Recently aqcuired a 1979 CB750 - The Run Down.

[tomaszzalewski]

Hello

First post, recently got a 1978 cb750 and got to working on it finally over the weekend. Got the bike started yesterday after taking apart the carbs and hand cleaning for now.

1 thing, is that I have an issue with the choke, when it pulls it doesnt engage the choke cable. I would like to keep the carbs and get a carb kit. They were generally not that dirty compared to other carbs I saw. The reason why the choke isnt engaging...I dropped the carb on accident After that I noticed the issue with the choke.

To start it I had to manually engage the choke. After some running, i try to turn choke off on my own and the bike cant stay running on idle.

The 2nd, the clutch engages, no play in it but when i put it into first and put the clutch in, the bike is still in gear. Is it just stuck? Will it get unstuck after it gets heated up with oil?

I also changed the oil with Shell Rotella 15w40. Is that an ok oil to use? or should I go with 10w40?

Cylinder 1 was back firing, i fixed that by tightening the boot from the carb to the block.


Just looking for insight. I am a 100% novice at these things but very eager to learn.

Thanks!

 

[hinksy]

You need to pull the carbs and clean them thoroughly . The passages for the idle circuit and the mixture screw could be crusted up and dont forget to check the accel pump works , the bike will bog otherwise . There are workshop manual downloads on this site , so have a look and see how to set up your choke . You may have bent the cable attatchments

 

[tomaszzalewski]

OK thanks for the input. I got an ultrasonic cleaner and some cleaning solution off km caruberator.

Will start on that this week to get them all cleaned up.

I wish I knew exactly what happened to my choke on the carbs. Pretty upset about it but we will figure it out!

This forum is amazing.

 

[cavemanrex]

I had a set of carbs on the last ZRX I did that were bad. 10 years of sitting in a storage with fuel. Stripped them down and unracked them twice and gave them a session in the heated sonic tub. I finally called someone I look up to and trust. He said it was the idle jet. I said "Nope I cleaned it." He said "You got to trust me on this." I did. Bought new jets from https://www.jetsrus.com/index.html. He was right.

 

[hinksy]

Forgot about your clutch , yes you can free it up by riding it . Check your cables free play first , it has adjusters at the handlebar and engine . Overtime the plates can stick together , whether it is rust from moisture or just non use . So if you can start rolling and put it in gear , just ride while pulling the clutch lever in and out untill it frees up . Sometimes you may need to brake and put a load on the engine as you go , but it usually will free up . But if it doesnt , then you`ll have to go in