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

The newer version of the 633a (can't remember the name) the one that came with my GT18 Craftsman has a release valve for pressure built into the top right side (input side) of the trans.

@MightyRaze Does it almost look like a grease fitting but doesn't stick out as much? I have one of those newer ones too but that's all I can see on it.

I will probably end up adding a vent next time I have the trans out.

Kind of reminds me of a pop-off valve.

Stream running today for a couple of quick photos.


Expedition deep in the jungle...ok it was 100 feet from my grandfather's house.


Almost rolled it trying to back down off this dirt pile. It was fairly steep getting up there.
The steering is a bit looser than it once was. Gonna need to shim some things up one of these days.

HASPIN PREP 2020! I decided that I don't want to risk fragging the gear flipped 633 that's been in the #64 since I built it. I'm taking the transmission out using one of the back tires to simulate using stuff available in the field...


I wanted to get an idea of how long a trans swap takes with normal hand tools so I timed it. From tractor completely together to transmission completely out took about 20 minutes. I think with everything ready to go and some practice that could probably be cut in half. If a 2nd person was there to help and maybe with a battery powered impact gun, 25 minutes to swap the transmission would probably be possible. Definately do-able between rounds of the Top Tractor Challenge if necessary.


I was going to swap in one of the new style 633's I have but I found out that the newer ones have wider frame mounts.


I wanted to swap out the gear flipped trans so I can weld the gears before it breaks. I have an older style 633 with the gears already welded ready to go in. The new style one (bare aluminum color one) is really kind of useless to me at this point, but I may be able to mod the case to fit the adventure edition later on.


Also, today I tried aluminum welding for the first time and it didn't go too bad. I didn't expect cast aluminum to weld as good as it did. Note the repaired spot around the upper mounting hole which was cracked. I welded a Z'ed shifter to finally solve the issue of my hand smashing into the belt cover in high gear. I've been talking about doing that for years, pretty much almost since I built it, so it should be nice to try it out. I think it will make things a bit easier, even though I've gotten used to being careful when I shift to 3rd.

The 633 with welded gears is now back in and everything is together. Used the steel pulley which is a lot lighter and should make shifting quicker I hope. The case on the new style 633 is also spaced differently where the input shaft is, so it would take a lot of modifiying to make it work with this frame.

Here's a pic of the new shifter setup. This is where 3rd gear now is, giving plenty of room to shift without smashing your hand into the belt guard at the right. Also it's a bit easier to reach now than it was. Just seems to be in a better spot.

I see the makings of a pit crew forming.

I need to get some people to join yeah. It took only 20 minutes to get everything unhooked and the transmission completely out and on the ground. But today it took 25 minutes to get the transmission back in and trans mount bolts tight WITHOUT hooking up anything else. It's a super pain to line them up, especially alone. Finally I got a bit of help and even then it wasn't easy. You could slot the lower holes in the frame and put studs in the upper trans bolt holes or something to make it quicker. Brake bands went back on quick in only a couple minutes.

Back when I was building the adventure edition to be ready in time for the 2016 Haspin meet, I was working on it about 4 hours every night and pretty much non stop all day long saturdays and sundays. At the moment, I can't seem to get quite that same motivation to finish the Simplicity Broadmoor RS project in time for the 2020 Top Tractor Challenge in August. So, that being said, the only option is to use the adventure edition again this year. (Simplicity brass still wants to see the flag flying out there even though we don't have a purpose built racer yet)

But last year at the 2019 TTC, I ended up down in 7th place. The adventure edition just doesn't have the power, plus it's a very top heavy and tipsy machine. Also, this year everyone is making improvements so the competition will be even tougher than in 2019. So what to do?

The 8hp flat head engines and the 10-11hp Briggs flat heads both share the same mounting holes and more importantly, the cranks end up in the same location. That means it will swap right on (as far as I know). The stock hood will not clear the 10hp engines however, since they are just a bit taller (about 1-1.5")

The plan is to swap this tired old 10hp Briggs on for the TTC only. Along with some other modifications, I think it should make the #64 a little more competitive. Maybe not a 1st place finisher, but at least give me a bit more of a chance. The 8hp is supposed to be about 305cc with the 10hp about 361cc. Look at the difference in port size.


