Mr.Modified's Simplicity Adventure Edition [2016 Build-Off Finalist]

Thanks! Yeah I have no idea why the belt flipped. Maybe it just got stretched and whipped around when I pushed the clutch in? Looks like everything is about the same. That belt was the original one though and survived two haspins. So it did it's job for sure. Now I need to replace it in the spare belt holder.

stopped and took a pic before any other action was taken ! sounds like true ATLTF Dedication ! I LIKE IT

I love a good story man. Seems like you covered all the ases when building this one. This is one of the greatest out there!

Thanks. One of these days I would like to get back to finishing up some of the modifications I wanted to do for a long time. It's about time to switch to a pumper carb I think and get rid of the float system. Nothing but problems with the vibration.

mowerjunkie03 wrote:

Hey man. Big fan of your build! If I'm not mistaken you used the BMI KARTS tractor tires on the front. Where did you get your 10in rims for them?

Thanks! Sorry I didn't see your post earlier. Must have missed it. Yes the wheels were from BMI Karts, they were on sale for $20 each with the tire already mounted on the rim. I think they are out of them now. I think they still have the tires but I didn't see the rims.

If anyone knows where I can still find those rims/wheels, I'm looking for a couple of them for my off road trailer build.

mr.modified wrote:

mowerjunkie03 wrote:

Hey man. Big fan of your build! If I'm not mistaken you used the BMI KARTS tractor tires on the front. Where did you get your 10in rims for them?

Thanks! Sorry I didn't see your post earlier. Must have missed it. Yes the wheels were from BMI Karts, they were on sale for $20 each with the tire already mounted on the rim. I think they are out of them now. I think they still have the tires but I didn't see the rims.

If anyone knows where I can still find those rims/wheels, I'm looking for a couple of them for my off road trailer build.

I'm also having some difficulty finding rims that size. I assume ther like 10×3-4 or something. Thise tires are such a good deal I think I might get them for my GT if I can find rims.

Planning on swapping to a tillotson diaphram carb soon to be ready for the Top Tractor Challenge Redzz is hosting in august. Had the tractor out the other day hauling logs and tree branches. It wasn't running too well and had issues keeping it running. It wouldn't really idle on it's own. It had always been touchy and flooded in with engine vibration but it was never so bad that it wouldn't idle. Probably sat too long and got plugged up so I might as well swap over now.

I'll have to weld up a new manifold and if I want to keep using the snorkel, I'll have to adapt the tube to the new carb. Also need to adapt a new brace to hold it and hook up the throttle cable which will probably be in a different spot.

mr.modified wrote:

Planning on swapping to a tillotson diaphram carb soon to be ready for the Top Tractor Challenge Redzz is hosting in august. Had the tractor out the other day hauling logs and tree branches. It wasn't running too well and had issues keeping it running. It wouldn't really idle on it's own. It had always been touchy and flooded in with engine vibration but it was never so bad that it wouldn't idle. Probably sat too long and got plugged up so I might as well swap over now.

I'll have to weld up a new manifold and if I want to keep using the snorkel, I'll have to adapt the tube to the new carb. Also need to adapt a new brace to hold it and hook up the throttle cable which will probably be in a different spot.

Sorry about your engine troubles but a carb should sovle the problem. Have you considered switching to a small Mikuni instead? You have a good shot at TTC because this is such a well rounded machine.

I happened to have a decent tillotson butterfly carb anyway so I figured I would use that. I think it's an HL-200 something. HL-235? Anyway, it's an ex race carb from a 5hp briggs most likely, but it's about the size of the 8hp intake port and has adjustable low and high speed jets. A mikuni would work good too I'm sure but I suppose then I would have to spend more time to get the jetting right.

I reckon this carb is worth a shot since you had it laying around. I forget, did you do any port work to this engine?

mr.modified wrote:

I happened to have a decent tillotson butterfly carb anyway so I figured I would use that. I think it's an HL-200 something. HL-235? Anyway, it's an ex race carb from a 5hp briggs most likely, but it's about the size of the 8hp intake port and has adjustable low and high speed jets. A mikuni would work good too I'm sure but I suppose then I would have to spend more time to get the jetting right.

I didn't you already had the carb. Well I wouldn't spend the money either if I could avoid it. Adjustability is gonna be key so the fact that the size is about right and it's decently adjustable is probably more important then anything else.

Looking forward to competing with you, also very interested to see how this thing runs with the new carb on it

Thanks people. Wondering if I should swap the con rod out before this event but ehhhhh, probably just leave it. Figured it's had some decent stress by this time but we'll see. I still didn't even get it to the garage yet. This weekend I should have it down there.

Got the Simplicity to the garage and cleaned it up a bit. Then removed the intake to swap to the pumper carb. Noticed one of the bolts had backed out a bit and the intake manifold was slightly loose on the engine. Found the gasket disintegrated. That would explain the recent running problems. I'm surprised that it ran at all. Looks like some parts of the gasket were completely missing.


So with the loose intake found, we had two options. Fix the problem and put the old carb back on for now, or continue with the carb swap. Chose to switch to the pumper carb since the old one would still flood as it always has. The new carb has a vacuum port which I'm pointing to in the pic. It happens to fit onto my old manifold after all, so I needed to add a port for it.


Here i'm drilling the hole for the vacuum port. Welded a cover on the side of the intake, the passage just leads to the middle of the intake tube. I left the old vacuum tube for the fuel pump I had before because the plan is to run both the original pump and the new carb at the same time anyway.

Another day of work on the #64 Simplicity before the up coming 2019 Top Tractor Challenge!
Today I replaced a bulb in the under-hood light and replaced the spare belts in the holder.
Then removed the cylinder head to check carbon build up and valve clearances.


