[JD]

dave from australia just ordered a tshirt and sent pics of his bike. it's a modern bike so I didn't put it on the site but it's still a cool bike. I've never heard of one before. dave says they're popular in australia and europe but were never sold in the US.

 

[joe c]

ducati clone in blue. like the trellis! pretty neat looking. they get all the cool stuff.


jc

 

[JD]

here's what dave said about 'em

here a couple of piccies of my bike - its a yamaha trx850 , 850cc parralell
twin, 850cc, water cooled, 5valave head, 5 speed manual, half fairing,
trellis frame and 270 degree crank.

 

[aaron]

Someone help me with the math...

parralell twin, 270º crank?

Anyone?

Aaron

 

[Chikor]

270??? it must run worse then a harley.....i cann't wait for my wife to finally give in to moving back to eurpoe with me!

"Ride Fast and Take Chances"

 

[jbranson]

Yep...270 degrees. 180 degrees..plus 90 = 270. Or 360 - 90 = 270.

It fires badump....badump...badump....badump...like that. Cylinders firing 90 degrees apart, then a 270 degree rotation of the crankshaft, one cylinder fires, 90 degrees later the other cylinder fires...then the crank goes around another 270 degrees and process starts over.
You can fire an engine just about any way you want, just cut the cam to match and there you go. Balancing is all handled by the fly weights on the crankshaft.
Like Harleys...they fire at 45 degrees apart I think.
JohnnyB

 

[aaron]

Wow... that's pretty cool. I guess I need to work on something other than British stuff once in a while. The little Honda was confusing enough when I started, mostly in explaining it then the actually working on it. John you didn't like my little º?

Aaron

 

[joe c]

dude, ive been trying to find that for a long time. how did you do it??


jc

 

[jbranson]

H¤£y §H|t h°w Did µ DØ thÅt ¿

Aaron, I like your ° .... although I hear the guys in P-town LOVE your ° .


Joe...it's a haxor trick....beware.

JohnnyB

 

[jbranson]

Aaron,
Actually the British kind of pioneered the 360° crank like the Honda uses. Don't numerous trumpet and other British twins use the same setup? Pistons move up and down at the same time but fire on alternating revolutions.
JohnnyB

 

[aaron]

¥ès Sí₧ they do. I just keep confusing the Honda stuff cause I've never really worked with it. I just assumed that most everything else wasn't 360º. I through ASCI stuff out cause I know your a nerd as well.


åªrón

 

[imslow]

I'm gonna stay away from you two from now on. Everytime you get together now all you do is go back to talkin computer trash.

It was better when you two didn't know each other so well. Then it was all cycle stuff.

Just jesting. Last time a tthe track you two were discussing the benefits of parallel 286 multiquarked bit processing with scuzzis driving the ram perambulator. Ugh. Whatever happened to the Kneuter valve?

Just missed a shift on the 175 today and it ran past 12K on the scitsu. unvelievable.

s

 

[joe c]

that and mcganzer flanges.


jc

 

[joe c]

i know how to do it, it just doesnt work in this forum for me. alt248 usually works, but for some reason not here.

im not a computer geek, i have too much tv to watch.

jc

 

[joe c]

°°360°°


num lock makes it go here. im still not a geek.


jc

 

[jbranson]

IMSLOW...Scott?

Missing a shift used to be the death knell of my engines. I was running the x4 camshaft with a head built by, well I won't say. Every missed shift was bent valves. Then I went to the x20 cam, wasn't quite so bad, every other missed shift was a bent valve.

Then I had the head done up proper. I've missed shifts and just buried the 12k tach..had to be 14k rpm. Everytime I would cringe, just knowing when I back off the throttle it would die and not run below 4 or 5k rpm. But to my surprise it takes the abuse just fine. Despite the fact that the valves are larger and heavier! Just goes to show you what proper spring rates and heights and bronze guides will do.

This Mike Rich guy does not fuck around. If you want genuine, pro race quality mods made then he's the guy to see. No guessing, nothing half assed or cobbed together, he does the kind of work you see on AMA superbikes. Computer flow bench, all kinds of engine simulation work, matching valve rates to rpm, valve weight and cam profile. He even flows the head to a specific camshaft profile. You gotta send him the whole head, assembled, preferrably with intakes and carbs attached. No just sending a bare head and have someone hog it out based on some kind of wives tale voodoo. Mike will break all the rules if the flow bench says that's what you have to do.

He told me one bit of very valuable information about the 175's vert heads. It's not the ports that are the problem, it's the valves. Mildly ported heads will flow about as much as the valves can pass. You gotta go with bigger valves if you want the big power.

What I can't believe is that so far the rockers and cam lobes seem to be holding up great. I have no doubt that if one wanted to throw the dollars at one of these engines you could see a usable 14k rpm. It would require Ti valves and new seats to keep the spring pressures down. But it's doable, and would sound great.

A project for another year I guess.

JohnnyB

PS. I know...a lot of talk to respond to a simple statement about a missed shift..but there you go..the wonder of modern medicine.
JohnnyB

 

[panic]

Most of the smaller Honda twins are 180 degree, which is why they sound so... strange. Some were built in both 180 (CB) and 360 (CL, where broad power band is more important).
H-D is 45, Indian is 42, etc. Some JAP 50.
The missing factor in firing and rotational order is crank-pin position. Even with a common (side-by-side) pin, offsetting the centerline will offset the firing order, which is either added or subtracted (duh) to the cylinder position (odd-fire Buick V6, etc.). Needless to say, many more combinations can be built than will run. The Yamaha XS650 (originally an A65 variant with 360) crank can be re-timed by simply re-indexing the splined connecting shaft between the L & R flywheel halves:
http://www.650motorcycles.com/XS277kit.html

 

[Chikor]

that's really cool....are you sure about the cl being 360 cranks? i don't remember mine being 360 and i blueprinted the top end just a few weeks ago, well maybe like 7 weeks ago or there abouts....

"Ride Fast and Take Chances"

 

[jbranson]

All the CB 125s (SS twin), 160s, 175s, and 200s were 360 degree.

JohnnyB

 

[imslow]

Yes, imslow=scott.

And along those same lines, I am no where near going fast enough on the 200 to warrant getting any high end head work done by MRich. I'd love to blow a grand on a head, but I'll only do it after I can get through corners fast enough to need it.

Since I've never bent a valve, what's the first symptom? The bike won't run?

I learned my lesson years ago when I was playing tennis with a guy who knew how to play. He had one of those old wood rackets, I was playing with sommthing like a Prince big head. He beat the crap out of me standing still. It's all about technique and skill-not power. So i am putting in my time on the track. One thing I learned from (Joe?) the old ironworker was to start looking much farther ahead on the track than I have been. When going around turn 3, looking up at the flag instead of that dirt on the left after the tires end. And looking up at the hill again when entering the bowl insttead of looking at the apex of the bowl. I don't know if it made me any faster when i did it, but it certainly made riding more comfortable.

evil

PS. anyone know if they are definitely doing sound checks at Loudon next weekend? JohnnyB, you might be doing tech--let us know!