Author Topic: CB750 Barn find project - First Timer  (Read 53639 times)

Offline Underdog1

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Re: CB750 Barn find project - First Timer
« Reply #300 on: April 19, 2017, 11:00:19 PM »
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?

Offline Mag1

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Re: CB750 Barn find project - First Timer
« Reply #301 on: April 19, 2017, 11:47:43 PM »
I used a 40mm upswept hoop, made an extra frame support just where the hoop starts to upswept, basically 40mm wide 4mm thick flat bar and welding that in place inside of the rear end, but level to the top of frame. This enabled me to weld on a tab slightly upswept to fit the fender. With the fender cut I used the mudguard hoop that attaches to the mudguard and forks, cut to size and welded that to the underside of the seat hoop to act as more robust fixing point to install the mud guard as it has 2 small bolts and is already shaped to the mudguard. Will take a close up photo and post up this weekend. The picture will show more than I explain.
Honda CB750K7 1977
Yamaha XS750e 1977
Vespa 100 (being restored)

Offline Underdog1

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Re: CB750 Barn find project - First Timer
« Reply #302 on: April 20, 2017, 11:52:07 AM »
I used a 40mm upswept hoop, made an extra frame support just where the hoop starts to upswept, basically 40mm wide 4mm thick flat bar and welding that in place inside of the rear end, but level to the top of frame. This enabled me to weld on a tab slightly upswept to fit the fender. With the fender cut I used the mudguard hoop that attaches to the mudguard and forks, cut to size and welded that to the underside of the seat hoop to act as more robust fixing point to install the mud guard as it has 2 small bolts and is already shaped to the mudguard. Will take a close up photo and post up this weekend. The picture will show more than I explain.


Yeah mate any more pictures would be really helpful. Still can't work out how you've got so much clearance at the rear end, perhaps your hoop is slightly longer than mine? On standard length wagon shocks my tyre with be rubbing hoopage and still be an inch from bottoming out.

Thinking about it surely using the front mud guard rather than the rear will mean less clearance.. as its narrower so the edges of the tyre will foul when theres still space above the tyre?

The tabs you welded for the front of the seat pan, do these get in the way of taking the battery in and out? i was thinking about drilling the threaded holes for the front of the battery tray and tool tray right through the frame and using those
« Last Edit: April 20, 2017, 11:57:02 AM by Underdog1 »

Offline Mag1

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Re: CB750 Barn find project - First Timer
« Reply #303 on: April 20, 2017, 06:12:43 PM »
The tabs I welded in at the battery box are more as a guide for the seat bolts to stop it moving around while riding, the rear is where I attach the seat and bolt into place. The battery and tray do fit in but it's a tight fit, but works for me. Will take some pics for you whereby hopefully you will work out what works for your seat pan and mud guard. For some reason the front fender works for me, I was thinking what would fit in there as I needed something to give some protection from water spray and any flying debris from the tyre. I did think leaving open, but looks better filled with the fender, and attach the rear light also. If your building your own seat pan what do you intend to use for fixing in place?. If I could turn back time I would weld in m8 or m6 nuts to the top side of the pan and use bolts, or find place to have it hinged and lockable. I know for next time!!
Honda CB750K7 1977
Yamaha XS750e 1977
Vespa 100 (being restored)

Offline Underdog1

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Re: CB750 Barn find project - First Timer
« Reply #304 on: April 20, 2017, 09:34:38 PM »
The tabs I welded in at the battery box are more as a guide for the seat bolts to stop it moving around while riding, the rear is where I attach the seat and bolt into place. The battery and tray do fit in but it's a tight fit, but works for me. Will take some pics for you whereby hopefully you will work out what works for your seat pan and mud guard. For some reason the front fender works for me, I was thinking what would fit in there as I needed something to give some protection from water spray and any flying debris from the tyre. I did think leaving open, but looks better filled with the fender, and attach the rear light also. If your building your own seat pan what do you intend to use for fixing in place?. If I could turn back time I would weld in m8 or m6 nuts to the top side of the pan and use bolts, or find place to have it hinged and lockable. I know for next time!!

Yeah I was going to go for welded m6 bolts on the top of the seat pan like you said.
I'm not going to be working on the bike again for a while so will have a good think. May even re work the rear hoop with a steeper angle to give more clearance

Offline Mag1

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Re: CB750 Barn find project - First Timer
« Reply #305 on: April 24, 2017, 09:35:34 PM »
here are pics as promised, this is how i mounted the fender
Honda CB750K7 1977
Yamaha XS750e 1977
Vespa 100 (being restored)

Offline Mag1

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Re: CB750 Barn find project - First Timer
« Reply #306 on: April 24, 2017, 09:37:09 PM »
last one, if have any questions let me know.
Honda CB750K7 1977
Yamaha XS750e 1977
Vespa 100 (being restored)

Offline Underdog1

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Re: CB750 Barn find project - First Timer
« Reply #307 on: August 13, 2017, 05:18:24 PM »
Yeah I was going to go for welded m6 bolts on the top of the seat pan like you said.
I'm not going to be working on the bike again for a while so will have a good think. May even re work the rear hoop with a steeper angle to give more clearance

Been super busy with work over the last few months and also bought and moved into a new house. Finally got a decent sized garage/workshop to use.

