My 2003 Murray Select All Terrain Tractor Build

Hey Everyone,

I am new to the all-terrain tractor scene. I've been a follower for years and have always wanted to be a part of it but never had the time or know how.... but now I am finally doing something about it. Fearlessfront, redneckcomputergeek, t-man's go karts, and mud king have all been inspiration's for me and I have been a long time follower of their vid's and work.

Here is my 03 Murray Select that I am using for my build. https://imgur.com/a/8Vc3K
The Craftsman that is pictured is the donor for the 21hp oppy. I swapped the 13.5 from the Murray in it, but it was short lived. You will see this in my build pics below shortly.

My plans/goals for this build are as follows:
-Swap in 21hp opposed twin engine. get it running nice and reliably.
-add larger capacity gas tank.
-add custom dual exhaust.
-add pull start.
-add foot throttle control.
-repair/restore brake functionality.
-repair and tighten up steering function.
-posi lock rear.
-pulley swap to achieve higher top speed. I'd love for 20 - 30+ mph if possible.
-run larger tires. thinking of putting the rears on front and getting a nice larger set of ATV tires like bear claws for the rear.
-add custom front and rear bumpers.

Basically I'd like to be able to hit the trails and hang with some buddies of mine on ATV's if I chose. I know I won't win any races or anything but I should be able to hang. I'd also love to find some all terrain tractor romps to join in on.

I have plenty of questions to ask about the 21hp opposed twin engine. I have very little experience with these, but we will get to those all in due time.

Over the past few weekends I got started on my build. Swapped the motors, mostly as planned. I've got a good friend of mine helping me with most of the work. Always nice to have an extra set of hands and to be able to bounce ideas off each other. I think I am getting him into the world of tractor modding as well.

Part 1:
https://imgur.com/a/Y2eJp

for part 1 we focused on removing the 13.5 OHV and swapping it to the Craftsman. I was going to use this to cut grass at my folk's place. Unfortunately it didn't work out, the 13.5 had a valve issue and blew after 10 min running. I knew it had an issue before I swapped it, though I thought it was just a dirty carb. I was wrong. Good news about this though is now we have a 2nd tractor either for parts, or for a second build in the future. Since my buddy is helping me, I think we are going to build another tractor so he can join the crew as well.

part 2:
https://imgur.com/a/rYtL0

for part 2 we focused on the engine install into the Murray. We had to add a choke lever/knob, replace the starter, change the throttle linkage so it was longer and we re-installed the previously re-purposed gas tank. It didn't take long before we got this thing up and running!

first running video: https://www.youtube.com/watch?v=dGGEPEJlp60&feature=youtu.be


For part 3 I believe we are going to work on some some tuning and reliability issues. I need to fab up some exhaust. I am thinking of running dual exhausts that exit like side pipes under the foot rests. Definitely need to try to get the brakes working, right now they don't and....well stopping is important...especially on the trail.

Right now I think the carb is running very rich and may need a cleaning, adjustment or replacement. the engine starts up fine when its cold, but once it fires up and either stalls or is shut off, it has hot start issues. the only way to start it once it has ran for a little bit is to manually close the throttle butterfly in the carb and try starting it with the choke on. The way the carb, governer, and throttle is set up on this engine, the throttle butterflies are sprung at WOT when the tractor is not running. Once it starts, they close to idle (assuming the throttle is at idle). For some reason, it just dumps gas into the engine like this and floods it, so it wont start unless I cut off fuel myself. Has anyone seen an issue like this before?

That's all for now folks. More updates once I can get to it. Hopefully soon.

Please let me know if you have any feedback, questions, or anything.

Thanks for reading!

