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Carb question. Smog related

Old 05-11-2011, 11:17 AM
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Carb question. Smog related

Ok so I removed all of the smog crap off my bike at the weekend. Installed some nice pair block of plates. Capped off any carb vacum ports with heavy duty caps where needed. Hooked up a long length of hose on too the front air sync port for balancing the carbs when needed. Everything went fine, bike runs good. My bike is all stock, stock cans, carbs, air filter.
Only question I have is this. On the front carb right handside is a vacum port that go's to air/cut/off valve. In a previous thread Inderocker stated to do this?

"Instead of plugging the vacuum line that went from the carbs to the air suction valve, just remove the "T" fitting and 2 shorter hoses and replace them with the longer hose that was running to the air suction valve."

Yet I remember reading somewhere on this forum in some kind of "sticky" can't find it right now, to vent this with a small airfilter? This just does not sound right to me? I think it was on the superhawk996.net?

At the moment I have a length of hose attached to the tee-fitting about 6 inches long capped off to try this mod to see if it makes any difference?

Personally I like the idea Inderocker states to do. I was thinking of using that tee on the other side of the bike for a vacum take off on the rear cylinder for balancing the carbs. Ie: placing the tee on the fuel petcock vacum line.

One last question. When balancing the carbs. Do I need to make sure that vacum lines are the same length?

Thanks guys. Steve
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Old 05-11-2011, 11:32 AM
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I'm not sure why you would want to vent that line... I would think that it would cause problems.

As for the same length, I'm not sure how much the compressibility of air would affect your signals in that stretch of hose, but I wouldn't chance it (I made sure my homemade one had equal length hoses). You're talking about the vacuum lines on your carb sync tool, right?
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Old 05-11-2011, 11:35 AM
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Originally Posted by [email protected] View Post
Ok so I removed all of the smog crap off my bike at the weekend. Installed some nice pair block of plates. Capped off any carb vacum ports with heavy duty caps where needed. Hooked up a long length of hose on too the front air sync port for balancing the carbs when needed. Everything went fine, bike runs good. My bike is all stock, stock cans, carbs, air filter.
Only question I have is this. On the front carb right handside is a vacum port that go's to air/cut/off valve. In a previous thread Inderocker stated to do this?

"Instead of plugging the vacuum line that went from the carbs to the air suction valve, just remove the "T" fitting and 2 shorter hoses and replace them with the longer hose that was running to the air suction valve."

Yet I remember reading somewhere on this forum in some kind of "sticky" can't find it right now, to vent this with a small airfilter? This just does not sound right to me? I think it was on the superhawk996.net?

At the moment I have a length of hose attached to the tee-fitting about 6 inches long capped off to try this mod to see if it makes any difference?

Personally I like the idea Inderocker states to do. I was thinking of using that tee on the other side of the bike for a vacum take off on the rear cylinder for balancing the carbs. Ie: placing the tee on the fuel petcock vacum line.
Yes that is some old misinformation..... it was posted a couple of places a while back but IMHO the line needs to be capped. The whole vent with a small air filter was kind of silly.

Just run the line without the "tee" and you will be fine.

Originally Posted by [email protected] View Post
One last question. When balancing the carbs. Do I need to make sure that vacum lines are the same length?

Thanks guys. Steve
It is really not that critical that the lines be the same length. You should try to keep them fairly close but a foot or two difference in length really isn't going to change the reading on the gauge.
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Old 05-11-2011, 11:37 AM
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Originally Posted by 7moore7 View Post
I'm not sure why you would want to vent that line... I would think that it would cause problems.

As for the same length, I'm not sure how much the compressibility of air would affect your signals in that stretch of hose, but I wouldn't chance it (I made sure my homemade one had equal length hoses). You're talking about the vacuum lines on your carb sync tool, right?


No don't want to that, just weird that there was a sticky saying to do this? Think the name was Paul scatterfield?

Yes talking about vacum line lengths for balancing carbs.
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Old 05-11-2011, 11:49 AM
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Originally Posted by [email protected] View Post
....One last question. When balancing the carbs. Do I need to make sure that vacum lines are the same length?

Thanks guys. Steve
Yes, it is important to be sure the vacuum is pulling equally from each carb.
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Old 05-11-2011, 11:58 AM
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Originally Posted by 8541Hawk View Post
Yes that is some old misinformation..... it was posted a couple of places a while back but IMHO the line needs to be capped. The whole vent with a small air filter was kind of silly.

Just run the line without the "tee" and you will be fine.



It is really not that critical that the lines be the same length. You should try to keep them fairly close but a foot or two difference in length really isn't going to change the reading on the gauge.
Thanks guys. I love this site.

Yea that just did not make sense to me either?

Well that save's me a trip to the auto parts store for a tee fitting. I will remove that tee and install it on the vacum petcock line. I think I can get the to lengths of balance hose's to within an inch or so of the same length, so that should be fine. Thank you guys.

One last question. Do you think it would be of any benefit to install a #4 shim/washer under the needles on a completely stock bike?

Last edited by [email protected]; 05-11-2011 at 12:00 PM.
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Old 05-11-2011, 12:17 PM
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Originally Posted by [email protected] View Post
Thanks guys. I love this site.

Yea that just did not make sense to me either?

