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

[BA80]

http://www.jetsrus.com/a_jets_by_car..._BS_series.htm

[rdmcguy]

Back pressure

NO I was not implying you were too cheap to buy mufflers.
More like covering my own as if people thought the idea was stupid...lol
actually had a couple on misc machines in youth.
like yourself I like a throaty growl at the expense of a little low end grunt.
It just twist the throttle a bit more down low.After all these bikes aren't lacking in torque

[skids]

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

Apples and oranges.

[D0wn5h1ft]

Vacuum synching will only matter at low throttle openings. Syncing carbs helps idle and take off but after that it's all about your air velocity and fuel metering.

I run open exhaust too and it's a turd to tune. You'll always have a flat spot in your RPM range because the cams on this bike have a stupid long valve overlap. It's dumb and I don't like it but unless you go with upgraded not 1970's technology and drop some megacycle cams + springs in there you're never going to fix it. And even then there are severe issues with reversion with CV carbs which will never get ironed out.

Take a look at this post by me: http://www.xs11.com/forum/showpost.p...2&postcount=11

I try to explain some of the issues people (including myself) have with an open exhaust on this bike. I'd like to say, though, many people misuse the word "back-pressure". All exhaust flow impedance is bad but what they're really referring to (and you can read this in the post I linked above) is a restricted diameter exhaust to increase exhaust velocity. Take a look at it and read the articles I linked in the post. You'll never tune it out with these junk CV carbs that come stock.

I'm working on experimenting with some older GSXR flat side carbs on my XS right now with open exhaust. They're much less sensitive to alterations in the intake air velocity as the slides aren't controlled by air flow, they are controlled by throttle opening. I've heard them called "real man carbs". The downside to flat slides is that they often require an accelerator pump because they respond poorly to rapid throttle changes (a temporary lean condition is created because a lot of air is introduced and the fuel flow can't catch up).

Long story short, open exhaust is always going to be a problem, you can't tune it out. This is coming from someone who ACTIVELY runs it and is living it right now. I'll tell you about my flat spot. I managed to get it under control but I had to go with a large advance on my ignition and go with a narrower exhaust tip to increase exit velocity. The flat stop (again, in HP) is still very evident and is at exactly 3k RPMs. Tons of low end and top end but it'll never be the same until I put the stock airbox and exhaust on and that's just how it'll be...

[Dylano*]

Thank you very much downshift, for all that info. Can't wait to read that link when I get home (at work waiting for the shop to get opened up right now) and I'm totally fine with an hp flat spot like you are talking about. The main problem I'm having right now is just making it around the block as it wants to die from running so poorly. It idles fine, and revvs fine stopped, but then when I ride it just wants too die under acceleration sometimes :-/ occasionally, it's hard to even get going 20mph. When it is hesitating, if I let off the throttle it USUALLY helps.

As for the apples and oranges post, that's exactly what I mean, some people say get the correct jets (bleed vs non bleed) most people say it makes zero difference.

Downshift, I ask you this, what size jets are you running?

[natemoen]

As for the apples and oranges post, that's exactly what I mean, some people say get the correct jets (bleed vs non bleed) most people say it makes zero difference.

I don't think there is anyone here that will say that having the correct type of jets verses having the wrong type of jets will say that it makes zero difference. It makes a great deal of difference.

The carbs were designed to be run with a particular style of jet and running a different style jet will greatly alter the air fuel mixture.

[D0wn5h1ft]

Thank you very much downshift, for all that info. Can't wait to read that link when I get home (at work waiting for the shop to get opened up right now) and I'm totally fine with an hp flat spot like you are talking about. The main problem I'm having right now is just making it around the block as it wants to die from running so poorly. It idles fine, and revvs fine stopped, but then when I ride it just wants too die under acceleration sometimes :-/ occasionally, it's hard to even get going 20mph. When it is hesitating, if I let off the throttle it USUALLY helps.

As for the apples and oranges post, that's exactly what I mean, some people say get the correct jets (bleed vs non bleed) most people say it makes zero difference.

Downshift, I ask you this, what size jets are you running?

All stock on the late model (1980) carbs except for mains. I don't know what year your carbs are but stock jetting for me is 110 mains - 42.5 pilot. There's no way running open exhaust should stop the bike from running and cause stalling. I ran mine with JUST the headers one time (no long pipe) and drove it all day. Its performance was garbage but it never stalled. There is something else wrong with your carbs/engine.

