Author Topic: One for the 250cc folk  (Read 101332 times)

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Offline JimL

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Re: One for the 250cc folk
« Reply #90 on: July 29, 2013, 09:21:46 AM »
I've noticed in a couple Honda plenums that I scrapped, the center two velocity stacks are a couple millimeter longer than the end two.  I have seen this in other stuff, also, and thinking there must be a reason.  It might be just Helmholtz noise abatement.  Perhaps worth some study?

Even my V-twins run best with uneven tuned length between the intakes, though its a different problem.

JimL

Offline generatorshovel

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Re: One for the 250cc folk
« Reply #91 on: July 29, 2013, 06:55:09 PM »
Looks good Tiny, any room to get a little more distance between the top of the bell mouths and the roof of the plenum, think I remember reading 1.5 diameters somewhere.

What did you get the green anodizing off with?, I've not done much alloy welding, guessing it needs to come off first.

jon
No Jon, theres 11mm between the plenum top, and the frame, and the intake flange on the head is 10mm tall, ladies wristwatch stuff
I wasnt looking forward to removing the green stuff, but mounted the units in the lathe and it came off real easilly using some coarse abrasive sanding sheets, then polished with #400 wet/dry
I've noticed in a couple Honda plenums that I scrapped, the center two velocity stacks are a couple millimeter longer than the end two.  I have seen this in other stuff, also, and thinking there must be a reason.  It might be just Helmholtz noise abatement.  Perhaps worth some study?

Even my V-twins run best with uneven tuned length between the intakes, though its a different problem.

JimL
Jim,
I think , from info gathered from other forums, the long / short stack lengths are to help the spread of power ?

Tiny
Tiny (in OZ)
I would prefer to make horsepower, rather than buy, or hya it, regardless of the difficulties involved , as it would then be MINE

Offline fredvance

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Re: One for the 250cc folk
« Reply #92 on: July 29, 2013, 07:07:02 PM »
On a stock Busa, they have two VS lengths. This is for better streetability. The first thing we do is put all short VS, for more high rpm HP.
WORLDS FASTEST PRODUCTION MOTORCYCLE 213.470
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WOS 2011 235+MPH
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Offline SaltPeter

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Re: One for the 250cc folk
« Reply #93 on: July 30, 2013, 01:16:56 AM »
Is there different intake requirements in a forced induction engine?

I have found that the shape of my airbox on my 2 stroke RGV has quiet a significant impact on the way it develops power.

Pete :?
« Last Edit: July 30, 2013, 01:20:15 AM by SaltPeter »
The Mission is to go as fast as possible along on that old Road Less Traveled.

Offline generatorshovel

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Re: One for the 250cc folk
« Reply #94 on: August 04, 2013, 07:05:15 PM »
Is there different intake requirements in a forced induction engine?

I have found that the shape of my airbox on my 2 stroke RGV has quiet a significant impact on the way it develops power.

Pete :?
I think the airboxes flex somewhat Pete, helping to even out the intake pulses, Blown engines get what they are given, hopefully, if well thought out, it's what they need ?

Getting closer to welding the plenum, BOV will be on top this time, with potential fireballs directed to the left, and down away from ME.



Tiny


Tiny (in OZ)
I would prefer to make horsepower, rather than buy, or hya it, regardless of the difficulties involved , as it would then be MINE

Offline generatorshovel

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Re: One for the 250cc folk
« Reply #95 on: August 15, 2013, 02:21:24 AM »
Great week here too, no racing, but,,,,,,



JN, this is what I wanted mate  :wink:


Tiny
Tiny (in OZ)
I would prefer to make horsepower, rather than buy, or hya it, regardless of the difficulties involved , as it would then be MINE

Offline generatorshovel

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Re: One for the 250cc folk
« Reply #96 on: November 09, 2013, 03:47:46 AM »
Work on the 250 continues.the piston oilers are plumbed


The fuel supply problems are solved (thanks Holley)



I sure hope the new plenum works ok (next job is to divert potential BOV fireballs away from the rider)










Tiny


Tiny (in OZ)
I would prefer to make horsepower, rather than buy, or hya it, regardless of the difficulties involved , as it would then be MINE

Offline tauruck

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Re: One for the 250cc folk
« Reply #97 on: November 09, 2013, 07:53:22 AM »
You've come a long way and been busy!. It looks great. Big power jump there. :cheers:

Offline wobblywalrus

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Re: One for the 250cc folk
« Reply #98 on: November 09, 2013, 04:02:16 PM »
Looks good, Tiny.  There is nothing like it.

Offline generatorshovel

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Re: One for the 250cc folk
« Reply #99 on: February 16, 2014, 04:14:01 PM »
The learning curve continues,,,,,
With the camshaft change, came 15 lb of boost, which, although it creates GOBS of power, it also gives me nightmares, so Iv'e gone from 25% underdrive on the blower, to 38%, which , hopefully, will get the boost level back to where it was with stock cams (10 lb)
Time is running out, a planned test run yesterday was halted by a sick coil, something that only appeared when the weather cooled down (from 110 degrees, to 60  :-o ) , the bike would not start, just tease.
Team member Bob, has spare coils, which I'll try later today.
Short clip of a warm up run with 15 lb boost

http://youtu.be/cS5dAJz90uo

The additional power resulted in clutch slip also, I discovered my "test tank" lacked adequate venting, and the thermostat was opening too slow, more jobs for Bob (me)

Tiny
Tiny (in OZ)
I would prefer to make horsepower, rather than buy, or hya it, regardless of the difficulties involved , as it would then be MINE

Offline tauruck

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Re: One for the 250cc folk
« Reply #100 on: February 16, 2014, 11:01:28 PM »
It sounds good. :cheers:

Offline wobblywalrus

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Re: One for the 250cc folk
« Reply #101 on: February 17, 2014, 12:51:29 PM »
The Burt Munro method.  Find a seldom used road and test there.

Offline Dr Goggles

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Re: One for the 250cc folk
« Reply #102 on: February 17, 2014, 02:35:35 PM »
Nice work T'fer....Now, are we pitting together?
Few understand what I'm trying to do but they vastly outnumber those who understand why...................

http://thespiritofsunshine.blogspot.com/

Current Australian E/GL record holder at 215.041mph

THE LUCKIEST MAN IN SLOW BUSINESS.

Offline generatorshovel

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Re: One for the 250cc folk
« Reply #103 on: February 17, 2014, 03:22:37 PM »
Nice work T'fer....Now, are we pitting together?

Yup. Chris Bryson wants a spot saved too.

LASLO WON'T START !

I'm workin' on it,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, :? :? :?
Tiny
Tiny (in OZ)
I would prefer to make horsepower, rather than buy, or hya it, regardless of the difficulties involved , as it would then be MINE

Offline Dr Goggles

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Re: One for the 250cc folk
« Reply #104 on: February 17, 2014, 03:54:53 PM »
You mean Agent 86?....I was just thinking about him the other day,then last night I was talking to Luke Zietar the guy making the 3d salt movie,he mentioned Chris , I laughed and said "he's a classic",he responded,"um,you're alll classics......"
You too Tiny.......

Few understand what I'm trying to do but they vastly outnumber those who understand why...................

http://thespiritofsunshine.blogspot.com/

Current Australian E/GL record holder at 215.041mph

THE LUCKIEST MAN IN SLOW BUSINESS.