'78 CB750 Restore

gearbot

New Member
Alright, I had purchased this bike over 2 years ago and finally got around (and had some extra cash) to get this project rolling.

I bought the bike for $250 off another student here at school. It was non running at the time but I didn't care, I wanted my 750.

Here's a pic of when I bought it.
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I later read up on the 750's and found out I had an F2 engine which was the "lemons" of the 750 lineup with their notorious valve guide problems.

I decided it would be cheaper to just buy a running engine instead of rebuilding. So, I was fortunate to stumble across a spare K5 engine 3 hours away from home. Had good compression so I picked it up.
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Cleaned the carbs (left are dirty, right are clean)
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I was able to get the engine running before I began cleaning it up.
Video

Had the frame, swingarm, battery box, etc. powdercoated gloss black.
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Picked up some shorty shocks since I'm a short kinda guy :D
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I'm still in the process of cleaning the engine from 30 years of road grime and leaked oil.

I'm having all the hardware replated since most of it was losing it's original luster. Should be back in a few days so I can install the engine.

Redoing the entire brake system. Rebuilding the calipers, purchased an aftermarket front master cylinder, looking for a rear rebuild kit, and replacing all the hoses with a Hel S/S set.

I purchased a set of needle bearings off of McMaster-Carr. According to the specs and my measurements, the bearings will fit into the swingarm but the swingarm shaft will need lathed on the ends (just a little under 0.25mm). So, if this all goes well, I should have a needle bearing swingarm for only $25. I'll keep posted on that.

I hope to be riding it in a few more weeks ;D
 
I vote you install the exhaust in the same way as in the video. Put a flapper on the end of the pipe, and install some air horns.
 
I'd like to buy your old F2 engine, let me know how much you'd want for it. I'm curious to know exactly what you mean about the valve guide problem, since I'm rebuilding a few of them.

Take care.
 
Sean said:
I'd like to buy your old F2 engine, let me know how much you'd want for it. I'm curious to know exactly what you mean about the valve guide problem, since I'm rebuilding a few of them.

Take care.

sorry, not for sale. i have intentions of rebuilding it with some killer aftermarket mods (they make big bore kits now for the F's: www.dynoman.net).

about the valve guide problem. check out the sohc4.com forums and look under the FAQs. read the "thoughts of hondaman" thread and find the post about the F's valve giude problems. apparently my bike fell into this category. when i checked the bikes compression before disassembly, the cylinders were as follows: 100psi, 90psi, 90psi, 0psi. when i looked at the 0psi cylinder, i could wiggle the exhaust valve a good mm or two inside the guide.
 
Thanks for the info. I thought the only major problem was the valve spring retainers.

The products from dynoman are great and the service is amazing.

Good luck on the rebuild. Are you going to use the 836cc or the 1000cc pistons?
 
nah, just the 836 kit. that's plenty for me.

here's my bearing swingarm mod.

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only cost me the bearings and a 24 pack of mt. dew (bout $30 total). a guy i know that runs the school machine shop let me lathe the swingarm bolt carrier down for the case of dew. there's a little play (just a few thousandths) inside the swingarm so i'll just find something to wedge in that small space.

still waitin for my hardware to come back from the platers... :-\
 
got bored, so i cleaned the wheels
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engine is all clean now and polished
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aftermarket front m.c.
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more powedercoated goodness
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Man even tho im more of a spokes fan, i always thought those wheels were the cats ass. They look fast going nowhere...
 
Tintin said:
Nice! What did you do to clean the engine?

from the earlier post of the greased up cases, i just degreased the sh*t outta them and used a little elbow grease and a brass brush. oncei had all the crud off I plugged all the holes and sandblasted the case. i then just did the 600, 800, 1000, 1500 grit sandpaper and final buffing with polishing compound for the covers. i'm just going to leave the case bare aluminum and let it age. i did the same thing to my kz cases an i like the outcome.

TonUpSoldier said:
Man even tho im more of a spokes fan, i always thought those wheels were the cats ass. They look fast going nowhere...

i'm actually a spokes kinda guy. that's the only thing i'm unhappy about with my bike. sucks for me because going to spokes is the biggest pain in the ass to convert. but that's later. my goal is to make it look like an older K model but with more modern stuff
 
got the engine back into the frame

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rolling...sorta. getting a little ahead of my self but i wanted to test the height

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having those drop shocks sure are nice. i can actually touch the ground with both feet. admit it, it's my tippy toes, but hey, it works!
 
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