Nutiket 1 #1 Posted September 9 Hello. I have a stock SK-486. Any ideas on how to make it faster? Share this post Link to post Share on other sites
Ed Kennell 42,468 #2 Posted September 9 Increased diameter of engine pulley Decreased diameter of transmission input pulley These require belt and belt guard changes. Increased rear tire diameter. May require seat pan and foot rest mods. 4 Share this post Link to post Share on other sites
wallfish 18,416 #3 Posted September 9 How fast do you want it to go? Changing the engine pulley larger or the trans pulley smaller accomplishes higher RPM at the trans. There are many pulley calculators online Share this post Link to post Share on other sites
953 nut 60,893 #4 Posted September 9 Perhaps an after burner would work. 1 2 Share this post Link to post Share on other sites
Nutiket 1 #5 Posted September 9 How would I know what to increase/decrease the sizes of the pulleys too? Share this post Link to post Share on other sites
wallfish 18,416 #6 Posted September 10 (edited) 22 minutes ago, Nutiket said: How would I know what to increase/decrease the sizes of the pulleys too? 1 hour ago, wallfish said: There are many pulley calculators online How would we know if we don't know what you're actually trying to do? Is this just to mow the lawn a little faster? Race it? How fast do you want it to go? I built a Wheel Horse that did 30 mph + The engine pulley from a Hydro driven tractor is an 1" bigger than the manual tractors. That's were you might want to start and gain a little speed Edited September 10 by wallfish Share this post Link to post Share on other sites
Ed Kennell 42,468 #7 Posted September 10 Pulley Size Calculator - Calculator Academy 1 Share this post Link to post Share on other sites
Pullstart 67,383 #8 Posted September 10 you won’t find the answer to your question in a manual. It’s gonna take a little trial and error and figuring. Just remember the belt guard on these is an integral component of the clutch system. You modify the pulley sizes, you’ll need to modify the belt guard to work. 5 Share this post Link to post Share on other sites
ri702bill 9,652 #9 Posted September 10 8 hours ago, Pullstart said: It’s gonna take a little trial and error and figuring. Just remember the belt guard on these is an integral component of the clutch system. You modify the pulley sizes, you’ll need to modify the belt guard to work. That says it all - almost. If you modify your existing tractor, the belt guard MUST be included. The not so obvious - engine swap along with pulleys? The obvious (to me at least) - wrong tractor to invest time and $$$ in?? ... and the one that pops up when done - how can I stop this damn thing???? To rephrase what @Pullstart said..... "there will be error, followed by a trial!" 1 Share this post Link to post Share on other sites
Nutiket 1 #10 Posted Thursday at 09:30 PM Thank you guys for the info. Going to do some calculating soon to figure out what size pulleys to get. I’ll make sure to keep the belt guard in mind. Share this post Link to post Share on other sites
kpinnc 14,899 #11 Posted Thursday at 10:10 PM I agree with what has been said about modification. Changing one mechanical aspect must be compensated for in others. I used to be a helicopter pilot, so I've lived the concept. I will say only this: (1) it won't take much to make significant changes to the speed of your tractor, and (2) the engine pulley will affect how the system works the least if you do not change the rear pulley. Just don't forget that (1) small changes are your friend, and (2) what moves must be able to stop to be safe. (3) Wheel Horses are known for having underpowered brakes. 1 1 Share this post Link to post Share on other sites
953 nut 60,893 #12 Posted Thursday at 10:59 PM @Nutiket, You have a gear jammer so this is not pertinent to your situation but for others who may use this thread in the future reference. All of the previous suggestions presume the transaxle is a gear jammer, if it is a hydro please disregard all of it except the larger tire diameter. 2 Share this post Link to post Share on other sites
peter lena 9,340 #13 Posted Friday at 11:57 PM @Nutiket check that upper rear idler pulley , known for failure and terrible undersize bearings , and related lubrication failures . another glairing thing to me , is the condition of that paint ! penetrating oil soak down , while in the shop . days / weeks wet , to soak in and feed recover paint , then a clean cloth mineral oil rub down , do it in stages , no rush , when paint finally looks , deep clean , a 6" electric palm buffer , and cleaner wax , just a light buffing , that paint stage is what you want , take advantage of it , did that on my 3 units . pete Share this post Link to post Share on other sites
