Flatslide spitting fuel out intake side?

[brblpop]

I knew I was going to need you guys!

I live in Nebraska and we are having some nice weather, so I went to get the Baggie (see my album for a couple pics) out this week but it didn't want to start after having sat for about a month. The battery was running down, so I took it out, topped it off and charged it.

On trying again today I had the seat off and the airbox open and it would start at full throttle, but didn't want to idle. I started smelling fuel and shut it off. I decided to take the air cleaner off and found the bottom of the airbox filled with fuel .

I sprayed some carb cleaner in the throats and let it sit for a while. Then I started it again (no air cleaner) and after about 2 or 3 seconds, fuel was spraying out of the right side carb into the airbox.

I'm guessing something is gummed up, even though I put Sta-bil in the last tank in anticipation of a little down time.

It has Keihin FCRs. I've worked on a lot of Mikuni CV's, but don't know anything about the Keihin's. So, does anyone have any experience that would indicate that this is fixable with liberal application of cleaner without removing the carbs, or am I looking at a tear down ? I wasn't able to see the linkage between them, so I thought maybe it could have vibrated loose and had only one 'working'?

They're a tight fit, so I'm hoping they don't have to come off.

[phlat65]

I cannot answer your question about the carbs, but I will add that there have been cases of carbs leaking fuel and diluting the engine oil supply. you should drain and fill the oil, and pull the plugs and crank the engine over. the fuel may be comming from the engine, and not the carb. since the fuel is gravity fed into the carbs, then running the engine should make no difference to fuel supply. you may have had 1 carb hang a needle, and fill the engine.

[keithcross]

Good advice that, I would turn the fuel off ifrst though. May I suggest that once you have done this, you try running the engine and once it starts, turn the fuel of if the problem still happens and see if it stops before the engine dies. Might be a stuck float.

Keith

[brblpop]

Thank you! As I've been thinking about this and discussing it with a friend, I definitely think it's float related.

I hadn't considered my oil being diluted with fuel though. Definitely worth the price to drain and replace once things appear to be fixed.

Looks like I get a lesson in the anatomy of the Keihin FCR. Always more to learn!

We're supposed to have good weather this weekend, so hopefully it goes quickly and I can get a ride in.

I'll post back what I find.

Danke.

[brblpop]

You nailed it Phlat!

I drained the 'oil' and got a pretty diluted mix of gas and oil.

I still pulled the carbs and went through them since the root cause was a stuck float. Everthing looked OK as I went through them. As difficult as they were to get off, it was worse putting them back in. VERY tight fit. If I had to jet it, I'd be looking for some sort of pod filter setup to help ease installation / removal. Fortunately, whoever put them on seems to have done very well.

I'm going to start shutting off the fuel at the petcock from now on. I got lazy with my last bike, because I never had a problem and quit doing it. Cheap insurance against this happening again.

Thanks for the input!

[phlat65]

good to hear! I have heard the throttle response with the flat slides is phenominal.

[DEmark]

It is possible to change the main jets without removing the carbs. If you do have to remove the carbs, collapse the airbox to carb booties and pull them into the airbox to get some wiggle room.

I am curious, what size main jets are you running, and do you have any motor mods?

[brblpop]

Yes, the throttle response it amazing. I came off of a GSXR-750 and could not believe how this thing jumps. I hadn't test ridden it for 30 seconds before I knew I was going to buy it!

I struggled for too long trying to get the airbox boots out the front before I finally collapsed them and pulled them out through the airbox. Duh! Getting everything back was definitely work though. The main problem is the crankcase breather hose coming that connects to the tube off the underside of the frame. This ends up right on top of the carbs and was a bear to get reconnected and in the way when re-installing the carbs.

On engine mods, the previous owner said that it has "stage 2" cams. I don't know any more than that. I'm not sure who's cams or any details on lift / duration. I did inspect the intake ports while I had the carbs off and they have not been polished, so I don't think it has head work. Not sure on piston/bore either. There are indications the head has been off, but it doesn't look like the cylinder has been.

As for the jetting, the main jet on the left (bigger?) is a 140, the right is a 145. The slow jets were both 55 and the main air jets both 200. It had slow air SCREWS instead of jets (yes!) that were at 2-1/2 out. I did not tear down the top end of the carbs, so I'm not sure what jet needles are installed or their clip positions.

I think if I had to re-tune them I would opt for a set of the fuel screws that can be manually adjusted. The Zip-Ty version is nice since it has the numbers on it to provide some reference. The Boyesen Quickshot acc-pump mod is supposed to be pretty impressive too, though not exactly cheap.

Patrick Burns' Keihin FCR tuning manual (I found v3.3) is a highly recommended document for anyone interested. A quick search on the internet will turn up a plethora of copies. The Sudco site also has a nice set of PDFs of exploded views. My carbs have a sticker indicating that they came from Sudco.

[DEmark]

I detailed mounting the FCR's on my Baghira here http://mzriders.com/viewtopic.php?t=698
After some experimenting, I am running 140 mains with a stock motor.

[keithcross]

DEmark

Good piccies, but I have one question. Do these carbs make much difference?

Keith

[DEmark]

Keith,
Yes, it runs a lot better, more power, much better throttle response, starts easier. I like the fact that it doesn't put the additional stresses on the motor that a big bore kit or a higher compression ratio does. It is still not the wheelie machine I want it to be, however I have the Enduro model, a HR motard model with the shorter swingarm would be better for wheelies. It is fairly expensive- $700usd, but if you are planning on keeping your bike for a long time, its worth it. I put them on my skorpion first then the baghira. They fit the Skorpion much easier.