoroughly read your posts and do it right!

Oh by the way i pulled one carb apart only to find my mains are 165s!!!! WTF!! and my floats were way off:bang head: soooo why did my bike run great!! before i pulled it apart and got 36+mpg around town with vboost full open???? with 165s?? those are way to big for a stock intake and exhaust system right?

 

[KJShover]

Yeah........ but i guess i would be okay to skip a few steps... not this time! im going to thoroughly read your posts and do it right!

Oh by the way i pulled one carb apart only to find my mains are 165s!!!! WTF!! and my floats were way off:bang head: soooo why did my bike run great!! before i pulled it apart and got 36+mpg around town with vboost full open???? with 165s?? those are way to big for a stock intake and exhaust system right?

Make sure all your jets are the same maker, it's easier to keep track of that way.

For instance. If that 165 is a Dynojet main, its only a little larger than the 152.5 Mukuni jet size. The dynojet equivalent to the stock Mukuni 152.5 would be thier 162.7 size.

Here is a comparison chart.
http://vmax.lvlhead.com/tips/jetsizes.htm

 

[[email protected]]

Pay close attention to the pilot jets. That seems to be the thing that wreaks havoc on most maxes. I borrowed some carbs to get up and running this summer and tore them apart before putting them on the bike. They looked just fine when I opened them up but decided to tear them down and found the pilot jet on all four carbs to be totally plugged up.

 

[65fury]

How do i tell if its a mikuni or dynojet brand? And my pilot jet in the jet block is a 37.5 is that to big or small? what size jets should i run? Ill have a 4-1 kerker exhaust and stock airbox so what size main jet should i use? Thanks


Jason

 

[KJShover]

How do i tell if its a mikuni or dynojet brand?

http://www.vmaxforum.net/showthread.php?t=2048

And my pilot jet in the jet block is a 37.5 is that to big or small?

Yup, those are stockers, the next bigger are 40's. I'd leave them at the stock size.

what size jets should i run? Ill have a 4-1 kerker exhaust and stock airbox so what size main jet should i use?

Leave it at the stock 152.5 or drop to 150 at first. Back the a/f screws out about 2 3/4 - 3, shim your needles with the shims I sent you. Then you'll be the same setup I'm running, I'm running great up here at 440 ft above sea level. I can prolly go down to a 147.5, but Its running too good to mess with right now.

This should give you a good starting point.

 

[65fury]

http://www.vmaxforum.net/showthread.php?t=2048



Yup, those are stockers, the next bigger are 40's. I'd leave them at the stock size.



Leave it at the stock 152.5 or drop to 150 at first. Back the a/f screws out about 2 3/4 - 3, shim your needles with the shims I sent you. Then you'll be the same setup I'm running, I'm running great up here at 440 ft above sea level. I can prolly go down to a 147.5, but Its running too good to mess with right now.

This should give you a good starting point.

Well according to the jet pic, mikuni is on the right and dynojet on the left? then my jets are 165 mikunis, why did my bike run good before i pulled the carbs apart? with 165 jets what do i need to change to use them? or should i just put 150s or 155s in? If it ran good with the 165s before then should i leave them? i noticed my float bowls were way off and i need to reclean the carbs(the right way:biglaugh thanks

Jason

 

[KJShover]

why did my bike run good before i pulled the carbs apart?

I'm thinking some junk got loose and is plugging up some things when you first cleaned them. [/quote]

with 165 jets what do i need to change to use them? or should i just put 150s or 155s in? If it ran good with the 165s before then should i leave them?

Personally I'd drop to 150's, the kerker will fatten you up a little.

i noticed my float bowls were way off and i need to reclean the carbs(the right way:biglaugh

That can throw you off big time. It's possible that the previous owner was playing with the jets to compensate for the float bowls.

we all have different versions of a strong max. Last year I worked on a friend's max (carb cleaning, set the floats, dropped him to 150 mains, then a good sync) he was impressed with the bike before, then it flat out scared him. this was with a totally stock bike.

So I'm thinking once your done and everything is back together, you'll be pleasantly suprised.

Kinda brings back some memories of when I had my XS11. The adage for dealing with the carbs was called the "triple clean" cause it took about 3 times to get everything right :biglaugh:

 

[65fury]

I'm thinking some junk got loose and is plugging up some things when you first cleaned them.

Personally I'd drop to 150's, the kerker will fatten you up a little.



That can throw you off big time. It's possible that the previous owner was playing with the jets to compensate for the float bowls.

we all have different versions of a strong max. Last year I worked on a friend's max (carb cleaning, set the floats, dropped him to 150 mains, then a good sync) he was impressed with the bike before, then it flat out scared him. this was with a totally stock bike.

So I'm thinking once your done and everything is back together, you'll be pleasantly suprised.

Kinda brings back some memories of when I had my XS11. The adage for dealing with the carbs was called the "triple clean" cause it took about 3 times to get everything right :biglaugh:[/QUOTE]


Thanks!!!

Yeah i noticed i had sediment in my bowls again when i started pulling them apart:confused2:, so im cleaning them REALLY good this time, im gunna get some 150s today at a local shop, what would getting larger pilots do for me? going from the 37.5 to a 40 or bigger do? i might get a few different sized jets just for the hell of it. Im really hoping fixing my float level, a good cleaning and 150s will fix my issue:biglaugh: cant wait for wednesday.... i get my exhaust!!! :eusa_dance:

jason