Nutiket 1 #14 Posted Saturday at 02:42 PM Hey guys thanks for all the info. I should probably make it known that I’m too young to even drive so this is why I’m working on the wheel horse for fun. We have a mower at my house already but my grandpa gave the Wheel Horse to me and said I could have it to have fun with as it was sitting at our rentals in the shed for multiple years. However, I’m still confused on how to know which pulley size to get and how to use the pulley calculators and how to know which rpm will relate to what top speed. Thanks again for all the support guys it really means a lot! 1 Share this post Link to post Share on other sites
Ed Kennell 42,468 #15 Posted Saturday at 03:12 PM The speed of the tractor is directly related to the RPM of the transmission input shaft. The RPM of the transmission shaft is determined by the RPM of the engine, the circumference of the engine pulley and the circumference of the transmission pulley. Pulley circumference = pulley diameter X 3.14 If you start with the existing engine pulley and decrease the size of a 5" diameter (15.7" circumference) transmission pulley to a 4" diameter (12.5" circumference) pulley your transmission input shaft RPM and your tractor speed will increase by 25%. 1 Share this post Link to post Share on other sites
wallfish 18,416 #16 Posted Sunday at 02:58 AM 12 hours ago, Nutiket said: Hey guys thanks for all the info. I should probably make it known that I’m too young to even drive so this is why I’m working on the wheel horse for fun. We have a mower at my house already but my grandpa gave the Wheel Horse to me and said I could have it to have fun with as it was sitting at our rentals in the shed for multiple years. However, I’m still confused on how to know which pulley size to get and how to use the pulley calculators and how to know which rpm will relate to what top speed. Thanks again for all the support guys it really means a lot! This would probably get you started speeding her up. No need to modify the belt guard by changing the trans pulley but you would need to get a shorter belt since the pulley size is smaller. https://www.surpluscenter.com/Power-Transmission/Pulleys/Finished-Bore-Pulleys/3-15-OD-5-8-Bore-1-Groove-Pulley-1-BK30-B.axd 1 Share this post Link to post Share on other sites
WHGuy413 2,787 #17 Posted yesterday at 01:17 AM My son spent the better part of last summer changing pulleys out on his b-80 “mud mower” some days I would come home from work and it would be crawling along in the back yard some days it would flying along. I think he has a 6” pulley on the engine now. It moves along but he still has plenty of power to play in the mud when we actually have it. I have to say he does have a 16hp v twin in it tho. 1 1 Share this post Link to post Share on other sites
953 nut 60,893 #18 Posted 10 hours ago On 9/13/2025 at 10:42 AM, Nutiket said: my grandpa gave the Wheel Horse to me and said I could have it to have fun with as it was sitting at our rentals in the shed for multiple years Being a family member the Wheel Horse should enjoy having some fun with you. Pullies and belts can be quite expensive for a student's budget so you you will want to get it right the first time. If you have had an Algebra class you will know all about ratios. If not you can take a look at your bicycle sprockets. A large pulley turning at a certain speed will make a smaller pulley at the other end of the belt turn faster. If the larger pulley is twice as big as the smaller pulley it will be a 2 to 1 ratio so the smaller pulley will be driven at twice the speed of the one driving it. In the case of your SK-486 the engine pulley (drive pulley) is about half the size if the transmission pulley (driven pulley) so this results in a speed reduction of 1 to 2, the engine has to turn over twice to make the transmission input turn over once. The pulley that John @wallfish suggested should do the job, if you went much smaller you would theoretically go even faster but the belt wouldn't have enough surface area contact with the smaller pulley and would slip. Have fun and be safe out there. 1 Share this post Link to post Share on other sites