Hello all,

If you've been reading my threads, you all know I'm bringing a 98 Smokin Joe back to live. Long story short, I purchased the bike from a service member that took the tank and fairings off to repair a leaking seam in the tank. Well, he got deployed (over two years) and had to get rid of the bike. I had the tank soldered and then sealed it. I got everything back together and she fired up, however, she was also spitting fuel. I shut her down and took a look. I found 4 connections on the front of the carbs that are not connected. Looking at the service manual, I MAY be drain tubes that should be connected to the "carb float chambers".

The following images are shots of the tubes. Can anyone tell me for sure if that is what I'm looking at and where the hell they connection back to the "carb float chambers" are? The first picture is a close up and the second is not, for reference to where I'm looking on the bike.

Service Manual




Close Up



Overview



Any insight is GREATLY appreciated!

Thanks,

BJS

 

the solution there, is to remove your carbs, get a new gasket set to replace the float bowl gaskets, along with the O rings that are on the drain screws you show, since I cant tell which may be leaking from here.

while you have the carbs off, clean them out inside. it never hurts to do that anyways.

 

Maybe I'm misunderstanding your suggestion. I don't think the carbs are leaking, but there are 4 nipples on the carbs that have no hoses attached to them. I can get some hoses to fit the nipples, I just don't know where the hoses lead to.

 

those are for draining the bowls manually. on my f4 the carbs are almost identical with the "nipples" on the bottom of the bowls as well but no hoses. As you can see there's no hole really in the bottom of the "nipple"...just off to the side, most likely it's the gasket around the float chamber or the o-ring on the screw that's bad, there's a small o-ring just under the screw head. Go to this thread (https://cbrforum.com/m_311016/tm.htm), you can see those carbs have the same thing but no hole for fuel to leak out. Me? I'd pull those carbs off and go through them completely. After you do that, sync em and it'll run 10x better I guarntee it. I just spent a good half hour earlier this week syncing mine to perfection and the difference is crazy. It's a lot less tempermental at low speed, no missing, no popping, etc.

 

Hey guys,

I was speaking to the previous owner. He said he also rebuilt the carbs, along with changing all hoses, etc. I know the problem could be that he didn't reassemble it correctly, however, I'm wondering if me flooding the engine could cause overflow from these drains? I know when I was first cranking the engine over, i was really twisting the throttle trying to get some fuel into the carbs / engine. I did this so much that I killed the battery before it even sputtered as if it were going to start. I then switched to reserve since I only had 1/4 of a gallon in the tank in case I had to drain and remove again and gave her some more twist of the throttle. Not long after I started seeing a little fuel come out then she started.

 

Okay, well I cranked her up again and discovered that the fuel is just running over the drains and that there appears to be a hose problem connected to the carb. I took off the tank and air cleaner and can see lots of fuel on one of the hoses. I'm in the process of removing it now.

As a side note, I've been trying out a few CBR forums and this one is by far the best. It's got a lot of activity and everyone seems nice.

KUDOS to CBRForum!

 

it could be that the o-rings on the tee fittings for the fuel inlets are bad. mine were and I had to split the carbs and change those o-rings.

as for reassembling incorrectly, it's kinda hard to do, it only goes back one way.

 

Well, I got the carbs off and you are 100% RIGHT! The O-Rings on the two right carbs are bad and it was spitting fuel. Now it's time to replace them. I'm a little intimidated by it, splitting the carbs. How difficult of a job is it not to screw up anything else? The original owner did a carb rebuild on them, then went to Iraq for 2+ years which is probably what caused them to go bad. While I'm in there I'm thinking I may has well replace the left O-Rings also. Anything else I tool around in there without being overly invasive?

BJS

 

its not overly hard to reassemble. I suggest taking pictures of how things are assembled BEFORE you dismantle anything so you have a visual reference.

if you're replacing O rings, you may as well do em all and not have to go back in later.

 

it's really easy and straightforward, it only goes together 1 way. the only thing that is a pain in the butt is where the butterflies are linked together between each carb, there's a pring and a tab that need to be in-line with the other carb's butterfly tab and spring, ultimately a screw goes through both of them. It's hard to explain but you'll get it, needlenose pliers are your best friend with that.