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Twin kohler questioms

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Hi All.

I am wanting information on a 1979 to 1980 twin kohler engines. Are there problems with these engines? 

Like governors rods breaking or blown engines. Anything like to know.

Thanks

Bill

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Some of the best information on Kohler Twins can be found on Brian Miller's website.

http://gardentractorpullingtips.com/a1miller.htm

These are the things that can be done to virtually any flathead twin cylinder engine to gain more power and torque:

spec over 24300  Series 2 Full pressure oiling system.

1.     Check that the cylinder walls are in good condition and not severely scored or worn. If they're in good condition, deglaze them, and if the pistons are reusable, install new piston rings.

2.     If it's a Kohler engine model KT17 Series II, KT19 Series II, M18 or M20, leave out the cylinder-to-crankcase gaskets and apply Clear RTV Silicone Adhesive Sealant instead. Doing this should allow the pistons to come approximately .030" closer to the top of the cylinders, increasing the compression ratio slightly. By the way - I've always preferred to use Clear RTV Silicone Adhesive Sealant for three reasons: Due to metal warpage (which is unavoidable in most cases), gaskets don't always seal the irregularities and imperfections between mating surfaces, especially thin metal covers; being it's an adhesive, it bonds parts together, forming a leak-proof seal; and being it's clear, a thin bead of silicone makes for a clean and professional-looking repair job. It can't be easily seen or noticed between the parts.

3.     Perform a professional valve job. If it isn't already, regrind the intake valve faces and seats at a 30°/31° angles, respectively, and regrind the exhaust valve faces and seats a 45°/46° angles, respectively.

4.     Set the valve clearances at .006" for the intake valves and .010" for the exhaust valves.

5.     Resurface the cylinder heads on a wide flat sanding belt or large diameter disc sander to remove warpage and restore flatness, and to ensure proper head gasket sealing.

6.     In each cylinder head, relocate tip of spark plug closer to exhaust valve. To do this, weld up the spark plug hole, bore an angled hole toward the exhaust valve, then cut threads and mill seat area able for installation of the spark plug.

7.     Use full synthetic 10W40 motor oil. Full synthetic oil don't get hot like conventional (petroleum-based) oils do. It's more slippery and remains cooler even after the engine has been in operation for several hours to better protect internal parts for longer engine life. And I don't think it matters which brand of synthetic oil to use, because they all pretty much do the same thing.


Information About the Kohler Engine Models KT17, KT19, KT21, and KT17 Series II and KT19 Series II Oiling Systems -

Kohler engine models KT17, KT17 Series II, KT19, KT19 Series II, and KT21 (snowmobile engine) all have a gear-driven gerotor oil pump, and use one of two types of pressurized lubrication systems.

The first design KT17, KT19 and KT21 engines use a pressurized SPRAY lubrication system. The oil pump delivers oil to the main bearings and camshaft bearings at approximately 5 PSI. Lubrication for the connecting rod journals is provided by oil sprayed from two small holes drilled in the camshaft in alignment with the connecting rods. The main bearings are under pressurized oil, but the connecting rod journals receive oil that's constantly sprayed through drilled holes in an oil passageway in the camshaft. If the wrong velocity of oil is used, or if the main bearings are worn, this will lower the oil pressure in the camshaft, and the pressurized spray lubrication system could cause insufficient oiling to the rod journals, especially the #1 rod (one closest to the flywheel), which will eventually lead to connecting rod failure. What causes the rod failure is if the motor oil isn't changed on a regular basis (once a year or every 25 hours of run time) and/or using non-detergent motor oil, being there's no oil filter for these engines, normal metallic wear fragments in the oil grind away at the  main bearings and crankshaft main journals, especially the rear main bearing and journal. This increases the oil clearance between the bearing and journal (oil clearance should be .0013"-.0033"), resulting in excessive oil drainback into the crankcase and providing insufficient oil flow and pressure through the camshaft (again, there is only 5 PSI oil pressure in these engines), which allows less oil sprayed on the connecting rods. This is why the design was changed to a full pressure lubrication system as explained below Ê. When rebuilding either engine, the main bearings should replaced with new ones and the crankshaft main journals (and perhaps rod journals, too) should be reground if worn beyond OEM Kohler specifications. If the crankshaft main journals are worn beyond specifications, the main journals can be reground to .010" or .020" undersize, and matching undersize main bearings will need to be installed. The rod journals can only be reground to .010" undersize, and .010" undersize rods will need to be used. In most cases, it's cost-prohibitive to have a worn or heavily scored crank journal welded up and reground back to STD size. Also, on these engines, one main journal can be reground undersize if it's worn beyond specifications (mostly likely the PTO end), and the other (most likely the flywheel end) can remain STD size if it's within specifications. But if the engine has an oil filter and if the oil is changed regularly, it's less likely that the crankshaft main journals and main bearings will not wear beyond specifications.

