why does an oval port have an advantage over a bridgeport motor for holeshot

[Hounddog]

Phill, there is nothing wrong with your answers. Pleasure boaters have different needs and don't think the same way as racers and racers don't always agree with each other.

[filthy phill]

How would you of answered each of those questions differently ?
Then I might be able to u derstand it from Your side.

[Hounddog]

As you study here are a few things to find out about.
- which is richer 100 to 1 or 50 to 1
- most commercial two stokes are premix, have lower compression and larger jets...why?
- if you have a direct oil injected 2 stoke and remove the oil injection what premix ratio should you use and should you change the jets.
- is it good that your two stroke starts with a puff of smoke?
- if you have too large a main jet what happens?
- does the idle change when you change to a larger main jet?
- should you change to a smaller main jet if the plugs are black?
- if you run race fuel do you run a smaller main jet?
- what causes the fuel lines to get hard?
- if you have a light white color plug reading with 50 to 1 premix what do you do to get it a bit brownish?

How would you of answered each of those questions differently ?
Then I might be able to u derstand it from Your side.

Racers are in competition with each other. They have a set of rules they must follow and a record book that shows best in their class. They all what to win and they are always looking for an edge over the competition. They spend hours working on getting the best performance and they are always rebuilding their motors. The motors have a very short life span. They don't care how it idles and how much smoke it makes. In circle and drag they only care about how quick an ET they can run. Competition is so tight at the top of the classes that it takes many small changes to be keep up with the top runners.
- to me 100 to 1 is richer. It has more gasoline in the mix
- commercial motors have to be more durable and have less parts that could fail. They run a lot of below normal octane fuel. Many racers prefer year old fuel in their low compression motors because they think that fuel gives bigger bang.
- on a direct crankcase oil injected motor, the amount of oil supplied by the system is far less than a premix, pure gas runs thru the carb, adding oil to the mix reduces the amount of gas i so I would initially run a larger jet.
- our motors smoke most of the time, at start up and on early acceleration.
- too large a carb can cause motor to bog off the line and have poor mid-range power
- idle goes up, doesn't matter , 1000 to 1500 idle is common and we do not shift.
- black plug colour is common because of idle to the pits.
- race fuel burns hotter, av gas burns cooler, many classes have spec fuel. Race gas sometimes works better with a smaller jet.
- I agree with you on the hard gas lines. ethanol and alcohol makes fuel line hard
- sometimes I will go 1 jet size larger or change the mix from 25 to 1 to 40 to one

[filthy phill]

there is no racers in Europe that would go anywhere near year old fuel, the gas is a joke here if a year old unless its sealed aviation fuel or sealed race fuel, but they would not do it by choice.
I understand the no shift due to a lot of racers running solid hub props.
I understand your black plugs because a lot of the race motors use a lot more oil than most recreation motors.

I was thinking of switching to 100LL to get fuel that is more consistent, but the price of it right now is a joke, its been heavily taxed and retails around £2.50 per litre, thats about
4 Canadian dollars a litre tat todays exchange rate...
might have to settle for shell vmax or Tesco 99. that will give me about 84 to 95 octane although here its called 99 octane ?????.

it would be a rise from say 89 octane to 95 octane , would this make any more power worth noticing ?

Like I say I am not after a full race motor that lasts a weekend, just chasing those few more revs. and trying to work out why some of these motors can rev to certain rpm without changing
out the electrics and raising the ports.

is there a variance in the oval ports actual exhaust port height and width and shape of different years or batches etc , mine is not a proper oval, its longer at the top than the bottom.

.