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Messages - RoMow

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   After doing some further research, I learned that the Deere Aercore 800 aerator uses a 25HP Kohler Command horizontal-shaft engine and a Peerless 820 transaxle, with a twisted-belt drive:

   You might want to stop by your local Deere dealer and check out the parts for your setup.  Might save you some time and unnecessary custom engineering. 


Driveline / Re: Mtd transmission 8 speed?
« on: October 03, 2021, 12:09:08 am »

   If you are still comtemplating this, I would suggest not to.  Or, in your words, "toss it."  Drag racing will require extreme starting loads "out the gate," and the 719 gearbox isn't designed for these forces.  And "modifying" it will not increase its durability. 

   Do you have the mower Model Number available? 

Rodney Rom 

Driveline / Re: Advice for marrying peerless 801 to horizontal shaft engine?
« on: September 23, 2021, 11:20:21 am »

   1.  Peerless Gear transaxles can be run with the input shaft in a horizontal position with the axle towards the bottom, cluster gears up.  This does not normally create a lubrication issue, but it probably wouldn't hurt to add 6-8 oz. of Lucas Gear Oil Additive. 
       Gear oil doesn't work well with the 801s because they are not made with lip-style seals, just O-rings, and will leak gear oil during normal operation.  You'd have to modify the case to accept lip-style seals like the MST 200s use with gear oil. 

   2.  Corvairs have been doing this since 1959, and are still doing it.  This is the easiest way to solve your problem, as long as you align the pulleys correctly.  Find someone in your area with a Corvair and study the pulley alignment. 

   3.  Peerless already offers right-angle gearboxes.  Get one off a boneyard commercial walk-behind mower deck. 

   4.  This would be the best but most-expensive solution, except that the outer end of the shaft on the right side rides in a bronze bushing.  You'd also have to modify the case to fit a ball or needle bearing to support the end of the shaft.  Unless you'd want to extend the left end of the shaft, which already rides in a ball bearing.  With a belt-tension load, though, you'd probably need a double bearing. 


Driveline / Re: Transmission/ drive line calculator?
« on: August 03, 2021, 12:14:05 pm »

   You should be able to combine the information from the following two posts at the top of this Driveline section to figure out what you need:,32459.0.html 


Driveline / Re: 35 chain
« on: August 03, 2021, 12:05:51 pm »

   Using #35 chain wouldn't be a good idea for two reasons: 
1.  The links do not have individual rollers on the link pins, thereby creating more friction than the 40- and 50-series chains; and 
2.  It is too small a chain for the loads produced during racing. 

   If you want to pioneer a racer using #35 chain and let us know how it works, we could add that information to the archives. 

Rodney Rom 
Rom's Reworks 
Butler, MO 


   Yes, that makes sense.  The one-piece cast-iron-block-with-cylinders K482 (18 HP - 47.7 CID) and K532 (20 HP - 53.7 CID) Kohler engines weigh 178 pounds.  I would also consider these "very heavy" for racing.  And these are horizontal-shaft engines, not available in a vertical-shaft version. 



   I'm not sure what Al means by "very heavy" but there isn't that much difference in the weights of these opposed-twin vertical-crankshaft engines:
Engine                           "Shipping Weight"       HP      Cubic-Inch Displ.           Ft.-Lbs. Torque     Compression Ratio
Kohler  MV18 Magnum              130#                     18              42.18                    29.0 @ 2500 RPM              6.0:1
Kohler  MV20 Magnum              130#                     20              42.18                    32.7 @ 2500 RPM              6.6:1
B&S      422700                  110#-120#                 18              42.33                     28.5 @ 2700 RPM 
B&S      460700                  110#-120#                 20              45.60                     28.0 @ 2700 RPM 

   I don't consider a 10#-20# weight difference "very heavy."   

   I'm working on getting the compression ratios for the other Briggs' engines. 