I don't know how many hours is on this engine or how worn out it is, but we'll see. Shouldn't be too hard to get it going after some cleaning up. This is pretty much the same engine that was on the Baja Sears.

HASPIN 2020! BIGGEST HASPIN EVER! So, things went well for the #64's 3rd Haspin. Had a few minor issues but nothing too serious. First was a slight running issue which I thought I had straightened out with the new carb. It may be in part due to a leaking fuel hose but have not fixed it yet to see. The other issue I had was the rear hubs came loose on the axles. On the first transmission that never happened and they stayed snug the whole time it was in the tractor. The only thing I did differently was putting never seize on the axles so the hubs wouldn't rust on. That may have allowed the bolts to move a bit and come loose. That's the only thing I can think of. I tightened them once and after that, the right size seems to have moved slightly again. It wasn't a big issue and didn't strand me. I did need a tow from @redzz02 once when I fouled a plug but I did have everything to fix it on the trail if I wanted too. Just that it was at night and we were close to being back anyway. It was easiest to tow it. Also pulled my winch cable off by running it all the way out and then rolling back without having it spooled any. It's only held in by a set screw. And also forgot my alternator switch and left it on all night draining the battery. It was so dead there wasn't enough power to activate the alternator so it wouldn't even charge on it's own. Didn't break anything anyway. Did pull a couple tractors out of mud holes with the winch and pushed Doug's nissan pathfinder out of a mud hole with it too. Think this was the first Haspin I didn't roll it.

Night before Haspin. #64 is loaded on the trailer and I added half a quart more gear oil to the trans.


Since I drove a separate car, this was my one chance to get a shot of the simplicity going down the road on the trailer. Risked my life for this shot! Didn't actually expect it to come out clear. Taken somewhere in PA.


620 miles from Simplicity HQ to Haspin, one of the stops along the way wednesday morning.


Making an un-nessesary firewood run just for the heck of it.


Weather was pretty much good the entire time and didn't get enough rain to really mess things up. It was very dusty towards the end because of it and also because a lot of people showed up to ride atv's, jeeps, side by sides ect. And the heavy traffic had an inch of powder laying on the main paths. I'd rather have dust than mud though.


Worked on the Simplicity a few times inside the @Doug Fackler "garage". Used some of his tools here and there too. Thanks Doug!






So the simplicity did pretty good. Still would be nice to have a back up light and quieter muffler. Steering is getting a bit loose but nothing horrible. Without some major work it will be tough to tighten up too much because most of the play is in the sears steering parts, the shafts are welded solid to the frame as they were in the sears tractors. I guess a lot of the wear would be on the removable pivots though. The rear hubs coming loose needs to be addressed. Maybe by drilling divets in the axles or removing the never sieze. Also might use new set bolts or sharpen the ends of them a bit where they hit the axle. Not quite sure but i'll look into it. I should probably eliminate the original fuel pump which is no longer hooked up. Right now the fuel lines are still hooked to it but I blocked off the vacuum to it. The current carb has it's own pump. It seems to be a bit too rich when both pumps are working together. Another thing I really want to fix it convert the underhood light and dash lights to LED. Probably the tail light too. The 194 incandescent bulbs are always burning out from vibration and I'm tired of messing with them. I may add white lights in addition to red under the hood so it's easier to see things when you want to do serious work. LED's would be better for under hood lights too since they wouldn't draw much power from the battery with the engine off. Which is usually how things are if you are broke down and checking things. Still have not had any pulley bearings go bad or any suspension/steering joints since I built it. Even the RFY ebay shocks don't leak much with all the dusty conditions. I never expected them to last that good. I probably use it less than some other people on here but still.


It was nice to see everyone out there again and glad no one got too seriously hurt! (Except craftsmanquad's buddy Luke but he survived) Things went pretty well. Don't know how many tractors we had but I think it was the most ever at one time.

Got the 10hp replacement engine torn down to the bare block except for removing the valves. Originally I expected this to have the balance weights in the side cover just as the 11hp engine did in the baja sears, as they are the same block more or less. But this one does not have the weights. Found out it does have a dual ball bearing supported crank and it's a steel sleeve bore. The rod bearing and crank looks good, piston and bore look pretty decent. The upper ring is stuck which probably happened as I tried to remove the piston without cleaning some carbon around the top edge of the bore.

