Topic: 1974 CB750, new bike, new owner, new user, and new questions :P

[poofdog]

I just listed a NOS mac megaphone muffler in the for sale section

[calj737]

Black from Regulator doesn’t turn on the M-Unit, it only provides the Regulator a battery voltage status. The BLACK from your KEY SWITCH activates the M-Unit.

The BLACK from the Regulator and Key are NOT grounds, they’re powered.

[piefairy]

Black from Regulator doesn’t turn on the M-Unit, it only provides the Regulator a battery voltage status. The BLACK from your KEY SWITCH activates the M-Unit.

The BLACK from the Regulator and Key are NOT grounds, they’re powered.

I mentioned that I have removed the key switch. With this being the case, should black then be connected with POS from the battery, and wire the LOCK to the POS end of the "global" kill switch I have installed? The "global" kill switch is between the M-unit POS and the battery. Sorry, its not on the diagram, I put it in today.

[calj737]

I’m not sure about how you will wire in a “Kill” switch that turns off the engine and disconnects the battery power to the M-Unit. You’re basically going to use a toggle switch and a relay? Sounds problematic.

In order to excite the M-Unit, you need to wire a switched 12v source into the LOCK port. It can not be full-time wired, so you need to sort this aspect out before you go too much further in your wiring.

[piefairy]

I have a 15 amp "on-off" switch wired in to kill the main power on the M-unit. I was planning to have the Lock get its POS from the same main. I re-read the wiring on the M-unit again. My setup would end up with the lights/aux always on unless the kill switch was pressed, correct?

[piefairy]

I was hoping that when bluetooth was out of range, the bike would be in a passive state with just the M-unit waiting to reconnect, and the "kill switch" would be used when the bike was going to sit for a while to save the battery.

[Bankerdanny]

Thanks for the info.

I did manage to join the club of 750 owners to snap their clutch lifter plate. I was tightening it slowly and working opposite bolts, but I think one of the bolt holes got hung up on the post. I was tapping the outsides of the lifter plate and I hear a "ting" and thought perhaps it was just seating itself. Went back to tightening and saw the tip move. Yarg, another part to order. I was hoping to be up and running next week. We will see.

Got frustrated and opted to stop after that, I will post up again when I get back at it.

Forum member Budman makes a billet replacement. He gave one away at the SOHC4 Family Reunion last August. Here is the link to his thread about it: http://forums.sohc4.net/index.php/topic,166504.0.htmlhash=item33d0a63a36:g:k10AAOSwIWVY~hos&vxp=mtr

[70CB750]

Thanks for the info.

I did manage to join the club of 750 owners to snap their clutch lifter plate. I was tightening it slowly and working opposite bolts, but I think one of the bolt holes got hung up on the post. I was tapping the outsides of the lifter plate and I hear a "ting" and thought perhaps it was just seating itself. Went back to tightening and saw the tip move. Yarg, another part to order. I was hoping to be up and running next week. We will see.

Got frustrated and opted to stop after that, I will post up again when I get back at it.

Forum member Budman makes a billet replacement. He gave one away at the SOHC4 Family Reunion last August. Here is the link to his thread about it: http://forums.sohc4.net/index.php/topic,166504.0.htmlhash=item33d0a63a36:g:k10AAOSwIWVY~hos&vxp=mtr

Ha, met him on ebay, looks like great improvement on the clutch.

[piefairy]

If I had seen those before I replaced mine with an ebay NOS, I would have gone that route for sure. I was wetting my pants the whole time I was tightening the bolts... What was worse, once I got to torqing them, I realized I forgot to bend up the tab on the lock washer, so I had to start all over. O-well. Its done now hopefully.

[piefairy]

I’m not sure about how you will wire in a “Kill” switch that turns off the engine and disconnects the battery power to the M-Unit. You’re basically going to use a toggle switch and a relay? Sounds problematic.

In order to excite the M-Unit, you need to wire a switched 12v source into the LOCK port. It can not be full-time wired, so you need to sort this aspect out before you go too much further in your wiring.

Cal,

I am having a hard time figuring out the reason it cant be wired to 12v full time. If I use the default double tap option on the start button, it will kill the lights and ignition, and without my phone near it, the bike cannot start correct? If that is the case, what is the problem with the LOCK being connected to 12v the entire time the main "kill" is on? I've been watching the videos from "Revival Cycles" and reading on it and I cant find an issue, but I am new to this thing and you have probably more hours of headache with it, and people like me, than I will in 3 lifetimes.

