NRG 140cc twin engine in progress.

speaking of twin engines:
http://www.suzuki-gt.co.uk/images/R...ision The X14-Motorcycle Mechanics Nov 83.pdf

 

Just finished a 172 twin it's savage racing it this weekend

 

nice! lot of hours work? did you sleeve a peice between the cranks and then weld them? i love stuff like this! is it road legal too?

 

also good luck with racing this weekend! what class you running?

 

Pressed together then welded easy to do now got it figured good

 

do you have a crank key type thing to keep it in place?

 

It's welded and pressed in to crank web
Pic of new crank bearings we run now

 

Are you running 2 ignition coils on the stator plate?

 

I got the twin back from PSN scooters today, they've had it for a few weeks to give it a shake down (damn good thrashing). Anyway Andy set the carbs up, transmission etc and it's still in one piece (crank joint etc) so can't be bad! Running 20.8 hp but on std carbs so pretty pleased. I'll need to fit a new drive belt /clutch as it tops out just over 60mph, getting there slowly.

 

I took the twin out for a little spin, it's "light switch" power, may need to up the roller weight to make it easier to ride on the road!

 

I like binary power, it's a bit like the old Yamaha 2-strokes from the '70s, nothing until about 9000RPM, then BAM!

 

oh my god. I love it. Awesome project!

 

With regards to running a 2-1 expansion chamber, I dont think it can be possible, I briefly studied expansion chambers as part of my acoustics module this year for presentation idea's. when a 2t engine fires, it sends out a positive wave of pressure, when this wave gets into the chamber it expands, upon reaching the end of the chamber this wave will bounce back in the opposite direction (thus becoming negative pressure), at the same time the motor will be scavenging, which helps this negative pressure get sucked backwards towards the engine, taking with it some unburnt fuel back into the cylinder.

If we had a single expansion chamber serving each cylinder then i could only imagine that the positive wave of pressure from cylinder 2 will intefere with the returning negative wave from cylinder one when they collide with each other, usually in physics, when identical positive and negative pressure waves collide they will simply cancel each other out and there will be no wave left at all, which could well happen in this case.

2-1 systems do exist for 2t motors as mentioned in an earlier post, but I dont think they would be expansion chamber exhausts.

edit: http://advrider.com/index.php?threads/multicylinder-2-stroke-into-one-expansion-chamber.758526/ ive just come accross this thread on my travels, so it does infact work, how it performs though i cannot say.

 

twin pipes will be better, what about a quad pipe? 1 into 2 each side? should maintain the back pressure i think

 

I started the twin up a couple of months ago! That's about it.

 

This is now for sale !!

 

Any pics of the finished article?

 

It's on the Bay but I'll see what I can do !

 

Found it! Very interesting... reasonable price too

 

How much did you sell it for marsh?