Author Topic: carbs hate me (Read 4418 times)

Vee Dub Nut · « **on:** October 11, 2005, 12:41:47 AM »

Ok guys heres the deal....

Some of yall may remember about a month ago I had a float get stuck open on me and it flooded out the number two carb. I took the carbs off, cleaned them, readjusted the A/F screws and put it back together. I found then that it was still on stock jetting with one shim under the needles. After i reassmebled it, it wasnt running as well as before. I ordered some 127.5 mains per the Bandit FAQ's and installed them, went to two shims on the stock needles, 2.5 turns out on the A/F screws, K&N drop in with the 2" mod. It ran fine except for a bad flat spot in the midrange. Dropped my stock filter back in and it ran ok. I have been busy with school and havent messed with it much since then. It has been running rich i believe, pops on deaccel now, and my fuel milage has been in the toilet. I have been gettin 26-30mpg in town and thats about it. Today I was driving home from class and stoped to fill up since i had to switch to reserve today. Put in 3.5 gallons and headed home. Not a block from the gas station it started to act funny again, just like before when the float got stuck. By the time i got to my apartment, it misfires under load.. if you let it sit and idle it runs real rough (only on three cylinders i suspect) and smells strongly of gas... Im pretty sure at least one of my plugs is foulded up, but the root cause is my carbs. I cant seem to get them running correctly, and i have the feeling its a little low on power.

I was half curious about Dales stage 1 kit. Are the needles significantly different than the stockers? I couldnt get my bike to run good with the K&N shimmed at aprox .05", i was curious if his needles have a different taper to help the fuel flow in the midrange for the incresed air flow? Im at my wits end.. i just want it to run good, im tired of messing with it. My schedule doesnt really afford me time to test by trial and error, i just want it to run good like it did when i first picked it up. Im pretty sure that i need a valve adjustment it sounds like i have one a little loose, the bike has 8k miles on it now, and it could possibly use a new air filter, or put the K&N back in it.

I was just hoping that maybe some one had some insite to my problems... would buying the jet kit help me, or should i really be able to make it work with whats in there now...

Current set up
127.5 mains
stock pilots (have some 35's that can go in)
2 shims on the needles .05" or thereabouts
2.25 turns out on the A/F screws
stock filter
2" mod

Im just sort of confused and frustrated with it at the moment... Oh yea i should also mention that Im thinking about taking it to a shop to let someone else sort it out.. im just trying to figure out what my best course of action should be

2005B12S · « **Reply #1 on:** October 11, 2005, 10:07:21 AM »

Any jet kit has needles that are significantly different from stock. They are tapered and much thinner at the bottom. I suspect your flat spot is lean as the stock needles are very thick and do not allow enough fuel until the slide is almost fully open.

I would not waste my time trying to shim the stock needles, they are designed to run with the stock airbox, filter, and mains. I can't see ever getting the jetting right by doing this.

I am running Ivan's kit with the airbox mod, I am finding it is very temp sensative, but when dialed in right, offers very good performance. I think any jet kit is better than trying to make the stock system do something it is not designed to do.

Good Luck, Ed.
2005 GSF1200SZ
1983 GS750ED

Vee Dub Nut · « **Reply #2 on:** October 11, 2005, 10:48:55 AM »

Thanks for the input.. im think im going to order a jet kit today...

PitterB4 · « **Reply #3 on:** October 11, 2005, 11:31:43 AM »

Just to throw out an alternative thought... Has it fouled the same plug both times? If so, are you certain you're getting strong spark to that cylinder? It's probably a carb issue but spark is something relatively easy to check and it would suck to rejet the bike only to find out you've got a loose wire somewhere.

Vee Dub Nut · « **Reply #4 on:** October 11, 2005, 11:47:19 AM »

i'll check that.. i dont know which cylinder is misfiring right now

im going to do some more diagnostics today

JayRo · « **Reply #5 on:** October 12, 2005, 12:15:17 AM »

