Author Topic: Cobra motor disassembly and rebuild  (Read 107665 times)

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Offline Bill/BentON Racing

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Re: Cobra motor disassembly and rebuild
« Reply #175 on: January 12, 2016, 08:23:14 AM »
Yep, Frank,  trying to do it right the first time , K, Bill
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Offline scottly

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Re: Cobra motor disassembly and rebuild
« Reply #176 on: January 12, 2016, 06:56:59 PM »
22lbs stock.   A fine balance no doubt!
Thanks, I was thinking the stock crank was heavier than 22lbs. It is indeed a fine balance between too much  flywheel inertia and too little. ;)
Don't fix it if it ain't broke!
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Offline bwaller

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Re: Cobra motor disassembly and rebuild
« Reply #177 on: January 12, 2016, 08:35:19 PM »
Early on I decided with some prompting from that Rieck guy that roadracing a middleweight it was wise to maintain some enertia by not removing rotating mass and helping drive off the corners. In drag racing why not lighten that mass since there is no further throttle modulation once off the line?
 

Offline 754

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Re: Cobra motor disassembly and rebuild
« Reply #178 on: January 12, 2016, 09:28:52 PM »
I think it depends a lot on how happy you are with the way it leaves the line..
Of course in bracket racing it should not matter..
Maker of the WELDLESS 750 Frame Kit
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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: Cobra motor disassembly and rebuild
« Reply #179 on: January 12, 2016, 10:27:52 PM »
Hole shot.
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline scottly

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Re: Cobra motor disassembly and rebuild
« Reply #180 on: January 13, 2016, 07:49:37 PM »
Early on I decided with some prompting from that Rieck guy that roadracing a middleweight it was wise to maintain some enertia by not removing rotating mass and helping drive off the corners.
In a roadracing situation, the goal is to provide an even power delivery to the rear wheel, rather than dump stored energy during the launch from a standing start. The best example of too little flywheel inertia I have first hand experience with was my '82 CR 480; it was impossible to ride it up a slight incline covered with packed snow and ice. Every time the cylinder fired, the rear wheel spun, throwing the ass end out to one side or the other, and I went down. My buddy on his '82 XR 500, which had 2-4 times the flywheel mass, had no problems on the slick surface. I later learned that a combination of slipping the clutch while applying throttle and riding the rear brake helped overcome the lack of flywheel in tricky situations, but it was touch and go at best. Honda added more flywheel weight every year after the original 480, to somewhat mellow the power delivery. ;) 
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Offline POPS 911

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Re: Cobra motor disassembly and rebuild
« Reply #181 on: January 14, 2016, 06:03:35 AM »
BILL: Take that rod out of those flat slides, seems more than a few folks gave you that tip = your head builder, FRANK IN THE 10'S, and ME. Good thing about running 29's with the built in throttle stop your S/E numbers can stay good until you want to set a new record [ on a minus - DA ] on any day at the track, or pick you up or down with your dial in from changing DA's in ST/ET from early morning passes to late rounds in the nights. That's why you buy a weather station.........

Offline Bill/BentON Racing

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Re: Cobra motor disassembly and rebuild
« Reply #182 on: January 14, 2016, 06:39:31 PM »
POP'S, thanks.  Here you go, we going lighter,lower, leaner, meaner, and longer! K. ;D, Bill
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1993 HRC RS125 | 1984 NS400R | 1974 Honda CB750/836cc (Calendar Girl) | 1972 CB 500/550 Yoshi Kitted 590cc | 1965 Honda CB450 Black Bomber | 1972 Suzuki T350 | 1973 88cc | Z50/Falcons Pit Bike | 1967 CA100| 1974 CB350 (400F motor)...and more.
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Offline bwaller

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Re: Cobra motor disassembly and rebuild
« Reply #183 on: January 14, 2016, 09:43:11 PM »
In a roadracing situation, the goal is to provide an even power delivery to the rear wheel, rather than dump stored energy during the launch from a standing start. The best example of too little flywheel inertia I have first hand experience with was my '82 CR 480; it was impossible to ride it up a slight incline covered with packed snow and ice. Every time the cylinder fired, the rear wheel spun, throwing the ass end out to one side or the other, and I went down. My buddy on his '82 XR 500, which had 2-4 times the flywheel mass, had no problems on the slick surface. I later learned that a combination of slipping the clutch while applying throttle and riding the rear brake helped overcome the lack of flywheel in tricky situations, but it was touch and go at best. Honda added more flywheel weight every year after the original 480, to somewhat mellow the power delivery. ;) 


Scottly, you need to try racing a TZ!

