Vanguard Peformance Stages

[slonomo]

I've never seen anyone post with the performance mods in one thread for the Vanguard engines. Here's my attempt.

Please, if you have something to add that would benefit, please do. Let's keep this thread clean for reference. Thanks!

For reference: Stock Vanguard Vtwins operate at between 2000 rpm and 3600 rpm and are stock governed to run at max rpm of 3600 see graphs

[slonomo]

Briggs Vanguard Vtwin 479cc 12hp-14hp-16hp

Stage 1
*Rev Kit - spring shims or HD valve springs, spring keepers, stronger pushrods
*Governor bypass - allows full throttle action and higher rpm
*This allows the engine to rev safely up to 5000 rpm without valve-train damage

Stage 2 Adds
*Camshaft - Stock 23hp engine cam or Cheetah type cam
*Carb upgrade - 2 barrel carb conversion from larger Vanguard engines
*This gives more power over a wider range of rpm say 2500-5500.
*Stock 23hp engine cam is a direct replacement and slightly better than stock, some will advance this cam one tooth for better low end rpm power.
*Cheetah type cam has higher lift and duration profiles for higher rpm power.

Stage 3 Adds
*Head porting and polishing, port matching
*Mikuni 34mm VM carb upgrade
*This will allow more air flow, more fuel, and more power

Stage 4 Adds
*Billet connecting rods and pistons
*Billet flywheel
*Billet roller rocker arms
*Alternator upgrade, automotive style
*This allows the engine to be operated at higher rpm more reliably. The billet flywheel frees up power and will allow the engine to rev quicker.

[slonomo]

Briggs Vanguard Vtwin 570cc 18hp, and 627cc 21hp & 23hp

Stage 1
*Rev Kit - spring shims or HD valve springs, spring keepers, stronger pushrods
*Governor bypass - allows full throttle action and higher rpm
*This allows the engine to rev safely up to 5000 rpm without valve-train damage

Stage 2 Adds
*Camshaft - Cheetah type cam

Stage 3 Adds
*Head porting and polishing, port matching
*Mikuni 34mm VM carb upgrade
*This will allow more air flow, more fuel, and more power, better throttle action, and better idle over the stock 2 barrel carb setup.

Stage 4 Adds
*Billet connecting rods and pistons
*Billet flywheel
*Billet roller rocker arms
*Alternator upgrade, automotive style
*This allows the engine to be operated at higher rpm more reliably. The billet flywheel frees up power and will allow the engine to rev quicker.

[slonomo]

If anyone has part numbers and specs for the upgrades please post. Items like the 2 barrel intake, carb, spacers, elbow etc would be helpful.

[slonomo]

Some 479cc engines come with the updated aluminum rockers. I'm not sure on the years these were available, but taking off the valve covers will reveal if they are aluminum or steel. The aluminum ones are the preferred version if you can find them.

[slonomo]

Building an exhaust is also a challenge for golf cart engines. I prefer thick walled steel pipe, cutting into pieces and welding together. Mufflers are all over the board. I've used stock Briggs mufflers, ATV mufflers, and tractor mufflers. The one I ended up with is a straight through tractor muffler 1 3/4" from Tractor Supply. They are available everywhere for less than $50. Sound is stock ATV type decibel level, although I've never measured it. Not quiet, not loud.

There is a version of this same muffler for a "Thermo-king" APU semi truck generator that has more insulation and thicker walls that's supposed to be quieter. I have not used one yet, price is higher.

[slonomo]

Carb upgrades to Mikuni style carbs is tricky. The biggest challenge is finding an adapter that will allow the use of the motorcycle carbs.

Performance 670 has one for the HF670 engine that the bolt pattern matches the Vanguard 2 barrel intake. You can then mount a flange type carb mount and choose the carb of your liking.

This one is a 42mm CV type carb from a Yamaha ATV. It works fantastic. At the moment I am still tuning it and trying to get it to run leaner at idle. Jets are cheap, $6 each for genuine Mikuni. I bought an assortment and just keep trying different combinations until it runs better. Keeping track of jetting is vital, so keep a paper journal of all the changes you make and the results of each change.

Backwater Performance sells an adapter called "Black Death" specifically for the 2 barrel intake on the Vanguards. I will be reviewing this carb setup also. They recommend the Mikuni 34mm VM style carb. Their carb comes prejetted for the 23hp Vanguard.

[BIKERMIKEYBLACK]

My 18 has the aluminum rockers they are the old style

[slonomo]

So I went ahead and ordered the Mikuni VM34 kit from Backwater Performance. The carb comes pre-jetted for the 23hp Vanguard, according to their website. It's not really a kit, truth be told, it's just the parts separately. The kit they sell is for "mudboats" and has a bunch of parts I didn't need. See their website for parts and prices. Call them with questions and details, they were very nice to deal with. Maybe we can talk them into making a golf cart kit and becoming a sponsor?

Parts Shown:
*Carb VM34 Mikuni
*Black Death adapter/manifold
*Carb boot
*K&N air filter

[slonomo]

Mounted on 23hp Vanguard in Yamaha G1 cart. Note: not complete, still some loose ends to tie up.