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23 Vanguard, ARC rods, springs and flywheel, precision 355 cam. 16hp heads o-ringed with Al's Titanium valves, Arias pistons, 36mm Mikuni's and 285lbs compression. its in my pulling tractor now and is real hoot.
Been awhile since I've been back on the buggy, but i have done some mods that have seemed to help out with the RPMs only topping out at 4500.
First off, I installed the Al Hodges Cam and it feels really good. Went out to Pismo Dunes and it had no problems getting around. Only problem I had was it would seldomly bog down when I would hit a big whoop and buck the rear. Im thinking it was the Carb Float. I'll lower the float a bit and see if that helps.
I also took the Salsbury 1190 Primary clutch to QDS to see what they could do for it. I had the 1800 RPM springs and Roy set me up with a 2300 springs.
The new springs made a good difference on the take off Torque, I like it alot better but it still maxed out at WOT at 4600 rpm's.
I had a hard time finding out what vehicle my Secondary Clutch was from and the closest I found was the Polaris RZR 800, except mine has .875 shaft with Keyway. Polaris RZR has a tapered splined shaft. I couldn't find any vehicles that use a .875 straight shaft with keyway. So mine must have been Bored and Broached.
I couldn't find a matching colored spring on any of the charts either! So I took the spring to get a compression test at a local Valve shop.
It measured 80/120 and when I did the marker test on the Sheaves, it was maxing out the belt at 3500 RPMs. Which makes sense being that the stock governed engine was 3600 RPM's.
So I went on the EPI Springs sight and ordered a new Secondary spring for a RZR 800, Light Green 125/220.
Now it's starting to get up in the RPM's. Maxing out now at about 5000.
This is my first CVT tuning rig so Im not too familiar on how it should feel or what the Tach should be reading during quick acceleration. It'll jump up to about 4000rpm's until the speed catches up and then it will work its way up to 5000 rpms, which is right about where I run out of runway.
Watching Nubs Drag racing video, it looks like thats common for a CVT engine to jump up in RPM's until the speed catches up then it continues to rise. But I could be wrong.
Another thing I did was get rid of my Harbor Freight Compression Tester and borrow my Mechanic friends Professional tester to get a good reading.
Its reading 160/165.
I also did a Leak Down Test and it showed 20%. Im not sure if that is normal or if it should be exactly at 0.
I could hear a very slight leak at the exhaust Valves, which are set at .003
I could hear more air from the from inside the oil fill. The Piston rings im sure are still stock so they probably could use replacing.
Clip from Pismo, Before new Clutch springs
Last edited by Hollywoodc; 09-10-2014 at 04:49 AM.
Really! So is there still more room for me to play with the secondary Clutch springs to get some more RPM's out of it, or should I leave it as is to be on the safe side?
Im still running the stock Flywheel and connecting Rods.
The next mod Im going to do is remove the cast intake after the Carb, and make a more smooth flowing shorter one.
I found this post and link on another forum. It may be too good to be true!
Yet it is a Chromoly rod as compared to the weight of a billet Rod.
"hello all , just wanted to pass on info on how to turbocharge the Briggs & Stratton big block 993cc v-twin producing roughly 100hp, And actually INCREASE durability (compared to stock engine) .
The weak point of briggs/kohler engines is there rods & pistons ( pistons are like paper?)
aliexpress.com store 722508 W9689 pindustry sells forged 4340 Chrome moly connecting rods(h type) for the 35hp 993cc Briggs vanguard V-twin for only 60$ a piece . The are rated for 1000hp so theres no way your snapping a rod LOL , . Performance vtwins sells Arias forged pistons for roughly 235$ pair and ecotrons.com sell small ihi turbochargers for 400$ complete all inclusive kit , oil cooler plumbng ect and precisioncams.com sells racing camshafts for 200$ . if you want to go nuts precision cams also has worked heads for the 993cc(35hp ) brigs big block v-twin for roughly 400$ . That will push hp up to 125hp at only 5500RPM . if you look around you can get a new 993cc big block briggs vanguard v-twin for roughly 1700$ so for about 2100-2500$ you will have a 100hp or 125hp engine that is BETTER than stock and an easy build .
I have seen them pushed up to 140/150hp in drag racing but the blocks crack over time . ( briggs/kohler engines use LOW grade metal hence 1700$ for new engine... high grade metallurgy pushes cost up = 8000-9000$ motorcycle engines ) BUT at 100/125 hp they last 20,000 miles . Why spend all the money to bore/stroke enigines and use high compression which costs$$$ when this set up is SO much more economical"
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