Topic: 77' cb750F2

[Beakin]

Hey everyone earlier this month I bought a 1977 cb750f2 for 500$(canadian).. and drove it home

Heres the first picture i took of it



The engine currently in it is a 73 and 72 i believe, It smokes and leaks quite a bit... I have the original engine in pieces..It was taken out due to Valve guide problems.. The PO said it lasted 80,000 kilometers before it started to smoke too much for him..

So first things first.. the engine: Ive been playing with the idea of rebuilding the 750F engine and swapping it in.. Ive been going through some valve parts and some things are out of spec.. The outer valve springs are a milimeter or so larger then stock, and the inner valve springs are just on the service limit line.

The pistons and bore seem fine, however the rings will need to be replaced.  Ive seen ring sets for 70$ (this seems outrageous) when you can buy a 850cc kit for 250 bucks and it comes with rings. ( Am i correct thinking that one set is for one piston?)


I guess my other option is to leave the current engine in, it leaks and stinks though.. I guess i could rebuild it instead of the F engine.. I also have a bunch of parts for the earlier model engine.

So any opinions?  is 80,000 kilometers just too much? Is this engine rebuildable with out breaking the bank too badly

I know some other things i need to get are:
sprokets
chain
brake pads

I already got tires, they had tubes in them, and apparently came stock with tubes. I always thought comstar wheels were tubeless.. I guess i just buy some tubes then..

[Ace]

Looks like you got the start of something good there.  To find an F2 with original pipes in good order is a great find.  My last engine rebuild/build cost just over $2000 and that was including labour and it was not stock engine.  I'd say pull the entire engine down, see what you got and that way you know you have a good engine to last another 80 000kms.  One rebuild I cut corners and only did the top end.  It was the bottom end that let go in a big way and cost big dollars to fix.  Now I pull it all apart, it saves the heart ache and the hip pocket later down the track.

If you want to save money, then a stock engine is a good way to go.  Bit more money then you can start to play around with more performance parts etc.  Port and polish and a good street cam and the F2 will start to come alive.  836 kit or 850 and then you'll have a ride that will put a smile on your face.  My F2 makes just over 75 HP on the dyno.

Which ever engine you put in it, might be a good idea to pull it down to at least to having the barrels off IMO.  Keep us posted on the progress and have fun.

[Beakin]

well the F2 engine is in a millions pieces which makes it a little bit tough to put back together.. Ive never taken apart a 750 engine.. im sure that would help. Im considering the 836 kit or the 850 kit.. or at the very least new rings and a good hone because the pistons seem to measure up nicely. The only thing i have measured that is out of spec is the inner valve spring. And then theres the problem with the valve guides.

Still not sure what path to take.. For now im just gonna get her road worthy and have myself a rat bike for a little while.. Once i figure out the engine situation ill strip everything down blast the frame and repaint or powder coat. then start up a nice cliché cafe build

how much adjusting do the carbs need with the 836 kit? at the very least you should change the main jets.. correct?

I always thought that comstar rims where ment to be tubeless. After trying to jam a valve stem into the rim and learning that they came with tubes stock i decided to find some new tubes for it.

Unfortunately the picture of the exhaust isn't worth a 1000 words , its worth 3,  piece of crap.  There are a couple holes and major road rash on the muffler, its gonna have to go.. I haven't decided on replacing the headers or not yet.. although i have a chance to pick up some 78 headers for 50 bucks that are in decent condition

[Beakin]

I started a random cosmetic project:

I made a mold of a side panel to fiber glass( the originals are both cracked ) instead of forking out the 100 bucks for the ebay ones.. but im gonna have to think of a mounting scheme for the new panels

[Flying J]

the compression on the f bike is different so a k big bore kit wont work. You need a big bore for the f bikes. Dyno man makes them. Also for side panels you can get them from LPM. about 120 i think shipped for both. http://lpmreplicaparts.com/index.html
im no expert on these bikes but i have done a ton of research so if you have any questions or need to know where to find somthing just ask.

[Beakin]

Great thanks.. I will keep that in mind

as for the pannels, i think im gonna make them myself, so far the mold looks decent

[Beakin]

I decided on the mac exhaust system.. The parts I get on friday will deem the bike road worthy.. Then Ill have something to ride while I rebuild the other engine.. I think the cafe build will have to wait a few months.. or at least until I strip everything down and blast and coat the frame

[Beakin]

new updates:

here is the new chain, tires and cleaned up sprocket area



I spent a while working on the tank but I impressed myself with the results

epoxy primer sanded with 600


I was lucky enough to have some left over porche paint given to me

you cant tell from the pictures but it has really small gold specs in it

here is the final product after a few clear coat attemps





ive decided to strip down to the frame for some sandblasting



right now everything is off, tomorrow morning its off to the sandblasters

Im hoping to be done with everything except the engine rebuild by the first week of September

wish me luck

ill be updating with some pictures soon

[Ace]

Gee that tank looks good.  Any swirl marks in the finish?  Did you have to clear coat it as I'm not sure about the Porche paint?

[Beakin]

well the porche paint was just a base coat

the clear coat is alot shinner plus if anything happends to the clear i can polish it out

I had some trouble with orange peel in the clear then some runs, after a few attemps i decided to sand out the orange peel and polish it

the sides are polishsed but i didnt need to on the top cause it turned out perfect

[Beakin]

stay tuned for some pictures where the painted stuff comes back on..

Im finding the seat to be a real bottle neck.

but everything else is looking pretty snazy

[Bonafide]

yessir ... everything is looking snazzy!! great project.