Problems at high speeds.

[fazersharp]

Done fucked up today!

Stripped the bike down last Thursday, got the old carbs off and new ones on today, all good until I found I had two screws left over

Actually you are lucky as a while back someone on here was a screw short - with the possibility of it had been lost down the head, we were all coming up with ideas of how to get it out a bit like the film everybody's baby (stuck down the well )
If I remember rightly the Focer in question was sitting on the missing screw

[Jamieg285]

I'm happy to be shot down here, as I have almost zero knowledge of carbs on the bike, but I do know more about the ones that sit on top of a 6.6 litre V8.  I figure there might be some commonality between the way they work.

I'm not sure I'll explain it very well, but here goes:

On the bigger ones that I have worked with, there are 2 ways the fuel feeds into the intake - vacuum and pumped.  When the engine is running it creates a vaccum in the intake, which sucks fuel in from the carb.  The more open the throttle the bigger the vacuum and the more fuel is sucked through, which in turns makes the engine run faster.  When you sudddenly open the throttle there is a lag, where the amount of fuel being sucked in relates to the original position of the throttle, so you don't get a sudden burst of acceleration, but you are waiting for the vacuum to build and suck more fuel. This is where the pump action comes in, and it is linked to the throttle.  When you open the throttle it squirts a bit more fuel into the intake, to cope with the lag - a bit of a boost to help things along.  On the carbs I've worked on, there's a lot of tuning you can do to this pump circuit, such as speed, volume and jet sizes, which all affect the lag timing and effect of the pump.

I'm wondering it the FZS carbs have a similar function, and you're not getting the pump action.  This could explain why you only see it on rapid throttle opening, but not when you open it gradually, as the lag effect will be slower/less obvious with slower throttle opening.

If it is this that's the problem, the replacement carbs may prove to solve your issue - but that doesn't mean this was the problem.  The only way to know for sure would be to fix the old ones and see if it works.

[Freza]

When I'm travelling at high (i.e. unrestricted autobahn) speeds, my 600 develops a real reluctance to accelerate.
I'll be doing over 7k rpm and when I open it up it just dies for about a second before picking up again, like I've actually switched the ignition off, which makes overtaking dangerous.
I've had the tank up and checked the fuel lines are in good condition, not kinked or blocked. I've changed the plugs and had it serviced but it makes no difference. The battery is in good condition, TPS is fine (jumping to 5k when tested) so I reckon the next stage is to check the carbs.
I've not checked the rubbers or stripped the carbs down because in my experience with car carbs, any leaking inlet rubbers or sticking needles affect the tickover/low revs more than high revs. Is that wrong though?
The next thing I was going to do is balance the carbs, but before I start I just wanted to know if there's anything obvious I've missed.
What do you  think?

It could be carburetor nozzles.
I've had the same symptoms after installing some aftermarket (wider) nozzles because I though I was gonna get some additional power (we did rejetting), instead I lost power and it would halt briefly at around 9k rpm, as if you've cut fuel supply briefly (for a second or so).
Returned stock nozzles and everything ok again.
If you already have stock nozzles, then maybe it's worth checking them out, maybe they need cleaning or something...
Good luck.

[BBROWN1664]

:agree

My sons FZS600 is in bits at the moment because of carb problems. The main jets are clogged as fec with crap. Yours could be similar.

[mr self destruct]

I found where the screws came from this morning, it was the air box.
There's an important lesson to be learned here; don't work on bikes when you have a depressed wife and manic toddler distracting you!
Got them back in place and got the bike outside to fire up with the replacement carbs, only to find them pissing fuel over the engine!
Seems they need a recon too.  :\  Granted, they were only temporary while my originals were away, but it's tipped me over the edge. I can't be fucked with the hassle any more.
Anyway, carbs have to come off again and I have to start from scratch, so if anyone wants a "project" bike with 69500 miles on the clock, not until the end of October and a comprehensive service history since 2013 for £600, give me a shout before my mood improves and I change my mind.

[vinnyb]

Hey mate, try not to get too down about it, don't do anything impulsive.leave it a while and see how you feel then.We've all been there, so we know how foccin' frustrating bikes can be. Just don't sell it until you're sure you want to, you may end up regretting it.