The reason Kohler didn't provide provisions for an oil filter on the first design KT17 and KT19 engines is because again, being these engines only produce 5 PSI oil pressure, there wouldn't be enough oil pressure to pump through the filter and then to the main bearings and spray on the rods. Also, being there's no provision (port) on the engine block for an oil filter to filter out contaminants from the crankcase oil, it'll be a good idea to glue a small rare earth/neodymium magnet to the inside bottom of the engine block to attract steel or cast iron metal wear fragments for continued full oil pressure and longer engine life. Sometimes some of the wear fragments do not drain out with the oil when performing an oil change, even when the oil is hot. The crankcase oil should be changed once a year or every 25 hours of run time. Be sure to use high quality 10W30 or 10W40 motor oil, too. The first design KT17 and KT19 are a very good engines and should last a long time, only if high quality motor oil is used, and the crankcase oil is changed on a regular basis and/or using non-detergent motor oil! Fresh high detergent motor oil containing a high zinc content anti-wear additive, such as ZDDP(Zinc dithiophosphate) is cheaper than a new engine or an engine rebuild.

The redesigned KT17 Series II and KT19 Series II (including all Magnum twin cylinder engines) have a full pressure lubrication system, much like in a modern-day automobile engine. The Full Pressure Lubrication System delivers oil to the crankshaft bearings, camshaft journals, and connecting rod journals at approximately 25-50 PSI. A spring-loaded pressure relief valve, located in the engine crankcase, behind the closure plate, regulates and limits the maximum oil pressure in the system. The crankshaft is cross-drilled for oil passages from the main journals to the connecting rod journals, and both the main bearings and connecting rod bearing surfaces receive full lubrication from an oil passageway in the block through the crankshaft. Oil does not spray out of the camshaft onto the connecting rods in the KT17 Series II, KT19 Series II and all Magnum twin cylinder engines. If there's no oil filter on a KT17 Series II, KT19 Series II or any Magnum twin cylinder engine (oil adapter port blocked off), it's still important to change the oil on a regular basis with these engines, too. Again, fresh oil is cheaper than an engine or engine rebuild. The first design KT17 and KT19, and the KT17 Series II and KT19 Series II engines look pretty much the same on the outside, except the first design KT17 and KT19 engine blocks have no provision (port) for an oil filter and no port to connect an oil pressure light or mechanical oil gauge. Another way to tell which engine is which (without completely disassembling the engine to see the crankshaft and camshaft for oil holes) is by the engine specification numbers. The specification numbers follows the engine model number on the affixed sticker or label. The specification numbers for the first design KT17 engines are 24299 and lower. The specification numbers for the KT17 Series II engines are 24300 and higher. The specification numbers for the first design KT19 are 49199 and lower. The specification numbers for the KT19 Series II are 49400 and higher. KT21 engines - All specification numbers (32120-32148).


FYI- Boring the cylinders to a maximum of .030" and installing .030" oversize pistons and rings will not help to increase the power much at all. It'll only add about 1/10th of a horsepower with virtually no increase in torque. What increases engine torque substantially is giving the engine a longer stroke. (Click here for an explanation of why a longer stroke works better.) But these engines isn't capable of this.

Nothing else may be needed to be done to the engine, except for perhaps perform a professional tune-up. Or better yet, install electronic ignition. Also, many twin cylinder engines have inadequate valve clearances and this robs the engine of proper operation and valuable power. Set the valve clearances at .006" for the intake and .010" for the exhaust. After performing the tune-up and resetting the valve clearances, the engine should start quicker, idle better, accelerate with less hesitation and produce more power and torque at any RPM.

To perform a professional valve job on a twin cylinder flathead B&S or Kohler engine, the parts that will be needed are: two head gaskets, two crankcase breather gaskets, intake manifold mounting gaskets and valve stem seals (for intake valves only). New valve guides, especially for the exhaust valves, may also be needed. But that's to be determined once the valves are removed. A quality-made valve spring compressor tool is required to remove and reinstall the valves. The valve faces and valve seats angles are to be reground or recut at 45° (intake valve face for Kohler), 30° (intake valve face for B&S) and 46° (intake and exhaust seats for Kohler and exhaust seat only for B&S), 31° (intake seat for B&S), respectively. If you can't do this yourself, a local automotive machine shop can do it for you. You'll need to take the engine or tractor to the shop to have the valve seats reground or recut. Make sure they're reground or recut at the proper angle, too! And it'll be a good idea to have both cylinder heads resurfaced on a wide flat sanding belt or large diameter disc sander to remove warpage and restore flatness, and to ensure proper head gasket sealing. The head bolts can be reused. They rarely go bad.

