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R1 Carbs Leaking Fuel From The Bowl Area...?


Guest windscreen man

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Guest windscreen man

Finaly I put fuel to my r1 carbs at the correct psi today , however they 3 of the carbs had a servere drip coming from the bowl area (where the bowl bolts to the carb) why is this and what do I do, thanx for all the help by the way chaps

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could be as obvious as bowl gaskets perished or the bowls are cracked or are the drain screws done up if they are similar to my Kawasaki carbs I had problems with fuel leaks that looked like it was coming from the bowls but was the floats stuck so fuel kept coming in and only place for it to go was out behind the air inlet trumpets

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Did you do anything with the carbs before fitting ie stripping,cleaning, rejetting?

Could be dirt affecting floats and needle valves,perished, damaged or missing seals,loose screws on the bowls, too much fuel pressure.

I had zx6 carbs on my red top, a facet cube pump,no pressure regulator, never had any leaks but I did strip and overhaul them all first.

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If they are installed at the correct angle then I would be looking at the float needle valves in case they are worn and giving too high a fuel level.. Don't overtighten the float bowl screws as this can damage the seal.

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could be as obvious as bowl gaskets perished or the bowls are cracked or are the drain screws done up if they are similar to my Kawasaki carbs I had problems with fuel leaks that looked like it was coming from the bowls but was the floats stuck so fuel kept coming in and only place for it to go was out behind the air inlet trumpets

 

Chris, I may have the same problem with my bike carbs.

Is it worth stripping them down and checking them out before fitting this weekend?

 

I will try to upload a picture, but I think it's where the 40mm silicone hose joins the manifold to the carb's.

Perhaps there are not lined properly and not fuel resistant?

 

any ideas?

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Hi fellas,

 

I had the same, re-stripped the carbs, replaced the float needles and seats - and bowl gaskets.

 

Re-set the float heights.

 

Fitted them back up - still leaked - albeit a bit less.

 

Dropped the fuel pressure from 3psi to about 2psi - cured no more problems.

 

Try dropping your pressure a little more.

 

Cheers

Edited by Fossett
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I had a similar issue but was actually a Face Palm prob.

 

Carbs at correct angle. Cleaned and all set to correct height but fuel dripping out?

 

Rechecked everything but still happening so after a few hours of buggering about I gave Richard a bell and confessed my incompetence.

 

We went through the same diagnosis I had previously completed but at the end of it the phone line from Dunsfold to Nottingham remained a muddle of confusion until we started chasing back the fuel line.

 

Turned out I had connected up the fuel to the overflow and not the feed in. Doh!

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Chris, this is where I believe the carbs are leaking:

 

post-12997-0-82174600-1422622488_thumb.jpg

 

Could it be that it is just surplus fuel in the bowls and that these have been siting in a box for a few months at the wrong angle?

 

Or should I look into replacing the silicone pipes?

 

Also I believe that are Keihin carbs from a fireblade, but have no history or info on them and wondered if we have any experts out there that might be able to shed some light on what repair kit I might need?

 

I noticed these on ebay and don't know if it's what I require:

 

http://www.ebay.co.uk/itm/Honda-CBR-900-RRW-Fireblade-SC33-918cc-1998-Carb-Repair-Kit-/140754990733?pt=UK_Motorcycle_Parts_13&hash=item20c5a6b68d

 

Any advice would be great.

 

Cheers Dino

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If they are leaking there then you have 2 problems, 1 the joint is not airtight, and 2 I suspect the fuel pressure is too high or there is is dirt stopping the needle valves closing.

 

Thanks Peter, cannot confirm any of this information yet, as I haven't fitted them to the car.

Just wanted to make sure I got most issues out of the way before fitting them.

 

Luckily I have a fuel regulator which I will set at around 2-3 and this should control the pressure issues.

If it's not the joint being air tight, then I was wondering about the silicone being porous and needs replacing.

Dirt in the valves - suppose a good carb cleaning, repair and rebuild exercise should be necessary before fitting them.

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until there fitted dean don't worry its after you have fitted them and they leak if the bowls have some fuel in them it will come out of every hole until the carbs are at the right angle and the right pressure and the float needles are adjusted correctly

Edited by tractor
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Guest 2b cruising

If carbs have been left to dry out, they leave a scum on all surfaces. This then goes rock hard sometimes blocking the jets and covering the needle valve seats leaving them to leak. Cleaning out thorough is a must. For the jets use a welding nozzle cleaner very carefully as not to increase the diameter. Green scrubber from kitchen should do the rest.

Altering petrol height in bowls is simply by bending of the brass lever under the needle valve.

Good luck this week end

Ken

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