The modifications to the intake manifold are complete. Removed the old throttle cable holder and welded the
vacuum passage for the new carb. Then covered the passage with JB weld to ensure a good seal and re-painted.


Removed light carbon build up from cylinder head and engine, made some slight flow modifications to the block and head.
Valve cover removed to check clearances. Everything looks to be within spec.
Still waiting on a head gasket to arrive in the mail before re-assembly.


Need to put the new carb on, replace the head and valve cover. Dump in some fresh fuel and see how it runs.
If everything seems ok, re-route throttle cable and lines to permanent locations for the new carb and adapt
carb to the snorkel tube somehow. The old carb was a different size inlet I think. Shouldn't be too bad.
After that, just have to clean things up, maybe re-shape the steering wheel a bit and grease everything.
Probably change the oil again and check the transaxle. I did have the cover off the airbox and the modifications I did
to that before haspin 2018 Seems to have worked well. The foam element now stays nicely in place and
there is more room for dirt build up. I think airflow might also improved since
there is more surface area for the air to get through the element.

As it turns out, I had an extra head gasket. So I put it all back together and tried to start it up with the new carb.
Pull starter cord knot came undone so I had to re-string that. Another try and the carb floods in pretty badly.
I didn't open it up and it was probably sitting for years. So from what I have read, it's probably gummed up and
the needle is sticking open. I did get it to idle pretty nice with the jets pretty much completely closed.


So the options this time are, buy a rebuild kit and hope this carb is a decent size for this engine.
Or buy a $17 copy on amazon brand new and not even have to take it apart.
Carb ordered. In about a week, I'll try the other carb, also an HL tillotson but a different model.
The one I ordered is supposed to fit harley davidson 2 stroke golf cart engines from 1963 to 81.
Something like that anyway. It's a similar setup. Engine seems to run good though with the head back on
so everything should be fine as far as that goes.


Also, the new vacuum passage in the intake seems to work well. Shouldn't be much issue there.

Nice job on adapting the carb mr.mod! Too bad about it flooding, but at least you were able to order a brand new one.

I'm interested to see how it performs with the different carb!

Nice job on the carb swap. This is the direction i would've liked to go on my 6hp i had on Budgie, i didn't have anything the right size though lol.

Thanks. I pretty much half way expected it to be gummed up a bit. But figured I might get lucky. Probably nothing wrong with this one but for only about twice the price of rebuilding it I figured just get another one.

Now days you can get carburetors so cheap for lawn mowers and things, I don't bother taking them apart unless it's a special item. I'll still save this one and maybe buy a kit for it later.

Might need it for a spare at the Top Tractor Challenge!

Just modify the heck out of the old carb and swap it on secretly if the competition proves to be too tough, haha.

Hopefully once I get one of these pumper style carbs going, then it'll be a pretty trouble free setup. Bumps and hills shouldn't change anything then. Also if I can get a much more consistent idle, it would make winch operations and things a LOT easier. When it's running bad half the time, I have to try to keep it running while I'm off doing things, hooking the winch cable or a tow rope. It's just a major pain.

Eventually after the carb issue is sorted out, I want to make a quieter muffler and maybe cut noise down in other areas too if I can. The clutch jumping/vibration issue could be fixed a bit also and that would also cut down on some of the noise.

What do you think is causing your clutch jumping? Bent pulley? A flat spot on the belt?

Nah, I'm not 100% sure but my theory is that, the jackshaft pulleys and transaxle pulley is too heavy and has too much momentum. Once it's spinning, it wants to stay at a constant speed. The engine on the other hand still has a flywheel, but I think the speed of the engine is like a wave. The rotation of the engine picks up speed fast when the cylinder fires and the piston moves down. Then it slows slightly as it moves through the exhaust, intake, and compression strokes. So I think that creates some issues because I think that change in speed is happening a lot faster than the jackshaft wants to change it's speed. For example, if the jackshaft and transaxle pulleys were aluminum and super light, they would tend to match the engines pulses more easily.

Also, most other tractors run a longer belt. My clutch belt is very short. A longer belt may stretch and give somewhat, which might help to smooth out those pulses. So there might be several issues working against it.

Adding weight to the clutch to stop or slow it from moving around is of course working the wrong side of the issue and not fixing whatever the problem is. But it should be a help and it's the easiest thing I can do without major changes at the moment. When I swap to another transaxle, I'll see about getting a lighter pulley. It's a tapered input shaft on the 633 and I had to run the cast iron pulley, that was all I had at the time.

In other news, I fixed my steering wheel for the time being lol.

Always great to see updates on this build.  It has been one of my favorites!

Thanks a lot! Haven't really been messing around with it much so it's good to get working on it again. Out of all the stuff I put together, this is one of the things I don't think I would want to sell. It just turned out fairly decent and worked the way I wanted it too. Sometimes you make something and it's just a pain and never works right. Kinda why I sold the baja sears. This one rides a lot smoother with the front suspension. Just over all a much better machine.

Still thinking of trying to do a long run with this at some point. Either from where I work to home (about 18-20 miles, mostly on an un-used railroad line) or a cross indiana run on back roads. Tractors are supposed to be legal out there from what I can tell. That would be about a 300ish mile trip from the top of the state to the bottom and I think if nothing broke and I could keep going, I could do that in two days. That would be some hard running but might be do-able. I'd have to plan the route and maybe have a GPS on hand. I was wondering if maybe somehow that could be turned into some sort of charity run type of thing. But I have no idea how that would work. At the very least, I'd get some video coverage and it would make a good advertisement for ATLTF.COM if it got shared around online.

Just make sure all the consumables you have replacements for. I would consider bearings and belts. I know you keep an extra...