Topic: Phaedrus: CB750 RestoMod - Update: 09/23/21 w/ new video

[bwaller]

Re torque Ron, I understand what you're saying. However when you consider what modern stuff is torqued to I really think these older engines couldn't be torqued high enough from stock.  Since you have studs, going more than stock torque is a good opportunity!

You're not the only one who has been carfeul on reassembly only to have it bite back, you'll get it.

[MCRider]

Re torque Ron, I understand what you're saying. However when you consider what modern stuff is torqued to I really think these older engines couldn't be torqued high enough from stock.  Since you have studs, going more than stock torque is a good opportunity!

You're not the only one who has been carfeul on reassembly only to have it bite back, you'll get it.

Yeah, I'm going to add a few more pounds before nailing it back together.

I blame myself for using an old (new, but dated) gasket. I should've popped for a new one. But it gives a chance to see if retorquing will work and add to the collective wisdom base.

If it doesn't, the new gaskets from CycleX will be here and I'll replace it. If it does, I'll have gaskets for the next project, or resell them to someone.

My first new CB750 I bot when I was 18, it was a K1. It leaked and was fixable under warranty. The mechanic suggested rather than the full gasket replace routine, just a retorque. It worked, and he got paid the full gasket replace flat rate.

[MCRider]

I just received the CycleX gaskets! Ordered Mon PM, recvd Thur AM. Still will reassemble as is to see if retorquing seats the old gasket.

Also pulled the oil filter cover. First time i pulled it, grit found in cover though none obvious in cartridge element. None this time. and none in the cam area, clean as a whistle.

I was afraid maybe I hadn't cleaned blast media from every nook and cranny, but now it looks good. Also, I looked online and there is the opinion that plastic blast media may not be harmful, or as harmful as the "glass" media. I would not trust that opinion, but its an interesting opinion.

[Jerry Rxman Griffin aka MuthaF'er]

Not wanting an "oil thread" type thing but I was thinking about your torque. Every time I get thinking I'm getting into trouble too  You guys correct me if I'm on the wrong track. Is/isn't torque the amount of stress you put on a bolt to stretch it to it's proper tightening level? Wouldn't this then be more relevent than thinking about the stress it's putting on the gasket? With this "theory" would/wouldn't applying stock torque figures allow for enough tightening to clamp down the nut on the bolt?

I understand what you are saying Ron and I don't want to sidetrack the thread either. Just food for thought. Helps me learn more too. Like your help with my clutch  I may have been one of the lucky guys. I did not snap any stock studs removing them and I cranked the HD studs to Jay's upper limit. Probably because I had extra anal orifice torque when I did both 

[MCRider]

Not wanting an "oil thread" type thing but I was thinking about your torque. Every time I get thinking I'm getting into trouble too  You guys correct me if I'm on the wrong track. Is/isn't torque the amount of stress you put on a bolt to stretch it to it's proper tightening level? Wouldn't this then be more relevent than thinking about the stress it's putting on the gasket? With this "theory" would/wouldn't applying stock torque figures allow for enough tightening to clamp down the nut on the bolt?

I understand what you are saying Ron and I don't want to sidetrack the thread either. Just food for thought. Helps me learn more too. Like your help with my clutch  I may have been one of the lucky guys. I did not snap any stock studs removing them and I cranked the HD studs to Jay's upper limit. Probably because I had extra anal orifice torque when I did both 

Not sure that I'm following you exactly. Also, not sure that i would want to say what torque is other than from a very lay persons standpoint. The torque on the nut translates to squeezing the gasket. Can't see anyway around it. What i uncovered was that at certain areas around the head the torque was 12 ft lbs. I'm sure i had taken them all to 16-18 at assembly time. Since we're trusting the HD studs did not let up any, and the nut did not physically back off, the only variable left is the head gasket (and the base gasket to a lesser extent.)

So I'll restore the torque squeezing force to 16-18, assume the gasket won't settle any more, and see what happens.

Taking it higher is tempting, but I'm afraid of breaking a stud. 

[Doctor_D]

My head gasket leaked as well on my build. The culprit for me was inaccurate torque readings on the studs caused by residual blasting media in threads.  Once I chased the threads in the block and wire-wheeled the threads on the studs, everything torqued down nicely. In the block at 8lbs with a little blue Loctite, and 22lbs on the head with Mike Reick's high-strength nuts - and not a drop since.

Anyway, congrats - glad it's (mostly) on the road.

