Lawn-Boy Model 'E' Twins (mockup)

[Rickracer]

If you got two more of those megaphones and welded the big ends together, you'd have expansion chambers, I guarantee you would pick up some power and lose some noise.

 

[Russ2251]

...and welded the big ends together, you'd have expansion chambers...

Not quite that simple. Requires a lot of math to get them right. Thanx for the idea.

 

[jr dragster T]

Nice work Russ. One question, How did you attach the pipe thread to the megaphone?

 

[Russ2251]

How did you attach the pipe thread to the megaphone?

Interference fit with aid of an arbor press. Same for exhaust flange for fitment to pipe and exhaust port.

 

[oscaryu1]

That's one beautiful setup ya got there Russ...

 

[Russ2251]

Youtube Lawn-Boy Twins

That's one beautiful setup ya got there...

Thanx.
Here's a short vid.http://www.youtube.com/watch?v=HQrBnmBh4wY

 

[Kaptain Krunch]

Holy Shnit that things got much better acceleration than i would ever imagine a centrifugal clutch could give.

Very cool.

 

[EagleTalons]

Looks like a blast to run! It would need to be a little longer for me to ride. :arf:

 

[Russ2251]

...that things got much better acceleration than i would ever imagine a centrifugal clutch could give.

They (clutches) don't ever get hot either...even with single engine.
Different story with drum brake. Gets almost too hot to touch.

Very cool

Thanx.

 

[Russ2251]

It would need to be a little longer for me to ride.

I'm 5' 10" and fit quite comfortably. Good thing as I do not want to destroy the original intended frame geometry.

 

[Kaptain Krunch]

They (clutches) don't ever get hot either...even with single engine.
Different story with drum brake. Gets almost too hot to touch.
Thanx.

I think i've said this before, but i have that same frame, well its not the same anymore, its 2ft longer and has a motorcycle engine in it (not done yet). Anyways, the drum brake got very hot in mine also, as did the clutch. What gear ratio are you running? and what kind of rpm do you think those lawnboys reach?

 

[Russ2251]

What gear ratio are you running?

17 tooth Noram clutch and 72 tooth driven which equates to 4.23:1. A bit steep, but does pretty well.

...what kind of rpm do you think those lawnboys reach?

Unknown. Tiny-tach indicates 5,852 rpm under load. I believe these engines to be capable of something more than that.
I do not wish to do irreversible mods to these power plants (such as porting), but am planning on replacing reed valves as suggested by Crazycart as posted in this thread starting with post #18.

 

[jr dragster T]

Really cool kart Russ! We need to race!

 

[Russ2251]

We need to race!

As I told Ironman (iirc), it would not be a race.

 

[jr dragster T]

Why would it not be a race? In the 1/8 mile your going to run out of gear pretty fast while my motor will still be pulling while the CVT clutch shifts.

 

[Rickracer]

No matter who wins, I get to take on the winner,

 

[Kaptain Krunch]

No matter who wins, I get to take on the winner,

Then i'll take you when my karts done. Although yours is prolly faster anyways...

Russ,

I've heard lots of good things about the Noram clutches, the one i had was a very cheap comet. Paying more than $30 for a centrifugal clutch just didnt seem worth it to me.

I'm not sure if you've seen it before, but i used to have the link to a site where you could calculate the dimensions for an expansion pipe. It seemed fairly complicated, but i think it would be worth it.

 

[Rickracer]

I just threw one together for my grandson's pocket bike from an old driveshaft I cut up, (yep, that looks about right, ), and it made about an 8mph difference, even though I added a muffler to keep the neighborhood happy.

If everything goes according to plan, I'll have it at the 1/8 mile dragstrip this coming Friday night, so I'll know just how quick it goes in a straight line.

 

[kitcarguy]

I will be sure to bring the video camera to work that day rick...haha.

If you do get out to the track come up to the tower and say hello

 

[Russ2251]

while the CVT clutch shifts

I do not wish to use a CVT so it would not be a fair comparison. I prefer the old school approach.
All things being equal...you wouldn't stand a chance.
Out of the box, Lawn-boy's will outlast/outperform anything (equivalently sized) China has to offer.
Take a look at what it cost you to "soup up" your clone.
All I did was add a $30.00 NOS carb and remove head gasket for more compression and voila...clone killer.