Author Topic: 15.5 hp  (Read 5339 times)

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Offline bountyhunter

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15.5 hp
« on: October 06, 2008, 11:06:04 AM »
Guys are the 15.5 command ohv motors any good to build for oval racing.A friend wants me to help him build one but I said should ask you guys first to find out about them! whats there good points and bad to building one.and can they run with briggs 31 ohv singles?



Offline amcchevy1

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Re: 15.5 hp
« Reply #1 on: October 06, 2008, 11:11:13 AM »
i dont race one but kohlers are built good, just get pricey when you upgrade them. this may be why you see alot more people running briggs, as well as the shear availability of engines. theres not near as many kohlers to be had.
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Offline CaseRacer969

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Re: 15.5 hp
« Reply #2 on: October 06, 2008, 01:01:52 PM »
As far as OHV singles go, they are a good motor but I don't know of any aftermarket parts for them.  Briggs parts are readily available and there are some parts for the Tecumseh.  If you plan to modify the engine, will be much more expensive to have custom parts made and alot of R & D will be needed.

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Offline cycloneracer

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Re: 15.5 hp
« Reply #3 on: October 06, 2008, 05:34:54 PM »
Give this guy a call
http://www.recmotor.com/index.php

He has built a couple of kohlers here in Iowa.  One runs very well, and has many laps on it.

The other I got to see the inside of............................but it was though a couple of holes in the block!   It was driver error, no tach, to many RPM's.

Only drawback is I think they are VERY expensive to build compared to a briggs.

Paul

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Offline jim russell

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Re: 15.5 hp
« Reply #4 on: October 07, 2008, 05:14:46 AM »
they are a good motor. there is no aftermarket parts for them. the only thing i have found is lifters. i ran a stock one this past season good runner but just won't hold up with stock parts when you try to run alot of rpm's. briggs there alot more out there and the aftermaket parts are real easy to come by. the the parts are like starbucks you can find them on every corner.
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Offline Butcher

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Re: 15.5 hp
« Reply #5 on: October 07, 2008, 08:01:56 PM »
Strong motor up to 6500 with mild cam, stiffer springs, mild port, and stock 380 tilly. In stock form its a good balanced motor, I feel better than briggs. Have run stock rod in modified singles over 8500+. Never broke a stock rod or crank. Availability of race type parts are limited, light weight chevy sb valvetrain componets will interchange with slight tweeking along with other makes for most all internal parts. Take measures and compare!!

Offline bountyhunter

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Re: 15.5 hp
« Reply #6 on: October 08, 2008, 05:53:28 AM »
were can I get price on springs and cam. you say stock bottom end good to 8000. wow thats good news. what about flywheel?


Offline cycloneracer

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Re: 15.5 hp
« Reply #7 on: October 08, 2008, 06:38:18 AM »
were can I get price on springs and cam. you say stock bottom end good to 8000. wow thats good news. what about flywheel?


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Offline jim russell

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Re: 15.5 hp
« Reply #8 on: October 08, 2008, 06:42:18 AM »
WOW 8000 RPM I THINK I AM GOING TO RY MINE AGAIN AND SEE IF IT WILL HOLD IT. THE ONLY PLACE I HAVE FOUND A FLYWHEEL IS MIDWEST SUPER CUB. THEY HAVE AN ADJUSTABLE FLYWHEEL BUT THE TAPPER ON THE CRANK IS DIFFERANT TAPPER IS WHAT THEY TOLD ME. THE FLYWHEEL CAN BE MADE EASY. MY DAD IS A MACHINEST AND IS MAKING ONE FOR MINE
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Offline mowdak1

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Re: 15.5 hp
« Reply #9 on: October 08, 2008, 08:49:01 AM »
Have your dad make a functional Caps Lock key for your keyboard while he's at it. It is consider shouting to type in all capital letters on forums, and thus impolite to do so. Turn caps lock off, and use your shift key to appropriately capitalize letters as necessary. PLEASE!

Offline jim russell

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Re: 15.5 hp
« Reply #10 on: October 08, 2008, 08:57:56 AM »
Sorry for that. The programs at require everything to be in cap. So used to leaving it on>
sorry left out work
Jim

Offline Butcher

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Re: 15.5 hp
« Reply #11 on: October 09, 2008, 04:36:01 AM »
Call lakota or midwest on the springs(stick with single unless u have made a billit cam). Some kohlers I have found had lighter valves than others, this is important to use the lightest valvetrain parts that will hold up, and only just enough spring pressure to keep from floating valves at rpm u run. Kohlers valvetrain is nearly 2x the weight of briggs in stock form. When getting into higher rpm 6500+ we have ran into rapid wear on lifter base when using a welded lobe cam even with polished smooth sides, edges and surface of lobe. A fully roller valve train eliminates most wear, I would recommend the lightest adjustable pushrods you can find so u can adjust quickly without swapping fixed pushrods, different height perches, or different thicknes lashcaps when using stock rockers. A welded cam is a weak spot in higher rpm, have seen many break due to heavier valvetrain and spring pressure. I recommend making a billit blank and gear and have the profile u prefer ground. The midwest flywheel is for a twin, there are none off the shelf for a single that I know of. If making your own use a good grade of aluminum and the stronger magnet from midwest. "IF" you can use a handheld starter, ditch the ringgear.