Topic: CB 750 Project 1 - Rides Well but a few tweaks needed

[timbo750]

Got the covers back from the polishes today. Will post photos when I get time and space to take them out of the box, they look quite good considering what they where like.

[MRieck]

Fork case = sliders (or lowers)

F2 forks will fit your triple, both stanchions are 35mm. But... you may run into trouble if you plan to keep your spoked wheels, as F2's were fitted with comstars. May need some ingenuity with rotor size/spacing, and spindle spacers will also be different. I'm sure it's been done though. I think you'll find a lot of people opt for a GL1000 front end.

I have done it.

[MRieck]

Honda Man - in reply, where all the bearings "extra clearance" I am thinking I may have normal for them all however I didn't ask when ordering so I don't really know.

With the final drive both original and the purchased set have a double row bearing and the set I purchased had excellent bearings and so I ma not changing them. this said though I think all the bushings are bronze from memory - I will check on that.

I have check the shift drum for anything other than excessive wear, but I got forks with shift drum I purchased so it all should match up there. I will just need to check the pins and holes for slop. the old drum actually rotated freely by hand before I pulled it apart so the holes in the case should be fine.

Once again HM your knowledge is outstanding and always grateful, I have ordered your book but it is very slow coming across the waters.

Some folks used to get the 'extra clearance' bearings for all 4 on the shafts, back in the Production Stock roadracing days of the 1970s. The theory was that they didn't need as much break-in time to release the friction, and since these bikes were often running at very high revs during our bouts, it made some sense. After I've ridden mine so far, though, I am keen with the idea of keeping the tight ones myself, just because the gear wear was so low that I used most of the gears again, changing just a few. The 'new' ones had more inner bushing clearance than the 'old' ones, even now, and none of them had measureable (or even observable) tooth wear toward their outside edges of the teeth. This latter would show up if the shafts were out of alignment for a long time from the twisting loads, and as much time as I spent near (or over) triple-digit speeds in those pre-marriage years, I was dead sure I would see this: sometimes I would be doing whole weeks of 1000-mile days for my vacations, changing oil every night. I see it in the later gearboxes (iron bushings) with far fewer miles, so it seems the bronze ones make a heck of a difference.

Thanks HM, the finally arrived today - took just over a month, I got parts from Dynoman in one week, strange. it would however seem strange that Honda would go backwards with cast bushings instead of the bronze, we may never know why.

15. The bronze bearings inside the tranny gears became cast iron on all the New Factory bikes I saw by 1974. By 1976 they were all cast iron.
18. The expensive "holey" drilled-and-lightened cam sprockets disappeared in favor of solid, as-cast versions.
19. The expensive 1-piece oil rings disappeared and became the cheaper ripple-ring type.

  My 750F has bronze bushings in the gears and that is 1975.
 The early cam sprockets were heavy, sold pieces....the later sprockets had the lightening holes. I just ordered a new OEM sprocket....it has the lightening holes.
 The 1 piece oil rings were dumped by every manufacture of engines as they do not seal as well and produce a lot of friction. They are also clunky, thick heavy pieces. Being cheaper to manufacture has no bearing on their performance. It happens. Ring packs have gotten thinner to reduce friction and improve performance.

[timbo750]

Fork case = sliders (or lowers)

F2 forks will fit your triple, both stanchions are 35mm. But... you may run into trouble if you plan to keep your spoked wheels, as F2's were fitted with comstars. May need some ingenuity with rotor size/spacing, and spindle spacers will also be different. I'm sure it's been done though. I think you'll find a lot of people opt for a GL1000 front end.

I have done it.

Got the front end sorted, I am keeping the later model set for the next build, I got a set K2 fork lowers from Bill, new progressive springs and new stanchions. I am hoping to start on putting that together soon but want to get the discs cross drilled first, I am also going to look for someone local that can lighten them and it seems I need to find someone with a Blanchard grinder. I am not exactly what it is yet but I will find out soon enough.

