B&S 49-series (810cm3/49ci) for aircraft use - TiPi's Q&A thread

Yep, many f us have slogged down the same trail, checking out alternatives. Also, the (smaller displacement) Kohler has a shipping weight of 151 lbs, vs the 101 lbs for the B&S 810. Now, much of that will be stripped off, but not all of it. Unless the Kohler box is very heavy, there's quite a weight difference.

 

The CH750 is about 4-5 kg heavier than the 49 (out of the box and stripped). I think the bulk of that is in the crankshaft (cast vs forged) and camshaft (cast vs built-up and sintered spoked gear).

 

There seems to be a LOT of weight in the flywheels. Even the billet aluminum numbers (ARC Racing) look to be about 7 lbs for this engine. If you skip the flywheel and the starter and went with a crank trigger ignition, lots of weight could be saved.

 

The starter and flywheel adds significant weight to a direct drive. I need a flywheel for my redrive to work. It will be hard to flip through the redrive.

 

you can keep the flywheel weight to a minimum by using alu for the adaptor and spider and place a steel ring as far out as is possible. The more radius you have, the less mass you need for the required rotational inertia.

 

That is why I have a car flexplate in my box of bits to use. 1/4 the weight of the original flywheel, 1/2 the inertia. I could do better with a custom one, but much harder than clickety-click on Amazon...

 

Nice, assuming they fit the starter pinion you've got. You can get bolt-on Briggs ring gears http://www.arcracing.com/6611gvg-arc-ring-gear-briggs-vanguard/ and steel flywheel hubs are only a click away. http://www.arcracing.com/6611hvg-arc-flywheel-hub-model-vg/ ARC steel. I thought I saw an aluminum hub yesterday, but it may have been a Kohler bit.

 

TiPi may have already answered this question, but FOR OUR PURPOSES, is there a worthwhile difference between the "Commercial Turf" and the "Vanguard" 810cc Briggs and Stratton engines? The big distributor I contacted was of little use, as is the Briggs web site.

49T877-0004-G1 27 hp 810cc Commercial Turf vs
49R977-0003-G1 26 hp Vanguard
Both have the 1-1/8 inch shaft. There ARE pretty obvious differences in the Air Cleaners, but we're going to strip that off anyway.

 

The Vanguards have chrome plated exhaust valves, upgraded piston rings. There may be other differences, TiPi gave a good breakdown by model number but the search function for HBA doesn't seem to be working for me right now.

Edited to add:
From a post by TiPi:

Here's the model # breakdown TiPi provided earlier in his "intro post":

Another TiPi post worth referencing for differences by model number:
Tipi post 730: Major part numbers cross-compare

 

Oh, and the Vanguard engines have a solenoid shift starter. The commercial series uses a larger unitary starter with Bendix gear.

 

thanx for this review!

 

Have you been out to Willowbank and seen the 'Dirt Kart' racers who's rules use these engines? They have a track (dirt) about halfway along that short road to the Willowbank Racetrack.

Lots of mods and valuable info to be had.

 

Two questions for TiPi about the oiling system:

1. Do you have any idea what Jan is using for an electric "priming" or "Pre-Oiling" pump? Small turbo scavenge pumps are out there at various price points, from about $50 for cheap Chinese gear pumps (link will die, but search "oil scavenge pump" https://www.ebay.com/itm/12V-Heavy-...-Gear-Pump-Scavenge-White-3-7GPM/123609634186), up to $200-$300 for decent looking US gear/georotor pumps http://www.rbracing-rsr.com/oilsystems.htm The Priming/Pre-oiling pump will be pumping COLD oil, so cheap diaphragm pumps might work as well.

2. I wondered if the Rotax sump tank could be used, until I priced one! Dedicated dry sump tanks are all over the internet, but they are almost universally too large (1 gallon and up). Did you fabricate the 2L tank depicted in your build thread? Would cheaper "breather" tanks work? http://www.jegs.com/i/Mishimoto/690/MMBCCMSTWOBK/10002/-1 many cheap Chinese copies out there. There are some larger ones as well. http://www.jegs.com/i/Moroso/710/85466/10002/-1 copies available as well.

 

I bought a used tank from a Polaris RZR. They are a little large (3.5 qt), but cheap used.

 

So the take away for me is that SOME modern ATV with 4 stroke engines have dry sumps. Good to know.

Buying used tanks off E-Bay looks tricky. ATVs are not thick on the ground where I live, so there is no EASY way to judge capacity/size. 2 quarts seem to be the smallest stock size. And it's hard to tell at first glance if an oil tank is for a 2-stroke oil injection system or a dry sump...

The larger displacement Yamaha Raptor, Honda FourTrax, previously mentioned Polaris RXR are some possible 4-cycle "donors" for tanks. Some ATVs use the frame as a tank (Kawasaki). And some machines (2013 and on RXR) have gone back to wet sumps...

 

If you know someone who can weld aluminum, a small dry-sump tank shouldn't be too hard to fabricate.
For 2 litres, you should be able to scrounge an offcut of large diameter tube as a starting point.

 

Think scuba tanks ..

I think they have use by dates on them too, not 100% sure on that though.

 

I looked for a looooooong time and finally found this design, suits my requirements perfectly (size, weight, number & location of threaded ports), and reasonably priced. The one I have bought is of good quality.

https://www.ebay.com.au/itm/Univers...e=STRK:MEBIDX:IT&_trksid=p2060353.m1438.l2649

 

it looks like a small in-line fuel pump (motorbike EFI), needs 2-3bar pressure and resistant to oil and temperature (still gets hot), also needs a built-in check valve. Plumbed from the sump to the pump outlet port through the pump cover.

 

The seller does not ship to USA, I asked if he would be willing to ship 10 at once.
JohnB