To me, it really sounds like an ignition/electrical issue. My guess would be pickup coil wires just because letting off the throttle will change the vacuum advance and move those wires and maybe(?) make them connect again. Start at stock jetting with the right pilots and go for there. I think you may have gotten a bit ahead of yourself with all of these changes. It should run enough to get it around the block with stock jetting.

[Dylano*]

Natemoen, ok I am going to start using only the non bleed type pilot jets, I feel as if that could at least be part of my problem.

Downshift, are you running those stock jets with pod filters as well? Or is that only with more open exhaust? To me it seems like the pod filters would necessitate larger that stock pilots more that open exhaust would, any thoughts?

By the way thank all of you for the help this far.
Greatly appreciated.

[DiverRay]

D0wn5h1ft has the correct idea. Go to a 1 over pilot and keep your 2 over mains, and try again. Rule of thumb for these cards: 2 sizes up on mains, 1 size up on pilots. You MAY want to go up to 2 over on the pilots, but they should NEVER step up higher than the mains! Also, be SURE the carbs have ALL the jets and passages clean.
If you have a single vacuum gauge, you can still get a close sync that would help a LOT. Sync #4 to #3, then sync #2 to #1, and finally sync #2 to #3. It will be close, and may make a large difference in trying to get it running correctly.
Oh, and you DID do a valve adjustment/check FIRST, right?
If it still has problems, then check the pickup coil leads. you can pull about 3/4" from the bike to the coils if you need to fix a break. If you need more wire, try to find the very fine FLEXIBLE wire to splice in.

[natemoen]

Natemoen, ok I am going to start using only the non bleed type pilot jets, I feel as if that could at least be part of my problem.

Hold on (I didn't read it all to see if you said what pilots you were using)! You want the air bleed holes. You want to be using Mikuni BS 30/96 pilot jets. They have 6 holes on the sides in a 2-1-2-1 pattern.

[BigRed]

Hey,
It's been mentioned a couple times already, but I'm going to tell you my story.

I put a NOS aftermarket performance exhaust on mine, and picked up a Dynojet kit to see if I could get a little more go out of it. I tried every combination of needle position and jet that came in the kit, and couldn't get rid of the new stutter that was happening under hard acceleration. Finally said "screw it, I'm going back to stock," but the stutter persisted. Turns out that my pick-up coils had come loose, and were just kind of rattling around under the timing cover.

All that to say checking your pick up coil wires is a helluva lot easier than pulling your carbs, so I'd do that first. In case you're not familiar with the procedure, you just pull the cover off the left side of the engine, and tug on the wires to see if you can make a couple cylinders die.

Hopefully I'll get a chance this spring to try the Dynojet kit again. The bike's only scary now... I want it to be terrifying again.

[Dylano*]

D0wn5h1ft has the correct idea. Go to a 1 over pilot and keep your 2 over mains, and try again. Rule of thumb for these cards: 2 sizes up on mains, 1 size up on pilots. You MAY want to go up to 2 over on the pilots, but they should NEVER step up higher than the mains! Also, be SURE the carbs have ALL the jets and passages clean.
If you have a single vacuum gauge, you can still get a close sync that would help a LOT. Sync #4 to #3, then sync #2 to #1, and finally sync #2 to #3. It will be close, and may make a large difference in trying to get it running correctly.
Oh, and you DID do a valve adjustment/check FIRST, right?
If it still has problems, then check the pickup coil leads. you can pull about 3/4" from the bike to the coils if you need to fix a break. If you need more wire, try to find the very fine FLEXIBLE wire to splice in.

Ok I will get one over pilot jets, no I didn't check/adjust my valves, as I cant find the pad shimms that are called for... BUT I'm pretty certain they are ok as the bike was running before, well.

Also I will ft my best to sync them with one gauge on Thursday, I'm sure it won't hurt!

[Dylano*]

Hold on (I didn't read it all to see if you said what pilots you were using)! You want the air bleed holes. You want to be using Mikuni BS 30/96 pilot jets. They have 6 holes on the sides in a 2-1-2-1 pattern.

See?! I keep getting thrown in loops over this! Hahaha


So, WHY, are the bleed type better than the non bleed which were stock??

[natemoen]

So, WHY, are the bleed type better than the non bleed which were stock??

The ones with the holes, the BS 30/96 pilot jets, ARE the stock jets. If yours has the no hole jets in it when you took it apart the someone else put the wrong jets in. Some of the kits even come with the wrong jets in it just because people don't know any better.

[motoman]

Vacuum synching will only matter at low throttle openings.

Sorry, an urban myth at best.