Float height doesn't make sense??

[Davehuge]

Hi all

Recently bought a 2004 EC300.

I've been trying to get the carburetor set up, I've made big improvements but it's not 100% right yet, I need some help/advice.

Carb is as follows...

38mm Keihin PWK38
Main jet 175
Pilot jet 40
Needle top notch (leanest)
Air Screw 2.5 Turns out

As you can see I've got it set pretty lean compared to most people's settings.

From Closed to 3/4 Throttle it's working really well. But it won't pull wide open throttle, feels rich. If I close throttle a bit I can coax it to pull the full open throttle.

I suspect the main jet is too big/rich but at 175 it's already smaller than a lot of people are running.

Another suspicion I have is that the float height too high. I've read some of the threads and I keep seeing the figure of 16mm quoted as the correct float height, but that just doesn't make sense to my carb. I measured it and it's already at 21mm. I'm sure if I set it to 16mm it would be running even richer and or overflow.

Is it possible that I have a different version PWK38? Bearing in mind that it's a 2004 model?

Any help/advice greatly appreciated.

All the best, Dave.

[Davehuge]

Forgot to say...

Air filter is clean and oiled.

I'm running at about altitude 300m (1000 Feet), temperature around 25'C (77'F).

Thanks, Dave.

[pscook]

Check your silencer packing. I had a clogged silencer and my bike (2011 300) exhibited similar tendencies. I tested the Keihin as well as a Lectron, no difference in symptoms. Swapped out the silencer and problem solved. It's worth a look to see if the silencer is plugged or not.

[Davehuge]

Yes, good point, I'll check that and report back.

Thanks, Dave.

[PEB]

Have you checked the reeds?

[Davehuge]

Reset the float height to the recommended 16mm and went for a ride today.

Bike's running great CLOSED to 3/4 throttle but still won't pull Wide Open Throttle.

I felt it was running rich and decided to do a plug chop. To my surprise it looks like it's lean. Currently on a 175 main jet. Definitely looks grey.

I've just ordered a 180 Main jet, see how that goes.

Yours comments...?

[Moto7man]

Originally Posted by Davehuge

Hi all

Recently bought a 2004 EC300.

I've been trying to get the carburetor set up, I've made big improvements but it's not 100% right yet, I need some help/advice.

Carb is as follows...

38mm Keihin PWK38
Main jet 175
Pilot jet 40
Needle top notch (leanest)
Air Screw 2.5 Turns out

As you can see I've got it set pretty lean compared to most people's settings.

From Closed to 3/4 Throttle it's working really well. But it won't pull wide open throttle, feels rich. If I close throttle a bit I can coax it to pull the full open throttle.

I suspect the main jet is too big/rich but at 175 it's already smaller than a lot of people are running.

Another suspicion I have is that the float height too high. I've read some of the threads and I keep seeing the figure of 16mm quoted as the correct float height, but that just doesn't make sense to my carb. I measured it and it's already at 21mm. I'm sure if I set it to 16mm it would be running even richer and or overflow.

Is it possible that I have a different version PWK38? Bearing in mind that it's a 2004 model?

Any help/advice greatly appreciated.

All the best, Dave.

This is a good thread on float height from another site.

http://www.allthingsmoto.com/forums/...ght-way-65541/

[Davehuge]

Thanks for that, interesting way to see exactly what's happening with your fuel level in the bowl.

[Davehuge]

By the way... after doing the wide open throttle plug chop and seeing the grey plug (as in the photo) I rode home then inspected the plug again. It was a nice chocolate brown/tan colour.

So it would seem I have good carburation at other throttle positions, just wide open throttle is lean. Hopefully the 180 jet I've ordered will do the trick.

All the best , Dave.

[Moto7man]

Originally Posted by Davehuge

Thanks for that, interesting way to see exactly what's happening with your fuel level in the bowl.

You are welcome, I thought it was interesting too.