The piston is the same as an opposed piston from what I can tell, but the rods will not swap over as the 10hp rod is much longer and big end bearing is smaller than an opposed rod. Otherwise I could use one of the billet rods I have from an opposed. I removed the governor and the bronze tube that the gov shaft runs through. It also had a low oil shut off which is a big plastic thing sticking into the block. I may weld both those holes shut with an aluminum welder just for the sake of cleaning things up.

I'll probably do a bit of port work and some profiling on the top of the block and cylinder head. Most likely mill the head down a little bit. The spark plug is more recessed into the head than on the 8hp heads so I might open that up a bit. I thought the 8hp flywheel would fit as they are the same diameter only lighter, but the taper on the crank is a different size. The 8hp flywheel is about 3 lbs lighter. I don't see an easy or safe way to lighten the flywheel without throwing it out of balance. May or may not do a hack weld job on the cam lobes. I'll probably lighten the cam some. Probably lighten the valves a bit and might run some stiffer valve springs. I've got dual springs for the opposed engines which may fit. I could possibly just run the outer springs, they might be stiffer than the stock ones on their own.

Should have some more guts the the 8hp engine anyway. Gotta get the tractor to the garage again and start working on it. The TTC is coming up quick.

Removed some things for the TTC. Ended up skimming about 66 lbs of un-needed weight off the adventure edition.

Battery 18 lbs
Alternator 11 lbs
Winch 13.4 lbs
Hood (with spare belts, plugs, lights, rack and snorkel box) 19 lbs
Lights and mounting hardware for everything, including alt belt and alt belt tensioner 4.7 lbs

Dropped the front end a full 2" using the shocks from the Broadmoor RS project. They are stiffer and will limit travel somewhat (unwanted side effect) but the lower center of gravity might be worth it. The adventure edition's frame is higher than most which makes it a bit top heavy.


Alternator and winch, fairly heavy items which were mounted up high and not needed for the TTC


10HP Briggs block stripped down


10hp Cylinder head as removed


Head after some work in the milling machine. Removed about enough so the valves just barely touch at stock lift with no head gasket. Then I needed to remove a small amount of material just to be on the safe side. With the gasket it should be perfect.

Simplicity just fits into the back of a mini van. Worked out nice that we didn't need to pull a trailer.


The #64 in TTC spec, 66lbs lighter, nose dropped 3", and 2 or 3 more HP


It was a huge difference over the original setup. Much better acceleration and much better handling.


TTC spec exhaust system starts off at about 1" at the port, then to about 1-1/4" before dumping into a megaphone. It has a bit of a crude mounting system with a single large bolt through the frame. You can't take it off without unbolting the engine as there is a section of pipe that sticks into the port and it won't let the mounting bolt slide out. For a one shot use it wasn't an issue.


Hood and grill are painted card board over a 1/2 conduit tubing frame work. Pretty fragile and a bit laughable, but must have only weighed a couple lbs compared with the 20lb stock hood with rack and accessories. Weight up high hurts center of gravity. 15-20lbs might not be that much, but it was all right at the highest and worst point.


The adventure edition loaded on the trailer for the short trip to the first course of the 2020 Top Tractor Challenge. Seen behind is Tom's wheel horse 'rusty' which would eventually take home the 1st place trophy after an epic day long battle...


Loaded back in for the trip back to HQ





Drawing straws for starting positions


The plastic thing over the carb is just a splash shield to keep water from getting sucked in. I didn't even run an air filter for the event. The intake off the original 8hp was cut and rewelded to allow the throttle to clear the new exhaust pipe. Everything was pretty hacked but it worked.


The quickly modded Simplicity managed a 4th place finish, which was way better than I expected. The extra power made it way more manageable on obstacles. I didn't really have any trouble getting up and over stuff.

How many of these changes do you think you’ll keep long term? Enjoyed seeing it run yesterday and I think it’s one of the better single cylinders I’ve heard

Thanks! It was good to see you made it out there! I think i'm gonna put it back the way I had it originally, but I may fix a few small things. For one I could get away with a much lighter and smaller alternator. I could build a bit fresher 8hp too and it may run a bit better if I finally get a carb that I can tune in correctly. The one I had on there was fairly close but too rich. I'll either have to find jets for it or run a different carb.