   These figures also apply to the horizontal-shaft versions of these engines.  Note that the Kohler engines develop more peak torque 200 RPM sooner than the comparable-horsepower Briggs engines. 

   And I find it interesting that Kohler can get two more horsepower from the same displacement just by tweaking the internals, whereas Briggs has to increase the displacement another 3+ cubic inches.  And the 20 HP Briggs produces less torque than their 18 HP...


Driveline / Removing the cover from a transaxle
« on: June 30, 2021, 01:31:37 pm »

   If you've ever tried to remove the cover from a transaxle, you know what a problem the RTV causes in preventing cover-from-case separation.  Try this: 

   If you're working on a Peerless Gear transaxle, the Service Manual Instructions tell you, after you've removed all the case bolts, to use the two screwdriver slots at either end of the back of the case seam to pry the top from the case.  Other manufacturers' instructions are similar.  I've never been able to get these to work, due to the grip strength of the RTV.  What I use is the Ma Bell knife shown in attached Photo 1 to begin the case-seam separation as shown in Photo 2.  This knife was used by phone-company linemen to open the lead-sheathed wire they used to use on the poles.  Since they don't use this wire anymore, my local phone-company lineman retiree gave me this knife, and it works great!  (Any similar sharp, wide-blade knife will do the same thing, but the Ma Bell knife also has the handy hammer-tap block.)  Tap it into the seam behind the differential gear until the top separates from the case. 

   CAUTION: Only tap it in enough to begin separating the cases -- do not tap it in too far or it will chip the differential-gear teeth. 

   After the case seam begins to open up -- it will usually 'pop' when it does -- and with the knife still holding the cases apart, take a straight-blade screwdriver and pry between the case halves on the right side.  Between the knife and the screwdriver, your cases should separate. 

   To complete the removal, you may need to use the screwdriver at the front of the case while holding the shift shaft down.  And if the axles start to come up when lifting the cover, tap them back down into the case.

   CAUTION: Use the knife and screwdriver carefully so as not to gouge the surfaces to which you will need to apply the RTV to re-seal the transaxle. 

Rodney Rom 
Peerless Gear Master Technician 
Rom's Reworks 
Butler,  MO 

Driveline / Re: peerless MST206 565 questions
« on: June 19, 2021, 08:10:08 pm »
Hello Bob, 

   "Again I am sorry about all the stupid questions but you can't learn anything if you don't ask questions." 
A wise teacher once told me that, with a few exceptions, "The only stupid question is the one you don't ask." 

   "1) Does this trans need to be clutched between every shift?" 
Yes.  A better answer is that if you are shifting "on the go," the transaxle needs to be "unloaded."  In other words, moving the shift keys between gears with the engine still applying a load to the transaxle will result in rapid damage to the tips of the shift keys and the mating notches of the shift gears. 

   "2) I am looking for a maximum ground speed of 22 mph; rear tires are 18" diameter." 
I doubt you will be able to get close to 22 mph with the MST transaxle.  You would need to turn the input shaft 6000-7500 rpm to achieve 22 mph with 18" tires.  Maximum recommended tire diameter for the MST is 20".  An 820 transaxle with a Gearset Upgrade on the final-drive gears would allow the speed you are wanting. 

   "3) How much can I exceed the rated 2000 rpm input-shaft speed?" 
I wouldn't recommend more than 3000 rpm unless you plan on replacing your input-shaft bearings regularly. 

   "4) I will have a vertical jackshaft in the build...hoping to set input-shaft speed to drive at approx 2500 rpm while only
    turning the motor around 1500/1600 rpm.  Is this possible?" 
Possible, but not recommended.  Your 14.5 B&S OHV single is air-cooled, and the slower you run it, the less cooling air you have flowing over the cylinder fins.  You will overheat your engine quickly running it below 3000 rpm.  Best to run it at the maximum governed speed -- 3400-3600 rpm. 

