Carbs Install

[Nurse Julie]

Odd job,

Yes, I understand that, the issue I have is that the white plate you mention was separate from the copper live tab (what the black wire is soldered on to). So even when fully assembled, white housing screwed down, the pin of the button nicely through and sliding into contact with the yellow/Red plate, the copper live tab was just pushed against the Y/R plate by the button spring and starter remained on.

I must have assembled it half a dozen times on the bike, but when I took it off, I could see no way to stop the live plate from moving under the springs pressure into the Y/R plate. I assume that live plate should be firmly fixed in the white holder, so they were a single unit holding it firmly against the spring pressure. Mine had separated, broken. So that 50p part caused my problem!

Sounds like someone tried to re solder the wire on and it got too hot, which melted the plastic.
The switch you have is very rare and hard to find, only fitted to UK / european K6's. Trigger has loads of switch gear parts here. If you send me your old rare switch, i can fit some parts and it will be as good as new FOC.
It would be a shame to lose a original part for the sake of one small part and 10 minutes work. 

[Sesman]

Hey, good on you Julie👍

[Martin6]

Sounds like someone tried to re solder the wire on and it got too hot, which melted the plastic.
The switch you have is very rare and hard to find, only fitted to UK / european K6's. Trigger has loads of switch gear parts here. If you send me your old rare switch, i can fit some parts and it will be as good as new FOC.
It would be a shame to lose a original part for the sake of one small part and 10 minutes work.

What an amazing offer. Very kind. I have a replacement on order, which I don't mind using. But, if it is not correct, I will take up your kind offer. 👍 I'll find out in a week or so.

It may well have been my fault, that bottom wire retaining plate was missing and the wire was hanging on by a couple of strands and I did try a repair in situ. That probably damaged it. Lesson learned (again!).

[Nurse Julie]

Sounds like someone tried to re solder the wire on and it got too hot, which melted the plastic.
The switch you have is very rare and hard to find, only fitted to UK / european K6's. Trigger has loads of switch gear parts here. If you send me your old rare switch, i can fit some parts and it will be as good as new FOC.
It would be a shame to lose a original part for the sake of one small part and 10 minutes work.

What an amazing offer. Very kind. I have a replacement on order, which I don't mind using. But, if it is not correct, I will take up your kind offer. 👍 I'll find out in a week or so.

It may well have been my fault, that bottom wire retaining plate was missing and the wire was hanging on by a couple of strands and I did try a repair in situ. That probably damaged it. Lesson learned (again!).

👍👍👍

[Martin6]

The aftermarket switchgear arrived and was surprisingly decent. The only issues were:
- different wiring colours, but several of the black wires had thin tracer lines and I was able to match them;
- the wire length is longer, suitable for US bars. I pondered cutting and reattaching the connectors, but chickened out. It is currently coiled within the headlamp bowl. I'm hoping there is sufficient space to avoid it pressing any connections apart.

I took the bike for a short warm up ride, then failed to dial the carbs in any better on just the pilot screws.
- still lumpy idle below 1500rpm
- slight hesitation opening the throttle from low revs, then pulls ok.

I think my cam chain is still loose. At low revs there's a bit of chain lash noise. So gasket needed and I'll remove the tensioner to check if it is free. Hoping desperately it's not the primary chain, but with 40,000 miles on the bike, i guess it could be.

[Martin6]

I would appreciate more advice, please. I thought I'd give it another go on the carbs. I did a 25 mile run, to warm it up on the whole, a nice little ride. But, hesitation on a light throttle, before it pulls and idle is lumpy below 1500rpm.

So, I tried to adjust the carbs. I don't really detect a sweet spot on the pilot air screw. I started at 1 turn out and hesitation is apparent gently rolling on the throttle (less then 1/3 throttle). At 3/4 turns out of the air screw, the hesitation was worse, but the idle initially seemed, 'perhaps' smoother but very difficult to be sure. I can turn the screw all the way in on individual carbs and not really notice much difference at idle. Idle seems lumpy below 1500rpm even with the screw out from 3/4 to 2 1/2 turns. I think it is running on all 4cyls.

