1961 CB72 ProjectJames
Thanks! I never thought that my thumb would act as some kind of time clock.... The thumb is all sorted now; just findng it difficult to make time for the project. I have been doing small bits but hopefully can get some more done this weekend. G
'60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160 '66 Matchless 350 '67 CL77 '67 S90 '77 CB400F Well - finally got back to the workshop for a bit more head work. This special tool worked fine at pulling the new guides in. They are a pretty tight fit so I popped them in the freezer and heated the head up to make the job a bit easier. Even so those bolts are high-tensile. After the gudes got really tight, I gave them a finishing whack with the brass drift I made for extracting the old ones, just to get them to seat on the circlips.
 Because the guides are an interference fit they need reaming to get the right clearance back after insertion.  I have a regular 7mm reamer and an expanding one which can be adjusted to shave just the right amount of metal.  The exhaust guides needed just a little touch but the inlets needed a bit more to get the valves moving smoothly. I measured the valve stems and the inlets were a fraction larger.  With the guides sized nicely I could move on to sorting the seats out. I'd done quite a bit of wok before deciding to renew the guides so this time it was just a matter of making sure that the new seats were concentric with the guide. I have a set of Neway seat cutters to do the 35, 45 and 60 degree angles. These are lovely to work with and have an expanding 'pilot' which fits in the guide giving a firm guide for the cutters. The one shown here is reversible with the 30 degrees on one side and 45 degree cutter on the other.  Within a range, the cutting blades can be set to give the right diameter seat.  The 30 degree cutter can have one of its blades replaced with a radiused one to give a curve between seat and head material to blend he two. With the seats done a spot of marking 'blue' gives an indication of how well the seat and valve are going to match up.  Next job is to lap the valves and use the cutters to trim the actual seating area to the right width. I might get a chance to do that at the weekend but there is a great classic race meeting at Donington at the weekend. Freddie Spencer is coming along with his championship-winning 250 and 500 Hondas... Might have to go and take pictures. :-) G '60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160 '66 Matchless 350 '67 CL77 '67 S90 '77 CB400F Sara
Thanks. Wow! Messages in Quadruplicate! Is that a record? :-) I need to get the valves lapped and then clean my grubby fingerprints from that lovely head. Donington is only about 1/2 hr away from my house so there may be time for both.... http://www.donington-park.co.uk/events/ ... -festival/ Somewhere I have pictures that I took of Freddie Spencer when he was riding the new Honda V4 with the fuel tank underneath the engine and exhausts on the top. It all sounded such a great idea at the time. The carbon-fibre wheels fell apart shortly after. G '60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160 '66 Matchless 350 '67 CL77 '67 S90 '77 CB400F
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