Evo Leaking Fuel

[bruces670]

hi all i have a 2011 evo 250 with keihin carb thats chucking fuel out of the overflow pipes,ive stripped it and its clean but still doing it do they need a similar mod to the rev 3s with the mikunis? ive googled it but havnt found much on them

[stork955]

G'day, the Evo's dont need mods to the carb. If fuel is running out of the overflows you have a needle and seat issue, a high float level or a punctured or otherwise "sinky" float. Have a close look in those areas.

Cheers,

Stork

[billyt]

"chucking fuel out of the overflow pipes,"

[copemech]

There is only one overflow pipe on a kiehin, and that is the one that exits off the lower portion of the bowl with a standpipe inside that normally extends abofe the level of the fuel. However, with sloshing about and such one may set spillage out them even on a well set carb.

There are a couple answers for this, one being to block it off with a cap. Another is to run the hose up over the choke valve(or carb body) then downhill to exit, as fuel will be trapped this way in the hose.

Either way, it defeats the primary purpose of it, however it is not totally neccessary, as the bowl vent tube on the other side is the one that does the work and is critical.

Other carbs such as the Dellorto do not use such a device, so if the float does stick, it will simply fill the motor with fuel instead, which is not good, yet chances fairly slim in most cases it seems.

As I have little like for peeing carbs, mine has been blocked off entirely on my OKO(kiehin copy) including removal of the internal standpipe for ease of bowl installation, with a BB sealing the hole.

Do as you like with fair warning, it is your decision.

[spenser]

I hav found that setting the carb float heights as per the "sticky" on the Beta forum (2008 with Keihin carb) the problem sorts out. The overflow/vent pipe on the side has been known to spill a bit as well if the levels are not set correctly.

[pindie]

Don't panic. It is only the tab which actuates the rubber tipped needles fuel flow not adjusted properly.

You need the carb clean and on the bench and in good light. Have a look closely at what point the brass tang affects the fuel flow valve. You can use the rev 3 guide to work this bit out.

Once this is set properly you won't need to block things off!

[overdale]

Normally the 2011 EVO Keihin is ok , but I have seen the overflow problem when the breather pipe was routed incorrectly.

There are two small pipes on the right hand side of the carb fitted to two aluminium stub pipes coming out of the top half of the carb. The one which points upwards is the vent pipe and the plastic pipe should be routed upwards through the frame and along the right hand tank side panel.

The one coming out horizontally is a sort of overflow and should be routed down under the carb and towards the swinging arm. If both are routed down over, a syphon can occur under certain circumstances and the carb will leak fuel.

When removing the carb, disconnect the upwards pointing vent and leave it on the bike, then it is always routed correctly up the frame!

When cleaning the carb, removed the float pivot pin, lift off the floats and needle and blow back through the float needle hole to ensure that no dirt is in the inlet connection which could get under the needle when in use.

To check the float height, see BETA forums and the pinned report on 2008 2t with Keihin.

Hope this helps!