Waste of money .....

[MonsterHPD]

Do you have some 900V carb cams? Be interesting to see the numbers with them.

If you are just looking for the cam specs, Brad Black has most of them listed in the MotoOne reports.

[pepeducat]

not at all, the 900V cams are really not optimal for filling the engine

I recently mounted GioCaMoto on a 900 large valve, it does not work.

So I did the assembly with cylinder heads 900 small valves, and it works, but the GioCaMoto has huge lift

Comparison of risers in red from GioCaMoto and ST2 / IE

[koko64]

If you are just looking for the cam specs, Brad Black has most of them listed in the MotoOne reports.

I was thinking about the valves clearance, missing on overlap with 900V cams. Maybe they have more clearance. Brad makes these cams work well in a hi comp 750 with big valves and porting. So do JD Hord and Doug Lofgren in USA . I figured that they should work with 800cc capacity.

[MonsterHPD]

I was thinking about the valves clearance, missing on overlap with 900V cams. Maybe they have more clearance. Brad makes these cams work well in a hi comp 750 with big valves and porting. So do JD Hord and Doug Lofgren in USA . I figured that they should work with 800cc capacity.

Ok, understood.
I have to admit I forgot to check valve-to-valve clearance when I tested for valve-to-piston clearance, partly because it seems to be a rather common mod. I will do, however. I don't have any 900 cams, could have checked otherwise.

[koko64]

You usually see these other cams in 900/944's. I wasn't sure about the dimensions of the 800 heads, combustion chambers, etc. I have no experience with 800's. My feeling is you could get away with more cam in the larger capacity 900 motor combustion chambers and their relatively small valves.

Others will have knowledge of what fits what and the margins involved. I have some 900v heads and I'll check the valve to valve clearance on overlap.

[Speeddog]

IIRC, 8mm stem 800 valves are the same part# as 8mm 900 valves, so same length and diameter.

Rockers are the same, and AFAIK the geometry of the head; cam centerline, rockershaft centerlines, all is the same.

So if ST2 cams work in a 900 head, they'll work in an 800 head.

Not infallible logic/assumptions, but I think it's correct..

[koko64]

 

When I checked the valve to valve clearance on overlap with some V heads (M900 1994, oem 43/38 valves and V cams), there was more like approx 1.2-1.3mm gap at the bypass point. Less gap past that point towards the valve seat, but the "fly by" was over by then if you get my drift. Edit: that's confusing. It's a reassuring visual gap.
They must sink the custom 44mm valves in a bit.
Are the valve angles tighter to fit the 43/38 valves in the 800? Does that pull the valve angle in away from the edge of the bore but reduce valve to valve clearance?

[koko64]

https://www.hordpower.com/gallery3/index.php/Dyno-Charts/album07/750ss
http://lofgrenperformance.com/750ss.htm
http://bikeboy.org/brads750m.html

Maybe they might work in an 800? Brad bikeboy has removed the lower rpm loss by advancing the 900V cams. If there are issues maybe this is a way out. I understand there are good alternative cams for the 900, but they work in a modified 750, so why not an 800?

Anyway, just an option if the ST2 cams don't work out.

[MonsterHPD]

Thanks for the info 

I'll check the clearances as soon as I have the heads assembled again. Right now I'm nearing the end of the porting job (tleast I hope I am ....), and after that I can start assembly. Hope to have the heds complete in a few weeks. 

[koko64]

The question in my mind is, what is the acceptable valve to valve clearance? Maybe Speeddog or others have some specs.

[pepeducat]

900V cylinder head and ST2 camshafts = 1.3mm at the crossing

[koko64]

not at all, the 900V cams are really not optimal for filling the engine

I recently mounted GioCaMoto on a 900 large valve, it does not work.

So I did the assembly with cylinder heads 900 small valves, and it works, but the GioCaMoto has huge lift

Comparison of risers in red from GioCaMoto and ST2 / IE

Thanks Pepe. Thats huge lift. The big valves hit the pistons?

900V cylinder head and ST2 camshafts = 1.3mm at the crossing
[/quote

[koko64]

900V cylinder head and ST2 camshafts = 1.3mm at the crossing

Thanks Pepe, that's consistent with my measurement of the 900V valves .

[MonsterHPD]

Thanks Pepe, that's consistent with my measurement of the 900V valves .

Acc to Kämna, 0.5 mm is OK on the 2V engines.
As mentioned, my ST2 with big valves is at 0.60 to 0.65, if I remember correctly. I plan to take the heads off again before I start it and see if it is possible to increase this to 0.8 or so.

[pepeducat]

DA06090 it is necessary to slightly reduce the diameter of the valves to remove what is not used and to resume the measurement on the piston so that it does not touch.

I did it once, it's a lot of work.

The second time I mounted them in 900V small valve cylinder heads, I just had to resume the measurement on the piston.

Acc to Kämna, 0.5 mm is OK on the 2V engines.
As mentioned, my ST2 with big valves is at 0.60 to 0.65, if I remember correctly. I plan to take the heads off again before I start it and see if it is possible to increase this to 0.8 or so.

I slightly reduce the diameter of the valves to remove what is not used in order to have a very acceptable safety margin, I learned this tip from Roand Simonetti