Decided to rework the rear hoop so bought a welder, learnt how to use it and did this this morning:

starting point-



















First thing I've welded in anger and pretty happy how its turned out. Should give the clearance i need at the back end.

Just need the rear mudguard bracket and it can get powdercoated.

Whats the best way to remove the frame/ model no. plaque thats riveted on? drill it out?

Offline Mag1

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Re: CB750 Barn find project - First Timer
« Reply #308 on: August 13, 2017, 10:19:16 PM »
Very nice handy work, and welcome back. You need to watch how you remove the vin plate, it's soft alloy plate, I think the rivets are brass?, it's also glued on the back. I just levered mine off with care, but it still split at the ends, but it's ok. Just stuck it back on using arodite.

What's next fender?.

Been off a while also, had to have a break away from the bike as it was doing my head in and started to hate it. But back on it now so get it finished.

Good luck, if you have any Q's fire away.
Honda CB750K7 1977
Yamaha XS750e 1977
Vespa 100 (being restored)

Offline Underdog1

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Re: CB750 Barn find project - First Timer
« Reply #309 on: August 13, 2017, 10:46:39 PM »
Very nice handy work, and welcome back. You need to watch how you remove the vin plate, it's soft alloy plate, I think the rivets are brass?, it's also glued on the back. I just levered mine off with care, but it still split at the ends, but it's ok. Just stuck it back on using arodite.

What's next fender?.

Been off a while also, had to have a break away from the bike as it was doing my head in and started to hate it. But back on it now so get it finished.

Good luck, if you have any Q's fire away.

Cheers bud, my first time welding anything other than runnin beads on a steel sheet, can't believe I payed a professional welder £130 to weld the original hoop on (that I provided!). My welder cost £150 and now I've added another string to my bow.

Just to clarify about the vin plate, are you saying you levered it off without drilling the rivets out first?

Offline JamesH

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Re: CB750 Barn find project - First Timer
« Reply #310 on: August 14, 2017, 09:31:24 AM »
On the VIN plate. Drill the rivets out first, then get some very thin metal wire and try and 'cut' the adhesive backing off behind the vin plate using the profile of the headstock to avoid damage to the vin plate...worked well for me (after I botched a K0 vin plate first time round duh...).

Offline paul G

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Re: CB750 Barn find project - First Timer
« Reply #311 on: August 14, 2017, 12:24:11 PM »
On the VIN plate. Drill the rivets out first, then get some very thin metal wire and try and 'cut' the adhesive backing off behind the vin plate using the profile of the headstock to avoid damage to the vin plate...worked well for me (after I botched a K0 vin plate first time round duh...).

You could also try the first part of the above with the rivets and then a hair dryer on the plate to get some heat in it.
This sofens the adhesive so you can get it off.
Always worked for me.

Regards,
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Offline Nurse Julie

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Re: CB750 Barn find project - First Timer
« Reply #312 on: August 14, 2017, 04:18:05 PM »
Great to see you back building Phil. I love this thread of yours.
LINK TO MY EBAY PAGE. As many of you know already, I give 10% discount and do post at cost to forum members if you PM me direct.
https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline Mag1

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Re: CB750 Barn find project - First Timer
« Reply #313 on: August 14, 2017, 06:08:58 PM »
Only other suggestion would be to remove the rivets, then heat up the plate with hairdryer, once heated up strip some old electrical wire and use in a sawing action behind the vin plate through the glue, keeping the wire tight to the frame. May work?.
Honda CB750K7 1977
Yamaha XS750e 1977
Vespa 100 (being restored)

Offline Underdog1

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Re: CB750 Barn find project - First Timer
« Reply #314 on: September 09, 2017, 09:20:48 PM »
Made some mounts for the mudguard today. Managed to get the look I wanted.





Not got my oil tank or battery tray at my house currently so need to check there's no interference - little worried about the oil tank not fitting properly now..

If needed I'll cut the mudguard down and move the brackets.

Almost ready for paint (after I've made some new seat pan mounts) now just need to make sure I haven't overlooked anything. If anyone spots something then please pipe up!
« Last Edit: September 09, 2017, 09:24:20 PM by Underdog1 »

 

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