And I wouldn't recommend using a cast iron block Kohler flathead engine on a motorcycle or any lightweight recreational vehicle. For reasons being, not only is the Kohler engines made of cast iron, which is extremely heavy compared to an aluminum block [V-twin or motorcycle] engine, the cast iron block Kohler are also flathead engines. They're designed for torque, or lugging power, and even if built to the max, a Kohler flathead would be VERY sluggish upon take-off and lack adequate power when accelerated, especially on hills. The vehicle would have to be geared so low, it wouldn't be any fun enjoyment or for practical use. This is why all (newer) motorcycles, ATVs, and other lightweight recreational vehicle engines have a short stroke (for speed), made of aluminum, with an OHV design, to be quick, lightweight and produce lots of power. Top of page


How to Convert a Kohler Command Pro V-Twin Vertical Shaft Engine into a Horizontal Shaft Engine -

FYI - Some people confuse a vertical shaft engine with a horizontal shaft engine, and vice-verse. They think being the piston travels vertically (side to side ó) or horizontally (up and down ô), that it's a vertical or horizontal shaft engine. But it's the position of the crankshaft that determines if it's a vertical or horizontal shaft engine. This is why they're called a vertical SHAFT engine and horizontal SHAFT engine. Otherwise, they would be called a vertical piston engine and horizontal piston engine, which is the wrong terminology. Anyway, the parts needed to convert a Kohler Command Pro V-Twin vertical shaft engine into a horizontal shaft engine are as follows. The parts below Ê must come off a horizontal shaft Kohler Command Pro V-Twin engine.

  • Drill the oil drain-back holes in the corners of the cylinder heads near the valve train so the oil can drain back down in the oil pan.
  • The oil pump must be changed (pickup tubes are different).
  • The vertical shaft engine has no horizontal mounting holes on the block. (They are on the sump cover.) So a couple of L-shaped engine mounting plates must be fabricated to convert the block into a horizontal shaft and mount the engine in the tractor frame.
  • Various holes in the block must be blocked off (drain holes are different, etc).
  • The intake manifold, throttle linkage and carburetor will also need to be swapped.
  • Everything else on the engine should work with no modifications. The PTO end of the crankshaft will be a little long, being it's made for a vertical shaft engine. But it'll still work just fine in the horizontal position.

FYI - The big price difference in horizontal vs vertical shaft engines is based on supply and demand. Equipment that require a vertical shaft engine are more plentiful, such as lawn mowers, riding mowers, etc. Therefore, whenever small engine equipment use a vertical shaft engine, this brings down the cost of production of the engine. Equipment that require a horizontal shaft engine are rare (nowadays). Therefore, the price on these engines are higher. Some manufacturers convert their products, such as logsplitters, for use with a vertical shaft engine. This allow them to sell their equipment at a lower price, due to the lower cost engine.

By the way - I don't build high performance V-twin engines and I know very little how to improve the performance of them because no one here in Missouri pulls them. The only contacts I have concerning V-twin engine builders and high performance parts are listed below Ê. Contact them and perhaps they can help you.

  • Al Hodge Performance V-Twins of Monroe, NC. He modifies the Briggs & Stratton Vanguard V-twins for all types of racing and performance applications. Output ranges from 25 to 42hp. Modified engine weight is around 80 lbs. He supplies engines for some of the fastest Cushmans in the National Champion lawn mower racers, tractor pullers, Class Champion scale sprint cars, ATV's, hunting boat upgrades, etc. All of his engines are non-governed and include solenoid shift, high torque starters. Sorry, he doesn't have a manual or any printed literature....he offers cams, billet rods, high compression pistons, mega-valve machine ported heads, titanium valves, rev-kits, roller rockers, billet push rods, billet rocker covers, stroker kits, etc. Give Al a call @ 704-291-7825 Monday thru Friday 10:00 am until 4:00 pm EST. E-mail: pki@trellis.net.
  • R.P.M. - Rader Performance Motors When Performance Counts, Count on Rader Performance Motors! Services Include: Complete Engine Building - Stock, Stock-Altered and Kohler V-Twins Custom Flow Bench Water Brake Dyno Tuning = Maximum Horsepower Dyno Tested, Track Proven Performance Contact: Mark Rader of Pataskala, OH | Phone: 740-927-3312 | E-mail:RPMark@sprintmail.com.
  • Frank Edwards of Galax, VA. Kawasaki water cooled V-Twin garden tractor high performance. Selling performance parts and building complete pulling engines. Call for details. 276-236-5305. E-mail:sdrawde@ntelos.net.
  • Lakota Racing ( http://www.lakotaracing.com/ )
  • Midwest Super Cub ( http://www.midwestsupercub.net/ )

Performance V-Twins ( http://www.performancevtwins.com/ )

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