I can't get my carb's tuned properly with exhaust and pods. ):

[Dylano*]

So basically here is the overall of it all.
1982 xj1100,
Basically open exhaust,
but it has two small turndown mufflers with an almost nothing baffle.
I also have pod air filters.

Stock pilot jets are 47.5. (I think)
Stock main jets are 112.5 (I think)

MY JETS are
Pilot - 55 (three steps up)
Mains are 117.5 (two steps up)

I've had the mains upgraded the whole time.
The pilot jets, I HAD stock but in order for it to idle and rev without popping and backfiring,
I had to have the pilot screws turned out 5 to 6 turns.
SO that is why I got the bigger pilot jets...


HERE is my problem now...
With the new jets in, and the pilot screws at 4 turns out, it idled and rev'd great while sitting still..
But when I wen't for a test ride, it would stutter on throttle.
But if I held the throttle there, the bike would seem to "catch up"

I though it was running lean still, so I turned the pilot screws OUT another 1/2 turn.
It seemed worse...

so I tried 1 full turn IN from there.
Even worse..

I don't know what to do.

Am I way far off on something?
Should I get way bigger pilot jets with basically open exhaust and pod air filters?

IM LOST! ):

Other info,

I'm nearly POSITIVE my floats are all adjust perfecly.
and I know allt he passages are clear and clean.


Hopefully one of you guru's can point me in the right direction.

[Dylano*]

I'm working on this project and am very excited to post pics showing you all what I have done.

I've been buildint this xj1100 into a giant cafe style bike.
It's coming along pretty sweet so far!

Right this very second though I am very frustrated.
Last night is when I was messing with it and I ran out of time.
Back to the work week!

Hopefully someone can give me some advise.

[motoman]

I'm working on this project and am very excited to post pics showing you all what I have done.

I've been buildint this xj1100 into a giant cafe style bike.
It's coming along pretty sweet so far!

Right this very second though I am very frustrated.
Last night is when I was messing with it and I ran out of time.
Back to the work week!

Hopefully someone can give me some advise.

First off, that's a fuel mixture screw, not an air mixture screw. Between head and carb is always fuel metering......between carb and air filter is always air metering.
Secondly, U gotta get some back-pressure from a half decent exhaust sysyem.
Since the carbs being vacuum actuated slides, air intake other than stock makes for some tricky tunin' to get to run ideally in ALL rpm ranges.
Their are several runnin' pods on there XJ's just cause of the apparant PITA air filter assembly.
Sure one of them will chime in with what worked for them

[Dylano*]

I am aware that it is for fuel metering.
I just can't seem to find the sweet spot,
I still feel like my jets are the wrong sizes or something because I'm just kinda stabbing in the dark on what sizes to buy.

But the larger ones SEEMED to be the right direction but I feel like I could just be so wroing about it.

As far as the exhaust goes, I've read SO much on different people saying different things about back preassure, that I decided to just go for it.

I showed an engine builder friend of mine the exhaust and asked if I should be worried about burning valves or anything and he said no.

Yeah hopefully someone with pods/exhaust or vast Mikuni knowledge can at least point me in A direction. haha

[rdmcguy]

Old school Snuff r nots?

Thinking out loud (or would that be typing out loud)
Who remembers the old school snuuf r nots.
Basically it was a washer that fit in the end of the pipe that you could turn
to either have exhaust flow almost unrestricted or turn it so exhaust would flow through the hole in the washer.
As I remember there was a small spring on top (to keep in whichever position)
that a bolt ran through attached to washer... acorn nut on bottom.
Tunable back pressure????
aaahhh the days of youth when you could not afford a proper muffler.

[Dylano*]

Haha something like that would not be too hard to fab-up, and doesn't sound like a bad idea on doing some tests! ...hmmm

If youa re implying that I couldn't, or can't get a better set of mufflers; I COULD, I just much prefer the sound of open exhaust.

Going for a muscle-bike/cafe sort of contraption..

Pus it just sounds SO damn good unplugged.

I'm normally working on old Nova's or something of the like, so that sound is pleasing to me haha

[Bonz]

Hi, have you sync'd the carbs? Do that first and foremost.

No back pressure, that thing is like a causeway letting everything go running through. Back pressure is your friend for tuning carbs and good engine performance.

Especially the XS.

I had the crossover tube disconnected on my 80G project bike, and it was even more limp below 3k rpm than normal. Got the crossover re-connected, and it was a different animal below 3k rpm. Rode a member's XS with MAC system, and same thing... not as strong as a stock system below 3k rpm.

[Dylano*]

The carb's are bench sync'd and pretty dang close.
I don't have 4 vacuum gauges currently, so I can't vacuum sync them.

If all I have to lose is a little power before 3k rpm then I will sacrifice it, I'll likely be above that most the time I am craving performance anyhow.

HOWEVER, if it will help me tune the carb's I might do something temporary...

Although, if I tune them with the back preassure then remove it I feel like that effort will have been lost... although it might bring me closer?

[motoman]

Hi, have you sync'd the carbs? Do that first and foremost.

No back pressure, that thing is like a causeway letting everything go running through. Back pressure is your friend for tuning carbs and good engine performance.

Especially the XS.

I had the crossover tube disconnected on my 80G project bike, and it was even more limp below 3k rpm than normal. Got the crossover re-connected, and it was a different animal below 3k rpm. Rode a member's XS with MAC system, and same thing... not as strong as a stock system below 3k rpm.

Can't sync unless he has the block-off 'thingy', if it still has the original XJ motor or head.

[Dylano*]

Oh yeah the YICS tuning thing?
Would syncing really be that far off without it?

I see what I'm sure are knock off tools on ebay will those actually work?
http://www.ebay.com/itm/The-YICS-Eli...151721&vxp=mtr

[Dylano*]

OH I FORGOT TO MENTION!

My pilot jets ARE the BLEED TYPE, and the stock ones were not..

I researched and researched and couldn't find anything that told me it mattered.
I could only find the size I wanted in the bleed option.

Maybe someone can tell me that matter a lot?

[BA80]

OH I FORGOT TO MENTION!

My pilot jets ARE the BLEED TYPE, and the stock ones were not..

I researched and researched and couldn't find anything that told me it mattered.
I could only find the size I wanted in the bleed option.

Maybe someone can tell me that matter a lot?

There's your stutter, wrong pilots. That'll do it every time.

[crazy steve]

Oh yeah the YICS tuning thing?
Would syncing really be that far off without it?

Yes it would.... You're wasting your time without doing a proper vacuum sync, and you'll have tuning issues that you won't be able to overcome with open exhaust. Many here have tried....

[Dylano*]

There's your stutter, wrong pilots. That'll do it every time.

So if I get the same size pilot jets, but the non-bleed type you think that would help?

[Dylano*]

Yes it would.... You're wasting your time without doing a proper vacuum sync, and you'll have tuning issues that you won't be able to overcome with open exhaust. Many here have tried....

OK, I'll get some vacuum gauges and get it vacuum synced, I'm positive it will help some, but I'm sceptical on how much :/