I will probably continue with the RS build for a faster machine but who knows. I may throw something together that's a little more conventional at some point too.

Checking Weights again. Here was the original specs Pre TTC tear down and hack...
Simplicity #64 Weight (No Rider)
-LF 116.6 lbs 23.3%
-RF 113.3 lbs 22.6%
-LR 125.8 lbs 25.1%
-RR 144.9 lbs 28.9%  

-Front Axle 229.9 lbs 45.9%
-Rear Axle 270.7 lbs 54%

-Total weight Pre TTC Hack no rider: 500.6 lbs

Now as ran with temporary mods in the 2020 TTC:
-LF 93 lbs
-RF 106 lbs
-LR 143 lbs
-RR 124 lbs

Total weight with TTC mods: 466 lbs

Couple of issues though, I notice that the RR and LR figures are virtually the same except swapped, which makes me think I made a mistake somewhere and wrote them down in the wrong spot. Also, I removed the 15-20 lb battery from the RR and that is not reflected in today's weighing for some reason. The original figures were checked again and again and averaged and with two difference scales. Today I was far less ambitious and these figures may be off by a couple pounds. But it gives and idea. Bear in mind the new 10hp Briggs is a bit heavier than the 8hp, so although I weighed 66 lbs of items removed, weighing the tractor in TTC spec shows only 34 lbs of reduction. Did not account for how much fuel was in the tank, although today it should be half or less, probably around a gallon (8 lbs)

I was totally blown away by your performance on this thing this year, it was like it was a totally different driver and tractor than last year, it ripped! ran great sounded cool and straight up got it done. great prep work man. seeing it without the winch I think it would look awesome with a mini gas tank like this up front like the old gasser dragsters, super pricey but Im sure you could make one out of one out of a camp propane bottle or something
https://www.amazon.com/Fill-Round-Spun-Aluminum-Tank/dp/B00JJOI9K6

Thanks! Yeah it seemed to work a lot better than I expected it to and I tried a couple of steeper hills at home before hand to get a feel for it. With the extra speed it wasn't an issue at all to rip up over stuff and it gave you a bit more confidence to just hit it. Before it was so sluggish to respond that you really couldn't do anything. That gas tank is pretty nifty tho.

Gonna see if I can use some knowledge gained this year to adapt the Broadmoor RS build to suit the new course conditions.

I was driving down the road about a week ago and I looked over to my right... There was an orange tractor with a big FREE sign spray painted on a piece of plywood leaning against it AND I ALMOST HAD A HEART ATTACK. HOLY CRAP A 70's SIMPLICITY! FOR FREE!!!! So I immediately went to get some assistance and came back to load it in.

It's in pretty good shape as far as the tin work goes. No one hacked the grill out to reach the spark plug as they sometimes do. And there aren't any dents in it really.


In theory I have enough parts now to build a second Adventure Edition. But who knows what I'll do with it. Can't beat the price though. I've been looking for one for awhile and now and then I'll see them on craigslist for $250-300 plus. I didn't really feel like paying top dollar for something that I didn't need right away. So this worked out nice.

nice score !

Even has hubcaps, nice!!

Nice one. I've seen these simplicitys with alternators on the side, I thought they were add ons. I guess not entirely.

Is that a starter generator?

Thanks people! Yeah actually it's a starter generator and some of them had them. My simplicity system 5010 did not so I guess only certain models and years. I don't know why briggs did it that way instead of the normal type charging system since that's kind of an old style setup for a vertical shaft engine. Technically I now have enough sears suburban and simplicity parts to build another copy of the adventure edition but that probably won't happen.

Build a copy specifically for the TTC and or haspin, and the original keep as the overland style build hahaha

That's actually a good idea and I've kinda thought of that too, but I think if I built one for the TTC or haspin, it would be better to not build the frame and front end the same way. Just because the original is a tad too high up. And then you'd kinda have a completely different machine. So I don't know. For now I guess I'll just keep it on hand till I need it. It's in good shape tho. And it is nice that all the hub cabs are there. Not like I'll use them but it's cool.

Right now I'm trying to clean up so I can eventually get back to the adventure edition. It needs some changes and then re-assembly after all the temporary mods from the 2020 TTC. Honestly I don't know about a simplicity entry for the 2021 TTC. The Broadmoor R/S project is in question at this point and I've been busy.