Offline Medyo Bastos

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Re: Cobra motor disassembly and rebuild
« Reply #184 on: January 15, 2016, 06:39:46 AM »

...Here you go, we going lighter,lower, leaner, meaner, and longer! K. ;D, Bill

great, get to ready for me to pick up!


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Offline Bill/BentON Racing

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Re: Cobra motor disassembly and rebuild
« Reply #185 on: January 15, 2016, 10:11:17 AM »
Check it out! K. Time warp! ;D
BentON Racing Website
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Over 35 years of experience working on vintage motorcycles, with a speciality in Honda SOHC/4 with a focus on the CB750 and other models as well from 1966 - 1985.
______________________________________
1993 HRC RS125 | 1984 NS400R | 1974 Honda CB750/836cc (Calendar Girl) | 1972 CB 500/550 Yoshi Kitted 590cc | 1965 Honda CB450 Black Bomber | 1972 Suzuki T350 | 1973 88cc | Z50/Falcons Pit Bike | 1967 CA100| 1974 CB350 (400F motor)...and more.
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Offline kmb69

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Re: Cobra motor disassembly and rebuild
« Reply #186 on: January 16, 2016, 08:26:32 AM »
What happened to the all time, record setting attempt with a Hondamatic thread?  ??? ??? ???
I thought that was gonna be real good and was all ears subscribed.  :( :( :(

Offline TurboD

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Re: Cobra motor disassembly and rebuild
« Reply #187 on: January 16, 2016, 08:30:51 AM »
^ What he said..

Offline dragracer

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Re: Cobra motor disassembly and rebuild
« Reply #188 on: January 16, 2016, 10:36:35 AM »
What happened to the all time, record setting attempt with a Hondamatic thread?  ??? ??? ???
I thought that was gonna be real good and was all ears subscribed.  :( :( :(


I just noticed it was missing myself. I'm sure Bill's project is still alive even if the thread was killed off. What exactly is the Hondamatic record and where can we find the stats???

Offline Jerry Rxman Griffin aka MuthaF'er

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Re: Cobra motor disassembly and rebuild
« Reply #189 on: January 16, 2016, 11:10:38 AM »
+4!!  I booked my flight already. Gotta have the special entertainment.
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline Bill/BentON Racing

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Re: Cobra motor disassembly and rebuild
« Reply #190 on: January 16, 2016, 02:04:18 PM »
What thread?  ;) ;D  It'll be back.....we got to work some things out, then I'll revive it. Project is not dead!! Jay at APE got my Cobra crank yesterday or day before. It will probably be the next runner. Stay tuned, Bill  ;D
BentON Racing Website
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Over 35 years of experience working on vintage motorcycles, with a speciality in Honda SOHC/4 with a focus on the CB750 and other models as well from 1966 - 1985.
______________________________________
1993 HRC RS125 | 1984 NS400R | 1974 Honda CB750/836cc (Calendar Girl) | 1972 CB 500/550 Yoshi Kitted 590cc | 1965 Honda CB450 Black Bomber | 1972 Suzuki T350 | 1973 88cc | Z50/Falcons Pit Bike | 1967 CA100| 1974 CB350 (400F motor)...and more.
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Offline POPS 911

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Re: Cobra motor disassembly and rebuild
« Reply #191 on: January 17, 2016, 09:49:50 AM »
HONDAMATIC FANS : I guess this will be the time I finally get one of my 7- CB750A HONDAMATIC on the track !!! Will finish off one and spend 2016 at my home track getting it dial in like the CM400A cc "TURTLE". I will not chase the dreamers road of the fastest but that of the winnings ticket collector for the most CONSISTANCE SOHC 750A. Will buy a 500cc water cooled V-twin HONDA for cheap and run in that V-TWIN class against those Harleys and that one Suzuki I saw at my last Valdosta event [ the 1982 Yamaha 920R chain driven big tank V-TWIN that I bought new in 83 would be my choice for that class.] Come on BILL you are the HONDA MASTER SHOP GUY so you could win on a w/c V-TWIN 500cc HONDA in that class, less bikes than any class except Top Fuel.

