Author Topic: New B4 owner with some ?s (Read 3626 times)

todius · « **on:** May 03, 2005, 10:29:21 PM »

Hi all. I've recently bought a Bandit 400 as a project bike. I've had an 01' B6 for a couple years, but always missed the thrill of my lil Ninja250 that I started on. The B4 just sounded like a good compromise between the two.

Having said that, the bike is definitely a "fixer upper". Right now she doesn't run. I'm currently in the process of cleaning/repairing the carbs. Is there a carb rebuild kit available for this bike? (I don't think I'll be that lucky). Most of the o-rings are shot, the float bowl gaskets are toast, a spring and washer are missing from one of the carb's pilot circuits and one of the spring seats that hold down the main jet needle is missing. Other than that, things look OK. Don't see any tears or holes in the diaphragms which is good.

My other question is, how many turns out is a good starting point (stock) for the pilot screws?

I'm sure I'll have plenty more questions (which I'll try to find with the search function first), but hopefully in this process, I'll be able to understand the B4 better and offer some help to others as well.

Zhi · « **Reply #1 on:** May 04, 2005, 12:06:40 AM »

2 1/2 turns out works well for me.

todius · « **Reply #2 on:** May 04, 2005, 01:06:05 AM »

Thanks Zhi.

Another quick question. There is a little washer and o-ring that is pressed upon by the spring in the pilot jet circuit. It's listed in the diagram in the service manual, but is not on the microfiche at Bikebandit.com or the one listed in the forum. Anyone have the part number for that little itty bitty o-ring or a suitable substitute?

Thanks,
Brent

(I knew I'd have more questions)

Maniac · « **Reply #3 on:** May 04, 2005, 01:22:21 AM »

Yeah, there should be a washer there if I understand you correctly...

O-rings... well, your gonna laugh. I got a lot of mine from ACE Hardware. No kidding, I bought three of their 'assortied O-Ring' packages and they had just about all of them that I needed.

todius · « **Reply #4 on:** May 06, 2005, 12:15:42 AM »

Thanks for the info.

Well, I looked here at work and managed to round up some o-rings that actually fit the carbs (woohoo!). Got everything cleaned up (the carbs had old caked up fuel all over). Getting the screws out was a pain, I had to slot several of them with a Dremel and back em out with a flathead. Replaced them with stainless allen head cap screws.

Anyway, put the carbs in tonight and she fired up for the first time.

She revs up good and clean, but she hunts at idle. If I give it a little choke, it'll race up to 8k or more. Also, if I crack the throttle slightly, it'll usually jump up in RPMs and will sometimes take a long time to come back down. I tried to synch the carbs as best I could, but without being able to maintain a steady 1750rpm, it's pretty hard to do.

I'm guessing I have a vacuum leak somewhere causing the poor idle. I've got a set of vacuum guages, and there doesn't seem to be anything jumping out at me, but who knows? The vacuum access ports are on top of the diaphragm cap; this seems kinda odd to me. I'm used to it being on the metered side of the carbs. It seems it would be easier to see a vac. problem if the access ports were located there (dunno, maybe it sees the same vacuum either place?)

Any suggestions? Think its a vacuum leak?

Jetting appeared to be stock. 102.5 mains. It had a small shim under each of the needles, but that's about the only modification I saw. Set the pilots to 2.5turns out. Set float height (using calipers) to ~14.5mm Bike has a Supertrapp slipon (stock header).

gsxr400 racer · « **Reply #5 on:** May 06, 2005, 01:11:08 AM »

heres the part number anyway
o-ring 13295-29900
washer 13291-29900

Maniac · « **Reply #6 on:** May 07, 2005, 12:15:58 PM »

Quote from: "todius"

Any suggestions? Think its a vacuum leak?

It's possible, but I'm more inclined to think you have an air leak that is leaning out the mixture. More than likely either between the intake boots and the head, or the intake boots and the carbs (may also check that the small O-ring under the carburator caps is still there). Try the old water-in-squirt-bottle trick.

1) Get an empty squirt bottle, fill with water.
2) Set to 'mist'
3) Start engine
4) Spritz water around the carbs/intake boots

If the RPMs jump or the bike starts idling rough (or stalling) then you are sucking air somewhere.

Got a Supertrapp as well? Probally should go ahead and get the K&N filter and rejet the old girl, made a huge improvement in mine.