Honda HRB 423 ( 16.5-inch) Throttle plate query, this doesn't look right?

[Billwood]

Hi All,
Newbie poster here. In Scotland (UK) so I may be in the wrong place.

I've just bought this vintage Honda HRB 423 self-propelled lawnmower. The speed control isn't working as it should, and the engine kill doesn't work properly (fails to kill the engine in the 'STOP' position). The way the throttle/speed cable is connected to the throttle-plate assembly doesn't look right to me. Doesn't look very 'Honda' and seems like it will wear the cable quickly.
The problem is, I seem to have a unit with a different throttle plate asembly to that shown in all the parts diagrams, so I can't check if there's a part missing, or if this has been bodged by a previous owner.

Can anyone ID this throttle-plate assembly and say if the cable nipple (ball-end) looks like it is fitted properly? Looks shonky to me! Thanks.

 

[StarTech]

Which one of the 10 versions of the HRB 423 is it? As the three IPLs I looked that at two did not even the right control assy. And the third used a cable with a Z bend and not a barrel (ball end).

So it looks you might have the wrong throttle cable. But to be sure we got to get down to right version of the mower.

 

[Billwood]

Thank you for your reply @StarTech. I hadn't considered wrong cable. I was thinking more of a missing part on the throttle plate assembly. But wrong cable is more likely.

My model is the one with 'Roto-Stop' blade clutch feature and self-propelled, SXE model, I think. I'll put more pics below to help with ID.

 

[StarTech]

Per the IPL it is the right cable. The problem appears to be the control assy. as it doesn't look like the one in the IPL.

Provided the serial number matches.

Honda HRB423 - SXE - MZBC 8000001-8099999​

Note there are two versions of the control for the above model and serial.

I circle where the cable would go the one below.


Here is a link where you can view the IPLs yourself.

https://www.gardenhirespares.co.uk/...mower-parts/honda-hrb-rotary-mower-parts.html

 

[Billwood]

Per the IPL it is the right cable. The problem appears to be the control assy. as it doesn't look like the one in the IPL.

Provided the serial number matches.

Honda HRB423 - SXE - MZBC 8000001-8099999​

Note there are two versions of the control for the above model and serial.

I circle where the cable would go the one below.
View attachment 73410

Here is a link where you can view the IPLs yourself.

https://www.gardenhirespares.co.uk/...mower-parts/honda-hrb-rotary-mower-parts.html

Thank you very much. Yes, those pictures match what I have seen when I search for the throttle plate asembly on Ebay (UK) etc. Mine looks different, but mine does match what I have seen in the user manual from Honda (see pic), even though no one else seems to use what I see in my manual?


Searching with image search produced images from a German web site which shows the same throttle plate assembly that I have, but with a Z-type cable termination. I think this is what I should have, but I can't find anywhere that sells it. Maybe it's a European thing? perhaps my used lawnmower was originally imported into the UK? Weird.

 

[StarTech]

Ahhh Now I see the problem as you got a HRB423K1 SXE not just a HRB423 SXE. Search for PN 17910-VA9-P01 as it appears to the correct cable but unable find any valid image and everybody seems to be out of them the UK and Europe.

Kinda hard to trust just one image as it may be wrong so a Telcon with a local might provide the answer.

 

[Billwood]

Thank you very much @StarTech. Having the part number and also the lawnmower model designation is a big step forward! Couldn't ask for more.

The cable does work, just not very well. Stops short of the 'choke' position on the control lever (even though the choke is activated) and the engine 'Stop' setting fails to kill the engine because the throttle lever does not push hard enough on the micro-switch.
I tested the kill switch and, as far as I can see, all it does is earth the black wire going into it. So I can easily rig up my own kill switch on the handle-bar.
I'll maybe put an order in for the correct cable (all suppliers showing 'back order' on that part) and just keep using the 'wrong' one until it fails (which it probably will because it is being flexed and pinched in the wrong place).

 

[Billwood]

The other fault with this machine is a loud, metalic scraping/whirring noise when the engine is running. This noise reduces significantly when the blade clutch is engaged to spin the rotor, so I'm wondering if the noise is coming from the clutch assembly when it is in neutral?

I tried running the machine with the fuel-tank & recoil assembly removed, to see if the noise was from there, but it remained even with these parts removed. There are no metal particles or any other nasty stuff in the engine oil.

I think this machine has been sat idle for many years, but in a warm, dry garage. It is in time-warp condition for such an old machine. Wheels look hardly worn.

 

[Mark H_NO]

I would check to see if I can make the noise by moving the blade with engine OFF, clutch disengaged. That should be easy enough to tell. Some kind of debris could have kicked up into that area and bent something... Something down there could have come loose also. Check all the pulleys to see that they turn freely, and don't run into anything. Blade clutches often have a pulley on a pivot arm, and the pivot can come loose.