My CBR1000A/F ...Again

[wobblywalrus]

Oz, I am going to use the MEZ exhaust pipe length calculator http://www.mez.co.uk/mezporting/exhaust_length.html.  It is one that I trust.

MEZ asks for cam timing data.  We quote cam timing degrees based on 0.050 inch lift in America, most of the time.  I vaguely recall the English customarily use another lift when they describe cam timing.  Possibly 1 mm.  George (MEZ) is dead, so I cannot ask him.  Do you know what lift the English usually use when they describe cam timing?  - Bo

[Queeziryder]

Hi Bo,
We use a variety, depending upon the cam maker;

1/ Zero lash opening point
2/ 50 thou lift
3/ Centre line on full lift

HTH
Neil

[wobblywalrus]

Thanks.  This is what I need to know.

[oz]

Phew,pleased someone else knew that one cheers Neil

[oz]

At Last the head is back its taken 41/2 months but the results are pretty darn good and the flow ratings are better than I could of ever imagined.
However the skim on the head should have been 15thou and for some reason, probably crossed wires it has ended up at 30thou so the copression is going to be alot higher than I had planned for.
Looks like the only fuel this will be drinking will be on the higher octane side of things or if that dont work maybe use bigger injectors and go methanol!

Exhaust new




Inlet now





Inlet before



Seats now



Seats before



Reprofiled chamber now



And before



The changes look quite subtle I reckon, barring the skim but the paperwork has shown huge improvments in the flow so now the work starts again pistons out and re pocketed re build and re wire the new ignition system in, and see what we get at the Dyno.

Cheers Oz.

[wobblywalrus]

The rise in compression ratio might not be as great as it would seem.  It looks like some metal was removed from the cylinder head around the valves when the combustion chambers were reshaped.

[oz]

Heres hoping Wobbly,
I think you are probably right as you cant really see in the pictures but he has relieved quite a bit of metal from around the valve area,he has also re cut the seats and back cut the valves so hopefully the pistons wont need too much modding on the pockets.

Cheers oz

[oz]

After the mess up on the welding of the head and the following distortion I was still a bit concerned that even after our brutal re leveling technique the cams may not be sit perfectly straight in the bearing faces.
I re assembled the head minus the valves and followers etc to see what the score was and lo and behold torqued up and fitted you can turn the cams by hand easily so thats at least one worry out of the way!
Cheers Oz

[oz]

Back again after another four month wait for piston modifications,well not strictly true a buddy who was going to modify the crowns / pockets etc. in a fortnight still has them so I bit the bullet and had another set made from scratch I just couldnt wait any longer.



They arrived on Friday night along with rings and things so Saturday was spent in the garage with my mate Daf instead of in the pub.



all went well and smooth



and by about 4ish job done timed gapped the works



yet another intake in the process



so there is a glimmer of light at the end of the tunnel but it could be someone with a  torch and another delay time will tell.

ttfn Oz

[oz]

Chopped two zx10 airboxes and extended by 30mm and patched in using the number plate plastics of my cb13



welded them together with a soldering iron



and hey presto!!



mounted the new box of tricks its nice to see things moving again!!



Cheers Oz pub time again

[oz]

I aint happy with the bottom end it seems a little tight when rotating the crank.
There has been no mods in that area this time and I cant figure out why this should be the case. Maybe a touch of rust as it has been open for so long,It has been covered but you never know?
So full tear down as soon as the new gaskets arrive and rebuild again,Damm still its better to sort it now rather than later.

[oz]

It seems the bottom end is fine and the problem is with the cams!!
even though after the distortion from welding the head was removed and cams were turnable by hand there must be a bit of distortion left in there somewhere.
I think that is going to have to be stripped and line bored across the journals.

I have had no experiance of this process do cams need to be built up and re ground or new bearings let into the head or is it dependant on how much comes out of the journals.





it only looks like it can be out by a couple of thou max but its enough to make it tight to turn over.
the alternative is cylindricaly grind the cams.
I really dont know the best option does anyone have any ideas on this.

Cheers Oz

[JimL]

Years ago I had to fix a 20R Toyota head that "didn't have a replacement option" (desperate men do desperate deeds).  I had to shim the caps on the center bearings (we punched holes in .002" gauges and used the bits for shims).  I hand shaped the bottom of the end bearings with crocus cloth and a wood dowel.

Engine only ran another 100,000 miles, run hard in an old truck pulling firewood out of the Rockies.

JimL

[WhizzbangK.C.]

Are you sure that what you're feeling isn't in the followers or valves? Before doing anything radical with the cam or journals, I'd reassemble the engine, leaving out the cam followers, and see how it feels. I've been burned by things like that before.

[oz]

Ah good point I hadnt thought about trying it without the followers, Looks like thats todays job I will give it a try.

Cheers Oz