Lawn-Boy Model 'E' Twins (mockup)

[Russ2251]

Thanx for the tip

 

[oscaryu1]

Max RPM so far is 6314. Higher RPM are realized at cooler outdoor temps.
Am going to play with intake length. Carbs were originally bolted directly to reed plate, then I increased it (via aluminum spacer) and definitely helped. Will increase another half inch. I have to be careful as one of my other engines suffered from carburetor icing. Same thing that brings down airplanes. Have to find a happy medium.

Orly? Weird things on our little 2 smokes. Longer intake actually killed overall power and ~500RPMs less at WOT. It was a 3-4" manifold

Maybe do with the reed setup we [lack]?

 

[newrider3]

I'm guessing your problem was the drastic change in length. Something like Russ is talking about with a .5" change at a time would probably yield more predictable results.

 

[Russ2251]

Well...I replaced my 72 tooth driven sprocket to 69 teeth.
Got up to 49.6 MPH (6152 rpm) when chain flew apart.
Seems I forgot to tighten half of split sprocket. My bad.
Snapped 2 of 3 hub bolts and bent up sprocket pretty good...
Everything back in order now, but here is result. Note that master link held.

"A chain is no stronger than it's weakest link."

 

[Russ2251]

New speed record this AM.
I run out of asphalt REAL fast:

 

[Kaptain Krunch]

Just saw the last video. Sounds good. I've probably already asked you, but have you considered trying to make a set of tuned pipes? Would be no easy task, but im sure you could handle it.

 

[Russ2251]

I've probably already asked you, but have you considered trying to make a set of tuned pipes?

Almost everyone has asked.
GoKarts of old did not have them. Sound would be ruined.
Video does not do the 2 cycle rumble any justice...must be witnessed in person to be appreciated.

 

[Kaptain Krunch]

Nothin like a straight piped/open port two stroke. Doesnt look like she's lackin power anyways haha.

 

[Russ2251]

When I throw mufflers on them...I lose 5 to 8 MPH.
I'm tempted to run them straight ported as a test.
A couple times won't hurt...might have to richen the mix a little.
I want to break the 50 mph mark in the small straight run that I have...before I run out of space.

 

[Thunderbird SC]

The current max rpm of my piston ported 2 strokes that I play with is currently around 8,380 limited to mostly airflow restrictions which can be ported larger. Another is to change fuels and get an advance/retard key to really rev em up.

 

[justin86]

Another is to change fuels and get an advance/retard key to really rev em up.

How does the key work? do you have a part number for that?

 

[Jerryburger]

It would still be fun to see that thing topped out where it has room to go. That parking lot is so short. I thought AZ had good wide open spots, but this prairie area is nuts. Start shipping it and yourself out here.... it'll see the 60's EASY.

 

[Russ2251]

Hey Jerry...
Good to hear from you!!!

That parking lot is so short

Yup, I can just hit 50 MPH before I have to stand on the brake.
A co-worker just turned me onto an small abandoned airport that is about a 40 minute trip from my house. I'm going to check it out this weekend.
I just want to see where this thing tops out at.
I do not think it will make it past 55...still a far cry from where they stood as 3,000 rpm lawnmowers!!!

 

[Doc Sprocket]

Lookin' really good, Russ, that's a dang fine "experiment" you're running, there! Tell me, at around 01:55 in the vid, is that a jet passing overhead, or your SONIC BOOM finally catching up? Lawn Boy. No. Launch Boy! Nicely done.

 

[Russ2251]

Thanx for the kudos!!! I deserve them.

 

[Doc Sprocket]

...And humble, too! Yeah, you do. Cheers!

 

[Jerryburger]

Yeah- I'll bet you can top 65! If the LBs run outta breath too quickly gear it taller. Just like the Salt Flats!

 

[Russ2251]

If the LBs run outta breath too quickly gear it taller.

I hear ya'.
But I am a torque kinda' guy. I don't want to lose that.

 

[alfalfa]

Hey Jerry...
Good to hear from you!!!
Yup, I can just hit 50 MPH before I have to stand on the brake.
A co-worker just turned me onto an small abandoned airport that is about a 40 minute trip from my house. I'm going to check it out this weekend.
I just want to see where this thing tops out at.
I do not think it will make it past 55...still a far cry from where they stood as 3,000 rpm lawnmowers!!!

you talking about the coram airport, off of 25 by the car wash?

 

[Russ2251]

you talking about the coram airport, off of 25 by the car wash?

Nope...Calverton.
I have not been out there as yet. I miscalculated distance. Will take closer to an hour to get there from my pad.