Author Topic: 1977 CB750 K7 Resto-mod, Knoxville (Read 100256 times)

Restoration Fan · « **Reply #400 on:** July 14, 2015, 06:27:33 PM »

All right, Nate! Getting close, man!

enwri · « **Reply #401 on:** July 14, 2015, 06:30:00 PM »

Looking good, you must be getting a bit excited about running it.
If you still have the carbs off, look down the throats and see if you can see if all the slides are opened exactly the same height.
Put a light behind them and screw the idle speed adjuster down slowly while looking and make sure they all close at the same time (no light shining through)
Or look up Bench syncing, even a tiny difference in height will effect the idle sound. Doesn't really matter once the throttles are open while riding, but makes all the difference when idling.
Vacuum syncing when its running is the proper way, but benching gets them really close.
The float levels are very important too, all the carbs have to be exactly the same or you may never get it quite right.
It may have been that which made it sound a bit chunky in the video, but no main jet in one certainly wont help.

SOHC4 Cafe Racer Fan · « **Reply #402 on:** July 14, 2015, 08:31:42 PM »

She's a looker!!

Desert-SOHC · « **Reply #403 on:** July 14, 2015, 08:35:38 PM »

Its getting close!!!!!!

AintNoEasyWay · « **Reply #404 on:** July 15, 2015, 06:21:54 AM »

Thanks for the encouragement, guys!

Quote from: enwri on July 14, 2015, 06:30:00 PM

Looking good, you must be getting a bit excited about running it.
If you still have the carbs off...

Carbs are still off. I'll look over them in the next couple nights to make sure everything is set properly. Is it okay to put thread locker or something on the main jets to ensure they stay in the emulsifier tubes this time around? Has anyone else ever had a main jet come out like that?

AintNoEasyWay · « **Reply #405 on:** July 15, 2015, 08:45:13 AM »

Any tips for getting oil pressure back in the engine on first start? I was able to find the following thread with some solid info: http://forums.sohc4.net/index.php?topic=12686.0. Just wondering if you guys have a standard procedure you follow.

I primed my oil pump after rebuilding it & put about a quart of oil in the cylinder head, as recommended by hondaman's book.

70CB750 · « **Reply #406 on:** July 15, 2015, 09:21:06 AM »

If you dont that, crank it up with Kill Switch off, it should pump oil pressure in less than a minute of cranking.

SOHC4 Cafe Racer Fan · « **Reply #407 on:** July 15, 2015, 11:50:08 AM »

Quote from: 70CB750 on July 15, 2015, 09:21:06 AM

If you dont that, crank it up with Kill Switch off, it should pump oil pressure in less than a minute of cranking.

Yep!

Restoration Fan · « **Reply #408 on:** July 15, 2015, 02:52:28 PM »

You guys are much braver than I am. I could not personally imagine starting an engine I rebuilt for the first time without having an oil pressure gauge. Even if there's a short in your oil light and it stays on, you know you don't have to worry when you peer down there and see that you're getting good pressure.

SOHC4 Cafe Racer Fan · « **Reply #409 on:** July 15, 2015, 03:32:02 PM »

Ron,

With the kill switch on, the bike will not fire, but just cycle the engine.

Restoration Fan · « **Reply #410 on:** July 15, 2015, 06:01:17 PM »

Quote from: CB750 Cafe Racer Fan on July 15, 2015, 03:32:02 PM

Ron,

With the kill switch on, the bike will not fire, but just cycle the engine.

I know. That's not what I mean.

In my case, that oil light stayed on because it had a short in it. I would have been crapping a brick in my pants had I not had the oil pressure gauge on there so that I knew for certain that oil was getting pumped up to the head.

I'm just saying that you get a whole lot of "peace of mind" for a pretty small price by using one.

enwri · « **Reply #411 on:** July 16, 2015, 06:09:44 PM »

It's a stressfull/exciting time the first turnover and start.
Cranking without plugs takes most of the load off the big ends and mains, oil in the head at least wets the valve gear, you can't unload the rockers.
Take the rocker caps off and try to look in the intake side, at the cam behind the rocker, the oil should be getting sloshed up on that side, the exhaust side it has been wiped off by the rocker pads.
It should flick a bit out of the exhaust side when running. You should also see it draining towards the front studs if you look down at the base of the exhaust valve springs.
If your oil light goes off when cranking, and comes on when it stops reliably, you should be able to trust it. Might take a while to fill the filter the first time.
When it comes time to fire it make sure all the throttle springs are on, and the idle screw is backed off to nothing, last thing you need is for it to race to redline as soon as it fires.

enwri · « **Reply #412 on:** July 17, 2015, 07:44:56 PM »

Hey Easy, do you have your wheel off and spacers out still? how long is your spacer on the sprocket side, between the hub and swingarm.
I've only got 10mm of spacer sticking out of the sprocket carrier.
Could you measure yours when you get a chance? thanks.
Cant find a definitive answer by searching, csml doesn't have lengths, just different part no.s

AintNoEasyWay · « **Reply #413 on:** July 18, 2015, 07:29:27 AM »

Hey enwri! I'm out of town for the weekend, that's why I haven't had any updates. I'll be home late tomorrow so I'll get back to closing things up on the bike on Monday night. My wheel is still off so I can definitely take a moment & measure the spacer for you if you can stand to wait a couple nights.

enwri · « **Reply #414 on:** July 18, 2015, 03:50:32 PM »

Thanks, no hurry.
Avagoodweekend.

