14 hp Briggs, performance parts or replace?

[Roger S]

I guess we'll see what the "little engine that could" can do

Did you buy the longer rods or the standard length?

Did you talk about head work with George? If not I can line you out on some simple port cleanup and blending. Which head gaskets will you use? I have the 1 barrel carburetor off my 18 that's been rejetted I could sell.

If you end up tuning your clutches, I'd work on the engine clutch, not just the one on the trans. The max is different than the argo, but in general I had to lighten the weights in it to let the engine get up into it's rpm power range. IE, stock the CVT limited rpm to 3600 or so as it "geared up".

This little 14 will just be waking up at 3000, and will turn 6000 without breaking a sweat. In fact George has over revved his vanguards a couple times over 10,000.

Also, the cam, rods, valve train would all fit in an 18 for future endeavors.

PM me if you have any questions.

[james8719]

My machine is a Max II. I went with the standard length rods. The factory head gaskets are the thick ones so I am replacing them with the older style thin gaskets.

I didn't discuss head work with George. My lawnmower mechanic use to build and race jr dragsters with his kids and he is going to replace the parts for me. He said he was going to slick up the ports and brake some edges. He honed the cylinders, and refaced the valves and seats. He is only charging me $100 for all of this.

George told me about turning 10,000 rpm in a Vanguard. He said that I should be able to run 6,000 rpm for extended periods and hit 7,500 without hurting the engine.

I have not considered the torque converter or clutch. What should i do with them?

[Roger S]

You can try the clutches as is. It may have enough power to suit you without "re gearing" them. But the only time you'll see any higher rpm is after the machine has run out and continues on a longer straightaway. And you'd have to get a max clutch guy in here to tell you how to mod the engine clutch, as the weight mechanisms are different than the argo I played with.

Tell your mechanic to leave the D shape in the ports, he sounds competent..

A header and straight through muffer will help, sort of a time consuming ordeal for some of us. Whipper should have it down to a science for the max II, after his recent bout of perfectionism.

[jpswift1]

Im dont know very much about the weights in the drive clutch, but as far as the exhaust goes, take a look at this article published by forum member micmac. He did a really nice job making a dual exhaust set up on his Max IV with this "build it yourself" kit.

http://www.6x6world.com/forums/aatv-engine-articles/467-custom-exhaust-your-briggs-vanguard.html

[budresiew]

Watch those clutches. You know the Briggs model drive clutch on a Max is only rated for 5000rpm MAX! Ever see a drive clutch come apart at high RPM? I've seen it on my buddies snowmobile when we were running across a field. Not something you want to be around. You need to address the entire engine and clutch system when you're talking more hp and rpm.

[james8719]

Watch those clutches. You know the Briggs model drive clutch on a Max is only rated for 5000rpm MAX! Ever see a drive clutch come apart at high RPM? I've seen it on my buddies snowmobile when we were running across a field. Not something you want to be around. You need to address the entire engine and clutch system when you're talking more hp and rpm.

Do I need to have the drive clutches rebuilt or get the clutches from a 2 stroke?

[whipper-ag]

Watch those clutches. You know the Briggs model drive clutch on a Max is only rated for 5000rpm MAX! Ever see a drive clutch come apart at high RPM? I've seen it on my buddies snowmobile when we were running across a field. Not something you want to be around. You need to address the entire engine and clutch system when you're talking more hp and rpm.

Excede the max rpm on your drive clutch, and you will get to experence an IED without going to Iraq.My son and I were standing right next to it when I bliped the throttle on my 50 horse. It exploded!! I can't believe neither of us got hit by anything. We never did find all the parts. Be carfull!

Whipper

[whipper-ag]

I now run steel guards over all my clutches. I'll be working on Bridget's Max SS guard this week.

Whipper

[Roger S]

Aw, James, just fire it up and go. If you want more, do the torque converter spring change. Don't go over.. what.. 35 mph or so on the top end. hehe

Whipper bought an aftermarket clutch for his briggs/attex

[james8719]

Whipper, what make and model of drive clutch do use to handle the high rpm's? I have been looking at Comet industries web site, but they don't give a maximum rpm range.

Will the driven clutch be o.k. with the red spring?

[hydromike]

You can calibrate a Comet 102C quite easily, but I'm not sure the weight and spring combos will work with a 4-stroke application. Always remember that the driven clutch can be more deadly, especially since when the engine on a two stroke is cranking at 6000 rpm, the driven clutch is moving quite a bit faster. I honestly don't know how these things hold up. I run 3/16" thick steel for guards on both racers. I still get squeamish.

~m

[jpswift1]

Mike, I dont have mcuh experience with experimenting with clutches, but I have heard that the 102C Comet it quite popular among snowmobile racers just for the reason you mentioned, its ease to adjust/calibrate. The 102C is a pretty big clutch so make sure you have enough clearance between your engine shaft and tub. Also, I believe that the 102C along with most snowmobile 2 stroke clutches, it is only for a tapered shaft. Every Max model comes with a keyed shaft. Just something else to keep in mind. And as far as the guard that you have on the racer to prevent any potentially dangerous situations with your clutch system, I think that is a very good idea and Im not too sure if I feel that safe with that flimsy Ski-Doo guard that Im using on my racer......3/16" steel sounds much better.

You can calibrate a Comet 102C quite easily, but I'm not sure the weight and spring combos will work with a 4-stroke application. Always remember that the driven clutch can be more deadly, especially since when the engine on a two stroke is cranking at 6000 rpm, the driven clutch is moving quite a bit faster. I honestly don't know how these things hold up. I run 3/16" thick steel for guards on both racers. I still get squeamish.

~m

[james8719]

I spoke with Don Jackson at Comet Industries today. He suggested the 94c duster torque converter and the 90d driven clutch. He told me the 94c is good to 8500 rpm and is available for a 1" shaft. I think I have my torque converter issue solved.

[Roger S]

If $ is a factor, the stock clutches will be fine, unless you run it out on top end a long way. Otherwise a nice, adjustable, safe unit would be great to let the engine rev a little.

Your II is a lot lighter than my 8, but neither of us will be seeing the kind of rpm that George and company turn. Their vehicles are much lighter and less rolling resistance, and our engines aren't putting out what theirs are. And with a cvt, the engine rpm is locked to one speed. Like mine was at about <3500 or so. Getting it up about another 500-1000 will take advantage of the broader power curve. Mine runs between 3 and 4000 most of the time. Topped out on level ground, it's never seen over 6000.

Also, I guess you're doing the 2 steel pushrods, and thinning the flywheel key for advance?

[Meinfield]

James,
Don is a great resource; he helped me set up a Duster Drive and Driven clutch to replace the oem clutches on my hustler. I have been very happy with the set up. The driven unit has 6 different tension settings and the drive unit is easily adjustable by adding springs and weights. The only down side is that the driven unit is only available to fit a 30MM(tapered), 1" or 3/4" shaft. Buy the 3/4" and have a machine shop bore it and re-cut the 1/4" keyway to fit the 7/8" output shaft of your t-20.

eBay Motors: Comet 90D Driven Clutch 3/4" Bore, 1-3/16" 212299A NEW (item 200133929448 end time Jan-22-08 05:27:01 PST)

Comet 94C Duster Clutches
Good Luck!