[timbo750]

  My 750F has bronze bushings in the gears and that is 1975.
 The early cam sprockets were heavy, sold pieces....the later sprockets had the lightening holes. I just ordered a new OEM sprocket....it has the lightening holes.
 The 1 piece oil rings were dumped by every manufacture of engines as they do not seal as well and produce a lot of friction. They are also clunky, thick heavy pieces. Being cheaper to manufacture has no bearing on their performance. It happens. Ring packs have gotten thinner to reduce friction and improve performance.
[/quote]
I actually have an original solid in good condition and also the lighter version with the holes but sure if I should get the adjustable unit. It seems most people use the adjustable as soon they go away from the standard cam.

[Retro Rocket]

Adjustable is good with stock cam as well, anything that help you dial in the engine better is an asset....

[timbo750]

got some photos of the parts covers, quite happy with the finish considering they were badly pitted with corrosion and had flakey chrome. Not the clearest of photos due to the light and with flash they actually looked crap so I wasn't going to put them up.

[SOHC4 Cafe Racer Fan]

Outstanding, painstaking polishing!

[Terry in Australia]

Going back to front ends and lighter discs for a moment, I'm thinking about using an F2 front end with a spoked GL1000 Goldwing wheel and discs on my son's CX500 Bobber. I could use a CB750 wheel as the hub is the same axle size and disc bolt pattern as the goldwing item, but I want to use the alloy rims off my old GL1000 roller.

The GL1000 discs appear to be the same size as the F2 discs, (I say "appear" as I don't have any F2 discs to compare them to) and about half the thickness of CB750K0-K6 discs. I'm not sure if the disc offset will work, but once I get another pair of discs I'll assemble it all and see if it's gonna work. Cheers, Terry.

[timbo750]

Terry, if you want I can measure what I have. Its not standard K or F as the spare set I have came of a police bike and the forks appear to F2 but the rims are spoked and it is a twin disc setup.

Project 1 CB750 - http://forums.sohc4.net/index.php?topic=126864

[Terry in Australia]

Thanks Timbo, I was regularly pulled up by the police back in the day on F2' cop bikes(when I was booked for doing speeds in excess of 180KPH in a 60 KPH zone on my F0, for instance)  and they all had Comstars, so I reckon your front end is off the first of the DOHC 750 cop bikes, they had the same forks as F2's, but with wire wheels.

Can you post some pics mate? Where in Melbourne are you? Cheers, Terry.

[timbo750]

I have them stored out the back at work so I will get some photos next week, I can measure a few things as well if you are interested just let me know what to measure.
I am over in Burwood East.

Project 1 CB750 - http://forums.sohc4.net/index.php?topic=126864

[Terry in Australia]

Thanks mate, if you could measure the OD and offset of the discs and the width of the hub that'd be great, as I can compare them to my GL1000 bits. Cheers, Terry.

[timbo750]

Thanks mate, if you could measure the OD and offset of the discs and the width of the hub that'd be great, as I can compare them to my GL1000 bits. Cheers, Terry.

Terry, here are the measurements for you. the discs are 132mm apart - outside to outside, the offset if 25mm - mounting plate to outside of disc and the OD of the disc is approx. 276mm - it is still bolted to the wheel with the axle installed so could not get an accurate measurement.

[Terry in Australia]

Hey thanks Timbo, and I love the twin speedo drive, I've got a couple of cop speedo's here, I was always interested in why I was booked for "Speeds in excess of 180KPH in a 60 KPH zone" until I bought one and realised that it only went up to 180 KPH!

The idea of having two speedo's (I believe) was so the cop could press a button and lock the speedo needle on one speedo to show the errant motorist what speed he'd been doing, while using the other speedo himself. (nowadays the cops just show you a digital readout on another meter)

I don't remember the cop showing me his speedo reading (my speedo said I was doing 215 KPH, so 180 sounded a lot better) because he was too busy swearing at me when he asked for my license and all I had was my learners permit?

