Problems at high speeds.

[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!

[mr self destruct]

Can anyone recommend a company to rebuild my carbs?


A quick internet search revealed JRS but is there anyone else that you guys think highly of?

[BBROWN1664]

Any local bike shop will do it.

[mr self destruct]

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)

I took the bottom off one of the carbs tonight and I think I see what you mean.








If the float valve doesn't seal then the fuel will be forced up the left most jet of the theee in the picture, spilling out of the left hole in the first pic. I think. So I'll order four of those valve kits and see what happens.

[darrsi]

Can anyone recommend a company to rebuild my carbs?


A quick internet search revealed JRS but is there anyone else that you guys think highly of?

This is where you really want to take your bike for the best results. Just remember you get what you pay for.


http://projexdyno.co.uk/index.php

[mr self destruct]

I took the float valves out and looks like the O-rings have seen better days.


So I've ordered a repair kit which seems easy enough to fit. My next question is, does the float height need setting as a matter of course or is it pretty much ok as standard?


In the above pic according to the Haynes manual, the float height needs to be set by bending the tab that the needle sits on. But surely if that's flat it's at the factory setting already?

[Disorderlypunk]

as you have the carbs out it is easy enough to hook a piece of pipe and see where things level out
check the manual on the height of fuel though as it changed part way through the manufacturing for some reason
y2k is 3mm above machined surface but i run mine at 4mm as im running the pods it seems the best performance and got rid of the 7k rpm stumble

[mr self destruct]

Good point, I'll have a crack at it when the repair kits arrive.

[mr self destruct]

Repair kits are here and look straightforward to fit, apart from one little ring. There are three o-rings, the largest of which I assume fits on the brass insert for the float valve, the middle sized one I think goes on the main jet, but what about the smallest one?

[unfazed]

The pilot adjuster screw 

[mr self destruct]

Nice one cheers!

[mr self destruct]

Finally managed to get the time to put the carbs back on and fire it up.
Do they work now? Do they fuck!
This is the spare set I bought to tide me over while my originals were sent away for a re-con. Only to find they pissed petrol out all over my engine because the float valves were fucked.
I changed them, and put them back on the bike three weeks later (I still have zero time to myself as explained earlier), and the bike just will not fucking fire up.
On top of this, I didn't bother sending the original carbs away because I had to spend the cash insuring my wife's car, so I'll have to do that now and have another month at least without a bike. 


Maybe the TPS needs setting or something, that's the only thing I can think of off the top of my head. Or maybe the diaphragms are bollocksed on these carbs.

[His Dudeness]

TPS won't stop it from starting and it's unlikely all the diaphragms are bad. I'd check the fuel is on first easy mistake and that the battery is charged then try and start it, if it doesn't go I'd take a plug out see if it's wet or dry and if it's sparking or not. If the plugs are very wet then it's probably flooding and it's either the float valves not sealing or the float heights are wrong. You could do a float height check with a clear bit of hose and if they're out it's carbs out again.

[mr self destruct]

Today I checked a few things, and the carb float bowls are filling up ok, there's a spark and the plugs are fine. It's spinning over on the starter so the battery's ok. However, with a spark plug out I'm not getting the faintest whiff of petrol, so the fuel isn't getting into the cylinder.

[bandit]

Are you using new fresh fuel.

[His Dudeness]

Today I checked a few things, and the carb float bowls are filling up ok, there's a spark and the plugs are fine. It's spinning over on the starter so the battery's ok. However, with a spark plug out I'm not getting the faintest whiff of petrol, so the fuel isn't getting into the cylinder.

Giving it full choke doesn't help? Is the idle speed set right? You could spray some easy start into the airbox as you're cranking it and see if it fires. If it does then you're definitely not getting enough fuel either into the carb or through it.

[mr self destruct]

The choke makes no difference but I'll get some easy start and try that next.

[Disorderlypunk]

as pilot screw o-rings were mentioned i thought i best check
-did you screw pilot screws all the way in and then out 2.5 turns
(dont worry you wont be the first person to forget to screw them out again [size=78%])[/size]

[His Dudeness]

check the idle adjuster isn't screwed way too far in too. unlikely but worth checking. you'll get it eventually. keep the faith

[mr self destruct]

as pilot screw o-rings were mentioned i thought i best check
-did you screw pilot screws all the way in and then out 2.5 turns
(dont worry you wont be the first person to forget to screw them out again [size=78%])[/size]

After a lot of pissing about I finally know the pilot screws are set correctly. When I did the seals I countered how many turns to screw them in and set them how they were before, which was 1 1/2 to 1 3/4, so I've set them all to 2 1/2 like you say.
It hasn't made any difference and the bike still won't start.

The sale offer is still on guys, take it off my hands for £500 and grab yourself a bargain project. Easy repair if you know what the fuck you're doing.

[His Dudeness]

You've confirmed spark and that your plug caps are on the correct cylinder right? So we're calling spark good. Compression was good before so it's probably good. Air filter I think you checked so air is good. Fuel seems the only question mark but no matter what you do to the carbs choke on/off, idle mixture screws adjusted, idle speed in or out, it all seems to make ZERO difference to the bike trying to start so to me that points to there not being enough fuel going into the carbs or not enough fuel getting through the carbs. After the work you've done it seems unlikely the carbs are blocked so I think the fuel supply into the carbs could be the issue. Try hooking up another fuel supply like a funnel or a bottle straight to the pipe that feeds the carbs and try and start it. Or try the easy start into the air box. If you're sick of working on it get a mechanic to look at it. It seems to be a frustrating problem but I don't think it's a massive one so you'll only regret selling the bike