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YouTube video - carb issue

Old 06-12-2010, 09:05 AM
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YouTube video - carb issue

This is a video of the issue i am having with the Hawk. The qaulity is not the greatest but hopefully you can get an idea. Notice the difference from smooth roll-ons and blipping the throttle. Its like a stumble of some sort. I shimmed the needles +1,+2,back to oem, Numerous air/fuel settings for each,checked the slide boots for damage and proper install,all hoses in the right place(no pvlir)air box tight,v-stacks correct,and i have covered just about everything i thought.(apparently im missing something) Picking up new plugs shortly. Good gas in the tank. mj's are clean. Slides operate smoothly and i hear the air being moved in and out. TPS done and synch performed. Sych hoses all buttoned up properly. I am at a loss fellas.

http://www.youtube.com/watch?v=e-5z_wukaj0
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Old 06-12-2010, 09:13 AM
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Check your plug wires too. I had one come loose at about 40k miles. Caused all kinds of fits for me. It had loosened up at the boot. They screw on. I had been arcing across some gap for probably 500 miles or more, bike running like crap the whole time.

Did you ever install a Factory or Dynojet kit on the bike? Are you on a stock filter or aftermarket? Some bikes just don't like anything but a stock filter. I was the exception and had no problems tuning mine.

Sounds to me like the slides aren't lifting quickly or soon enough. That could be a vacuum problem somewhere.

"It ran great all the way up until ___________________________." Please fill in the blank.
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Old 06-12-2010, 09:29 AM
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Originally Posted by Hawkrider View Post
Check your plug wires too. I had one come loose at about 40k miles. Caused all kinds of fits for me. It had loosened up at the boot. They screw on. I had been arcing across some gap for probably 500 miles or more, bike running like crap the whole time.

Did you ever install a Factory or Dynojet kit on the bike? Are you on a stock filter or aftermarket? Some bikes just don't like anything but a stock filter. I was the exception and had no problems tuning mine.

Sounds to me like the slides aren't lifting quickly or soon enough. That could be a vacuum problem somewhere.

"It ran great all the way up until ___________________________." Please fill in the blank.
I didnt check the boot but i will when put the new plugs in. The carbs are all oem as well as the filter. I put the devils on and developed a flat feel in the torque curve around 3-5000 rpm. So i did some research and decided to shim the stock needles and do a carb synch.(jet kit not in the budget now) It ran good,not great id say, but strong before i pulled the slides to shim the needles. I pulled the air box, lifted the carbs from the boots, removed the slides(pita on the front) pulled the needles,shimmed, put all back together,synch, and then problem. Pulled carbs completely after that,slotted the mixture screw,adjusted 2.25 out, put it all back and still the same. Choke out still the same. It has to be a vacuum problem?

(gotta pick up plugs and some other stuff-thanks for the responses-be back shortly)

Last edited by dshakes; 06-12-2010 at 09:32 AM.
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Old 06-12-2010, 02:57 PM
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Did you forget to plug the front cylinder vacuum hole?
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Old 06-12-2010, 03:52 PM
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I have been chasing a single cylinder misfire for weeks, and finally got it. You have to go down the checklist, seems like you are almost there and have the tough stuff done. This is what I did.
  1. Diaphram in petcock-take out and look for pinholes in light. Check in tank filter too.
  2. Clean air vent tube in tank, over flow tubes from carbs.
  3. check, clean, or cut fresh connections on all vacuum hoses especially one on petcock.
  4. Check spark plug boots. I found my misfiring cylinder had a lot of corrosion between wire and boot where boot screwed onto wire. I cut 1/2" off wire and used my spare new boot to get a pristine connection.
  5. Check electrode on spark plug for cracks.
  6. Clean grounds on coils.
  7. Carbs off, all jets out, cleaned with spray solvent & compressed air, check slides/diaphrams for pinholes. Check floats for cracks, needle seat on float operated smoothly.
  8. Check cylinder to carb boots for cracks/holes/overtightened or hard rubber.
  9. Unscrew choke cable from carbs, clean passages, needles, and lube cable.
  10. Check TPS, at idle and full throttle.
I did all these and found it was running perfect when the carbs were installed back on the bike. I found the bad spark plug connection when I went to pull the spark plug and the boot came off. I put on the new spark plug boot but it did not fix the problem, I checked before tearing into the carbs, but would have been a new problem in a few more miles.

