CB750 Barn find project - First Timer

[Underdog1]

Well got things sorted today, wasn't too bad apart from one for some reason I can't get a 10mm socket onto one of the 6mm head bolts (all the other were fine, think it's just the casting of the head itself stopping it) and ended up rounding it out with PD3..

Had to drill the head off the sucker to pull the cylinder head and then it came out easy. Tried for ages with an impact driver but it just mullered it.

Got those pesky pin things in and bolted everything back up, cam towers back on, cam on and timing set. Just need to build the rocker arms up and I'm back to where I was yesterday.


head off with the missing pins


The bolt that didn't want to play fair


Lucky I had a spare knocking about so could get it back together right away

[Underdog1]

Had another couple of house in the garage today with a stinking hangover.

Top end is all buttoned up now which is pretty satisfying.



Question - the oil pressure sensor, is it supposed to screw all the way in? Mine seems to bottom out with a mil or so gap. Also is it worth using a bit of honda bond on this as it previously had something on it when I removed it.



I need to figure out how my seat pan rear mud guard is going to bolt up so I can fab the brackets up and get the frame to the powder coaters. Basically I'm going to cut my rear guard down so it looks something  like this:

 
Which will mean I need to have a bracket here which I can use to bolt both the rear of the seat pan and cut down mud guard to. Will keep the plastic liner thing too if I can



I need to get the wheel back on to be fair so I can properly see how it's going to look. Only thing I'm concerned about is how securely the mud guard will be attached by just two bolts.. might get some up and down movement as the metal is only thin. Also it might me a bit on the low side as the one in the picture I posted seems much more tucked up. Perhaps the seatpan on that bike has an arched section to allow this?

Also did a little more work on the seatpan today and made a curved section to nicely cover the rear tank mount, just need to get it welded on. I think I'm going learn to weld soon as it's so annoying having to rely on someone else. Still unsure how the front of the seatpan will mount to the frame as I'm keeping the battery holder and tool tray underneath so there's not going to be much space

[Underdog1]

Remade the little hump for the seat pan today as I wanted to keep it as low as possible which meant I needed a 'longer' hump. Only actually ended up slightly lower but I want a thin seat.





Hopefully the welder can fill in any small gaps for me as it doesn't sit perfectly flush.

Been thinking about how I want the read end to look. As it is now the rear mudguard will sit a little bit low for my liking:



I'd quite like it to be tucked up as so:



Which would mean he seat pan would need to have a hump on the rear of it to accommodate the intruding mudguard. I don't think I have either the tools or skill to do this, and I'm also unsure how uncomfortable it would be for a passenger with basically a thin layer of foam covering it..but I'm going to put some more thought into it and maybe see if there a local fabricator who I could use.

[Underdog1]

Mocked the back end up to check clearance.






Got a couple of inches above the wheel and an inch or so clearance in front:



I've got some Hagen shocks with adjustable dampening that I'll use but they are the same length as standard shocks. What's the least amount of clearance I can get away with?

[captaink]

Should look pretty mean when its finished.
Reminds me of Sons of Anarchy

[Underdog1]

Should look pretty mean when its finished.
Reminds me of Sons of Anarchy

I'll just be pleased if it get finished to be fair!  Its challenging learning as I go but I enjoy it a lot and I don't think it will be my last.

Just had a thought - if I get my new shocks on there with the springs removed I'll be able to simulate it bottoming out and see if the tyre hits anything.

The easier alternative would be to mount the tail light above the side mounted number plate as I already have this mount:

https://www.amazon.co.uk/Prison-Motorbike-Motorcycle-Number-License/dp/B00Y16L134

[Underdog1]

Took he springs out my Hagen shocks to see if they would bottom out before the tire hits anything, no suck luck, still got an inch or so to go.



Might get away with it if I have he dampening on it's hardest setting and if not I can just source some slightly longer shocks.

