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

[bilabonic]

First part, there is a hole in the 'carb unit' in the side that goes into the main jet, i did only notice this today tbh and hence i played/triple checked the bowl/float level to make sure it was reaching it, can't be down via eye...I was even naughty and cut away the plastic shroud that prevents the bowl being fully removed...But at least i could/can now fully drop the bowl/operate the float valve and say 100% fuel is filling.

There is no lead cap cap on idle/mixture screw, are we referring to the one that protrudes a brass needle into the main chamber. (this is the one that has to be screwed out approx 1 1/2 turns) i HAVE seen videos' i think on other models that have this protective cap i think from memory.

The gaskets are spot on mate, i fully understand.... I used to work on bikes as a kid with my mate/grandfather, used to make our own, always used a tiny bit if grease back them on Honda 90's etc....

I can dissemble it in 2 mins now, messed with throttle spring etc, tried all positions with manual choke/run.

The only screw that is not fully accessible requires the the throttle/spring loaded screw adjuster screw to be remobev first to get access to it, this screw has no adjustment either but can be sprayed into......

I'm thinking as mad as it sounds it's spark/coil? I've seen it happen on Golf Buggies, but common sense is telling me no mate.

Thanks for replying John.

Lmk if you need any pics and i can provide them.

 

[Burnerman]

Just for info, if you google Honda HRB 476 carburettor you can reach exploded diagrams courtesy of LS Engineers which may be of help.
Anyhoo.....have you tried starting the thing with the throttle flap jammed on the fully open position? I'm only asking this because you mentioned some confusion regarding the throttle flap operation - just thinking, if the throttle flap can't operate it'll be difficult for the engine to run quickly.
Applying logic, the fuel level (engine off) needs to be just below the top of the emulsion tube so any suction by the engine sucks the fuel into the venturi.
I don't know if the emulsion tube can be fitted upside down but if it was it would be an issue.
(Sadly I notice the price of a genuine replacement Honda carb is just under the ton which is pretty heavy).
John
As an edit....the float isn't upside down? The needle valve has a thin wire link that holds it onto the float.

 

[Burnerman]

Just referring to your post #31, I've never had a Honda igniter fail in this way. However, some machines tend to eat plugs but this usually gives a problem when the engine is hot. Yours needs an NGK BPR6ES or equivalent (Champion N9Y) and it's worth using a new one.
John

 

[bilabonic]

There's only one way the float can physically fit i think, it's not symmetrical and it's just held in with the stainless pin. (plus the float valve sits in it's correct slot on the float).

I read a lot of threads/posts online regarding the NGK plugs failing (OEM with Honda), so i have replaced it a Champion, plus tried another 'copper core' plug, i know they are used everywhere an common.

But that fault seems to be through heat after several minutes of usage.

I have looked at new carbs on ebay, they 'look' similar but getting a direct replacement via the Mower number does not work, i need to find the exact carb number tbh.

I'm lost atm mate........

 

[bilabonic]

I have one valve i can control/view from intake, maual choke/idle off. That's the first one from viewing from air filter.

I can't see how the inner one operates tbh, it has a solid rod plus spring loaded....

I have 'played' with both whilst a mate has the manual one forcefully depressed/choke OVER closed to keep it running. it does alter revs slightly, that's it.

When checking bowl/float etc today my mate helping was convinced it ran without the choke being forced BUT the bowl nut/top large seal of bowl was leaking petrol??????

Lost again mate

 

[lostinthelight]

did find one tiny hole blocked in the emulsion tube (where it has 4 squirting out just one was blocked).

Do you mean 4 or 4 pairs of holes ,I thought there were more than 4

 

[bilabonic]

It's 4 pairs maybe more (8 large i think), plus the associated lower smaller holes below.

One of them was blocked, it was nothing imo, but it's clear mate, it's an even 'fountain' was sprayed into it, even distrubation.

I can take a pic if you wish?

I honestly presumed the main jet, under the EMT was the problem when i first stripped it as it was loose, not secured at all, i wound it in first. 4 turns 'loose'!

Removed, cleaned, refitted....Tripe checked the EMT was the right wat up...Can you confirm that, the LONG end goes into the carb... Doubting myslef now pal..

 

[lostinthelight]

Yes small end in first which is visible when you look past the choke ... This is an advisable watch for anyone thinking if stripping a Honda carb although I don't agree with his , imo, over zealous use of tip cleaners in the jets.

 

[Burnerman]

Here's a pic of the emulsion tube - referred to a 'main nozzle' shown upside down?
https://www.ereplacementparts.com/nozzle-main-p-554982.html
Thinner, longer end in first or am I losing my sanity?
John

 

[lostinthelight]

Just come in from sorting the carb off a Honda GXH50 , the central bore of the ET had a hard green coating almost blocking it, cross holes are definitely clear
Anyone wanting fine jet cleaners, these took 2 weeks to come from China.
https://www.ebay.co.uk/itm/133595454890

 

[Burnerman]

Off a Belle Minimix perhaps?
John

 

[bilabonic]

The place i took it to after failing had the actual Honda Nozzle cleaners, they also tried it several times in various configurations in their ultrasonic bath.
They could not get it to run and they fitted a reconditioned carb, anyway it's all up and running.

Cheers all