Another "fuel gushing from carb" thread - Harley Davidson Forums: Harley Davidson Motorcycle Forum
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Old 08-14-2008, 12:10 AM   #1 (permalink)
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Another "fuel gushing from carb" thread

This time with an '85 FXRS (Lowrider Sport). Evo, 1340. It's got a Screamin' Eagle carb on it of about the same era. It's a Keihin, but it differs both from the stock carb of the time and the later CV carbs. Idle mixture screw on top, accel pump on left, K&N style aircleaner, funky bottom-attach bracket for the air cleaner.

My bike sat for a couple of years, ran great at first this year, and just recently started puking gas. It shows all the symptoms of a dirty needle/seat, except that (with the bowl off, of course) I can manually work the float and cause the flow of gas to stop. I cleaned it and blasted it with carb cleaner anyway, and the gushing still happens upon reassembly.

I've had the bowl off several times this year, as I put on new pipes and was trying to find the right jets. During the last rejetting I thwacked the float pretty good with my hand while fiddling with something else. I inspected it, and it did not appear to have any holes or cracks, but I'm wondering if it has (somehow) lost its buoyancy and is no longer rising with the gas. Again, I can work the float by hand and cause the gas to stop flowing, but the gas rising in the bowl isn't enough to stop it.

Oddly, it worked for the first ~4 miles after the rejetting, and only then started gushing gas. How can that happen if it's the float?

The worst part was the reaction I got when I called dealership parts dept asking for a rebuild kit for this ~25 year old carb. Turns out that, oh yes, there's a kit, but it's $400. (!?!?) There's a float, but the part number I was given (27887-87) cross references to the float in a Sportster carb. It could be the same part, but it doesn't sound right. And of course it's a special order, can't look at it, the dealer is 25 miles away, requires special orders to be paid in advance (apparently in person)...

Is anyone familiar with this carb, and can you give me a real reference for the float part number?

In classic "closing the barn door after the horse" fashion, I have now installed a fuel filter...

Any other ideas? At this point I'm seriously considering scrapping the whole carb and finding something (hopefully used, NOS removal, whatever) I can put on it to salvage the remainder of the riding season.

-- Sam
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Old 08-14-2008, 12:47 AM   #2 (permalink)
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While your hand is strong enough to force a seal The float will never exert that much pressure I'd check and make sure any O-ring or seal on the needle valve is not cracked, flatend or got hard. Check the mechanism for binding or corrosion and take the float off and throw it in a can of gas for a half hour or so to see how it acts before you chunk out alot of money. Used to have alota old carbs on Ebay for decent prices havent looked lately.
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Old 08-14-2008, 01:27 AM   #3 (permalink)
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Damm $400 for a rebuild kit???

Was the carb gushing fuel before you "thwacked" the float? If not, you probably just knocked it out of adjustment.

If it did leak before, the float valve tip is probably worn or hardened, and needs to be replaced.

A rebuild kit for the stock Keihin "BH" butterfly carb (non CV) used between '76 - '89 runs about $25 thru Drag Specialties (DS PN# 289089) etc....


Hard to say if this same kit is the one you need for your carb without determining what carb you have.
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Old 08-14-2008, 01:39 AM   #4 (permalink)
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Does it look like this?

Keihin BD carburetor.



Instruction sheet:
http://www.chrishajer.com/bike/XLF/29081-90C.pdf
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Old 08-14-2008, 11:23 AM   #5 (permalink)
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Quote:
Originally Posted by Dave63 View Post
Your dealer parts guy is a retard. You can buy a new carb for that price.
Yeah, that was my general opinion, too.

Thanks Kainam for the pictures above. It is the Keihin BD, which according to the PDF file, is indeed a Sportster carb. Of course mine uses a different mounting system and aircleaner.

That Drag Specialties #289089 kit sounds right, but if that's the float in the sort of left-middle of the picture (the round thing with the brass center) that's not the same float. Mine's a sort of half round donut shape that fits around the main jet housing.

No, it did not gush gas before I smacked the float. But it didn't start leaking gas for several days after that incident, either. I think there was even one more rejetting involved before the gas started flowing.

Since I can manipulate the float and stop the flow I'm assuming everything is moving freely. I've inspected the needle and seat and didn't see any obvious damage. I'll take a look at the level, though there's nothing to gauge it by, so I have no idea if it's correct.

Thanks for the help. At least I know what carb I'm dealing with now (I think).

-- Sam
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Old 08-14-2008, 12:19 PM   #6 (permalink)
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I'd keep my eyes open for a stock CV carb that someone took off their bike to upgrade.
They are a much better carb than the butterfly style Keihins. If you could score a stock intake for a '90 - '98 Evo, that would be good too.

