1981 CB-750 Cafe my first bike project

[TY81]

Hey everyone, I'm new to the site and new to on-road bikes in general! I picked up this '81 CB750 the other day after doing a lot of research on café platforms and as you all know, if you research café racers the name "Honda CB***" comes up again and again. so the bike was for sale for $900 and I talked the guy down to $675.

Heres some pictures of the bike when I brought it home

So the first problem is that the engine seems to be knocking, but once again im totally new to the CB scene and im not 100% sure what the bike SHOULD sound like in the first place.... It idles pretty good once its warmed up and it shifts nicely too. the odometer reads 9128 miles but Im sure that's not correct, so I don't know exactly how many miles are on the bike.

the second problem is that when I try to start the bike it wont even attempt to engage to starter motor most of the time, so I have to sit there and keep pressing the button until it decides to work... im thinking its probably the starter solenoid that is faulty but if you guys have any ideas as to what it could be id appreciate the input!

Problem #3. the battery seems to not be recharging because when I got the bike the guy told me it wasn't charging and we had to jump start it, but when I got it home I jumped it and then rode it around the neighborhood for a little bit and then it sat for the rest of the night and most of the next day, then when I got home from work I checked how much the battery had in it with a multimeter and it was reading about 11.7 volts, but when I went to try and start it I couldn't get the push start to work so I gave up for now until I get some input from this forum... I should also say that the battery is brand new so that shouldn't be the problem.

also if anyone knows of any good resources for OEM 750 parts (especially electrical components) id really appreciate to know about it!

Anyways, im really looking forward to this project and iv always loved the café style bikes! im glad I found this forum and I hope to be an active member of the online community! thanks for any help and input!

 

[bagoony]

I had the same issue with my battery. You might need to replace your stator or alternator. When I took a look at my stator, it was pitch black. The wires should be brown.

 

[nickp]

looks like that exhaust is worth more than you paid for the bike... Original 2-4 exhausts are worth $1000 plus at home here.... had the same electrical issue with my 81! Go through these steps to see what you need to replace out of the three charging components http://www.hondachopper.com/garage/...ng_system/troubleshooting_charging_system.pdf

And as for the knocking.. it could be anything from bearings to an oil pump. Might need to take a stethoscope to the engine to find out where its coming from, then work from there.

 

[amc49]

Draining the oil will tell the tale, look for bits in it.

Oil pumps don't knock, they kill the motor which usually killed them first.

Calipers and discs say '80 model rather than '81...........speedo change too which verifies it even more, '80 had the 85 mph speedo that Joan Claybrook saddled that year with, safety issue she said. That speedo is the 150 mph one.

OP is a year old.