I did find that my vacuum port cap was off the front cylinder, but replacing it did not fix the problem or make it run any better. It probably did not come off until I started messing with the motor, as I had a 8" long vacuum hose and plug on it. I cannot imagine it was off since the last time I rode the bike, it rode perfect for a 200 mile trip.

What I think finally fixed the problem was #9, I had corrosion in one of the choke cables that was preventing it seating the needle fully and it was playing havoc with the motor trying to run with one cylinder on partial choke, one not. My choke cable was kind of hard to pull out, that should have been a big hint to me.

There could have been something in the carb passages as well. I also found my idle mixture screws were not set the same since the last time I adjusted them, my piece of crap d-shaped screw tool that came with the dynojet rounded itself and was not actually turning the d-shaped screw head but felt like it was. I had been running it like that for a year so it was not the problem, but it sure idles smoother now.

It runs great now, eventhough I have not yet synched the carbs again.
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Old 06-12-2010, 04:17 PM
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my vote, bad coil. If it happens that quickly, you will be able to pinpoint which cylinder by pipe temp. Get an infrared heat gun and take some measurements while this is occurring and see which cylinder is colder (measuring temp of head pipe). Just my 2 cents.
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Old 06-12-2010, 05:07 PM
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With that said, remember the carbs do not have the same main jets, so one cylinder will run hotter than the other one by design.
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Old 06-13-2010, 01:01 AM
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Thanks for all of the recommendations guys. Im at my wits end with this problem. To the point of sitting there staring at the carbs and trying like hell to think of what i am missing. TJ, I will run that checklist and see if anything comes up. Thanks man. zmaniv, I have the synch fitting in the front cylinder vacuum hole with a plugged vacuum hose attached. Autoteach, i will see what i can do about an infrared gun and try to get some results. Again, thanks for all of your help guys.
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Old 06-13-2010, 01:46 AM
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Originally Posted by zmaniv View Post
Did you forget to plug the front cylinder vacuum hole?
Please explain this in detail.
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Old 06-13-2010, 02:53 AM
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Originally Posted by autoteach View Post
my vote, bad coil. If it happens that quickly, you will be able to pinpoint which cylinder by pipe temp. Get an infrared heat gun and take some measurements while this is occurring and see which cylinder is colder (measuring temp of head pipe). Just my 2 cents.
it could be a bad coil, but "normally", what ever that means, bad coil issues manifect when the engine / coils are hot.

It appears that there is not enough gas, or too much air.

1. check that the PAIR removal is complete, plug the line from the front carb, use a screw, silicone and a clamp on the end of the hose. Plug hole in airbox. A 5/8 rubber chair leg tip works well for this. Use block off plates on the valve covers, get them from the classifieds - they are the best and cheapest at $15 shipped.
2. remove all sync tubes, just to rule this out. Put the allen screw back in the front sync hole use thread sealer, put the rear cylinder / petcock hose back in place, use a fresh (new) hose. No "T" joints.
3. be sure that all hoses are attached properly, especially the petcock hoses and tank hoses. You may also check the petcock diaphram, but I do not think that is it, but maybe.

see if that works

4. remove the subfilters foam (just to rules this out)
5. remove the air filter element (just to rules this out)

see if that works

6. re-clean out carbs, including slides, check for free movement (do not replace subfilter foam yet)
7. I do not think this is a jetting issue, but return jetting to stock, again, just to rule this out
8. I do not think this is a TPS issue, but recheck for 500 Ohms, the TPS should be rotated almost all the way counter clockwise.
9. check the choke cables. There is a 1-to-2 junction under the carbs. Sometimes the outer cable housings can get pulled from the fittings, causing the choke (ok enrichment circuit) to be on all the time.

see if that works

10. see who lives near by that can help.