[MCRider]

My head gasket leaked as well on my build. The culprit for me was inaccurate torque readings on the studs caused by residual blasting media in threads.  Once I chased the threads in the block and wire-wheeled the threads on the studs, everything torqued down nicely. In the block at 8lbs with a little blue Loctite, and 22lbs on the head with Mike Reick's high-strength nuts - and not a drop since.

Anyway, congrats - glad it's (mostly) on the road.

Thanks DD. As bwaller said above, glad to know others got bit and recovered. I've got a good feeling about this. And for the little I rode it, sure felt good!

[MCRider]

Got it to 20ft lbs. Each time it popped and let loose to go a little higher, my heart was in my throat. That should be enough.

Waiting on those trick Yamaha Cam sprocket bolts from MRieck. Figure I might as well take the opportunity to upgrade. The stock bolts have such a small area of "purchase" it was always an issue with me, only a few corners of the stocks bolts hex head would grab the sprocket as the slot did away with a 360deg grab.  Don't know of any that actually ever slipped, but I'll feel better with the new flanged bolts that have a built in washer.

My new best friend from KV Racing brought over my sidestand today. It was still warm from the surface grinder. He took as much meat off the bottom as he could. He mentioned the chrome (Brown's) was particularly hard to get through, and the weld (Saldana) was really professional. So I'm putting it on right now. He said if that wasn't enough, he'll figure someway to make it shorter adn still look stock.

[terza96]

I been reading your tread for a week with big joy ,from the begging ,amazing job   
Unbelievable , what to say congrat Ron ,big time !!!
This make me embarrassed that I even start my resto and the tread as an amateur 

[mick7504]

Ron,

Just  Just   

Mick

[Ecosse]

ron, you're almost to a hundred pages! don't quit now!

[MCRider]

ron, you're almost to a hundred pages! don't quit now!

Thanks, yeah I'm a little behind on updates, still tinkering though.

[Tintop]

We could just babble on about what type of wax would be best for the new paint.  That should fill a couple of pages.  Kind of like an oil thread.

[RAFster122s]

First car and bike analogies on motors are like apples and oranges but consider that torquing head bolts on a cars I've done motor work on are in the 70-80 ft-lb range and our bikes are in the 20-22 ft-lb range...
quite a difference.

The modern multi-layer steel head gaskets (having read several articles on them recently...including what everyones favorite source for solid copper mc head gaskets had to say on the subject) are like the name says multilayer and I guess I could understand corrosion causing a gasket to age but don't think they would have a shelf life per se, probably a function of older vs more modern methods of manufacture and material technology.

Im sure you'll get her sorted out Ron. I'm hoping your retorque did the job...but, won't you need to do it one more time after you put somemiles on it?
David

[MCRider]

Thanks for all the posts since the last update. Can't believe missed one. Nevertheless work continued on. I had removed the cam hardware and retorqued the head to 20ft lbs. Received the flanged cam bolts (Yamaha) from MRieck and reinstalled the cam hardware. I had marked the adjustable cam sprocket and reinstalled thusly, avoiding another "degree it in' session, to expedite the restart.

The rocker box reinforcement bolts had begun to rust, so we replaced them with chrome. Had to cut all 8 to length.

Tweaked the front fender mount which had never suited me. No it does, took a few hours.

Still tweaking the sidestand by grinding the bottom off, slow going as it gets real hot real fast, but think we are almost there. I hesitate to take it out witout a functional sidestand as if i need it, it may fall over high side.

Restart occurred last night 8PM. Thing starts right now and runs real good, as best i can tell without actually riding it. Idles well, takes throttle, without hesitation, runs at 3000 steady without burbling, etc. But it is a real mosquito fogger. 

At the moment gaskets appear dry. But upon inspection during the reboot, it became apparent to me that maybe the oil isn't coming from the gasket but from inside the exhaust port! That would mean either the guides are leaking or the rings aren't seating and allowing a lot of blow by. So the plan is to ride it for 50+ miles and see if it gets better. If not the head comes off and goes to Mike for an exhaust side valve job. (Intake too if it needs it).  You see many years ago when the head was done, i made this (stupid) decision I'd be cool and put the no seal (less friction) K0 exhaust guides in it. Well now 12 years later i couldn't care a whit about that, I'd rather have no smoke.

If need be Mike will put modern bronze guides with seals in it. The first machinist told me the Manley valves were OK as far as stem wear was concerned. Being made of what they are, Mike said he can regrind them to fit.

So that's the plan. film at 11. (No vid just stills). I'll try to get some vid before the next teardown if there is one. I think it sounds real good.

