Topic: CB500/550 valves finally done!

[speedracer741]

Well after countless delays I have finally got 2 sets of 500/550 valves done. 1mm oversize on both intake and exhaust. Now I wish that I had made more than only 2 sets since there are 23 steps in turning a rough blank into a finished valve. I wish I would have gotten some progress pictures but here are some finished ones:

[WFO]

They sure are purdy..

[olds-cool]

Nice job!  I wish I had the skills and equipment needed to do stuff like this

[moham]

Very nice. Have I seen those on ebay?

[speedracer741]

Yep, I just listed the first set today. If they sell I will order up a few more sets of blanks and do a bigger run. One set was for my downdraft head project but I can always make more.

[mmtsquid]

Those look great!
So, do these simply drop in, or do I have to make other mods to make them fit?

[speedracer741]

The valve seats would need to be cut for the larger valves. This would best be done using cutters such as in a Serdi. Also if using larger valves you would want to do everything else to get the most out of the changes such as porting, carbs, cam and exhaust. Oversize valve installation should always be part of a total engine build with all components selected to work well together.

[MRieck]

The valve seats would need to be cut for the larger valves. This would best be done using cutters such as in a Serdi. Also if using larger valves you would want to do everything else to get the most out of the changes such as porting, carbs, cam and exhaust. Oversize valve installation should always be part of a total engine build with all components selected to work well together.

I agree. The throat and seats need to be opened up to 90% of the valve diameter to realize true potential

[bwaller]

So these intake valves are what 29mm? Mike, if the ports are opened up to 90% which is ~26mm would a 26 or 27mm carb be a decent match? (I have a set of these so please say yes!!)

Here, to roadrace in middleweight production, porting, a cam & different carbs is within the rules but the bore needs to remain stock plus 5% max. Next problem with seating larger valves deeper in the chamber is finding a piston with some dome to bump compression. No such beast I'm afraid at least for a 58.5mm bore.

Turboguzzi was going to try to get someone to do a few sets, but the masses didn't want stock bore. Anyone else have any ideas for pistons? I've heard that Ross will do a four piston minimum, but I haven't called them yet. Any experience with these folks?

Chris, have you finished a head with these babies yet?

[speedracer741]

The intakes are 28.5mm and exhausts are 24mm. I have seen some posts on installing the Mikuni VM carbs from KZ and GS bikes. That seems like it would be a pretty good setup. If your cam isn't huge you may not need to seat these deeper and unshroud at all. Cam mockup with the stock valves would be the only way to tell and would be a good idea before any work is done with valve size modifications. My own head project is going pretty slow so I haven't gotten a chance to get to valve seat work yet. I just got some radius cutters for the Serdi in the small sizes needed for the 550 head. I may just machine one of my heads soon but I won't be able do much else until other things are completed. All of my heads have already been modified for my downdraft port project and I don't have the cams yet. I want to send Megacycle several cams at once.

[crazypj]

You really want a carb slightly larger than the throat size but the actual size also depends on the average length of the port, cylinder capacity and flow rates.
PJ

[MRieck]

So these intake valves are what 29mm? Mike, if the ports are opened up to 90% which is ~26mm would a 26 or 27mm carb be a decent match? (I have a set of these so please say yes!!)

Here, to roadrace in middleweight production, porting, a cam & different carbs is within the rules but the bore needs to remain stock plus 5% max. Next problem with seating larger valves deeper in the chamber is finding a piston with some dome to bump compression. No such beast I'm afraid at least for a 58.5mm bore.

Turboguzzi was going to try to get someone to do a few sets, but the masses didn't want stock bore. Anyone else have any ideas for pistons? I've heard that Ross will do a four piston minimum, but I haven't called them yet. Any experience with these folks?
Chris, have you finished a head with these babies yet?

I have seen their Harley pistons. They are equal to any good, modern piston such as CP, JE etc

[MRieck]

 If you don't mind me asking what blanks are you using?

[speedracer741]

I ordered them through my work from SB International. They are used for Honda/Acura applications. 5.5mm is a pretty common size for 16 valve car engines and the import racing community has great aftermarket support. Turbocharging is very common and there are good alloys available which made these a great choice. I have a bunch of 7mm blanks now and am doing a small run for the 350 twin.

[fuzzybutt]

ok i know this is an old thread but i have a question. is there any hardening of either the tip of the stem or in the seat area?

[speedracer741]

The tips of the valves have been hardened after machining and is why the keeper grooves and tips have a dark color. Steel valves like these don't require additional hardening of the seat area as the forging itself is already quite hard.