Author Topic: 78 F3 rebuild  (Read 2891 times)

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Offline superbike

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78 F3 rebuild
« on: January 09, 2012, 06:12:44 PM »
I am looking for some insights from the group.  My intentions are to begin the rebuild of a 78 F3.  I put 500 miles on the bike this past year.  The bike ran well, no issues, but would like to run through it and bring it into confident condition.  Plans are to start with the engine.  Odometer reads 35K.  I would like to do the top and perhaps even punch it out to 836 and up the performance, but it does not look like the parts are out there to do it.  Please advise.

Offline seanbarney41

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Re: 78 F3 rebuild
« Reply #1 on: January 09, 2012, 06:39:50 PM »
tons of guys on here have done it, do some reading in the project shop section...you may learn a few things, performance builds of these bikes are rarely a "budget" endeavor, 836 doesn't get you a silly power gain without some quality headwork, you may be pleasantly surprised by the performance lurking in your motor as we speak, proper tuning can often satisfy resulting in a gearhead who loves to ride more than wrench...where in MI are ya?, there's lot's of MI members for help and guidance
If it works good, it looks good...

Offline Retro Rocket

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Re: 78 F3 rebuild
« Reply #2 on: January 09, 2012, 11:44:33 PM »
The F2-F3 have different pistons to the K models, CycleX has everything you need.....

http://www.cyclexchange.net/Honda%20Page.htm

There you go.... ;)
750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
If You can't fix it with a hammer, You've got an electrical problem.

Offline superbike

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Re: 78 F3 rebuild
« Reply #3 on: December 21, 2012, 03:16:11 AM »
Thanks to both of you for your comments.  As the story goes had some work done on the bike by notable mechanic in the area.  Advice was to put the breather box back on and adjust the valves, new plugs, wires and a few other minor things.  The bike ran well when it went in to the shop and reasonably well when it came out.  The idle wants to climb and will not stay steady with adjustment.  That’s the end of the story other than to thank you both for your comments albeit almost a year since your replies.

Offline madScientist

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Re: 78 F3 rebuild
« Reply #4 on: December 21, 2012, 05:43:22 AM »
I'm doing this same thing right now. See the link to my build in my signature.

My bike is going to be my daily rider so I'm doing everything I can to give it the best chance of being reliable. Focusing on the engine (not the wiring, suspension etc) I took the whole thing down to individual components. Inspected everything, replaced the parts that are prone to wear, put it back together with all new seals and gaskets.

If you go this route it will not be cheap and can be time consuming. Here's the break down of what I've spent / projected to spend (i have part numbers for everything if you want them. PM me):

Primary chains (90)
HD Cam chain (30)
every o-ring (90)
primary chain tensioner (it may not look bad but trust me...it is) (80)
every seal (35)
gasket set (90)
main bearings (140) - inspect prior so you know what color you need if you need to swap them
rod bearings (90) - inspect prior so you know what color you need if you need to swap them
rod bolts - (90) - mine were way stretched
Dynoman 836 kit (500)
boring by APE (200)
head rebuild (500) - titanium retainers, new springs, ss valves, bronze guides APE
cam chain tensioner (50) - i'm going with a manual tensioner
OPTIONAL: head porting / polishing by mrieck ???
OPTIONAL: cam (200)


And there you have it...
You CAN do great things...with enough beer.


78 cb750f
http://forums.sohc4.net/index.php?topic=113293.0
70 CL350 Street Tracker / Cafe
http://forums.sohc4.net/index.php?topic=125641.0
83 KZ1100ltd
76 GL1000
71 Kaw H2 (to be built)
77 cb750A (sold)
74 cb125s (sold)

Offline superbike

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Re: 78 F3 rebuild
« Reply #5 on: December 27, 2012, 02:01:04 PM »
Thanks for the insights on parts and cost as it kind of confirms what I think my direction will be with the motor and that is to get a knowledgeable mechanic involved.  I wrench, but not to that extent. Now can anyone help with this?  I am looking for information regarding the movement of the foot controls from their standard position rearward to the passenger peg location.  If anyone has experience in doing the latter and sharing their riding satisfaction with the move as well as resources for the linkages, your insights would be appreciated.  A particular concern of mine is the set up of the rear brake.

Offline Retro Rocket

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Re: 78 F3 rebuild
« Reply #6 on: December 27, 2012, 02:07:27 PM »
I think you'll find that the rear peg mounts are way too far back, you need some properly placed rear sets.... Plenty of info on the forum about these mods.... ;)
750 K2 1000cc
750 F1 970cc
750 Bitsa 900cc
If You can't fix it with a hammer, You've got an electrical problem.

Offline seanbarney41

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Re: 78 F3 rebuild
« Reply #7 on: December 27, 2012, 02:08:17 PM »
search rearsets...I doubt you want them as far back as the passenger peg location
If it works good, it looks good...

Offline superbike

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Re: 78 F3 rebuild
« Reply #8 on: December 27, 2012, 07:00:07 PM »
Good insights, Thanks!  There is a wealth of information in this forum.

Offline superbike

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Re: 78 F3 rebuild
« Reply #9 on: December 28, 2012, 06:39:37 PM »
OK .  Now moving on with this project, it could use a killer headlight, looking at a Headwinds, but am open to alternatives.  Looking for something to go with the theme of an Aristream?  Airsteam as in Airstream Trailer.   Yes this is a tribute bike to a bit of Americana.  I would like as flat as possible housing for the hearlight, but the right mount could make it all OK. Who knows what?  HELP!








trailer

Offline superbike

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Re: 78 F3 rebuild
« Reply #10 on: January 11, 2013, 06:14:38 PM »
OK it looks like there are not any suggestions on a good and flat headlight.  Moving on, as this project is a suggestion on a rear suspension/shock set-up would be appreciated.  Looked at some of the historical information on the site, but did not see any clear ideas as a result.  Again this is a 1978 750F that needs new rear shocks.  Any proven ideas on length and manufacture would be appreciated.  I am of average height at 5'10".  Promise to post some pictures soon as this machine is taking shape.   THANKS