Keep up with atv's shure its posible. My hole goal in my murray is to do so. Thats one of the reasons for suspention. Mine runs 30 now non governed. But plan to change that soon enof. I wont to hit the 50 mark.

next time, you should post your pics on the forum here. we try to discourage posting to personal blogs and pages.

either way, looks awsome! my buddy has a murray just like that. its torn down to a frame right now. im gonna help him make it into something awsome. shame about that 13.5, but ive seen that happen several times. oppy runs good. sounds like it is skipping every now and then though. good luck with it, really like it so far... needs some rubber...   

looks good so far!

Thanks for the feedback everyone.

I promise imgur.com is a safe site used for image sharing by millions. It's very quick and safe for uploading images and sharing them. I will try to use the built in tools on the forum for my next update.

When I got the oppy up and running, it was it's first time running in almost 2 years after the starter died on it while it was in the craftsman. I loaded the gas tank with seafoam and lucas fuel system cleaner to try to clean out the carb a bit. That is why it was running a little rough and smokey, it wasn't exactly happy at first.

Thankfully it cleared up as I ran more fuel through it and it runs much smoother now, though like i mentioned previously, I think it still is running very rich. I can literally watch gas splash out of the carb when trying to start it. Does anyone know how I might be able to fix this? It has trouble hot starting as a result, i have to force the throttle butterflies closed to start it or it will flood. I've never messed with one of the carbs with the fuel pump built in. Is it hard to do? I also find it odd that the throttle is actually at WOT when the motor is off, then the governor shuts it to idle once the thing starts. Is this how it's supposed to work?

Is there anyone on the board who might be an expert in these opposed engines? This one seems to be in good shape, all of the seals look good. It runs strong. Doesn't have any knocks, though it seems to be a bit rattly at certain RPM's. I definitely have some questions about these motors though. Since it's not OHV I definitely don't want to over rev it, but I would like to get the maximum revs out of it than I can safely. Does anyone know the typical operating RPM range of these things?

Are there any common problems or issues I should look out for? I know i should put the covers back on the heads as they will keep the engine cooler and direct air properly. I will do so once I am using the tractor more, they just get in the way for now while I am working on it.

Also, I want to eliminate all of the electrical safety switches. Right now the brake switch is causing an issue so I have it zip tied. I believe someone told me to cut the wires and connect the orange to the starter to fix this. What about for the blade control safety switch?

Lastly, can anyone recommend a good rear pulley size that might work well for this thing? I am using the stock front pulley right now. I was thinking of going with a 4 inch rear pulley? Are there any that I can buy that might be a direct swap? I am hesitant to have to cut pulleys and weld the center sections like I see in other videos. I am not the greatest with precision and centering things, so I would prefer to not have to modify it to make it work.

I am sure I will have many many more questions, so thanks ahead of time for answering and dealing with me. I will learn in due time.

Also BTW, my screen name basically every where else on the internet is brad08stanggt. I used to have a 2008 Mustang GT. I now have a 98 SVT Cobra so I have been trying to update my screen names on new forums.

Thanks everyone for your help, support and feedback. I am really looking forward to this build and being able to hit the trail with this.

I'll list the things I know about your questions.

I think the 21hp is a new four screw carb (four screws on the outter fuel pump plate) meaning its a fixed jetted carb, unadjustable. Most engines i have are at wot when starting, including my v twin. Maybe you need a carb clean or rebuild and that might bring it back to acting stock. Does it have a automatic choke, like the throttle and choke cable lever is the same one?

I guess if you want a safe rpm range, maybe around 3800-3900. But guys on here (Mowron group that went to 1puglifes) run there opposed in governed, and I think valves float around 4900-5300 ish, don't quote me. But the wrap them suckers out with no issues.

Common issues is things across the board as far as small engine go. Such as starter gears, starter rebuilds, dipstick seal, carbs not running right, coils going out. But they are solid engines and you should have to worry about much.

There is a few electrical questions already posted here. If your searching comes up dry, I'll make you a diagram on how to re wire it.

