Heymow - Lawnmower Racing Forum

Engine Help => Kohler Engines => Topic started by: tractorbuds on November 14, 2013, 06:01:12 am

Title: Kohler Single 490cc Mild Build Help
Post by: tractorbuds on November 14, 2013, 06:01:12 am
Here's what I have. CV492S

MWSC: new style aluminum flywheel, springs, retainers, racing hyd lifters, copper gasket.

Going to run stock internals, fresh rings, valve job, clean up the head a bit, for a season and go from there.

I am wondering if I am better of running a small block head to increase compression or just shaving the existing head? If shaved, how much? If I do go with a long rod and piston combo next year, I don't want to find myself in a situation where the head has been shaved too much to handle the new displacement.

Also, I've been told not to exceed 6000 rpm on stock internals, what compression number should I be aiming for?

Finally, am I going to get away with running the stock carb, reworking fuelling, or am I better of switching to something else? Gotta stay on a budget though.

Thanks for your help. Just trying something different than B&S for the heck of it!

Title: Re: Kohler Single 490cc Mild Build Help
Post by: Burton for Certain on November 14, 2013, 10:26:11 am
Hydraulic lifters will keep it from going over 6,000. Weakest link is the cam if ya doing anything crazy with it. small block head is fine.  Find a carb off an old k series kohler single.
Title: Re: Kohler Single 490cc Mild Build Help
Post by: Cromwell C4 on November 14, 2013, 11:01:40 am
The stock balancer is also a weak point. Don't go any higher than 6k rpm with that in there, or it will be a time bomb for sure. Put the right parts in one of these and it will be a front runner.
Title: Re: Kohler Single 490cc Mild Build Help
Post by: tractorbuds on November 14, 2013, 05:26:14 pm
So use a small block head instead of shaving? Or, is one going to be way better than the other?

Also, on the K series carb, I assume I'm looking for one to gain fuel mixture adjustment? Is it a direct blt on?

Sorry for al the questions and thanks very much for your advice.

Rods, JR
Title: Re: Kohler Single 490cc Mild Build Help
Post by: Mowerstompin on November 15, 2013, 06:55:14 am
The carb you want is a kohler carter #30 off the kohler k series motors.
Title: Re: Kohler Single 490cc Mild Build Help
Post by: Cromwell C4 on November 15, 2013, 10:25:58 am
I would just use the head you have. Clean up the ports and do a really good valve job. And yes the #30 carb is the one to use. They can be hard to find but i was able to get a few new ones. 8) A Tillotson HR would be best but not sure if your rules allow that or what class you are building it for.
Title: Re: Kohler Single 490cc Mild Build Help
Post by: valleeracing on November 15, 2013, 01:37:03 pm
What are you guys doing to remove the balance shaft?
Title: Re: Kohler Single 490cc Mild Build Help
Post by: tractorbuds on November 15, 2013, 04:51:37 pm
I wasn't planning to do anything to the bottom end at all, just running stock internals with fresh rings. I realize I am going to have to watch how high I rev it, and I'll play it safe. We run the Honda too, really nice torque, so we don't have to get too concerned about making them scream.
Title: Re: Kohler Single 490cc Mild Build Help
Post by: tractorbuds on November 17, 2013, 07:11:23 am
Hey guys, what are your feelings about the aftermarket #30 carbs on ebay? Anyone tried these.....I have had my fair share of grief with old carbs, sinking time and money into them and unfortunately have nothing on the shelf to start with so I'm in a situation where I have to spend money. For my application, an $80 aftermarket carb is looking pretty intriguing. Your advice appreciated.
Title: Re: Kohler Single 490cc Mild Build Help
Post by: Jeff McKelroy on November 17, 2013, 09:02:45 pm
Hey guys, what are your feelings about the aftermarket #30 carbs on ebay? Anyone tried these.....I have had my fair share of grief with old carbs, sinking time and money into them and unfortunately have nothing on the shelf to start with so I'm in a situation where I have to spend money. For my application, an $80 aftermarket carb is looking pretty intriguing. Your advice appreciated.

No midrange for roundy-round.  for pulling, they work great.  I have two new ones, sans choke if you're still interested in one.
Title: Re: Kohler Single 490cc Mild Build Help
Post by: tractorbuds on November 17, 2013, 09:15:52 pm
I am running this old Walbro LUA carb from an Onan on my 35 ci Vanguard, a direct bolt on for horz application, simple mixture adjustment and I am half tempted to fab an intake a just try it on the Kohler.
Title: Re: Kohler Single 490cc Mild Build Help
Post by: Cromwell C4 on November 17, 2013, 10:06:14 pm
The OEM kohler #30 carbs work great for pulling and racing. That's what I would use if rules wouldn't allow a Tillotson.
Title: Re: Kohler Single 490cc Mild Build Help
Post by: tractorbuds on November 18, 2013, 01:53:56 am
OK. I'll get on the hunt for one.
Title: Re: Kohler Single 490cc Mild Build Help
Post by: tractorbuds on November 24, 2013, 08:44:49 pm
Hey guys, I suppose I can call MWSC, but what should I be torque ing the head to when using a copper gasket?
Title: Re: Kohler Single 490cc Mild Build Help
Post by: Burwell555 on November 25, 2013, 12:56:15 pm
Copper headgasket and fire ring from MWSC, 30 foot pounds