AintNoEasyWay · « **Reply #415 on:** July 21, 2015, 06:23:14 PM »

Hey enwri, not sure how to send photos through message so I'll just upload it here. Is this the spacer you're referring to?

enwri · « **Reply #416 on:** July 22, 2015, 01:43:09 AM »

Thanks, it was the other side I was after, but forget that, you must be getting close to starting it now.
Keep doing whatever you're doing.

AintNoEasyWay · « **Reply #417 on:** July 22, 2015, 05:47:08 AM »

Quote from: enwri on July 22, 2015, 01:43:09 AM

Thanks, it was the other side I was after, but forget that, you must be getting close to starting it now.
Keep doing whatever you're doing.

Oops! If you still need it, I can measure it for you in a couple hours when I head home for lunch. No trouble at all.

I was gone all weekend but hope to close everything up by end of this weekend. The check list for finish keeps growing though! The old hub/flange I ordered off eBay came this weekend & the bearing retainer in that one came out much more easily. I'll get that all back together during lunch today. Then I have a bunch of odds & ends to deal with:

- Reset cam chain tensioner
- Go over some tiny nicks in the engine paint that occurred during install
- Check float levels in carbs
- Check my clutch & get all that hooked back up
- Change out the small sprocket for the new drive chain I have
- Get grease in the swing arm & reinstall
- Get wheel back together, reinstall
- Install exhaust
- Switch engine bolts to other side (not sure if it matters, but I installed them backwards)
- Refill the master cylinder
- Install carbs, clutch & choke cables, all miscellaneous parts

I think that covers just about all of it.

AintNoEasyWay · « **Reply #418 on:** July 22, 2015, 06:01:20 AM »

Hey cal, I think so!

enwri · « **Reply #419 on:** July 22, 2015, 07:43:46 AM »

Quote from: calj737 on July 22, 2015, 05:52:05 AM

is it this one?

Thanks Calj,
Would that be the greasy spacer from an early wheel? I think the late ones are longer, for the big carrier.

Sorry about the sidetrack,

but I saw a photo of a 77 750 with about 15< mm gap on the sprocket side when mine has only got 10mm. not sure which one is right.
Also have another spare sprocket side spacer that would make it about 7-8 mm gap, chain lines up pretty well anyway, I'll leave it how its been unless yours has less than 10mm sticking out of the sprocket carrier. Yours should still be stock, this ones been around.

Are you going to video the start? or is that just tempting fate..

AintNoEasyWay · « **Reply #420 on:** July 22, 2015, 09:52:15 AM »

Ok enwri, still not sure if this will help, but here are some photos.

AintNoEasyWay · « **Reply #421 on:** July 22, 2015, 09:53:30 AM »

Ok, rear wheel flange is good to go. What a pain in the a$$ that was!!

AintNoEasyWay · « **Reply #422 on:** July 22, 2015, 05:00:38 PM »

Okay guys, I've got a couple questions. First, I just replaced my old drive chain sprocket the goes in the engine. Is there a torque value for this?

Second, I checked the float levels on my carbs & it looks like they're set at 12.5mm, which is the value I got from here: http://www.hondachopper.com/garage/carb_info/float_levels/float_levels.html. I know others set there's to 14.5, but my bike ran well at 12.5, so far as I could tell. Should I still change them to 14.5?

enwri · « **Reply #423 on:** July 22, 2015, 05:40:53 PM »

Are the carbs upside down when you measure the level? It depresses the springs in the needles too much when they are. Tip them on their sides so the floats will hang and just touch the needles without depressing the springs.

You will never really know which float level is best until you clear tube test them individually.
It doesn't take much of a difference in float buoyancy, or a difference in the spring in the end of the needle valve, or maybe even bent floats, to make a big difference in the final level.
Make sure the upper vents are clear and fill the carbs really slowly.

Have to add, setting by the float level was good enough when everything was brand new, newer replacement/aftermarket parts may change things though.
My levels are closer to the 14.5 to keep the level a few mm down from the bowl edge.

Desert-SOHC · « **Reply #424 on:** July 22, 2015, 07:34:40 PM »

I was under the impression that the raised portion of the counter sprocket goes to the engine, that is unless you have one with the it on both sides.

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Author Topic: 1977 CB750 K7 Resto-mod, Knoxville (Read 100256 times)