A 4" pulley is generally a good pulley to stick with. Tractor supply should have a hub that welds to the inside of your pulley of choice, keyed shaft. If you want a bolt on deal, get a steal pulley from tractor supply or surplus center online should have something.

redlinemotorsportts wrote:

I'll list the things I know about your questions.

I think the 21hp is a new four screw carb (four screws on the outter fuel pump plate) meaning its a fixed jetted carb, unadjustable. Most engines i have are at wot when starting, including my v twin. Maybe you need a carb clean or rebuild and that might bring it back to acting stock. Does it have a automatic choke, like the throttle and choke cable lever is the same one?

I guess if you want a safe rpm range, maybe around 3800-3900. But guys on here (Mowron group that went to 1puglifes) run there opposed in governed, and I think valves float around 4900-5300 ish, don't quote me. But the wrap them suckers out with no issues.

Common issues is things across the board as far as small engine go. Such as starter gears, starter rebuilds, dipstick seal, carbs not running right, coils going out. But they are solid engines and you should have to worry about much.

There is a few electrical questions already posted here. If your searching comes up dry, I'll make you a diagram on how to re wire it.

A 4" pulley is generally a good pulley to stick with. Tractor supply should have a hub that welds to the inside of your pulley of choice, keyed shaft. If you want a bolt on deal, get a steal pulley from tractor supply or surplus center online should have something.

Thanks redline!! There are 2 seperate controls for throttle and choke. It's a bit weird, even on the craftsman, the throttle works in the opposite direction that is shown on the "dash". what is "turtle" speed is actually increasing RPM and towards the "rabbit" is actually lowering the RPM down to idle. I think the previous owner had replaced the throttle and messed with it, possibly screwing it up. It works otherwise though.

The starter has already gone twice. It was dead when I got it. I replaced it with the cheap $40 amazon replacement, then that one died within a few months. I could not find this starter with the steel gear, only plastic, but this time i got a OEM briggs replacement.

I will search the forums for what I need to correct the wiring. I also want to add a volt gauge eventually and push button start. So it would be good to just become more familiar with the wiring anyway.

Thanks for all of your helpful info. I will also check out the pulleys at tractor supply. I dont mind getting the hub and welding it on. I just didnt want to cut up a pully to try to get the hub then try to weld that on a new pulley.

Oh and the rear original pulley is most likely seized on the shaft, redneckcomputergeek on youtube has a torch and candle wax trick to get the pulley off. if you have a puller drill holes in the original pulley, put bolts in the pulley and puller, and pull it off. That works good.

redlinemotorsportts wrote:

Oh and the rear original pulley is most likely seized on the shaft, redneckcomputergeek on youtube has a torch and candle wax truck to get the pulley off. Of if you have a pulley drill holes in the original pulley, put bolts in the pulley and puller, and pull it off. That works good.

Thanks for the tips. When I looked at the original pulley, it most definitely looked seized on. Thought I am impressed how lucky I got with the pulley on the motor, as it came off with minimal effort. Maybe I'll luck out, but if I don't at least I'll know what to do. I do have a few pullers and I've seen redneckcomputergeeks video, which I think will help too.

Thanks!

Hello Everyone.

I've had the chance to do a few test romps around the yard with the Murray. So far it's running pretty good except for my issues with the carb. It still seems to be running very rich and I have to manually hold the throttle butterflies closed with about 1/2 choke to get it to start up. Once its running and warmed up, it runs fine. Is the recommended fix to just replace the carb?

The next things I am planning to do are to pull the trans-axle to lock it, do a pulley swap, and fix the brakes.

I am also planning on running my custom exhaust as well. I know that I can remove the factory manifolds and use 1/2 brass pipe instead, but I'd prefer to use the stock manifolds and weld up my own exhaust. I gotta figure out though where I can get the smaller diameter steel tubing i will need for this.

After the trans-axle and exhaust are taken care of, I will work on the electrical system (removing all safety switches), procuring and installing a larger gas tank, and taking care of any repairs, etc the tractor is going to need, like front axle work, etc.