[mr self destruct]

Hey mate, try not to get too down about it, don't do anything impulsive.leave it a while and see how you feel then.We've all been there, so we know how foccin' frustrating bikes can be. Just don't sell it until you're sure you want to, you may end up regretting it.

TBH mate I've never been into bikes, I've been into riding if you know what I mean. I don't care what I ride as long as I can ride. The maintenance and mechanical side of it is just shit I've got to do to enable me to do that. So if that becomes too much I'll write it off and get something that needs less work. Or preferably no work.
I was hoping this bike will last me until my Mrs gets out of this rut she's in and gets back to work. Then I'll be straight down my local dealer and get something brand new.

[mr self destruct]

I've found the problem with the replacement carbs, they're passing fuel out of these small holes on the inlet side (see attached pic) when the fuel pump is running.
https://flic.kr/p/WX7kaQ


What could be causing that? And is it a simple fix?

[vinnyb]

  That's fair enough, I know what you mean. What sort of thing are you looking to replace it with?

[mr self destruct]

That's the million dollar question!  :lol
I've yet to see a new bike that ticks all the boxes that my Fazer does.
MT09, Z900, Street Triple, GSXS750, all perfect except for the lack of a fairing.
Tracer 900, butt ugly and not comfortable.
Tracer 700, v-strom, versys etc, not enough bhp.
Sports bikes, too cramped for my knackered knee.
Cruisers, I love cruisers but hate cruising. I like to take corners!
Damn shame Suzuki dropped the 1250 Bandit so soon.

[mr self destruct]

Also, how do you embed pictures from Flickr? What worked with Photobucket doesn't with Flickr.

[BBROWN1664]

float valves stuck open.

[Disorderlypunk]

yeah if your only pissing out fuel when pump running the float valves are open
your pump should stop after a few seconds if you havent run in a few days but i bet yours is running non stop
off come the carbs again bud
(im only running pods so im laughing tomorrow if i have to take mine off for float adjustment)
i cant get a fuel filter till next week so might reverse my fuel filter and run it for a bit to back flush my filter
(through a coffee filter into a jerrycan before anyone panics lol - i always use a coffee filter when draining tanks)
ooh there is a point - does the fazer have a in tank pre filter ? off to search i go

[bandit]

Disorderlypunk, I would say yes.


https://www.ajsutton.co.uk/product/yamah...ly-1?uid=0

[Disorderlypunk]

thanks for that - distracted and didnt search - so there is another thing to have a look at MR Destruct lol

[mr self destruct]

Good point! Carbs are off so I'll look at the float valves tomorrow.
So those small holes, do they lead to the float chamber to allow ventilation to it or something?
If I didn't know better I'd say they were accelerator pump jets, but they're facing the wrong way for that surely?

[Disorderlypunk]

ok got confused untill i read previous posts
basicly they let air in while your throttle is closed (pilot)(sorry if im writing this in basic terms but its easier for newbies in the future)
so if your float needle valve is open and letting in fuel your main jets are effectively closed so this is the easiest route for your fuel to flow through
- 90% sure its a jammed float needle problem
could just be a bit of crap made its way through if not its a new needle valve assembly 5-10 quid on ebay but make sure you replace the whole bit and not with (ooh there was a bit of that in a spares box)
hope its making sense i am better at doing than explaining (which is why i fail written exams lol)

[Freza]

Sorry for stealing your thread, but since we're talking about similar problems here, could I ask what could cause this issue on mine: every time after finishing a ride, if it's passed more than 15min, when I turn to ignition, the pump starts working but shouldn't. You can hear it clicking several times. Then the engine starts (with difficulty) and when it starts you can smell the gasoline.

My mechanic serviced the carburetor recently and changed some rubber seals, for which he suspected could be causing the trouble. For a few days the bike was starting normally and pump wouldn't click after a ride, but now it started clicking again and starts with a difficulty again
What could be causing this ?

[Disorderlypunk]

ok freza - can you start this in a new thread i have a few possibilities for you.
just go onto http://foc-u.co.uk/index.php/board,15.0.html
and click new topic (dont want things to get too mixed up)

[Freza]

ok freza - can you start this in a new thread i have a few possibilities for you.
just go onto http://foc-u.co.uk/index.php/board,15.0.html
and click new topic (dont want things to get too mixed up)

Did. Please delete my post. Thanks!