Thanks for the help

Edit,

Nevermind, finally found it. If I ignore the lock input in a keyless configuration, the bluetooth will be the lock signal. But back to the black wire from the rec/reg, should I then run it to the battery POS?

[calj737]

But back to the black wire from the rec/reg, should I then run it to the battery POS?

No, because then it will be constantly energizing the field coil and kill your battery. LOCK port or one of the AUX ports please.

[piefairy]

Question on my neutral switch. The neutral light is always on. I have removed the guts of the switch, the housing is stuck, and put it together. It seems to have continuity from the ball seat to the ground screw threads no matter if the spring is depressed or not. I believe this is incorrect, but I want to make sure before I replace it.

Thanks

[calj737]

Correct, incorrect.

[piefairy]

Correct, incorrect.

So you are saying that I am correct that it is incorrect to have this continuity and it needs to be replaced?

[calj737]

I am.

[HondaMan]

This is entertaining to read!

[Jerry Rxman Griffin aka MuthaF'er]

"housing is stuck"?? In the engine? If so, under the shifter side cover, jiggle the shift drum in and out.

[piefairy]

Well, I thought it was stuck until I finally saw a good image of the underside of the engine. Apparently there is a retaining bolt with a key'd washer that holds it in. (I was wondering how it would stay sealed without threads). Now I just cant figure out how to get that bolt loose. Its on top of the frame and I cant get a ratchet in there or a good grip with it with pliers. Any suggestions?

Also, I started wiring in my idiot lights today. The oil pressure light turns on as soon as I give power to the engine, I assume this is correct since the engine isn't running? Its a low pressure sensor and not a high pressure sensor correct?

Also, to whomever on this forum posted about using a syringe and backfeeding the brakes from the bleed nipple up, THANK YOU. Made life so much easier than trying it the traditional way with a bleeder pump.

[calj737]

The oil pressure light turns on as soon as I give power to the engine, I assume this is correct since the engine isn't running? Its a low pressure sensor and not a high pressure sensor correct?

That is correct.

[piefairy]

Is the bolt that holds the neutral sensor switch in a 6mm head? I've only found 1 vague reference to it, and I need to get a crescent wrench for it.

[70CB750]

Is the bolt that holds the neutral sensor switch in a 6mm head? I've only found 1 vague reference to it, and I need to get a crescent wrench for it.

Pretty sure it is M6 -  wrench size 10.  Get a metric 1/4" socket/ratchet set. They are like $10 at Lowes.

[piefairy]

I have a ratchet set but I cant even get the 10 socket over it without hitting the frame, it will not seat fully on the bolt, only about half way at best. I am planning to try a crescent wrench next.

[piefairy]

Here is a one off question... are the 1975 cb750 corbin seats able to fit on the 74? The mircrofische seems to list all the same parts, but that doesn't mean the welds are in the same place.

Thanks

[piefairy]

Ok, I'm getting frustrated with this damn neutral switch. I got a crescent 10mm wrench on it and it just skips off when trying to unscrew it. I've tried getting a socket head on it, but it hits the frame even before I attach the socket wrench. I did cut down a 10mm socket head so it will fit over the bolt, but I still don't have room to put the wrench on it even with a right angle drive adapter. I hit it with a propane torch today to try and loosen it up, got it hot enough that the paint on the engine started to bubble and burn off (didn't want to get much hotter in case there were internals or seals that may melt). Still no luck. I cant think of anything else to try except pulling the engine to get it loose and I REALLY don't want to do that. I am about to just gut my new neutral sensor and put the insides into the old one and use liquid gasket to seal it back up, but that would still leave the oil drip coming from the old switch... Anyone have any ideas? I'm at a loss for what else to try. The bolt head is literally directly over the frame tube on the bottom of the bike with not much clearance, a 1/4 drive socket will not fit on without cutting it down.

But on the bright side, the wiring is done short of the speedo, its been a pain to find a motoscope mini in stock anywhere but finally have one coming. As long as I can at least plug the neutral hole, she should be running tomorrow or saturday at the latest. Just in time for the long weekend 

[calj737]

Remove the rear engine hangar bolts. Block of wood under oil pan, jack the motor. You might also need to loosen the forward bolts to allow the motor to pivot on them. No need to “pull it”.