Topic: Another "F'ed" CB750F

[JohnPayne]

This is my first CB, and my first project bike. I am loving it so far, the more I tear into it, the more beautiful it becomes to me. It's an F3, with 28k miles on it. The #4 cylinder wasn't firing, and when I when to look at the tappet adjust to see if that was this issues...there was no tappet adjuster, it had come off and was floating around in the cylinder head. So, I began to strip it down and pull it apart over this long Labor day weekend. The motor is out (laid the bike on it's side, it was pretty easy actually with a couple of helpers) and I just took the head off. I will be sending to Mike Rieck with a head rebuild kit from Cycle Exchange. If there is any pointers or tips you guys have for me in the process please feel free.

This is what it looked like when I first got it and cleaned it up (Not running):

 



The phantom tappet adjuster:


And it's spark plug:


The tear down:





#1


#2


#3


And #4 The one that was missing the tappet adjuster, When I took off the head the valve spring was just floating freely around as well.


The worst looking piston:


The command center:

[JohnPayne]

I wasn't planning on doing past the head engine tear down wise. Whats your opinion on this? Like an idiot I didn't do a compression test before hand to see if a really needed to. Any recommendations on cleaning the cyliners/pistons?

[gearhead ed]

Good luck with the rebuild. I have a 1978 f3 and I just replaced my cam tower pucks. I cut my frame so that I could leave the motor in place. I have used a soft wire wheel in the past on the piston tops and it worked for me. Check out the 750f thread for some builds.

[Jerry Rxman Griffin aka MuthaF'er]

CycleX do a "head rebuild kit" for a F2/F3?

[JohnPayne]

Part # #F2-007
on :

http://www.cyclexchange.net/Engine%20Partsr%20Page%20Valve%20Trane.htm

[Retro Rocket]

If you plan on doing any miles on that bike you may want some decent tires. Those things will track like a #$%*, i would only use them on a slow round town special, definitely not a highway or touring bike...

Mick

[JohnPayne]

Hah, yeah. They look terrible as well. Unfortunately they came brand new with the bike. Maybe I will toss them on craigslist or something.

[Retro Rocket]

Hah, yeah. They look terrible as well. Unfortunately they came brand new with the bike. Maybe I will toss them on craigslist or something.

They do look cool and would suit a nice little rigid for bar hopping,  but your F bike will like you more with some decent tires....

Mick

[JohnPayne]

So, if I have the head off, do you guys think should I just keep going and do piston rings? Anything else as well?

[Jerry Rxman Griffin aka MuthaF'er]

It's a crap shoot at this point. Can't hurt but may not be needed but not sure if you can get the rings anymore. On the shelf next to the hens teeth. Much discussion about that but I haven't heard anyone that has found off the shelf F2/F3 rings. You may have to ship off the pistons to Total Seal for cutting and fitting.  If you install a frame kit you won't need to tear your whole bike apart to ring it later (if needed). And the law of averages states that if you do something proactive like that you won't need it anyway.

Anything else?? How much cash or credit card do you have left? I will have well over $5000 in my engine. I'd say maybe $10,000 is about the ceiling but $7000 will get you a damn fine engine like mine. Seriously! Doing the head, etc and a 836 kit is probably good enough for the first time. Next step is bigger pistons, rods, and carbs. Save that for the next time you need to get into it.

[JohnPayne]

Hah, I would love to do 836cc. Right now is not the time financially, I am only working part time because I am in school. I am probably working with $1500-2k budget. I want to do, new front and rear suspension $400, Yoshi replica exhaust $300, powdercoat wheels and frame (not sure about the price of that yet), the head rebuild will be about $700 after Mike R is done porting it and putting all together. I guess I will see where it takes me and what this addiction makes me buy (probably more than i need).

[tweakin]

I have a set of New old stock F2 piston rings, never been used, in original packaging. 

Shoot me a PM if you are interested.

Hah, I would love to do 836cc. Right now is not the time financially, I am only working part time because I am in school. I am probably working with $1500-2k budget. I want to do, new front and rear suspension $400, Yoshi replica exhaust $300, powdercoat wheels and frame (not sure about the price of that yet), the head rebuild will be about $700 after Mike R is done porting it and putting all together. I guess I will see where it takes me and what this addiction makes me buy (probably more than i need).

[MasterChief750]

chem dip will take the carbon right off the pistons. i think the rings are still available from honda.

[JohnPayne]

Whats your method, put chem dip into the cylinders? Or remove them and dip?

[MasterChief750]

remove them then dip is what i did. works well on the head combustion chambers as well let them sit for a day prolly each and it will wipe off.

[HedNut]

I love F'n Builds!!  Cool stuff....Looks like you got a great bike there!!
With my K8 I'm up to somewhere between $1300-$1600... including the cost of my bike ($300) So far... you can get a lot done with that if you're "thrifty".... I didn't get any head work, powdercoating, exhaust or new suspension...yet! ahah  But your bike seems to be in a bit better shape to start off with!

Cheers! I will be watching this one!