   "I will also be adding a go-kart disc brake on either side of the transaxle or is the internal brake of the transaxle good
    enough as a service brake or is it more of a parking (brake)?" 
Go with the go-kart disc brakes.  There is no internal brake on the MST transaxles, and the external brake is, as Peerless Gear states, a "parking brake," even though most mower OEMs use it as the vehicle brake. 

   "If I have to or want to change out the clay-type lube for a premium 90 weight synthetic, I would also like to add a drain
    plug with a magnet." 
MST transaxles already use a petroleum-base 80W-90 gear oil, not the clay-based Bentonite grease.  Adding a drain plug would be possible, but with the design of the MST bottom case, one drain plug will not drain all the oil -- you would need four drain plugs, one at the bottom of each section.  And as thin as the case is, you would need to weld on thicker reinforcements where you wanted plugs.

   Hope this helps. 

Rodney Rom 
Rom's Reworks 
Butler, MO 


   I'm surprised no one has Replied to your question by now, but I'll try to help with what I know. 

   The Kohler opposed-twin engines have an aluminum crankcase with removable cast-iron cylinders that are held to the crankcase with six bolts each.  The Briggs & Stratton opposed-twin engines have a one-piece block where the cast-iron-liner cylinders are permanently made as part of the crankcase.  The heads of both engines bolt to the cylinders. 

   I personally prefer the Kohler engines, as I feel they are better engineered.  Yes, they're more expensive, but that is the result of the better engineering.  They're also more durable.   

   To use them for racing, the B&S governors are easier to remove to prevent internal disintegration when revved beyond the normal governed speed.  Kohler opposed-twin governors, on the other hand, require a lot of engine disassembly to access the governor-gear/flyweight assembly for removal.  But this is probably a moot point, as most racers will be disassembling the engine anyway. 

   As to upgrades, I'm not familiar with any commercially available ones.  My philosophy has always been that if I need more horsepower, I get a bigger engine.  Trying to circumvent factory engineering to gain more horsepower usually results in decreased durability.  Of course, there are always the standard tweaks such as porting and polishing the intake and exhaust passages; maybe stiffer valve springs to allow higher RPMs; larger carburetors; tuned exhaust system; etc.  And you can always groove the heads using Somender Singh's method which allows better combustion burn for more power.  (This will work on any L-head engine.) 

   Hope this helps...

Rodney Rom 
Rom's Reworks 
Butler, MO 

Kohler Engines / Re: Stock engine RPMs
« on: May 05, 2021, 01:12:45 pm »
   Part of Kohler's engine test lab includes spin-testing flywheels.  Each flywheel is properly installed to a clean, dry, motor-driven-and-monitored shaft, then hand-torqued just like the manual instructs.  The flywheel is mounted into what resembles a large safe with very thick walls and a big door.  RPM is then run up to the point of burst.  They need to survive at least 2X the normal rated speed of 3,600 RPM.   

   After bursting, everything that still stays on the shaft is out of balance and the lab floor will shake as the speed comes back down. When the door is opened, there will be a pile of broken parts with magnet bits stuck all over the inside of the chamber.  All flywheels pass the 2X3600 mark -- 7,200 RPM -- and many of them hit 10,000 RPM. 

   Anytime a new flywheel is developed, whether for a new engine or as a new flywheel design for a current engine, it gets qualified/tested. And anytime a modification is made to an existing flywheel, it gets qualified/tested. 

   Many Kohler engines are set to run 3750 no-load speed.

   Keep in mind that lubricating the tapers or using an impact wrench to torque a flywheel are always bad ideas.  Broken flywheels result from lubricating the tapered shaft or over-torquing the flywheel bolt/nut. But properly hand-torquing a stock Kohler flywheel on a clean, dry taper will safely allow in excess of 5,000-6,000 RPM.   

   As noted above, this is Kohler's flywheel-test information.  I'm still trying to get information on Tecumseh, Briggs, Kawasaki and Honda flywheels. 

