Zxr400 Carbs

[Dam_buster]

right as a few of you know my zxr400 has been off the road for a little while,

getting it started took a while and it wouldn't idle properly, so im assuming its gummy fuel in the carbs,

now i removed teh fuel tank and air box to view the carb inlets and you have the "dash pot" style slider that moves up and down, and the butterfly type valve behind which moves when twisting the throttle,

now these dash pot sliders, how do they open up? are they operated on a vacuum? im quite confused about it all. the bike seems hesistant to rev, and sticks at 6thou.

now im thinking bout removing the float covers and giving them a blast with some carb cleaner, to get rid of any gummy fuel,

but would a good blast on the bike free up the carbs and get rid of that "flatspot" whilst revving?


hope this all makes sense, just desperate to get this baby on the road!

Hope to hear!

JIM
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Yamaha R6 5EB, BMW 328i Touring, BMW 328i Coupe

[DaveH]

Its the rate of the air passing past the sliders that draws them up. Not sure if adding redex to the fuel will help clear out the carbs, or just block the jets a bit.

Is it cleanfuel that you're using, or stuff that was already in the tank, and if so how long was it sittng?
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https://www.timhastingsracing.co.uk/

ZX7R & ER6F

[Dam_buster]

i put new clean fuel into the bike, but the bike has been standing since december, reason why i think its gummy fuel.

so i might swill this tank out again with clean fuel, pour it out, fill it again, and put some redex carb/fuel treatment in it.

so the slides go up and down whilst the engine is on. brilliant thats what i wanted to hear, and not, "their supposed to move with the throttle" lol

i'll get on the case of that today,


cheers for the speedy reply

jim
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Yamaha R6 5EB, BMW 328i Touring, BMW 328i Coupe

[DaveH]

Have you drained the carbs already?
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https://www.timhastingsracing.co.uk/

ZX7R & ER6F

[Dam_buster]

not yet, removing the carbs today to take the float covers off, give them a good clean out.
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Yamaha R6 5EB, BMW 328i Touring, BMW 328i Coupe

[DaveH]

[Dam_buster]

right well today i had the float covers off, gave them a good spray with carb cleaner, made sure the floats were moving freely. re-assembled and tried to fire her up....

nothing just starter motor lol


put some fuel additive in with the fuel,

but just waiting for the carbs to fill with fuel now really.

so will this take some time with constant starter motor action?


hope to hear.

jim
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Yamaha R6 5EB, BMW 328i Touring, BMW 328i Coupe

[DaveH]

Hmm, has it not got a fuel pump, or are any of the pipees kinked and thereby restricting the flow of the petrol....it shold be gushing in there til the float valves stop it
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https://www.timhastingsracing.co.uk/

ZX7R & ER6F

[Dam_buster]

cheers for the tip will have a look, it does have a fuel pump!

will have a look


cheers

jim
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Yamaha R6 5EB, BMW 328i Touring, BMW 328i Coupe

[Dam_buster]

right had a look, but didnt see any kinked pipes or anything,

had the bike started, today, it revs really high 4,5,6 k and then goes down to 1k then stalls, got a mega idle problem,

any ideas how to sort this?

JIM
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Yamaha R6 5EB, BMW 328i Touring, BMW 328i Coupe

[DaveH]

Does it usually cut out after about the same length of time?

Sounds like fuel starvation, immediately after it stalls switch the engine ignition off and see if you can drain any petrol from the carbs...if it is fuel starvation, it may be accopmapnied by a loud ticking from the fuel pump.
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https://www.timhastingsracing.co.uk/

ZX7R & ER6F

[Dam_buster]

how do i go about draining fuel from the carbs? is it that lil sprung screw on the nipple on the bottom of the carbs?

if its fuel starvation, whats needed more fuel in the tanks? it has 5l in it,

jim
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Yamaha R6 5EB, BMW 328i Touring, BMW 328i Coupe

[Dam_buster]

what am i looking for when opening these bleed nipples? lots of fuel coming out??
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Yamaha R6 5EB, BMW 328i Touring, BMW 328i Coupe

[DaveH]

[Dam_buster]

and if its not draining fuel then its fuel starvation?

possible faulty pump?

what will running with the fuel cap open do?

sorry for all the questions

but thanks for your speedy replies!
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Yamaha R6 5EB, BMW 328i Touring, BMW 328i Coupe

[DaveH]

It could be a faulty pump, with the fuel tap closed, but fuel in the carbs, disconnect the feed to the pump and see how strong the suction is.

I suggested running the bike with the fuel cap open incase the petrol tank breather pipe was blocked and it was creating a vacuum in the tank and preventing proper fuel flow.

One other thing in migh be worth checking is for an air leak between the carbs and the engine. Spray wd-40 liberally over the area and see if the engine note changes..
____________________
https://www.timhastingsracing.co.uk/

ZX7R & ER6F

[DaveH]

Not stupid questions at all, only hope you can get it working and if not that someone else can chip there tuppence worth in as well as I'm running out of ideas...
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https://www.timhastingsracing.co.uk/

ZX7R & ER6F

[Dam_buster]

cheers bud, i will have another go tommorrow evening,.

will try runnin with the tank open, and the wd-40 trick. then i will try the pump.

so i have to get the bike running, then turn it off, and drain the carbs to see if they are filling properly.?
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Yamaha R6 5EB, BMW 328i Touring, BMW 328i Coupe

[DaveH]

[Dam_buster]

cheers buddy your a star!
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Yamaha R6 5EB, BMW 328i Touring, BMW 328i Coupe

[M1ke]

I'd put money on it being the fuel pump, sounds exactly like the symptoms i'd expect.

The only other thing that makes it rev high is if you forget to attach the suction pipe to the fuel tap from the carb (should be the petrol pipe + suction pipe attached)

I'd say 95% your fuel pump though.

[Dam_buster]

what would make it high?

the pipe from the fuel tap to the carb.. thats the main feed for fuel?

have you any pics or illustrations to help explain


cheers for the info!!

JIM
____________________
Yamaha R6 5EB, BMW 328i Touring, BMW 328i Coupe

[DaveH]

If its got a fuel pump then it won't have a vacuum operated tap and therefore won't have the vacuum pipe between the carbs and tap.
____________________
https://www.timhastingsracing.co.uk/

ZX7R & ER6F

[Dam_buster]

right got the bike started again today, had a fiddle, gonna adjust my choke etc. do i want to go tighter or looser, if when i open the choke it revs to about 6k?

just checked for suction from the pump "took the feed line from the tank and hit the starter"

And couldnt seem to feel anything?

should i feel some definate suction?

just about to check the carbs for any drainage.


cheers guys!

JIM
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Yamaha R6 5EB, BMW 328i Touring, BMW 328i Coupe

[Dam_buster]

drained the carbs, well 3 of 4 as i cant get onto the last one

but to give an idea how much came out of each one, id say about half of a 500ml aerosol cap.?

so i no the carbs are filling.

just the revs are now sticking, and i felt for suction from the pump and i couldnt feel any.

also if i rev the bike hard, it will stall..

spark plugs?

hope to hear.

jim
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Yamaha R6 5EB, BMW 328i Touring, BMW 328i Coupe