[MCRider]

For a laugh. Click link and scroll down to bottom.
http://forums.sohc4.net/index.php?topic=110039.0

I was thinking about getting some shots with a bikini model.

[MCRider]

Here's the cam sprckt bolts. No big deal, but the old bolt rt is simply a hex head. On a slotted sprocket only two tips of the hex actually grab the sprocket. The Yamaha bolt (lft) has a flange which will have a greater "purchase" on the sprocket.

While I've never heard of a hex only bolt slipping, the flanged bolt sure feels better. Thx MRieck.

[MCRider]

I plugged another oil pressure gauge in to check the first, Stewart Warner. It reads 80psi v the 70psi on the Joker gauge. Jumps to full pressure right off idle. So I guess its true. I was concerned the Joker gauge was reading too high.

Bottom end must be set up real tight. I did the crank, APE did the conrods. Will need some breakin.

Bike is set up for a ride this afternoon if I can get out of the office. Gotta get some miles on it to diagnose the smoking.

[MCRider]

Just attempted a ride. Tested the brakes before the end of the driveway. The rear made a clunk and became very firm. Relaxing the adjuster got me back to the shop, but I got to findout what happened.

In the meantime, discovered the headlight ears hit the tank. Would have been upset (with myself) had it been more than a gentle tap.

real popular headlight ears. Surprised no one else has mentioned it. Maybe an adjustment up or down will clear it.

[MCRider]

Sorted the brake, long story, just poor assembly. Went for a ride today, up and down local streets. About 10 miles. Too early to say about the leaks and smoking. Certainly less leaking than before. But it ran well. Goal is to get 50+ miles on it by Sunday. Diagnose it and decide if we're going to whip the head off or not.

Got it into 5th, all works well. As others have threaded, the clutch friction point is out there, esp compared to the modern hydraulic on my FJR. But functions perfectly. Under power plates may slip. Too me that would be a good problem. Its a 20 yr old clutch and they are cheap and easy to change.

Front end feels like a hardtail. usual suspects, alignment of tubes, alignment of fork brace, too thick of oil, too much preload, or air. Sorting comes next.

Very hot, ambient temp near 100F. Oil temp drop to reasonable expectations: 20 at idle, 40 at 3500rpm. Didn't go much faster than that. 5000 rpm but i forgot to look at the gauge.

Heavy sigh of relief and a little disappointment. But mostly relief.   

Still got the nagging sidestand problem. With the foot almost ground off, well pretty far anyway, barely makes a change in the angle. If I soften the suspension it will be dangerous, and the susp needs softening.

I just bot 2 stands from eBay to experiment with. Machinist told me it would be hard to weld to the chrome ones I have, without grinding the chrome off, or acid. Better to start with OEM finish, cut and weld to proper length..

I could just bend one, but I just don't like that look.

[Tintop]

Haven't looked into this, but could you swap it for a 500/550 stand, maybe even a 400 one??

'edit' of course that & having to chrome it would add afew more pages with pics.'

[MCRider]

Haven't looked into this, but could you swap it for a 500/550 stand, maybe even a 400 one??

'edit' of course that & having to chrome it would add afew more pages with pics.'

There is a thought! It'll be hit or miss. But some stands are cheap on eBay (others are pricey, no logical progression).

I could go down to CycleRecycle Part II and compare with their stash. But that's such a big deal and my time is limited. Going to eBay for 500/550 right now. Ck the fish for springs, if same length, may be on to something.

And of course we want to stretch this out as long as possible!   

PS: It does use the same spring! That's a big part of the battle. But no reason for the stand to be shorter really. Its a smaller bike but not necessarily lower. Still I'll pursue it.

[seanbarney41]

Just to let you know, 550 stand is longer than 750! ...on my K5 anyway, was running 14.5" shocks for a while and my 750 stand was too short, so I popped a 550 stand on there and it worked good, although my 750 stand is slightly bent

[CBJoe]

FYI.... my CB650 Stand is appx. 8"

Not sure how that compares to a 750.  I've think i might have an extra one you can have if you want it.

Cheers, Joe

[Terry in Australia]

Looking good Ron, unless there was a lot of slop between the exhaust valves and the K0 guides I really doubt that it's the cause of the smoking, my K0 didn't smoke at all with 30-odd thousand miles on the odometer, so I'm guessing it's stuck rings or glazed bores, or both. When you take it for that 50 mile ride, don't baby it, if you get it warm enough it might just fix itself. Cheers, Terry.