Took the frame to a relatively local place to see if they could fab up the 2 brackets I need to hold the mud guard in place and showed them how I wanted it to look.. he guy basically told me hey charge £45/hour and it could run into a few hours fettling bits about so I didnt bother.

Had a fastball from work as well today which means I'll be very busy for the next 9 months so this is going to have to take (yet again) a back seat 

Plan is now to purchase a welder and learn to do things myself, so if anyone is selling one please let me know 

[MrDavo]

Question - the oil pressure sensor, is it supposed to screw all the way in? Mine seems to bottom out with a mil or so gap. Also is it worth using a bit of honda bond on this as it previously had something on it when I removed it.

Definitely no, don't screw it all the way in. I'm not sure what it is about the thread, as it doesn't bottom out against anything as far as I know, but someone on here (or maybe .net in the USA) b*ggered up their cases big time by doing this, there's a taper at the end of the thread, after a poster had tightened it up all the way, then a nip to make sure it didn't work loose, he noticed the crankcase was cracked.  .

If both threads are OK there's no reason why you should need to use sealant, and if you get any of it in the oil gallery it could kill your cam by blocking the cam oil feed in a driiling somewhere where you can't ever find it.

[Bryanj]

Thread is N(ational)P(ipe)T(aper) NPT and designed to get tighter as it screws in so DO NOT attempt to Bottom the fitting

[Trigger]

Longer shocks effect the front end handling big time.
Are you sure you want to use that chrome rear, there are many different ones on the market.

[Underdog1]

Longer shocks effect the front end handling big time.
Are you sure you want to use that chrome rear, there are many different ones on the market.

Never really considered anything else as I just have this to hand, plus all the ones on eBay look terrible. Was going to sand it down to give it a brushed look

Any suppliers you recommend? I might as well have a look

[Trigger]

I don't think the rear guard in the bike shed picture is a SOHC one, looks smaller. I am also a little surprised that I can't find any details on the build of the bike.

[Mag1]

Underdog, have a look at the pics i uploaded in the newbies where I was doing what you are currently doing 10 months ago. I tried with oversize rear mudguard but was too big, in the end went with purchasing mangled front mudguard and cut to size, this way you have extra clearance and also easier to attach tabs to. One thing to muck up now is your seat fixings and more importantly access to fix your seat down either by bolts/wing nuts or hinged. Your right to stay away from welding shops unless they know what they are doing, due to hourly rates and finding a solution for you. Best to look on all forums and Google pics for ideas. If I could and roll back time is weld hinges to the frame and bolt that to my seat, but heyho. As trigger has said also, don't raise the rear end this will upset the geometries / effect steering and ride ability. Enjoy

[Underdog1]

I don't think the rear guard in the bike shed picture is a SOHC one, looks smaller. I am also a little surprised that I can't find any details on the build of the bike.

The bike was built by redeemed cycles, he's done a few really cool old SOHCs

https://en-gb.facebook.com/RedeemedCycles/

Here's a pic of the high sort of shows the mudguard a little better. Perhaps he had just cut the front half off..?



He was able to get more clearance because his rear hoop has a much steeper angle, something I failed to consider earlier on.

I may just do something  like this:



As I have a side mount number plate holder which I can attach a tail light to, not sure on the legalities though.

[Underdog1]

Underdog, have a look at the pics i uploaded in the newbies where I was doing what you are currently doing 10 months ago. I tried with oversize rear mudguard but was too big, in the end went with purchasing mangled front mudguard and cut to size, this way you have extra clearance and also easier to attach tabs to. One thing to muck up now is your seat fixings and more importantly access to fix your seat down either by bolts/wing nuts or hinged. Your right to stay away from welding shops unless they know what they are doing, due to hourly rates and finding a solution for you. Best to look on all forums and Google pics for ideas. If I could and roll back time is weld hinges to the frame and bolt that to my seat, but heyho. As trigger has said also, don't raise the rear end this will upset the geometries / effect steering and ride ability. Enjoy

Yeah I like how you did yours actually, you just seem to have way more clearance at the back end than me somehow?