Any thoughts?
Slide adjustment? I'm wondering if the slides may not be seating fully. I thought they were when I had the carbs off to clean. I hear a clack from them going back down and it seems to be in unison.

Float height or stuck float(s)? I measured and adjusted to service manual spec. I measured from the rim just inside where the gasket seats, to the float, at the float position when the needle just gently starts to seat. There is nothing coming out of the carb overfow pipes. But might this be connected to the oil level issue below?

Pilot jet blocked again? But it does idle and starts OK without throttle when warmed up.

One other significant finding. The bike had just had an oil change. When I checked the oil, the level was fine and it was clean. I checked it again after my run and it is now half an inch over the upper line, with a slight emulsion and an odour not quite of pure oil. It seems thinner, but it was hot. There was dripping from the end of the valve cover breather pipe, which seemed almost clear, not really oily. Could this be fuel contaminating the oil? What could cause this? I did forget to turn the fuel tap off when I filled the tank and paid. Maybe 5mins at most.

Appreciate advice / commiserations/ encouragement!   
P.s. my tyre stayed up, the back brake now works, as does the starter button! 

[McCabe-Thiele (Ted)]

Are you comparing the change of oil levels whilst on the center stand on level ground on a cold engine?

Breather pipe might just be doing it's job venting off from a warm engine?

I would not panic just yet.

[Oddjob]

Have you checked the float level height?

[Nurse Julie]

Are you comparing the change of oil levels whilst on the center stand on level ground on a cold engine?

Breather pipe might just be doing it's job venting off from a warm engine?

I would not panic just yet.

It's a 750 Ted, it's a dry sump system, it has a seperate oil tank. You check level when engine hot. On a cold engine, there is a higher possibility the oil has sumped and not returned up to the oil tank.

[McCabe-Thiele (Ted)]

Forgot about the tank system - just trying to ascertain if the oil levels were checked in identical circumstances. If I do an oil change I fill it close to level, fire it up to ensure filter is full of oil then check it again & top up if needed.

[Martin6]

Yep, the oil checks were done on the centre stand. Sumping is a possibility. But I checked it first time within only a couple of days of it last being run. I'll change the oil before I start it next and see what it looks like. 

Is it possible fuel can drain into the head without troubling the overflow pipes?

Odd Job, yes, I scrupulously checked the float heights, then rechecked, before reassembly. I could be doing it wrong, but I followed the two YouTube videos posted by Spanner Rash, on his CB750, which helped me understand the procedure in the Honda manual.

I think another carb cleaning day is in store...

[McCabe-Thiele (Ted)]

We did have a member here a while back who accidentally left his fuel tap on - the petrol drained into the sump iirc causing damage when he tried to start it.

I assume the petrol went into the inlet manifold via an open valve into the cylinder head / piston area - drained into the engine. Are you sure your fuel tap is closing fully?

[Martin6]

Ted, Yes, the tap seems OK, no leaks when I have the tank off. I did leave the tap open for about 5 minutes, when refuelling.

[McCabe-Thiele (Ted)]

Might be worth disconnecting the outlet - fitting some pipe to check if the valve is passing internally overnight.

[K2-K6]

"Pilot jet blocked again? But it does idle and starts OK without throttle when warmed up."

Two elements to this circuit that can run you round in circles.

Assuming that the fuel jet isn't blocked, it can just flow full to that capacity without impediment. Its mitigated by the air supply which is modulated by the screw.

If this air route is blocked, then you'll see no response to changing positions, just that the idle mixture is fixed at any speed according to venturi vacuum only, so not full rich when starting but not low like it should be.

So it'll work in a fashion but without the idle mixture graduation it should be able to use in smooth tickover as will be permanently rich, not seen as you get higher revs as it acts normally there (idle jet is maximum flow) but lumpy when you try and let it idle.

This also forces you to use more slide lift just to keep it running (to counteract the rich idle mixture) and again keep chasing your tail with this in never being able to set a competent position for general running.

So very detailed clean and blow through/verification of air passages should bring these to working correctly.