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Honda CB750/900/1100F SuperSport Website: SuperSport Forums


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Bucko
CB1100F
CB1100F



Joined: Dec 15, 2003
Posts: 2732
Location: Vancouver BC

PostPosted: Sun Apr 12, 2020 5:29 am Reply with quote Back to top

Just thinking out loud....

By just changing the cams (if such things were available), one could convert an inline 4 engine into a 'double twin' where 1 & 4 fired at the same time and 2 & 3 fired 360 degrees later. Maybe it would need a larger flywheel, and ???? Just wondering if anyone has ever heard of motor like that? Bet it would sound cool.
 
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Captain
CB1100F
CB1100F



Joined: Jan 02, 2009
Posts: 2198
Location: New Zealand

PostPosted: Sun Apr 12, 2020 7:24 am Reply with quote Back to top

Actually they donít and will fire 180 deg apart so you would end up with a 180 -540 -180 - 540...... If you tried this on an F you would break cam chains in very short order due to the doubling of load across the entire range. The only way around this is an increase in chain size and spec similar to the Yamaha R1 cross plain (similar phasing) and this necessitates a different gear on the crank.
FYI this is very easy to do on my billet crank and I was considering this chain upgrade in the future.

Captain

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Hondo57
Black CB900F
Black CB900F



Joined: Jun 20, 2014
Posts: 1760
Location: Grand Rapids, Michigan

PostPosted: Sun Apr 12, 2020 11:47 am Reply with quote Back to top

I would be interested in that as a future project

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nlovie
Black CB750F
Black CB750F



Joined: May 30, 2015
Posts: 898
Location: United Kingdom

PostPosted: Sun Apr 12, 2020 3:01 pm Reply with quote Back to top

only 3rd hand info: have heard of folks flipping the cams on the honda VF 750 RC36 motor

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Bucko
CB1100F
CB1100F



Joined: Dec 15, 2003
Posts: 2732
Location: Vancouver BC

PostPosted: Sun Apr 12, 2020 11:09 pm Reply with quote Back to top

What got me thinking of this was reading somewhere that someone made new cams for a parallel twin to turn it into a 'Twingle' (I know - not a real twingle).
 
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BlueThunder
Red CB1100F
Red CB1100F



Joined: Jun 12, 2006
Posts: 8916
Location: Long Island, NY

PostPosted: Mon Apr 13, 2020 4:19 pm Reply with quote Back to top

What would be the advantage of making the bike a double twin?

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2014 CTX1300A - Black Thunder aka Predator
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Bucko
CB1100F
CB1100F



Joined: Dec 15, 2003
Posts: 2732
Location: Vancouver BC

PostPosted: Mon Apr 13, 2020 5:49 pm Reply with quote Back to top

Probably none otherwise somebody would have done it. Maybe more low end torque?
 
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f4fast
Friend of the Board
Friend of the Board



Joined: Jul 09, 2005
Posts: 22488
Location: Long Island,N.Y.

PostPosted: Mon Apr 13, 2020 5:58 pm Reply with quote Back to top

BlueThunder wrote:
What would be the advantage of making the bike a double twin?


If the result would be like the Yamaha R1, my understanding is the cross plane crank puts power down differently, in a way that allows the power strokes not to overwhelm the rear tire while accelerating.

I think the concept gained traction ( pun...yuk yuk)from flat track applications when putting power down on dirt is the difference in winning and losing.

Wasnít aware the Honda Dohc engine had extensive wheelspin out of corners , that the cross plane crank offered substantial advantages for the trouble....maybe after you are 150+ hp?

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CBX-tras
Silver CB900F
Silver CB900F



Joined: Mar 12, 2012
Posts: 1348
Location: Clinton Twp, MI USA

PostPosted: Tue Apr 14, 2020 12:24 pm Reply with quote Back to top

On the CBX , the cams can be installed (by mistake) to actually do this and has been done due to a printing error in one of the FSM.

You'll get about 20 miles on the motor before the cam chain breaks then BAM all those tagged valves and broken guides.

Here's what a 4 cylinder might look like:

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J.R.
CBX-tras
Certified Master Motorcycle Technician Since 1978
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PGSmick
CB1100F
CB1100F



Joined: Nov 04, 2004
Posts: 2373
Location: Newton, MA

PostPosted: Wed Apr 15, 2020 8:57 pm Reply with quote Back to top

Holy shit. That's some printing error! How would one spot that they had a misprinted CBX FSM?

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Peter.
1100 X 2 & 750
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CBX-tras
Silver CB900F
Silver CB900F



Joined: Mar 12, 2012
Posts: 1348
Location: Clinton Twp, MI USA

PostPosted: Thu Apr 16, 2020 11:59 am Reply with quote Back to top

PGSmick wrote:
Holy shit. That's some printing error! How would one spot that they had a misprinted CBX FSM?


You'd need to know what you're working on and recognize that something just isn't correct.

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J.R.
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