I hope to have another update in the next few weeks.

Thanks!

I have a similar need to fab a custom exhaust on my project. O'Reilly autoparts has varying sizes of exhaust pipe. You can get this flexy stuff (which Ill be going http://www.oreillyauto.com/site/c/search/Flex+Pipe/N0075/C0022.oap ) or find that 1 inch Metal electrical conduit and a manual conduit bender and weld it on.

The conduit was recommended to me by a local Mower shop. I was chatting with the guy there, and he used it to put a better exhaust on his tractor when the original broke.

Your project detail is fantastic! I wish i had taken the time to record my early steps as well as you have here. I plan to add my project to the boards soon, once "Phase 1" is complete.

Sounds like you want to do some trail riding, which is what I want to do as well. In Virginia we have some wonderful mountain trails you can camp on for ATV camping. i plan to hit these up this summer.

Keep up the great work youre doing, and get your buddy hooked too. Im trying to do the same here

RCTankboy wrote:

I have a similar need to fab a custom exhaust on my project. O'Reilly autoparts has varying sizes of exhaust pipe. You can get this flexy stuff (which Ill be going http://www.oreillyauto.com/site/c/search/Flex+Pipe/N0075/C0022.oap ) or find that 1 inch Metal electrical conduit and a manual conduit bender and weld it on.

The conduit was recommended to me by a local Mower shop. I was chatting with the guy there, and he used it to put a better exhaust on his tractor when the original broke.

Your project detail is fantastic! I wish i had taken the time to record my early steps as well as you have here. I plan to add my project to the boards soon, once "Phase 1" is complete.

Sounds like you want to do some trail riding, which is what I want to do as well. In Virginia we have some wonderful mountain trails you can camp on for ATV camping. i plan to hit these up this summer.

Keep up the great work youre doing, and get your buddy hooked too. Im trying to do the same here

Thanks for the advice on the exhaust and feedback. I think I am going to try to find some 1 inch metal conduit! that should work perfect for me, especially if I can get a bender too for it.

I am definitely planning on doing some trail riding once the build is ready. Nothing too serious, but definitely some fun stuff. I think I already have my buddy hooked. We have a spare Craftsman LT1000 with no engine right now. We are going to look either for a nice engine for it or possibly a entire new tractor w/ engine to start on a project for him....then use the LT1000 as a parts tractor.

Pull your spark plugs and tell me if they are black and wet, or white-ish and ashy. That will help determine if you are too rich, or too lean. I'm thinking you are actually too lean; "starts easy when cold, and won't refire after running."


Also; Do you still have the complete muffler from the OHV single? I'll buy it from ya.

that is the problem i had! it is caused by a bad coil/magneto

B440 wrote:

Pull your spark plugs and tell me if they are black and wet, or white-ish and ashy. That will help determine if you are too rich, or too lean. I'm thinking you are actually too lean; "starts easy when cold, and won't refire after running."


Also; Do you still have the complete muffler from the OHV single? I'll buy it from ya.

Hey B440. I do still have the complete OEM muffler off the 13.5 single. If you want it, just send me your address info and I will try to send it to you in a reasonable amount of time. No charge, just pay me back for shipping. I'll try to find out the shipping costs before I send it. Doubt it would be much. I'll go the cheapest route. I am only at the tractor and where all the parts are on the weekends, so I'll have to wait till next weekend at the earliest.

1997 Murray wrote:

that is the problem i had! it is caused by a bad coil/magneto

I thought this might be it too, but I really think its the carb based on my findings below. If I hit a road block with the carb though I will def look into this. Thanks.

Mitch'sgarage wrote:

wow, keeping up with atv's, that is going to be tough with low-revving engines compared to powerful atv engines.

It definitely won't be easy. I am not expecting to keep up with ATV's in a speed contest by any means. I will be slower. With no suspension I need to take certain terrain slower to not break things. I'd like to though be able to take the same trails and get to a to b along with them....although a bit slower likely.