Luckily he asked me what I do for a job, and when I told him I was in the Army he softened right up and told me he was a Vietnam veteran, and dropped the charge to speeds in excess of 130 KPH in a 100 KPH zone, and I got an 80 dollar fine. (and kept my learners permit, in those days I don't think they could take it off you?) Cheers, Terry.  

[timbo750]

I once overtook an unmarked cop car on a back country road, I knew it was a cop as I went past so made sure I slowed down. he pulled me over and asked why I was speeding, I said I was bored. The road was dead straight for more than 60k's, I don't think he knew how to reply. anyway as I was living in Queensland at the time and visiting parent's I had interstate licence and rego and he either couldn't be bothered with the paperwork or couldn't actually prove what speed I was doing. No fine just a warning.(mind you I was not doing anywhere near 180)

[Terry in Australia]

Ha ha, gotta love country cops Timbo, when I picked up my Triumph Rocket III from Whyalla in South Oz in 2009 and rode it back to Melbourne I passed a highway patrol cop going in the other direction and I was doing well over 200 KPH.

I shiit myself and slowed right down, expecting him to turn around and give chase or radio for a road block further up the road, but after about 30 minutes, I realised that he didn't do either. Later in the day I was cruising along happily at around 160 and saw a cop car coming towards me, so I slowed down, but all the cop did was wave to me and continued on.

I decided that this was a SA thing, so maintained my (illegal) speed until I hit the Victorian border. Once over the border I slowed right down (to around 120) for the remainder of the trip, because (1) it was pissing down rain, and (2) Victorian cops aren't nearly as progressive as SA cops.........

[timbo750]

Not much to report in the way progress. I have been sorting out the shed to make as much room for the assembly, anything not being used regularly or for the bike has been stored and moved some things around to give me more floor space.

I have decided however to cross drill the rotors and did a lot of research and found a printable pattern on the xs650 forum, turns out the xs650 has the same diameter disc so it fit perfectly.

the bad news is I tore my calf muscle yesterday so things might stay slow for a while but I will post pictures when as things happen.

[Terry in Australia]

Oooh, spirally...........

[timbo750]

There three patterns all split into quarters.  Print 4 and tape them carefully like we all did primary school and then tape to the disc and use a centre punch.  I only have a basic drill press with no luxury of an index wheel so this should work fine.
 
Does any one know if it makes which way the spiral holes are in relation to the rotation of the disc?

Project 1 CB750 - http://forums.sohc4.net/index.php?topic=126864

[edwardmorris]

There three patterns all split into quarters.  Print 4 and tape them carefully like we all did primary school and then tape to the disc and use a centre punch.  I only have a basic drill press with no luxury of an index wheel so this should work fine.
 
Does any one know if it makes which way the spiral holes are in relation to the rotation of the disc?

Project 1 CB750 - http://forums.sohc4.net/index.php?topic=126864

Godffrey does rotors all the time, he may be able to give you some good pointers and answer questions of the trade

[timbo750]

I have finished cross drilling one of the rotors but I think I need some holes closer in.

Does anyone know what inside measurement I need for the cross drilling. I will post some pictures when I can, having internet issues and I can't post images at the moment.

Pictures Added:

[timbo750]

I was getting ready for some assembly this weekend, I have cross drilled both rotors and painted the centres, triple trees are painted and waiting bearing fitment and fitment to frame. I was making up a list of bolts I need to get, I was looking at the mounting points for the caliper's on the fork lowers when I noticed that the threads on the right hand side are damaged.

I got these fork lowers a while ago and must of missed it, they were a little dirty when I got them and needed de-chroming so I probably did not look for it. Now I need to get the holes welded drilled and tapped, and then repolished again.

[Terry in Australia]

Oooher, them's big holes mate! Cheers, Terry.

[timbo750]

As mentioned  I got the brake rotors cross drilled but I have not run the countersunk bit on the holes. Can anyone tell me if this is mandatory? I was going to do it but somehow forgot and now I painted the centres and will only do it if have to.

also I got the damaged fork lowers dropped of to get repaired and should have them back in about 2 weeks. In the meantime I am going to get the front wheel sorted with the rotors and speedo drive.