Topic: Anybody else weigh their bike???

[Geeto67]

Hi Dannie
     I have seen it done! It does work!
     A single expansion chamber for each cylinder is better.
          TomC

The kawi triple is a two stroke a 3 into 1 will not work. Dannie

yes there have been 3 into 1 expansion chambers for motorcycles and snowmobiles. Their usefulness depends a lot on the engine layout and porting. Lots of snowmobiles do very well with them. They were made for kawasaki triples in the 70s but are largely considered junk because they give the worst performance (worse than stock pipes - but ironically they are the best sounding pipes). Some guys with suzuki GT750s have found that they work ok with their bikes. They are really not as efficient as a decent set of individual expansion chambers.

[CrisPDuk]

The kawi triple is a two stroke a 3 into 1 will not work. Dannie

didnt know that 2 strokes had to have an exhaust for each cylinder .. any reference to good articles or sources on 2 stroke tuning .. am looking to get an RD350 project next season ..

Stan Stephens is the man for UK two stroke tuning

Don't know about the rest of the world, but there must be some good ones here in Thailand. The locals on their scooters could give a 125 GP rider a run for his money

[wardmoto]

ditto on the damper....especially with the diet.  If you removed it, "head shake" would mean the same thing as "dear Jesus my lord and saviour, I just s**t my pants because my throttle deflection angle factored with my rake and trail numbers has elicited a DEFCON 5 response with respect to my sphincter and my underware...can you help me Jesus??"  That my friends, is what you call an analogy!  Picture this....(sorry, not a Honda SOHC story) I am on my Suzuki SV 1000S (71 ftlbs/116rear wheel hp) I exit a favorite 3rd gear right hander that opens up to nothing but fenced farm pasture.  If I stretch the throttle cable, I will see 5th gear and the crest of a small hill at an indicated (not accurate as I have done gearing changes) 105mph.  The Suzuki might as well be a diesel as it pulls like a freight train from 1 rpm to 9500 (despite 11k plus redline).  At the crest of the hill, I am not at peak torque or hp  or at WFo, but I know if I don't crawl on the tank Like Mick Doohan, I am done for.  Despite my efforts, the front end flails and flops until it rejoins earth and its oscillations get turned into heat in my steering damper!!  I go back as often as I can!  Also, I know it is beyond the scope of most of our machines, but the 50/50 weight distribution is a car thing.  Bikes are an engineering enigma..read MOTO GP Technology...you will be in amazed at the lengths they go to to get the optimal balance, and how important it is.  Just ask Aprilia and Kawasaki!!!

[grumburg]

I thought about just getting one scale, but got caught up in the moment and bought two.  I'll have to double check the weights with one and see what I get.  Gravity is gravity, right?

Dammit, what am I going to do with that extra scale now? 

How 'bout I give it to my wife for Valentine's day?  Women like gifts like that right?

All you need to do is explain the black tire track

[vintage_racer]

This one must be around 350lb

[Geeto67]

it is a 550 so you are not saddled with the extra weight of an external oil tank and lines. It doesn't surprise me that you can get a shared case SOHC down to 350lbs or even lighter. It is the 750 that is a pig even on a diet.

BTW to put this in perspective - a Ducati Sport 1000 sportclassic is 394lbs and 92hp. If you can get a street cb750 down to 390lbs and close to the same hp, you'd have an interesting race. You'd also eat thruxtons for breakfast at 451 lbs and 69 hp.

Are Comstars lighter than spoked rims?

[vintage_racer]

Don't know much about Comstars, I'm using aluminum rims on stock hubs but the wheels are still quite heavy comparing to modern stuff.
I also removed the generator and now runnig a total loss system (have to charge the battery every evening).
Since the pictures were taken I also removed the front fender and installing 1 1lb fiberglass pice.
The 4->1 system is very light as well.

All in all, it's about the little details, the frame is probably as light as any steel frame (from Ducati or other).
The air cooled motor is relatively heavy, probably 25lb over somehing more modern.
There must be another 10lb-15lb that can be taken away by carefully replacing stuff, but this wouldn't be that easy/cheep.
I'm running a 130/70 race only M23 Avon, this tire is very heavy (and good for maybe 2000 k'm of track use). 

Dan