Hey Vee
I think our bikes are cousins! I purchased my 99 B12 a little over a month ago and been having problems with the carbs, similar to yours, right from the start. I also have been having carb issues. I thought my bike was stock when I bought it but I was quite mistaken. I figured it had a jet kit in it because of the 2" mod on the airbox. In the month I have had it, I have fouled 2 sets of plugs. 1st it was cylinder 1 and 2. Then after I synced the carbs it was 3 and 4. When I pulled out my carbs I found 127.5 main jets in it. I thought that was the problem at first because the bike had the stock can, so I complained to the dealer and he gave me some 112.5 mains to see if that would help. Well, after taking out my carbs, changing the jets, giving everything a quick clean, putting it all back together with some new plugs, cylinder 2 never fired. After going through a bunch of stuff like checking the coils and wires and stuff, I realized that I was flooding that cylinder like Katrina (intended for levity only). I wanted to check and see if my float needle valves were holding good so I put the petcock in prime with the bike off and the next thing I knew is that gas is pouring out the vent tubes all over my chain. Well, if I lived in the city, I would have thrown my self in the path of oncoming traffic, but I don't, so I had to be content with laying out a nice long string of obscenities.
My carbs are back out on the workbench again and I'm trying to really give them a good cleaning. The float needle valve seat is a pain to get in there and get clean, but I'm a pretty sure that is the problem. I think that may be the problem with your bike too. With these vacuum petcocks, fuel is only flowing when the bike is running. Fuel level in the float bowl is critical, escpecially if you ride like a normal human being. This seems like the most logical diagnosis for your bike as I am living with a similar problems. Also, if you want to check and see which cylinder is misfiring without pulling stuff apart is just when you first start it up, when the bike is cold, start touching the exaust pipes. The one that stays relatively cooler than the others is your misfire. I hope I don't need to put a warning on how hot the exhaust can get. Good luck on it.
Keep up the fight. My wife has already nicknamed my bike "The Dud"

Vee Dub Nut · « **Reply #6 on:** October 12, 2005, 12:25:12 AM »

thanks for the input!

im doing a valve adjustment this weekend, going to drop in a new set of plugs...

also planing on pulling the carbs again to double check the floats, and tweak with my needles some more so i can run my K&N...

I'll be sure to keep yall posted, thanks for the encouragment, it had me pretty down yesterday, it was just one more thing that didnt seem to be going right for me lately.. lifes to short to be stressed out all the time

once i get it running well you better belive im going riding

terrebandit · « **Reply #7 on:** October 12, 2005, 12:38:19 AM »

So it was running right when you got it? Why not put it back to the way it was???

I have a 2000 model and am running the HS stage 1. I'm at the same elevation as you. I get 39 mpg max (ave is like 36 mpg). Mine runs perfect at Dales standard setting (1st clip and one shim on the needles).

Vee Dub Nut · « **Reply #8 on:** October 12, 2005, 01:18:12 AM »

well the float got stuck on me... i took them apart and ever since then i cant seem to get it running correctly...

when i had it apart i noticed it was on stock jetting, so i thought it would be a convient time to bump up the jets to get it matched to my pipe..

Vee Dub Nut · « **Reply #9 on:** October 12, 2005, 10:51:05 PM »

Ok here is the new news...

I pulled the carbs today to check my floats and jets for anything out of the ordinary.. nothing seemed out of place...

I set the A/F screws to 3 turns out
I shimmed the needles to .062"
With K&N and 2" mod
(127.5 mains and stock pilots and float height)

Its running almost perfect. I still have a little bit of a flat spot in the midrange at about 5k which seems really odd, especiall being shimmed so much... I am planning to do a valve adjustment and put in new plugs this weekend. Do yall have any suggestions to try to get my midrange to pull nicely, any thing I can check?

Thanks for the input!

tacoman · « **Reply #10 on:** October 13, 2005, 02:48:17 PM »

Just one question, was there any grit in the carb when you took it apart? The only reason I ask is that your problem occured after filling up at a gas station. I had an old Honda that had some rust/scale inside the tank. When filling up, if I squeezed the nozzle full on, there was enough pressure to wash off some of this scale. The crud would find its way to the needle, clog it, and I'd get flooding. Just something else to look at.

Red01 · « **Reply #11 on:** October 13, 2005, 09:27:29 PM »

Along the gas station train of thought... I once filled up at a gas station while they were getting filled up from a tanker and got water in my gas. Since then I never get gas from a station while a truck is there, or if I know one has recently been there.

Vee Dub Nut · « **Reply #12 on:** October 27, 2005, 11:37:11 PM »

Just an update.. i bought and installed dales stage 1 kit and all my problems are solved, it has never run better!

Thanks for the input!