Few problems id like to run past use pros

[MarkMRS4]

So it started yesterday when out riding... My carb spat fuel out every pipe thats on it!

Tryed to turn the fuel off via the petcock but no such luck. It kept flowing out fast!


So i broke down the carb cleaned it all and thought id check my jet size while am here, which turened out to be 27?

Took the petcock out and its rusted and all gunked up so i think il try replace the whole lot rather than a repair kit.

I checked my float height with a great deal of difficulty i think the tab touches and it reads rouchly 20/21mm

The mods i have are open airbox, k&n and full fmf exhaust. Is this the correct jetting for these mods?

Anyone ever had this problem with there carb?

Any help would be great!

Mark

 

[Blaaster]

There should be a #290 - #300 main in there.

If there was gunk in the tank, then gunk would most certainly have got into the needle and seat assembly causing the carby to flood.

Ii is not ok to think that the float is set correctly, it must be set correctly!

Float level should 20 to 21.5mm on a stock carby.

you want to turn the carb and hold it on a slight angle to measure the float height, like shown here......

it should just barely be touching the inner needle, not depressing it,

It is possible to check the fuel level by attaching a length of clear plastic tubing to the drain nipple , lifting it up the side of the carby, and cracking the drain screw.

The fuel should show in the pipe to the level of the carb body above the float bowl gasket.

 

[MarkMRS4]

When i tried to measure it the tab slightly touches it but the needle doesnt lift any out the seat.

Its hard to measure with a tape and carb in the other hand lol!

Where can i buy a larger jet from? What difference will this make?

Thanks
Mark

 

[Herpderplol]

A larger jet will cause it to run richer.

If you are running stock jet with the FMF, you are running the engine too lean, which will cause many problems in the near future

 

[Blaaster]

When i tried to measure it the tab slightly touches it but the needle doesnt lift any out the seat.

Its hard to measure with a tape and carb in the other hand lol!

Where can i buy a larger jet from? What difference will this make?

Thanks
Mark

Mark the difference will be the motor will not be destroyed by too lean a mixture.

Scribe the measurement on a bit of metal or stick or make up a template, sure saves holding a tape.

 

[MarkMRS4]

Is the size 27 jet stock jet? I took it for granted that ment 270 my bad.

Am from the uk so sourcing these parts are quite hard as no real company specialize in yamaha parts more polaris.

Where do use guys go for jets?

Mark

 

[Herpderplol]

The interweb I:I

 

[Blaaster]

I am from Australia and I by mine in the US mainly on Ebay or from Jets R Us mikuni, keihin, hitachi, holley, jets and carb parts

 

[Herpderplol]

Would this be the correct one?

GENUINE MIKUNI HEX MAIN JETS 4/042

 

[Motocrossguy17]

Is the size 27 jet stock jet? I took it for granted that ment 270 my bad.

Am from the uk so sourcing these parts are quite hard as no real company specialize in yamaha parts more polaris.

Where do use guys go for jets?

Mark

mark if you give Ian E a call he will hook you up with jets i got mine from him ranging for 270-310 and a bigger pilot jet and it wasn't anymore than £13 that was delivered.