Mikuni BST34SS Carb in an 1100

[Retched_Kat]

Hello all!

I haven't been on in a while, I've been busy in my garage rebuilding my 1988/1991 GSX1100F. Finaly finished it and now it is time to get it running proper. It ran but it ran very hot and had a strange idling behavior I didn't like. I recently took apart the carbs (never done it before but I figured hey, I'm a smart guy) and now I have almost everything clean and ready to put back together. My question though is why do some people say that the '88 has the 34SS carbs and '91-'93 has the 36SS? Some threads I found on here say that all pre models of the 1100 have the BST34SS carbs. I have one set that came with the '91 engine and one set that I got from a guy who owned an '88 and they are identical. Do I even have the proper carb for my engine? Also, where is the best place to order STOCK jets for these things? both carbs have non-stock crap in them I don't want... stuff is destroyed and stripped anyway.

Thanks in advance!

(My avatar pic over there is the finished product of my winter slaving)

[arsenic]

The GSX1100F had BST34SS carbs in the US from 88-93. The GSX1100G has BST36SS carbs. In the US the GSX1100F always had 34mm carbs. If anyone tells you differently they are incorrect or just stupid. Both photos you posted are BST343SS carbs, those are correct for the GSX1100F.

[loneraider]

If I were you I would order a Factory pro jet kit and
new emulsion tubes since you have the carbs apart.
If you have done all the other work on your bike adding these parts
to rebuild your carbs is like icing on the cake with a cherry,!!
Factory pro has a setup for stock air filter & exhaust.

[Retched_Kat]

If I were you I would order a Factory pro jet kit and
new emulsion tubes since you have the carbs apart.
If you have done all the other work on your bike adding these parts
to rebuild your carbs is like icing on the cake with a cherry,!!
Factory pro has a setup for stock air filter & exhaust.

Any way you can post the link? I looked on there earlier and they said they didn't carry parts for the BST34SS...

[loneraider]

www.factorypro.com


still looking for the exact link but search around there, you'll find it

[Retched_Kat]

I'll keep looking there. I had two sets of carbs both of which i took apart and put back together so if I find something I want to put in later I have no problem pulling it apart again.

Question though: I cannot find the stock setting for the pilot screw on this bike. The guide I was following just said it was preset. I know I need to tighten it as much as I can and then come out maybe 1 3/4 turns? I have a "stock" exhaust (read: previous owner wanted more noise so he drilled hols into the baffles. I fashioned some sheet metal caps for it to reduce the noise and get the stock pressure back) and I have a K&N air filter in it as well.

Really appreciate the help guys

[arsenic]

2.5 turns out, that's the optimal starting spot. The Factory Pro tuning guide will tell you the same. Even with stock jetting, 2.5 turns out works best. Lose the K&N, it's not helping anything. You want the stock paper air filter element.

[Retched_Kat]

OK so I ordered a stock filter as the K&N came with the bike.

I put the carbs back together after replacing all the O rings (no new needle seat or anything, just O rings) and the bike will not start. There is suction on the fuel vacuum line and the diaphragms bounce ever so slightly. After about 10 mins trying to start it, I pulled one of the drain screws and filled up an identical float bowl cover about 90% of the way with fuel...

Floats were set with a micrometer 14.5mm from the lip of the bowl to the highest point on the float while open. I cannot figure out what isn't happening properly here... Is there too much fuel in the float bowl?

[shpielers]

Airbox/filter installed will help. How old is the gas? If it's not fresh, worth a shot. When you were putting everything together, did you replace spark plugs/verify they got good spark?

[Retched_Kat]

Airbox/filter installed will help. How old is the gas? If it's not fresh, worth a shot. When you were putting everything together, did you replace spark plugs/verify they got good spark?

The bike was running last week. Plugs are a year old but it never had to turn over more than once to start. I rode it to work and back and filled up with 93 octane from Shell on the way home so the gas is as fresh as could be. Most of the problems I have read about after a DIY carb clean is a sputter of white smoke here and there. Should there be that much fuel in the bowl? I drained it out and like I said there was enough to fill the bowl. Should the valves be moving more? They only shifted up and down slightly... Maybe I should spray some starting fluid in there to get it going a bit..

[subforry]

Starting fluid is bad, avoid using it.

Are the butterflies closed - seated. Some guides tell you space them open. If they are open too far then no vacuum, no lifting the slide, and no starting. Same reason shpielers asked about the air box.

Start with them closed, once it catches use the throttle, then if it dies use the screw to open the butterflies just a little bit, maybe a half turn. Try again and repeat until it idles without throttle. Then sync them.

[shpielers]

Starting fluid is bad, avoid using it.

Are the butterflies closed - seated. Some guides tell you space them open. If they are open too far then no vacuum, no lifting the slide, and no starting. Same reason shpielers asked about the air box.

Start with them closed, once it catches use the throttle, then if it dies use the screw to open the butterflies just a little bit, maybe a half turn. Try again and repeat until it idles without throttle. Then sync them.

I go with having the adjuster screw just touching the plate, no pressure on it.

Just a thought - if you were cranking on it for 10 minutes you might have worn the battery down a far bit. If you have a charger, throw it on for a bit. Couldn't hurt anything. I've had a battery low enough it would turn the starter but not enough power for good spark. 1st time starting a bike after the carbs are off/drained always seems like a pain in the ass, at least for me.

Btw - if you find a link for the FP jet kit, would you please post a link? I'll be needing one of those for my own 1100 build.

[thebird_19]

http://katriders.com/vb/showthread.php?t=111630&highlight=factory

This is the thread I read when I was rebuilding my bike and have been running the kit they say doesn't fit for a couple of years now.

[shpielers]

Sweet, thanks for the link, bookmarked!

[Slammer46]

Yup bookmarked also