Quick update guys:

I tried to make some progress on this project this weekend...unfortunately with little success.

First was carb issues:

The issue's with the carb seem to have gotten worse. I honestly think this is an issue with flooding/running rich. This weekend I went to fire it up. It fired up right away at first but I didn't adjust the choke right away correctly and it stalled. Then it wouldn't start at all. I can see gas just pouring and splashing in the carb, i can smell it strong and it comes out of the exhaust too. Only with the throttle manually held close does the gas not just pour in, but obviously it won't start with no fuel and little air.

I pulled the plugs. They are pretty new and looked good as expected. Some carbon build up, but not much. They looked identical, so I wouldn't say one was worse or different than the other. They were though COMPLETELY SOAKED in gas. I gave the motor a few turns with the starter and you could see gas just spraying out of the spark plug holes. I dried them off and hit them with the wire wheel. Put them back in, boom tractor started right away and ran for a bit. I shut it off, and again the same issues starting. Pull the plugs, dry them off, clear gas from cylinder chambers and it will start again.

I tried to clean the carb with some seafoam, carb cleaner, etc....no dice.

Again, the problem I am noticing, is that since the tractor starts with the throttle wide open, the carb is just DUMPING fuel in there. It even splashes out of the carb, with the choke on or off and comes out of the exhaust. When it's not starting, and I am trying to start it, you can see puffs of smoke come from the exhaust along with tons of unburnt fuel. I honestly think it just floods the heck out of itself.

What do you guys think? I am thinking about just replacing the carb altogether. I know I might be able to clean it if I take it apart, but I've not had much luck when doing this in the past and would prefer to just swap out for a new one and have the added reliability.

the second issue: stuck donor wheels and tires.

I was going to drop the trans-axle on the Murray so I can get started on the locker and pulley swap. Before I did that though, I wanted to get an idea for the stance, tire size, etc that I would be running on it. I was going to put the rear wheels and tires on the front axles and the rear wheels and tires off of our parts LT1000 on the back. Again, just to get an idea of how things would look and feel.

The huge problem we ran into? Well the rear wheels are so rusted on the axles of the LT1000, we couldn't get them off. Anyone deal with this before? I'd hate to destroy a good trans-axle, axles, or the wheels I wanted to use. But wheels are just rusted/welded on the axles and won't budge. We tried to use some heat, PB Blaster, Heavy hammers, pry bars, everything we could throw at it. I used a harmonic dampener puller even and maybe we were able to get the wheel to move 1 or 2mm off the axle. Anyone run into issues like this before? Any advice on how i might be able to get the wheels off without destroying too much? I think they have literally never been removed from the tractor.

Since we struggled so much this weekend we ended up just calling it a day on the project and leaving things where they were for now.

Hey guys. just did some research quick on my carb. I can't believe briggs wants over $200 for a replacement carb! Looks like they go for about $100 used too even on e-bay.

I wanted to just replace it so I wouldn't have to deal with the hassle, but not for that kind of money.

That being said, what do you guys recommend? Do you think it can be cleaned? Is there a rebuild kit or something anyone could recommend? I've never rebuilt a carb before, so not sure if learning on this carb is good idea or not. Better late than never I guess.

Thanks for any feedback.

98svtcobra wrote:

Hey guys. just did some research quick on my carb. I can't believe briggs wants over $200 for a replacement carb! Looks like they go for about $100 used too even on e-bay.

I wanted to just replace it so I wouldn't have to deal with the hassle, but not for that kind of money.

That being said, what do you guys recommend? Do you think it can be cleaned? Is there a rebuild kit or something anyone could recommend? I've never rebuilt a carb before, so not sure if learning on this carb is good idea or not. Better late than never I guess.

Thanks for any feedback.

