fuel flow issue

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SeattleZXR
Posts: 33
Joined: Wed Jun 24, 2015 2:38 pm
My Bike: Kawasaki ZXR400

fuel flow issue

Post by SeattleZXR » Fri May 06, 2016 3:17 pm

This is my second ZXR400 and both bikes have had the same problem. I have taken them both to a dyno shop and they are properly jetted showing a slightly rich condition.
While riding on the street though both bikes have suffered from what I think is a fuel flow issue. If you start in 1st gear, accelerate to redline, then do the same in Second gear and then the same in 3rd gear at some point the bike starts to cut out like it's running out of fuel.

My theory is that the engine is using fuel faster than the fuel can enter the carbs. What would cause that?
I checked the fuel pump an it is working, the fuel line is new and clear, the filter is new and clear. What else could it be? Does putting an exhaust system on and then having to put in larger main jets make for a situation that the stock fuel pump can not keep up with?

The bike runs fine under normal acceleration and riding. It's only when I set out to have fun does it have the problem.
https://youtu.be/sPyiOG8LUTY

Most recent bike came up with 57.70hp last one was 2hp less.

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Miles
zxr400 oc member
zxr400 oc member
Posts: 466
Joined: Wed Apr 30, 2008 11:00 pm
My Bike: ZXR 400 L3
Location: Bangor, Northern Ireland

Re: fuel flow issue

Post by Miles » Fri May 06, 2016 3:57 pm

From the top of my head you have tank - filter - fuel tap - pipe - fuel filter - pipe - pump - pipe - carb

If fuel is getting to the carbs and the pump is working then maybe your floats aren't letting enough fuel in. Maybe check the heights.

Another thought is an uprated fuel pump. Increase fuel flow

SeattleZXR
Posts: 33
Joined: Wed Jun 24, 2015 2:38 pm
My Bike: Kawasaki ZXR400

Re: fuel flow issue

Post by SeattleZXR » Fri May 06, 2016 4:09 pm

Miles wrote:From the top of my head you have tank - filter - fuel tap - pipe - fuel filter - pipe - pump - pipe - carb

If fuel is getting to the carbs and the pump is working then maybe your floats aren't letting enough fuel in. Maybe check the heights.

Another thought is an uprated fuel pump. Increase fuel flow

Do you know of a uprated fuel pump? I was thinking maybe I'd install and Pingal high flow petcock and high flow filter. Maybe try to open up the gas tank breather a bit too.

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Miles
zxr400 oc member
zxr400 oc member
Posts: 466
Joined: Wed Apr 30, 2008 11:00 pm
My Bike: ZXR 400 L3
Location: Bangor, Northern Ireland

Re: fuel flow issue

Post by Miles » Fri May 06, 2016 5:16 pm

No don't know of one but if you google I'm sure your find them.

Do you flat sides on your SP?

SeattleZXR
Posts: 33
Joined: Wed Jun 24, 2015 2:38 pm
My Bike: Kawasaki ZXR400

Re: fuel flow issue

Post by SeattleZXR » Fri May 06, 2016 5:25 pm

Miles wrote:No don't know of one but if you google I'm sure your find them.

Do you flat sides on your SP?
It's not an SP it's a L2. I found a SP tail and put it on there

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fstarocka
Posts: 40
Joined: Wed May 04, 2016 6:33 am

Re: fuel flow issue

Post by fstarocka » Fri May 13, 2016 9:17 pm

Make sure your tank isn't vapor locked.. Pump supplies way more fuel than ull ever burn in a few seconds..

U might have a powder oxide clogging ur jets.. Make sure you lightly brush hard enough to break it down without scoring the brass.. I take a snug fitting twisted copper wire and twirl it thru mains.. Lightly scratch around jet opening too..

Also check the gauze beneath each carb seat isn't clogged up.. Or needles sticking.. Even a tiny film of fuel varnish residue can make a needle slightly sticky.. Esp the tips of the needle..

Also check inside the seat, I take a cotton bud and 600 grit dry and sand inside the walls of seat plug.. Oxidized fuel and brass powder can also decrease the needle clearance..




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