   Now, having said that, and having watched Knoot's video, I need to say that the Kohler we ran to 5,700 RPM did not have any counterbalance mechanism inside, just a well-balanced crank, rods, pistons and cam.  The Tecumseh V-twins being raced don't have counterbalancing mechanisms, either, but I don't know what RPMs they're producing.  What I saw on Knoot's Briggs video looked like the oscillating counterbalance weight self-destructing, and the oil that came out of the crankcase looked quite dirty and black, which would tell me that the internals had a lot of wear from the dirty oil.  This may have helped contribute to the self-destruct.  What was the RPM at the point of disintegration? 

   And Paul keeps mentioning "insurance companies and a 3,650 RPM maximum."  Which insurance companies?  Would a stock Kohler running it's governed 3,750 RPM be uninsurable?  Maybe the insurance companies are using outdated information from when the flywheels included the cast-in cooling fins.  The new unfinned flywheels with separate plastic fans can safely spin much faster, as Kohler's tests -- and my own experience -- prove. 


Kohler Engines / Re: Stock engine RPMs
« on: April 25, 2021, 08:49:54 pm »

   So, any engine run over 3650 RPM requires a billet flywheel?  What if the manufacturer's allowable maximum RPM is 3800-4000?  Some are --depends on the engine's Type or Spec Number. 

   I didn't post this to create issues -- my apologies if it did -- I was just noting that the engines can do this without self-destructing internally. 


Kohler Engines / Stock engine RPMs
« on: April 25, 2021, 10:56:14 am »

   In the Driveline section, there is a post entitled "Getting speed out of Drive Shaft Mowers?" and one of the questions was about tweaking the governor to get more than 3600 RPM from the engine.  One of the Replies cautioned about going beyond 3800 RPM.  Allow me to share an incident from a factory service school:

   In February of 1999, I attended the Kohler Engine Level 2 Factory School in Kohler, Wisconsin, and on Thursday afternoon of the 5-day school, the class was given two Command 25hp V-twin engines to "do with whatever you'd like."  Since in our shops, we only see an engine needing repairs after it's been damaged, we decided we'd run one wide open and the other without oil.  For the wide-open engine, the instructor wired the governor open, set the engine stand outside (just in case), and started it up.  The tachometer read 5700 RPM -- for 45 minutes!  It never missed a beat, and would have run faster but the valve springs began floating, so 5700 was its maximum RPM-- well above the "recommended" governed 3600-3800 RPM.  Even with the factory muffler, the sound was impressive!

   Engine RPM limits are dependent on keeping with the design engineering of a maximum metal stress in a stock engine of 2,500 feet-per-minute (FPM) of travel, with allowable momentary speeds of 3,500 FPM.  An engine with a 3" stroke will travel 6" per revolution.  This engine turning 5000 RPM is at the 2,500 FPM industry-acceptable limit.  And with the precision manufacturing and materials of today's engines, these stresses are even more controlled.  An engine with a  2.75" (2-3/4") stroke can run over 5400 RPM to reach the 2500 FPM limit.  The stroke on the CH25 Kohler engines we maxed out is 2.64" which, at the 2500 FPM stress limit, is 5,681 RPM. 

   This applies not just to Kohler engines, but to all engines -- Tecumseh, Briggs & Stratton, Kawasaki, Honda, etc.

   Hope this helps. 

Rodney Rom 
Rom's Reworks 
Butler, MO

Driveline / Re: peerless 820 transaxle
« on: April 24, 2021, 01:54:25 pm »
   The aluminum Kohler 24 112 04-S Fan Spacer mentioned in the previous thread is shown in the below picture.  The pencil line is where I cut the spacer 3/16" from the shoulder.  When cut, the finished spacer dimensions are: 
1/4" (0.250") ID 
3/8" (0.375") small OD, 1/4" (0.250") long 
1/2" (0.500") large OD, 3/16" (0.187") long 
   If you are making your own spacer from scratch, you can make the large OD larger for more support, if you want. 

Rodney Rom 

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