• Enter the March CB750 Supply gift certificate giveaway! It's easy... Click here, post something, and you're entered into the drawing!

1972 CB750 winter project, build

HaydenRackson

CB750 New member
Messages
3
Reaction score
0
Points
1
Location
United States
*

image7_zps3b248a5e.jpg
 
Last edited:
I am a fellow motocross rider...never got the opportunity or had the money to race though. Do a compression test that will let you know the health of the motor. If it runs good then it should be good to go on the inside. I highly suggest getting a good honda manual for it...they are a little expensive but the information is far more accurate then some of the aftermarket manuals I have run across. Tune up has a list of items on the old 750's. Plugs, replace or at least clean the points....then set timing and dwell. adjust valves, adjust timing chain. The carb issue kind of concerns me...the choke is very simple so not sure why they coudn't get it to work. Get that figured out because they are kind of cold blooded especially if the jetting isn't right on with the pods. Carb sync is critical on these motors so I am suspect it is correct if they couldn't figure out the choke.

Cams do wake up the 750 but...you need to replace the rocker arms with a new cam and they are unavailable from Honda, so you have to send them off and have the hard welded..about $550 plus about $250ish for the camshaft. Before you consider going into the motor ask lots of question....also visit Dynoman Performance, A.P.E. and Cycle X which are the go to places for the 750 motor. I have experience with the motors so ask away!
 
I agree with what dirtdigger says. These motors are pretty bulletproof and if it only has 13K miles it's probably in good shape. Other than the carbs, focus on the valve and timing chain adjustments. Most people didn't do either and adding pretty new performance parts on a valve train full of lash is money wasted. I tried a few things and personally I found the Cycle X optical trigger ignition was the best. I doubt it makes much more HP but it sure revs faster. Good luck.
 
dirtdigger, I appreciate your reply, racing motocross is awesome also was lucky enough to race a lot of hill limbs and hair scrambles. Both are extremely fun and completely different. I did a compression test it is good, also inspected the choke, it works if you manually push it over but the cable that runs up to the bars does not work/is not hooked up anymore which is why the precious owner couldn't figure it out. He also was too nervous to take off the cap to replace the clutch cable. So he may not have been that mechanical. Tonight it wasn't raining so I was able to get the bike in the driveway and drain the oil/replace oil and filter. Also replaced all spark plugs which was a pain because the cast on spark plug #2 slot was not machined very well and was damn beer invisible to fit a socket in there so I had to spend about 20 minutes grinding down a 18mm socket so it would fit inside the slot. Basically the socket was slightly too think and it would not slide all the way in. But would fit fine on plug #1, 3, and 4. Also I replaced the clutch cable. Bike already runs better. Tomororw morning I'm going to check the valves and timing chain adjustment. Then I just need to wait for the next paycheck so I can order necessary parts. I inspected the bike more tonight and realized the too triple clamps are starting to crack so that's been added I my list of parts to replace.

Thanks tommycarl! I have downloaded a few different manuals and have began reading through them.

And thank you motogtp I am going to out the cams off for a while until I'm able to get everything else replaced and back in running order since the precious owners have done some sketchy wiring and have used random bolts/nuts to replace old ones. Going to get to early and get back to working on this thing. So far everything's been pretty straight forward. Next on the list is just wait till pay day and order up the next parts on my list.

Thanks again guys. Here's some photos from tonight.

image.jpg
 

Attachments

  • image.jpg
    image.jpg
    260.6 KB · Views: 141
Some one must have done some weird cobbled together setup on the choke because these bikes didn't come with a handlebar mounted choke cable. There should just be a lever on the left side of the carbs that you flip up to close the choke.
 
Back
Top