16 HP vanguard needs better fuel

[Cdwamsley]

I have found my Vanguard 16 HP doesn't like the regular 87 octane fuel. It surges and runs rough on it. I put octane boost or seafoam in the fuel and problem solved. Has anyone else experienced this? It may be the ethanol

[jpswift1]

I have found my Vanguard 16 HP doesn't like the regular 87 octane fuel. It surges and runs rough on it. I put octane boost or seafoam in the fuel and problem solved. Has anyone else experienced this? It may be the ethanol

it could be the Ethanol. I hate that crap. All of my small engine machines from my 6 wheelers to lawnmowers to my motorcycles don't like it. There was a directory of each state and the gas stations that sell Ethanol free gas. A Google search might turn up something, but I can't remember it off the top of my head.

[Nubs]

Yep, Ethanol added fuel and small engines that sit for a month er' longer will have problems.

[Toys4Me]

I mix seafoam and that's all I put in my AATV's. Doing this I haven't had any issues yet.

[Noel Woods]

I use at least mid grade gas, use seafoam, replace plugs yearly, etc., I also run my machines once every week or so just to get them up to operating temperature and burn some fuel through the carbs. When they are home, I keep a couple gallons in the tank, run them for awhile, then add some fresh fuel to the tank as well.

Marinas are also a good place to get non ethanol fuel, you will pay more $$$$ but as little as amphibs use, well worth it. I've also found some gas stations that sell the non ethanol fuel nearby.

[Tomo]

Hi ,
Although sea foam and higher quality gas can make up for the issues of a vanguard engine there are other issues to check also.
The better gas and sea foam can hide/mask other issues
This is not to alarm people but just to make u aware ,as follows Basically the engines cannot suck well enough when they get a little aged
When the engine cannot suck the amount of fuel it requires it will flat spot ,surge ,hesitate ,can require more choke [adds fuel]
A compression check will be 130psi at cranking ok but A COMPRESSION CHECK WILL NOT ALWAYS DETECT THIS
Do a leak down check and u will find air leaking past the rings.[listen at breather /oil filler ]
Why u ask? the factory v twin briggs vanguard top ring is pathetic together with a very poor hone cross hatch in the bore
Recommend to hone in a machine shop hone machine to get the job 100%
In summary the gas v twin vanguard engine blocks are made by MITSUBISHI in Japan and the remainder bolt on parts are made by the cheapest bidder Typically China but have found USA and Japan parts also
The top ring has has a very shallow depth
The top piston ring groove is pathetic also and does not hold the ring well at all

tomo

[Nubs]

I handle and build Briggs Vanguards every season for My toys and I'm yet to see any of the problems with ring or piston design that leads to poor performance. I would be very interested in any links and or pictures that support this last post

[Tomo]

HI Nubs
I am talking factory stock pistons and rings .
When u have built many of these engines including different brands kohler etc plus other full size industrial machinery experience tells me even after a quick glance that the top ring is pathetic . The top ring is typically the same or very close to the second in size and fit . Of course the factory ring will seal but not for long compared to a full width ring . The piston does not need to hold onto the ring very well but it will still seal but not for as long as a better designed piston .The main reason for the smaller depth top ring is to allow for the piston dish .It needs material to keep it together . When a ring is not held properly it causes ring flutter [form of vibration ] The only advantage of the narrow top ring is the less drag at high rpm .A horsepower increase may be achieved
Vanguards are similar to kohlers they all have design flaws
eg the lifter head needs to be bigger in a vanguard to allow for more aggressive lift or at least the same then as a kohler
This is not my opinion this is what I have seen during my day job
eg after sending the block to the machine shop the cross hatch patterns last a lot longer than the factory patterns [operational machine hours ]
eg kohler vtwins 25hp were specifying cross hatch at 33 degrees . This does wear out rings badlyand and causes oil consumption . Rehone at 45 degrees cross hatch and new after market rings = no more issues
Always hone air cooled engine in a honing machine for best results . The bores distort from heat so the best sealing is needed
tomo

[Cdwamsley]

Thanks guys, this has been an educational thread, I guess for now I will run better fuel, and when it looses so much power it won't pull my fat butt I will look into a rebuild.

[Nubs]

Switching out to better fuel will solve the only problem your facing now and down the road