CB750K8 Project

[royhall]

Best deal on valves I found were Kibblewhite valves from CycleX in the states. Good valves and still cheap even after postage and the dreaded import duty.

[martin_uk]

Hi,
    Helicoil taps are a specific size to suit the helicoil, and most helicoil sets include the appropriate tap and fitting tool for each size of coils in the set!---ken

Thanks Ken
I suspected that was case but try to be an optimist 

[martin_uk]

Helicoil/ V coil inserts and tap arrived today for M4 thread on carb float bowl screw.

2015_0306seat0018 by nitram2010, on Flickr

2015_0306seat0015 by nitram2010, on Flickr

Thread cut

2015_0306seat0012 by nitram2010, on Flickr

Made up inserter tool using ally roofing nail with slot cut in end

2015_0306seat0019 by nitram2010, on Flickr

2015_0306seat0020 by nitram2010, on Flickr

[martin_uk]

Fitted multi block connectors to handle bar switch looms

2015_0306seat0022 by nitram2010, on Flickr

Decided to go with new DSS replica headlamp bowl

[martin_uk]

Finished cleaning up the head and found a nasty surprise in exhaust ports

2015_0311eng0007 by nitram2010, on Flickr

2015_0311eng0008 by nitram2010, on Flickr

Very deep pitting, Im guessing caused by resting water over a long period of storage?

The head on K8 has F type exhaust fitting, but is not marked like a F1 with 392 cast mark,  but has K8 hand stamped.

2015_0311eng0009 by nitram2010, on Flickr

2015_0311eng0011 by nitram2010, on Flickr

Looks like I need to find another K8 or F1 head, as its going to be alot of work to weld up unless anyone knows of a fix to seal pitting and can cope with heat?

[Trigger]

Martin, I cant really see from your pictures on how bad the ex ports are. If they are pitted, try to gas flow the ports.

[martin_uk]

Picked up tank, petrol flap and side covers today

Images dont fully show how good the colour is, as it really sparkles.

2015_0312tank0006 by nitram2010, on Flickr

2015_0312tank0001 by nitram2010, on Flickr

2015_0312tank0004 by nitram2010, on Flickr

2015_0312tank0007 by nitram2010, on Flickr

[martin_uk]

Martin, I cant really see from your pictures on how bad the ex ports are. If they are pitted, try to gas flow the ports.

I may try grinding back to see how deep they are, could be welded and reground and sealing faces definately need attention.

Considered exhaust paste,  probably would work on the sealing face.

Will ponder

Due to get my original F1 crankcase that had broken top right engine mounting back from welders, which will need fettling as well.

[JamesH]

Paint's looking lovely martin. Great colour that....

[martin_uk]

Paint's looking lovely martin. Great colour that....

Thanks James, I now keep seeing similar colours on new cars  and thinking it was the right decision:)

[martin_uk]

Picked up the cylinders after rebore and asked the opinion of guy who is a very experienced engine restorer on exhaust port pitting and after viewing was not concerned, so I just cleaned up with die cutter.

Ended up fitting 2 ex and 2 in valves due to wear at stem top

2015_0318eng0013 by nitram2010, on Flickr

I went to +1mm, because I managed to find original Honda pistons and rings and thought it was overkill, but a shadow of the bore corrosion remains.

The specialist didnt feel it would be a problem so have fitted as they are.

2015_0318eng0008 by nitram2010, on Flickr

Last CB750 I did found cylinders dropped suddenly whilst assembling so took precaution of using some plastic paper binder cut down to limit travel.

2015_0318eng0003 by nitram2010, on Flickr

I used standard piston ring clamps which are a fiddle to remove after piston engaged, so have ordered the Honda part from DSS as I have 2 more engines to do

2015_0318eng0004 by nitram2010, on Flickr

2015_0318eng0019 by nitram2010, on Flickr

[bytio]

What piston to bore clearance did he do on REBORE?

[martin_uk]

What piston to bore clearance did he do on REBORE?

He said Honda clearance very tight, but as he has been doing the Honda engines since the 70's and worked with Dixons racing, left it to him.

I can find out if you need info.

[JamesH]

Martin - did you sort a set of  pipes in the end? I came a cross as set of 4 HM405 Original Sankei pipes lurking in the back of my garage last night (don't ask). I bought them to cut-down / modify the silencers for mock-megaphone 4-4 setup but looking at them it would be sacrilege to cut them up.

If interested I'll try and get some pics taken. They owe me a bit mind..

James.

[martin_uk]

Martin - did you sort a set of  pipes in the end? I came a cross as set of 4 HM405 Original Sankei pipes lurking in the back of my garage last night (don't ask). I bought them to cut-down / modify the silencers for mock-megaphone 4-4 setup but looking at them it would be sacrilege to cut them up.

If interested I'll try and get some pics taken. They owe me a bit mind..

James.

Hi James
I am 3/4 there 

Just need a HM405  No1 cyl  Left upper marked SL plus exhaust mounting brackets.