Topic: 77 CB750 Starting Issues

[chevy357]

So I have a 77 CB750 with about 40k miles on it, and here recently I have had trouble getting it to start in the morning.  About a couple of weeks ago it started making this loud noise when I try and start it, and it seems like the starter doesn't turn the motor over as strong as it used to. It just turns it over kind of slowly, enough to get it started but it usually takes a good minute for the bike to fire and stay running.

So my question is what's causing this? Is the starter bad?

Thanks,
Ben

[bollingball]

The starter may be reacting to another problem. You did not tell us near enough info about the bike. What state is the battery in all the wires and the grounds. When did you do the last 3K tune up?? How clean are the carbs? How long have you had said bike? I could go on but.

                                           Ken

[chevy357]

Sorry about the lack of info. Just trying to figure out if the starter is bad or what is making the noise when it starts.  As for the info on the bike I bought it last year and completely rebuilt the bike, besides the motor, because it ran fine. I did disassemble the carbs, cleaned and rebuilt them.  The carbs have pods on them and im running the stock headers with a 12" muffler without a baffle. I re-jet the carbs to a main jet of 135. The battery is brand new. I replaced the stock Rectifier with a new one as well. I replaced the points ignition with electronic ignition with band new coils, wires, and plugs.  Ive only put 3500 miles on it since i rebuilt it last summer, and since then i have changed the oil twice, because i wasnt sure how it was taken care of by the previous owner. As for the starter im not sure how old it is, up untill a few weeks ago it was starting perfect.

Thanks

[mycb750k6]

Did you test the new battery? Sounds like it needs a charge even if it is new. You may have run it down.

[chevy357]

Did you test the new battery? Sounds like it needs a charge even if it is new. You may have run it down.

I thought that as well but the battery checks at like 11.5 volts when not running, and a little above 12 volts while running.

[Stev-o]

+1, check that battery and confirm it has 12+ volts and the connections are good.
Many guys keep there batteries on trickle chargers to keep it fully charged.
Report back.

[MoMo]

the battery should read 12v and then go up to almost 14 when increasing rpm's.

[bollingball]

How does it start with the kicker. Plus1 charge the battery over night to see if it helps. The noise could be from the starter clutch not the starter. You said this happens in the morning. Does it start normal the rest of the day?

                                  Ken

[chevy357]

How does it start with the kicker. Plus1 charge the battery over night to see if it helps. The noise could be from the starter clutch not the starter. You said this happens in the morning. Does it start normal the rest of the day?

                                  Ken

It starts good though out the day after it warms up. But it stills makes that noise.  I havent ever used the kick start especially when its cold out in the morning, because how long it take to start with the electric start.

[bollingball]

First off 11.5 is to low. If your batt is low the starter drags it down even more all this is taking power away from the coils and makes it harder for the bike to start. Using the kicker gives this power back to the coils and makes it easier to start other than your right leg
It looks like more than one thing going on here 1)low batt. Why? 2) starter clutch noise. 3) charging this is what I would do first. 1)Start charging batt. over night don't cook it. 2) Check all wires in the start circuit and the grounds while the batt is charging. The next day take the batt off the charger and let it sit not used for 1 to 2 hours and then record the voltage reading.it must  or should be 12.6 or higher mine reads 12.8 to 13.2 and will for 3 days.
 If batt. looks good hook it back up start bike. With meter on batt. increase RPM's record readings every 1000 rpm's up to 4K and tell us what they are and we can go from there Hope this helps We will talk about the noise later.

 Ken