Ride on lawn mower carb replacement needed.

[Taipan]

Hi All

Long story short we have a ride on lawn mower with a knackered carb. I think the man who was supposed to fix this actually broke it. Anyway he said it’s cheaper to get another carb from China* (Ali express?) than it is to mess about with this one? I won’t get to see this for a couple of weeks but that would give me time to order another carb. Anyone recognise the carb type from this pictures?

*longevity isn’t a factor, just getting it running is what’s needed.

[Skub]

@wull Is the lawnmower man.

[David]

Order based on the make and model of the mower...as long as it fits the stubs it should be fine. I do this with chainsaws etc, alwzys works out and usually less than a tenner.

[kendo57]

https://www.ebay.co.uk/itm/364132481779 ... R4Lv15a8ZA

[Taipan]

https://www.ebay.co.uk/itm/364132481779 ... R4Lv15a8ZA

/thread! Nce one, thanks!

[wull]

Better late than never not that it matters now

What did the guy do to break it? Have you stripped it down and attempted to clean it? What were the symptoms? Just bear in mind the governor arm, rod and spring when putting it all back together, that could potentially be your culprit depending on what was happening or not happening.

[Taipan]

Not sure what really happened. A local repairer came round to fix the problem of the revs hunting and it cutting out. He stripped it down and then said it needed a new carb and basically walked off? The owner had the "I wants" and used it as an excuse to buy a shiny new one as it had this one over 10 years. So my 87 year old f-i-l now has it but I suspect the once brilliant mechanic who now no longer knows a spanner from a screwdriver has tried to fix it and has given up and called me in. Without looking at it but knowing the carb has definitely been removed, i'm really looking for a quick result. I dont want to put the splinters of the old carb back together if a new one is sub £20, but I will have to (reluctantly) check if I can bung it back on and sort it before ordering a new one as he "doesn't want to spend a lot of money on it" and wont thank me for just buying a new one

[David]

A tenner (or £18) on a new one will save you hours of piddling around withe old one. How much is an hour of your time worth?

[Taipan]

Popped round today. Still not sure whats happened here but i had it running in about 10 minutes. It is overrevving a lot but a that mainly seemed to be the stop screw or whatever its called was adjusted too far in? A clean up of the linkages appears to have sorted the throttle sticking open and I think the linkage rods were bent and binding as well but I've tweaked them a bit and all seems well?

@wull I left the stepdad to put the covers back on but I think its a Techumesh?

[Count Steer]

Popped round today. Still not sure whats happened here but i had it running in about 10 minutes. It is overrevving a lot but a that mainly seemed to be the stop screw or whatever its called was adjusted too far in? A clean up of the linkages appears to have sorted the throttle sticking open and I think the linkage rods were bent and binding as well but I've tweaked them a bit and all seems well?

@wull I left the stepdad to put the covers back on but I think its a Techumesh?

Tecumseh?

eg https://www.amazon.co.uk/ZAMDOE-6400 ... XRm&psc=1

[kendo57]

Its hard to see from the pic , but the throttle wire looks very close to the bracket on the right side .
Could this wire be in the wrong way round .

[wull]

The throttle cable is in the correct position, what you want to pay attention to is the governor arm behind and the spring that’s attached to it. If it’s revving too high then this is more than likely what could be causing it, you can adjust the spring, mount it at a different height as there should be multiple holes and this can vary the tension meaning the butterfly won’t open as much. What’s meant to happen is when the engine starts to rev higher than intended the flyweights on governor gear within the engine pop out and push on the governor arm overpowering the spring tension and close the butterfly on the carb, so you can arse around and adjust this to try and bring the revs down, this is going on the basis that this is your problem.

What I’d do if I were you is next time you have it running is press on the governor arm with your fingers and see if the revs drop to where you want it to be, you can then try and adjust it by putting the spring in different places and keep trying it, another thing you can do is adjust the governor arm itself but it looks like access will be tight but maybe not, it’s hard to tell by the picture.

Edit: just had a closer look as I was trying to add to the picture, it looks to me that the rod going from the governor arm is going to the choke instead of the throttle butterfly, the rod from the governor arm always goes to the throttle butterlfy.

[wull]

Red shows the governor arm and spring, the rod from here goes to the throttle butterfly.

The green shows the choke lever and rod, this goes to the choke butterfly which is always the air filter side of the carb.

Looking at this set up I’m guessing the throttle lever at the operator station is one that shows tortoise, rabbit and then the choke sign, what happens is when you put the throttle lever to choke it moves that lever (green) that controls the choke when it gets to that point. It only does this when it’s move to the upmost position, so when you move the throttle lever from slow to fast etc it does nothing to this choke lever, it’s only when moved far enough (choke position) that it finally moves that lever.

So fit them the right way first, see how that goes, hopefully all good and you won’t need to adjust the governor or spring.

[kendo57]

Edit: just had a closer look as I was trying to add to the picture, it looks to me that the rod going from the governor arm is going to the choke instead of the throttle butterfly, the rod for the governor arm always goes to the throttle butterlfy.

Yes , good spot.

[Sunny]

On the cause front, I had to have a new carb in my <3 year old Stiga this year because E10 fuel had rotted the seals.

It cost significantly more than £10 for a new one, and it's now getting the finest E5 money can buy.

[Rockburner]

On the cause front, I had to have a new carb in my <3 year old Stiga this year because E10 fuel had rotted the seals.

It cost significantly more than £10 for a new one, and it's now getting the finest E5 money can buy.

My knackered old Mountfield (came with the house) gets the 98RON/E5 that's been sat in the garage awaiting use in the JAPton.... It definitely prefers it!

[Taipan]

Red shows the governor arm and spring, the rod from here goes to the throttle butterfly.

The green shows the choke lever and rod, this goes to the choke butterfly which is always the air filter side of the carb.

Looking at this set up I’m guessing the throttle lever at the operator station is one that shows tortoise, rabbit and then the choke sign, what happens is when you put the throttle lever to choke it moves that lever (green) that controls the choke when it gets to that point. It only does this when it’s move to the upmost position, so when you move the throttle lever from slow to fast etc it does nothing to this choke lever, it’s only when moved far enough (choke position) that it finally moves that lever.

So fit them the right way first, see how that goes, hopefully all good and you won’t need to adjust the governor or spring.

Yup, bang on the money. Swapped the rods round and I could see everything working properly. It was sort of sticking a bit, but that was to do with those little plastic things that fit between the rod and the bracket. One of them was sort of mangled up and once i'd twisted the rod round to fit in its groove it was all good. So thanks a lot wull you took the guess work out of it all. I'm much obliged as is the f-i-l who said he would have given me a drink for fixing it but it was really down to a bloke on the internet! Can't argue with that I suppose!

[wull]

Glad to help

[Taipan]

Just been round there with a charged battery and gave it a go. A click from under the seat somewhere, but its turning the engine over. I started looking around it, and there's a lot of broken wires that I assume were for the headlights and all the throttle rods were missing. Bless him, he lost it a bit at the end, and I have no idea what he had done to it. Everywhere I look things are loose and have all manner of odd nuts and bolts on it and the cowling is about 30 feet away upside down and full of water.

It's well over 10, possibly even 15 years old, and i think his partner would be better investing in a new one. TBH its a bit upsetting seeing his handiwork. The man used to rebuild things like Rolls-Royce transmissions and various diesel engines etc. I guess he was frustrated at my fixing it before and took it apart to see what i'd done. Ho hum.