JB
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Old 06-13-2010, 06:22 AM
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Originally Posted by ranchomice View Post
Please explain this in detail.
He said he did a carb sync. Just reminding him to remember to plug the hole that the carb sticks plug into.
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Old 06-13-2010, 06:51 AM
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I am sorry, I didn't read close enough (I know, dont say it) and thought that it was an intermittent problem. Make sure that the cvs are moving properly, not "smoothly" which is a measure using ones finger, by blasting some air at the passages that lift the slide. If you have a cv boot pinched, you may not be getting the slide movement you want, even though it is moving freely. The guys have given you a laundry list of items to check (because they read clearly) and I would just run through everything they have for you.
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Old 06-13-2010, 07:02 AM
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Originally Posted by ranchomice View Post
Please explain this in detail.
I ordered the joint boost fitting from bike bandit and screwed it into the front cylinder fo carb synch purposes. I ran a piece of vacuum hose to the left side of the bike and plugged it with a cap while not in use. I attached the hose with a zip tie to the joint boost. It seems good and tight. I cut the rear cylinder hose and inserted a "T" fitting and capped it off when not in use.
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Old 06-13-2010, 07:09 AM
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Originally Posted by autoteach View Post
I am sorry, I didn't read close enough (I know, dont say it) and thought that it was an intermittent problem. Make sure that the cvs are moving properly, not "smoothly" which is a measure using ones finger, by blasting some air at the passages that lift the slide. If you have a cv boot pinched, you may not be getting the slide movement you want, even though it is moving freely. The guys have given you a laundry list of items to check (because they read clearly) and I would just run through everything they have for you.
No worries, we all do it now and then Thanks for the recommendations. I will sit today and go through everything and see what happens. Thanks guys.
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Old 06-13-2010, 07:40 AM
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Originally Posted by dshakes View Post
I ordered the joint boost fitting from bike bandit and screwed it into the front cylinder fo carb synch purposes. I ran a piece of vacuum hose to the left side of the bike and plugged it with a cap while not in use. I attached the hose with a zip tie to the joint boost. It seems good and tight. I cut the rear cylinder hose and inserted a "T" fitting and capped it off when not in use.
Rip it all out and put it back to its original state. This is simply to remove it as a culprit. You can put it back in afterwards. We need to remove variables. JB
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Old 06-13-2010, 07:45 AM
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sure sounds like slide vacuum issue to me... are you sure they are seated properly ? they can come out of the groove easily while installing the spring/cap.

tim
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Old 06-13-2010, 01:23 PM
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I have put everything back to its origanal state. I put myear to the air box and it just sounds like the vacuum is out of wack somehow. I am 100% sure the diaphrams are seated correctly. They have to be. I dont know. It seems also that the right side exhaust is warmer than the left. I know Hawkrider rider said due to jetting differences they will be slightly different but i dont know? Another video maybe to drum up some ideas? http://www.youtube.com/watch?v=0WztitYpQFM
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Old 06-13-2010, 03:41 PM
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I may not be understanding your problem but... In your second video you say you are watching the slides move as it's running. I assume you are running it with the airbox off? This creates an extremely lean condition which Will not allow it rev freely. If you're getting the same results with the Devil pipes but with the air box on then you are still having the same issue. Those pipes are huge and flow very well. Moving that much air will require larger main jets.
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Old 06-13-2010, 03:59 PM
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These are great videos - very helpful. So when you put the airbox back on with no filter and no subfilter, and start it up, it behaves the same as before? Then put the filters in and try it - same thing?

What number check are you up to on my list?