What kind of engine is it? And in my opinion i would try cleaning it and try that is it doesn't work then rebuild the carb. And if i did all that and the carb still didn't work i would try and get a used one off a parts engine before i would pay 200. For a parts engine go to a junkyard or buy a cheap tractor with the engine with the parts you need one it.

Craftsman1998 wrote:

98svtcobra wrote:

Hey guys. just did some research quick on my carb. I can't believe briggs wants over $200 for a replacement carb! Looks like they go for about $100 used too even on e-bay.

I wanted to just replace it so I wouldn't have to deal with the hassle, but not for that kind of money.

That being said, what do you guys recommend? Do you think it can be cleaned? Is there a rebuild kit or something anyone could recommend? I've never rebuilt a carb before, so not sure if learning on this carb is good idea or not. Better late than never I guess.

Thanks for any feedback.

What kind of engine is it? And in my opinion i would try cleaning it and try that is it doesn't work then rebuild the carb. And if i did all that and the carb still didn't work i would try and get a used one off a parts engine before i would pay 200. For a parts engine go to a junkyard or buy a cheap tractor with the engine with the parts you need one it.

It's a 21hp opposed twin.

Carb - Sounds like your float is stuck open.

Wheels - What I did was to get in behind the wheels with a long crowbar. Set that on the axle, and right up against the flange of the wheel. Then hit the end of the crowbar.

This will drive the wheels off. Seems to work better than trying to pull them off.

Make sure you have the end of the crowbar in the most advantageous place. Don't just sit it against the back of the wheel. Lay it on the axle, and slide it down until it touches the flange. Then you are ready to start driving it. Also, spin the wheel, and relocate the crowbar, after each smack of the hammer. Don't just keep hammering in one place.

Have some patience and let the percussion do the work. Don't try to force it all at once.

When I went to put them back on, I used a round file and sandpaper on the insides of the flanges. And a flat file and sandpaper on the axles. To clean off all the rust. Once I had a slip fit, I greased the heck out of everything before putting it back together. (An attempt to keep them from rusting on, again.)

for your carb, clean it. clean it very thorough. i dont believe in buying a new carb, ever. get a rebuild kit, which will consist of a needle valve, o rings and probably a float. possibly jets too.

as far as getting the rim off the transaxle, Redneckcomputergeek on youtube has a nifty candle wax trick that he uses on pullies. it might work for your rim. if not, youre going to end up cutting it off

you should try what i did leave the rim on the tractor and put the new tires on it

thanks everyone.

I am going to order a carb rebuild kit and see if I can successfully rebuild the carb. Watched a few videos on youtube. Definitely seems doable.

I am going to take a look at redneckcomputergeek's candle trick and otherwise just keep trying to use muscle and be careful to get the wheels off the other tractor.

Can anyone recommend a carb and fuel pump rebuild kit? I am going to rebuild the carb and fuel pump. Watched enough how-to videos on youtube. I definitely think I can handle it as long as I am careful and follow the steps in the videos.

Also, does anyone have any spare gas tanks laying around? The type that would go in the front under the "console". My tank is a small 1.8 gallon tank. I have been looking for the larger 2.8 gallon tank but I can't find any for a reasonable price. If anyone has one that might work for my application I would gladly buy it from you for a reasonable price.

Thanks again everyone! I look forward to continuing this build and hitting the trails soon!

Hey everyone.

Quick update. I ordered a Briggs and Stratton 693503 OEM Carb Overhaul Kit. Don't think I'll have time this weekend to do the overhaul, but I am hoping I will for next weekend.

Once I get the engine running better, I will be able to continue with the actual build, but no sense working on anything else if I can't get it to start and run correctly.

I should be picking up another LT1000 in the next few weeks as well. Hoping that will enable me to do a few thinks like swap out the 5spd trans-axle for a 6spd. Also likely will swap out the front axle for the heavier duty ones from the LT1000.

I will keep everyone posted.

Thanks.