Honda HRB 476c -Will not start, only runs for 2/3 Seconds??

[bilabonic]

Hi All

Pulled my old once reliable Honda HRB 476c for its first start for the season ans was shocked that it would not start!

It has always been ok if not for sometimes needing a bit of extra throttle/disliked being sat at full idle/tortoise.

Anyway i have done the usual, with full tank fresh fuel, replaced oil, replaced plug, checked coil and gap/cleaned gap, checked there is fuel in bell housing.

Is my next step a full carb clean with new gaskets?

Thanks in advance.

 

[Burnerman]

First step before getting stuck in....is the engine getting full choke? It won't like to start without it, but once it does go all should be well once it's warmed up a bit.
John

 

[bilabonic]

First step before getting stuck in....is the engine getting full choke? It won't like to start without it, but once it does go all should be well once it's warmed up a bit.
John

Yes, i removed the air filter and can see it fully functioning from fully open to virtually fully closed.
It is an old manual choke not the newer wax auto type.

Thanks for the reply John!

 

[Burnerman]

Certainly it looks like a carb clean is in order, but if you turn the petrol off and remove the float bowl, check inside for any rust traces which may give you a clue. Although the float bowl is plated, any water in the fuel will rust the thing.
John

 

[bilabonic]

Certainly it looks like a carb clean is in order, but if you turn the petrol off and remove the float bowl, check inside for any rust traces which may give you a clue. Although the float bowl is plated, any water in the fuel will rust the thing.
John

Just removed the bowl, that plate is a bloody nuisance though (presume it's there for heat protection?).

I only have one bolt on the bottom/no extra drain bolt to the side.

Bowl was full of petrol a normal and had zero rust and a few tiny bits of sediment, nothing much tbh.

I also turn the petrol on and lifted/lowered float manually and the petrol flowed fine, so i presume the float/pin and float needle are ok.

Cheers

 

[Burnerman]

Yep, that's a good test for the float valve. I guess its carb off next, followed by the removal of the main jet and the emulsion tube above it. You'll need a can of carb cleaner to help you here.
John

 

[bilabonic]

Yep, looks like.
I have a few large tins of carb cleaner here plus a can of compressed air (not sure how powerful that is tbh).
I will strip it all down i think, remove the main central jet and the emulsifier tube, also noticed there are tiny holes in the side of the carb plus one that is adjustable/a brass needle from watching a video (needs to be turned all the way in and 1 1/2 turns out?).
Also i can see another screw that can be removed/sprayed in but to access it i need to remove the throttle over rev control screw?

My terminology is not there yet...I can provide any pics as required.

Thanks

 

[Burnerman]

Basically remove all of the carb guts as you can and give them and any drillings a good spray with the cleaner.
The jet under the brass screw is the pilot jet but you can't remove that one.
John

 

[bilabonic]

Well i have stripped it, cleaned it all and now it will run BUT with choke fully on?
It will not run in 'Rabbit mode' or 'Turtle mode'...lol. What are the correct terms please?
Whilst running it is still hunting and the plug is dry when removed compared to before (when it ran for 3 seconds it was wet..)
Also when i try to engage the blade it starts to cut out, i can get it operate but i have to apply more pressure to the choke/handle by pressing down/closing the butterfly valve even more....

I presumed it would work fine after the clean as the main jet was approx 4 full screw turns out, i presume it sould be screwed in all the way to hold/push the the emulsion tube up into the chamber.

I am now at a loss tbh, i must of removed it several times, sprayed every orifice, checked every jet/nozzle/hole and used a full can 300ml cleaner!!

Gasket seal 'look' ok, the only damaged one was on the intake side after the annoying 'plate'.

 

[lostinthelight]

Main jet should be snug against the ET but not too tight or it will be difficult to get back out again in the future

 

[bilabonic]

Main jet should be snug against the ET but not too tight or it will be difficult to get back out again in the future

That's what i have put it back as, strange that it was at least 4 turns loose and worked last summer........
What could the problem be, the main jet and ET are 100% clean, they have been cleaned numerous times.
Gasket passing on intake after the carb???
Thanks for replying.

 

[Burnerman]

For sure, if the engine will only run on full choke then there is a serious fuel blockage somewhere!
Prime culprits are the main jet, and the emulsion tube above it must be clear all the way through.
I assume you checked the needle valve above the float?
John

 

[bilabonic]

I have triple checked the main jet and ET, sprayed hell into all places/side holes etc
Did not poke any wires/gut line but 100% they are all clear by 'eye'.

Yes removed the pin, float and pin. All cleaned, resembled and tested fine.

 

[lostinthelight]

Anyone who dabbles into machinery with a Honda carb should find this vid invaluable.

 

[Burnerman]

Not what we wanted to hear
The rod linkage from the governor to the carb.....is everything free and the throttle flap moving nicely?
An unlikely next....did you put the emulsion tube the right way up? You should see the brass end visible in the venturi.
John