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Author Topic: CB750 F2 Devils bike, has power that can hurt  (Read 2239 times)

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Offline Ace

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CB750 F2 Devils bike, has power that can hurt
« on: September 12, 2012, 06:01:31 AM »
Hi all, I finally got the the F2 back on the road after a dropped intake valve 12 months ago.  Running 895 cc kit with a new Webcam 63b grind, mikuni 29mm smooothbores with pods and Tingate Racing exhaust (Australian Made). 

Took it out for a road worth certificate.  Gave it a bit round a corner in second gear and spun up the back wheel and kick sideways.  Backed off straightened up and kept going.  This bike has got some power now unleashed by the cam and the smoothbores.

Running 20 pilot jets, 120 mains with needle clip on 3 position.  Sitting about 3000rpm 55 mph in 5th gear and go WOT, engine doesn't stall or stutter it just gets on with the job.   The higher the revs the harder it pulls.  I backed off at 7000rpm and up to 90 mph as I'm still running in the engine.  The bike runs effortless and is a a good ride.  You must be careful though as it will put you sideways quick.  I guess the hard compound rear tyre doesn't help in the cold.

A bit of history with this bike, if something can go wrong it will with this bike.  Oil leaks from the head, dropped valve, burnt wiring harness, broken side cover, tuning issues with stock carbs.  Oh and today, I couldn't get the bike registered because the frame number in the system wasn't updated when I changed frames last year due to a bent frame (found that out via a speed wobble at high speed around a corner).  It's the devil's bike alright.  Hopefully now I can tame the beast.  ;D

Enjoy all!! Ride free

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1971 CB750 K1 - Sold
1978 CB750 F2 Supersport - Sold
1981 CB900 Bol d'or - Sold
2006 CBR1100 XX Super Blackbird - Sold

Offline Wheelhorse77

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Re: CB750 F2 Devils bike, has power that can hurt
« Reply #1 on: September 12, 2012, 06:21:46 AM »
Good job on seeing her through!
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77 750F2 ressurected from the dead
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Offline Jiminy Indy

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Re: CB750 F2 Devils bike, has power that can hurt
« Reply #2 on: September 12, 2012, 08:19:58 AM »
Yo Ace - love to see some photos. Just picked up a '77 F2 awile back and trying to decide what to do with her.
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Offline ChuckG750f1

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Re: CB750 F2 Devils bike, has power that can hurt
« Reply #3 on: September 12, 2012, 08:31:35 AM »
Ace-We need pics...a lot of us can't read ;)  Keep the shiny side up! -Chuck
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1976 CB750 f1
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Offline Ace

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Re: CB750 F2 Devils bike, has power that can hurt
« Reply #4 on: September 16, 2012, 01:50:55 AM »
Righto, sorry for the delay fellas, don't get online to the forum much these days. Went to the motor vehicle registry on Friday and filled out a statutory declaration stating the history of the frames and they accepted all my paperwork.  The devil's bike is no road legal!  ;D

Hopefully the pictures will turn out.
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1971 CB750 K1 - Sold
1978 CB750 F2 Supersport - Sold
1981 CB900 Bol d'or - Sold
2006 CBR1100 XX Super Blackbird - Sold

Offline Terry in Australia

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Re: CB750 F2 Devils bike, has power that can hurt
« Reply #5 on: September 16, 2012, 05:11:38 AM »
Very nice Adam, a wolf in sheep's clothing! Cheers, Terry. ;D
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Offline ekpent

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Re: CB750 F2 Devils bike, has power that can hurt
« Reply #6 on: September 16, 2012, 05:25:56 AM »
Quote from: Terry in Australia on September 16, 2012, 05:11:38 AM
Very nice Adam, a wolf in sheep's clothing! Cheers, Terry. ;D
Gee Terry saying something nice about an F bike. He must be in a chipper mood today   :o      :D
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Offline Terry in Australia

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Re: CB750 F2 Devils bike, has power that can hurt
« Reply #7 on: September 16, 2012, 05:32:27 AM »
Ha ha, well it is an F2 Eric, the lesser of the 2 evils............  ;)
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I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)

Offline Schnell

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Re: CB750 F2 Devils bike, has power that can hurt
« Reply #8 on: September 16, 2012, 05:52:48 AM »
Quote from: ekpent on September 16, 2012, 05:25:56 AM
Quote from: Terry in Australia on September 16, 2012, 05:11:38 AM
Very nice Adam, a wolf in sheep's clothing! Cheers, Terry. ;D
Gee Terry saying something nice about an F bike. He must be in a chipper mood today   :o      :D

Not really. He said that it looks like a sheep.

;)
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A good traveller has no fixed plans and is not intent on arriving. --Lao Tsu

primary: 1974 Honda CB750
long term, now resting: 1981 BMW R100/7
project: 1971 Honda CL350
project: 1974 Honda CB450

previous:
1975 Honda CB750
1973 BMW R90/6
1981 Suzuki GS650
1973 Honda CD175

My little website: http://frankfoto.jimdo.com/

Offline Ace

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Re: CB750 F2 Devils bike, has power that can hurt
« Reply #9 on: September 16, 2012, 03:32:13 PM »
Quote from: Terry in Australia on September 16, 2012, 05:11:38 AM
Very nice Adam, a wolf in sheep's clothing! Cheers, Terry. ;D

Thanks Terry.  Do I dare mention that you helped with this machine...  ;D
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1971 CB750 K1 - Sold
1978 CB750 F2 Supersport - Sold
1981 CB900 Bol d'or - Sold
2006 CBR1100 XX Super Blackbird - Sold

Offline Terry in Australia

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Re: CB750 F2 Devils bike, has power that can hurt
« Reply #10 on: September 17, 2012, 12:31:35 AM »
Ha ha, dare away mate! ;D
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I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

"Crazy is a very misunderstood term, it's a fine line that some of us can lean over and still keep our balance" (thanks RB550Four)

Offline Ace

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Re: CB750 F2 Devils bike, has power that can hurt
« Reply #11 on: September 28, 2012, 02:41:14 PM »
Update.  Still tuning the carbs.  Did a plug chop and noticed a light tan colour with white patches on the plug.  I know I need at least one size up in pilot jet as with the airscrew winding it closed the revs keep climbing so I've ordered 22.5 pilot.  Adjusted the needle clip to 4th position and the bike in the mid range performs a hell of a lot better. 

Got the problem with the frames sorted.  Now I just have to run the engine in and then go for a run on the dyno.  It previously pumped out 72.3 hp at the rear wheel with a good mid range cam, standard pipe and airbox.  Head has been ported.

The 63b cam kicks in well (pulls hard) at 5000rpm.  ;D
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1971 CB750 K1 - Sold
1978 CB750 F2 Supersport - Sold
1981 CB900 Bol d'or - Sold
2006 CBR1100 XX Super Blackbird - Sold
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