Article on retrofitting a CV carb to pre-'90 Evos:
http://www.harley-performance.com/cv-carburetor.html


Hopefully, in the mean time a simple float adjustment gets you going again.
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Old 08-14-2008, 01:09 PM   #7 (permalink)
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Yeah, thanks, that (replace with a CV carb) looks like an option. I've never been particularly thrilled with the SE, but it worked (up till recently).

FWIW, upon further reading, that part in the rebuild kit I questioned above is not the float, but the accel pump diaphragm. So it looks like the rebuild kit doesn't contain the float, anyway...

-- Sam
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Old 08-23-2008, 01:22 PM   #8 (permalink)
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Pardon me while I dredge this up again. Been spending more time at the range with my new AR than worrying about my ride...

Quote:
Originally Posted by Kainam View Post
I'd keep my eyes open for a stock CV carb that someone took off their bike to upgrade.
They are a much better carb than the butterfly style Keihins. If you could score a stock intake for a '90 - '98 Evo, that would be good too.

Article on retrofitting a CV carb to pre-'90 Evos:
http://www.harley-performance.com/cv-carburetor.html


Hopefully, in the mean time a simple float adjustment gets you going again.
I've had my eyes open for a CV for a while now, and have seen a few come and go on a certain auction site for less than $100. You indicated, "a stock intake for a '90 - '98"; What makes the '99s and later different? Most of the ones I've seen have been '00 and later, or have no indication of year, and I don't know what to look for.

The good news is that my current Keihin BD already uses a rubber boot to mate the carb up to the manifold, as well as a two cable throttle system. These are both required by the CV, according to the above-referenced article, and are conversions I won't have to do.

I do wonder how the carb is bracketed onto the engine though, as this BD I have is very different than the stock setup. It looks like I may need to get a complete system, with carb, bracket, air cleaner housing, etc. My BD uses a rubber mounted K&N filter, a cover that screws into that, and a bracket that attaches between the cover and the block. Yeah, that's broken a few times...

-- Sam
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Old 08-23-2008, 04:12 PM   #9 (permalink)
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Quote:
Originally Posted by Yosemite Sam View Post
Pardon me while I dredge this up again. Been spending more time at the range with my new AR than worrying about my ride...


I've had my eyes open for a CV for a while now, and have seen a few come and go on a certain auction site for less than $100. You indicated, "a stock intake for a '90 - '98"; What makes the '99s and later different? Most of the ones I've seen have been '00 and later, or have no indication of year, and I don't know what to look for.
IIRC, prior to '90, HD intake runners were made of rubber. Post '90, when the CV carb came out, the intake runners were made of aluminum again as they should have been all along IMO. Post '98 was when the Twin Cams came out.

When buying a used CV carb, be wary of any that have the "Dyno Jet" modded slide. Seems these cause as much problems as what they were attemting to "solve" when doing this.

Quote:
Originally Posted by Yosemite Sam View Post
The good news is that my current Keihin BD already uses a rubber boot to mate the carb up to the manifold, as well as a two cable throttle system. These are both required by the CV, according to the above-referenced article, and are conversions I won't have to do.

I do wonder how the carb is bracketed onto the engine though, as this BD I have is very different than the stock setup. It looks like I may need to get a complete system, with carb, bracket, air cleaner housing, etc. My BD uses a rubber mounted K&N filter, a cover that screws into that, and a bracket that attaches between the cover and the block. Yeah, that's broken a few times...

-- Sam
In stock form, the CV carbs are bracketed to the motor via the air cleaner backing plate. Any air cleaner assembly, HD or aftermarket, designed for a CV Evo would work for you.

As far as the rubber carb flange on your current intake, it "should" fit the CV.
I'm not sure where your intake will put your carb as far as air cleaner mounting bracetry goes, but I think it should be pretty close to the stock location. If not, there's always a stock or aftermarket evo CV intakes in rubber boot style carb mounting or flanged carb mounting.

I prefer the flange style mounting system and solid aluminum intakes, but that is JMO.

One other thing, you will probably have to change out your throttle cables. On the CV carb models, the inner length is longer with respect to the outer sheath compared to the pre CV model bikes.
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Old 08-23-2008, 04:22 PM   #10 (permalink)
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Thanks for the reply, again!

FWIW, I swapped out the old rubber intake runners to an aluminum manifold back when I was playing very similar carb games in 1986. I went through the stock Keihin, a used, air-leaking S&S, into the current Screamin' Eagle (Keihin BD), which I also got used. Always a fun time!

-- Sam
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