Well that save's me a trip to the auto parts store for a tee fitting. I will remove that tee and install it on the vacum petcock line. I think I can get the to lengths of balance hose's to within an inch or so of the same length, so that should be fine. Thank you guys.

One last question. Do you think it would be of any benefit to install a #4 shim/washer under the needles on a completely stock bike?
Yes it would help as would installing the #48 pilot jets.
In this tread I gave the basic set up : https://www.superhawkforum.com/forum...-set-up-24769/

and it works well with everything from stock up to around 115hp, once you get past that point (or a full stage 1 motor) you might need to up the mains one size, but each engine is different.

On basically stock engines .020-.040" of needle shim works well, as i stated in the original thread, this will need to be tuned to each engine to get optimum results along with the final pilot jet setting.

There is no one "magic" setting as each engine has a little different flow characteristics. I'm pretty sure you already know this but in case you didn't or someone else is reading this thread, I just wanted to restate it.
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Old 05-11-2011, 03:58 PM
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Originally Posted by 8541Hawk View Post
Yes it would help as would installing the #48 pilot jets.
In this tread I gave the basic set up : https://www.superhawkforum.com/forum...-set-up-24769/

and it works well with everything from stock up to around 115hp, once you get past that point (or a full stage 1 motor) you might need to up the mains one size, but each engine is different.

On basically stock engines .020-.040" of needle shim works well, as i stated in the original thread, this will need to be tuned to each engine to get optimum results along with the final pilot jet setting.

There is no one "magic" setting as each engine has a little different flow characteristics. I'm pretty sure you already know this but in case you didn't or someone else is reading this thread, I just wanted to restate it.
Thank you. Yes I read that thread a few times, as well as all the other carb threads. I may go and install a shim under each needle. Bike runs fine at the moment. Idle is nice and constant, I going to balance the carbs to see where they are at. Then maybe play with a shim under each needle. See if it feels any different.

At the moment I'm really enjoying being back on the Superhawk, does not feel as powerful as the last 05 I owned, but that could be just because I was riding my GSXR1000 for the last 3 years. Post up some pictures soon. She's a real nice ride. Can't believe no one else in San Francisco brought her. All stock with only 11,000 miles, never dropped, sargent seat, tank bra, Ohlins rear shock and front end all done by Kyle racing. Handle's great on Dunlop roadsmarts tires. Just installed some galfer brake lines & Ebc HH pads, and T-rex frame sliders. Just need to buy a crg front brake lever and she is all finished. Once I change the roadsmarts out, I'll try some sport tires on her and hit the track.
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Old 05-15-2011, 10:02 PM
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air/fuel screws?

Hey guys, pulled the carbs off yesterday as I have been having a little bit of a fueling issue around 2,000-3,000 rpm when usings small throttle openings while splitting traffic. Plus wanted to try the shim trick.

Question when I pulled the carbs off, the throttle air/fuel screws had no brass plug covering them? is this normal?.

Anyway I went and slotted the air/fuel screws. Place one shim under each needle (in addition to the factory shim) adjustered the TPS. Set front air screw at 2 3/4 turns out and rear at 3 turns out. Did not change the pilot jets. Hooked up my tee piece in the fuel tank vacum line and routed both vacum take off lines to be by the choke lever for easy carb balancing. Have not balanced the carbs yet, as my friend has I set of carbs sticks, so going to borrow them next week.

As soon as I fired her up she idled better, no more hesitation at very low rev's. I'm really happy with this fix. Worked great. Bike fuels and feels perfect now through-out the rev-range. I'm very interested to balance the carbs to see where they are at? Can't imagine it getting any better?

Anyway, just wanted to say thanks to the forum, after reading lots of carb,shim,pair,smog threads this job was real easy to do. My bike runs so sweet right now, and is so much better to work on with-out a bunch smog crap and hoses in the way.

So all thats left to do now is balance the carbs, and ride her. Went for a quick ride today, she ran great. Saw over 150mph on the clock no problem. Happy to be back on a Superhawk. Post up some pictures when I get a chance, having to much fun with her right now.
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Old 05-15-2011, 10:35 PM
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For what it's worth, before I got rear ended at a red light in March, 2010, I had stock cans. I'd shimmed my needles .020" and cleaned the carbs (after I lost #2 cylinder due to a clogged pilot jet). It was running better than ever, no complaints, then 1 week later...BAM!

That's how I got my Yosh slip-ons, courtesy of AAA, the insurance company of the clueless 19 year old who rammed me from behind. After I got my bike back 8 weeks later with the slip-ons, I put in the 48 pilots.

So, you're probably good with the needle shim, but those stock 45 pilots are tiny. Just keep them clean.

Oh, and there are no plugs on the pilot screws from the factory, just the D-screws.
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Old 05-17-2011, 09:41 AM
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Thanks for the info on the air/fuel screw plug. Yep I was able to remove those with a pair of tweezers. Then slotted them for easy adjustment. Reading a few threads on here made the carb removal a painless job. I think I could have them off the bike now in about 30 minutes and adjusted and back in, in about the same time. Had no problems with the plastic choke screws/thingys. When I'm done with the carb balacing and all happy with the air/fuel screw settings. I'm going to take it to my local bike shop and have a few dyno runs done, with the AFR readout and see where she is at.
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