Side question: what kind of CCTs are those and when did you install them? If my list does not cover it, you may need to check for a jumped cam chain, but that is not for a while yet.
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Old 06-13-2010, 04:01 PM
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Originally Posted by inderocker View Post
I may not be understanding your problem but... In your second video you say you are watching the slides move as it's running. I assume you are running it with the airbox off? This creates an extremely lean condition which Will not allow it rev freely. If you're getting the same results with the Devil pipes but with the air box on then you are still having the same issue. Those pipes are huge and flow very well. Moving that much air will require larger main jets.
I have watched with the lid off but the problem is with the lid on and secure. The problem arose when i pulled the carb slides to shim the stock needles just for the reason of the devils. I put it all back and crap... many beers and curse words later here i am. Those are the devils from you by the way. I am still working on it feverishly. Leaving friday for cherohala and deals gap for a nice long 4 day vacation. Need the Hawk running at least good. Thanks for the info inderocker.
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Old 06-13-2010, 04:04 PM
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Ahh, so it still does it with the airbox on, the carbs reset to where they aere and the stock mufflers installed?
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Old 06-13-2010, 04:22 PM
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Airbox on, the carbs reset yes, but i did not put the stock mufflers back on. Let me try that and see what i get. I just dont remember it acting up like that even after i put the devils on. Although i did notice a change in the torque curve from the more free flowing pipes. It was running lean to begin with from de-baffled oems. I will take that to the drawing board and see what happens. Thanks Daniel.

Do you know the stock setting for the air/fuel mixture screws? How many turns out? Like a dumb*#s i forgot to record them before i changed it.

Last edited by dshakes; 06-13-2010 at 04:28 PM.
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Old 06-13-2010, 04:39 PM
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I had a cv boot out over 1/2" and the slides moved nearly identical. I had to go back in because it wouldn't take throttle like it should. Not saying it was your problem, but that despite my efforts and experience, I had it happen and could not tell a difference between the slides moving by my own hand.
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Old 06-13-2010, 04:50 PM
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Originally Posted by autoteach View Post
I had a cv boot out over 1/2" and the slides moved nearly identical. I had to go back in because it wouldn't take throttle like it should. Not saying it was your problem, but that despite my efforts and experience, I had it happen and could not tell a difference between the slides moving by my own hand.
I will put that on the list. Thanks teach.
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Old 06-13-2010, 04:58 PM
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that is included in #6
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Old 06-13-2010, 05:01 PM
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The technique that I use is:
1. get the spring fully compressed into the cap
2. Insert cap and slide into carb, catching the slide so the spring doesn't shoot out
3. Gently work slide up and down with light pressure on the cap. The pressure will push the boot into the groove.
4. Very carefully check to make sure it is in place.
5. Screw down cap
6. You can verify for a leak by pressurizing the atmospheric vent (use your mouth- otherwise you can tear boot)
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Old 06-13-2010, 05:32 PM
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Originally Posted by autoteach View Post
...6. You can verify for a leak by pressurizing the atmospheric vent (use your mouth- otherwise you can tear boot)
Just like in the movie "Airplane". Be sure to post a video of that.
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Old 06-13-2010, 05:47 PM
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Originally Posted by residentg View Post
Just like in the movie "Airplane". Be sure to post a video of that.
Guy does have a sense of humor!!!
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Old 06-13-2010, 05:57 PM
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Originally Posted by residentg View Post
These are great videos - very helpful. So when you put the airbox back on with no filter and no subfilter, and start it up, it behaves the same as before? Then put the filters in and try it - same thing?

What number check are you up to on my list?

Side question: what kind of CCTs are those and when did you install them? If my list does not cover it, you may need to check for a jumped cam chain, but that is not for a while yet.
The filters in/out etc.. did not change the problem,just varied it. I covered about everything on your list with the exception of a few things. I did smooth down a bur on the rear slide thanks to the list. I am just wondering if the problem is that i switched to the devils and then went in adjusting things and nothing is close to where it was before and the pipes are just wreaking havoc now. I tried 2.25 turns out with the carbs back to stock and got some popping on decel after deciding to take a test ride and the hesitation deal when cracking it open. This is a rich condition generally correct? I cant remember. Or is it lean when it crackles through the exhaust? Went back in and did 1.75-2.00 turns out and that was a decrease in performance.
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Old 06-13-2010, 06:09 PM
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decel popping = lean pilots, needle
did you check the choke cables?
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