Offline Jerry Rxman Griffin aka MuthaF'er

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Re: Cobra motor disassembly and rebuild
« Reply #192 on: January 17, 2016, 10:33:17 AM »
There you go Pops  ::)  Quit distracting Bill  ;)  He already has his hands more than full......

Looking forward to seeing your bike(s) in the pits eventually. You REALLY need to start off at Valdosta to get it dialed in for your track championship.  ;) :)  Bring Weeks with you too.   
As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline POPS 911

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Re: Cobra motor disassembly and rebuild
« Reply #193 on: January 17, 2016, 10:55:02 AM »
That would be a 1989 HONDA HAWK GT 650 water cooled V-TWIN TO RACE IN THE V-TWIN CLASS. Not a 500cc HONDA.

Offline Bill/BentON Racing

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Re: Cobra motor disassembly and rebuild
« Reply #194 on: January 17, 2016, 04:57:20 PM »
POP'S, that could work. RC51 might put a few on the trailer also! 2016 sure going to be interesting for sure.
BentON Racing Website
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Over 35 years of experience working on vintage motorcycles, with a speciality in Honda SOHC/4 with a focus on the CB750 and other models as well from 1966 - 1985.
______________________________________
1993 HRC RS125 | 1984 NS400R | 1974 Honda CB750/836cc (Calendar Girl) | 1972 CB 500/550 Yoshi Kitted 590cc | 1965 Honda CB450 Black Bomber | 1972 Suzuki T350 | 1973 88cc | Z50/Falcons Pit Bike | 1967 CA100| 1974 CB350 (400F motor)...and more.
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Offline NalleyRacing

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Re: Cobra motor disassembly and rebuild
« Reply #195 on: January 17, 2016, 08:15:09 PM »
Cant forget about purple rain!!

Offline Bill/BentON Racing

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Re: Cobra motor disassembly and rebuild
« Reply #196 on: January 18, 2016, 05:01:41 AM »
Just needs a momo! ;D
BentON Racing Website
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Over 35 years of experience working on vintage motorcycles, with a speciality in Honda SOHC/4 with a focus on the CB750 and other models as well from 1966 - 1985.
______________________________________
1993 HRC RS125 | 1984 NS400R | 1974 Honda CB750/836cc (Calendar Girl) | 1972 CB 500/550 Yoshi Kitted 590cc | 1965 Honda CB450 Black Bomber | 1972 Suzuki T350 | 1973 88cc | Z50/Falcons Pit Bike | 1967 CA100| 1974 CB350 (400F motor)...and more.
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See our latest build 'Captain Marvel' CLICK HERE

Offline Jim F

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Re: Cobra motor disassembly and rebuild
« Reply #197 on: January 18, 2016, 11:42:49 AM »
and I have an RC51 and a TL1000R...........................hummmmmm
2002 RC51 1000 (SP2)
1983 GS1100EC Suzuki
2002 998 Dukati (Customers Bike)
1992 KTM500 2 stroke
1975 CB750/836 Honda
1978 GS750/840 Suzuki

Offline Bill/BentON Racing

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Re: Cobra motor disassembly and rebuild
« Reply #198 on: January 18, 2016, 12:11:28 PM »
C'mon Jim! ;D
BentON Racing Website
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Over 35 years of experience working on vintage motorcycles, with a speciality in Honda SOHC/4 with a focus on the CB750 and other models as well from 1966 - 1985.
______________________________________
1993 HRC RS125 | 1984 NS400R | 1974 Honda CB750/836cc (Calendar Girl) | 1972 CB 500/550 Yoshi Kitted 590cc | 1965 Honda CB450 Black Bomber | 1972 Suzuki T350 | 1973 88cc | Z50/Falcons Pit Bike | 1967 CA100| 1974 CB350 (400F motor)...and more.
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See our latest build 'Captain Marvel' CLICK HERE

Offline dragracer

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Re: Cobra motor disassembly and rebuild
« Reply #199 on: January 18, 2016, 02:49:57 PM »
Bill, did you get the engine started yet? I think you mentioned you would be cranking it the other day. How about a report with video. Inquiring minds want to know. I'm in need of some motivation right now and seeing your progress might give me a kickstart.