100hp on crank, around 80hp on wheel is possible with 836cc. (65 mm pistons)
I know a guy that measure 86whp DIN with 62mm pistons. Pistons shaped for chambers, rather high compression. Vintage racer.
My K6 had probably closer to 80whp in the 80's and first years of its comeback 2014.
17:48 sprockets. (Stock 18:48), stock wheel size.
Ported head and a rather modest cam, Action Fours SS1 that served the bike well during long tourings in Europe in the 80's.
It had Mikuni TMR32 carbs when measure the power on Dyno 2015. Rather open 4-1. But it worked fine with stock carbs with less restrictive pods earlier in the 80's.
The in valves were F2 34 mm valves, stock 28mm ex.
I have another head today with Kibblewhite 33.5/28.5mm valves that has similar output.
Important to use guides that are sunken enough in head or CycleX guides made for higher lifting cams.
The K style valve keeper grooves are very tall and can enter the guide seals causing huge oil consumption.
Dynoman DP295 cam often recommended. My bike had that profile for a while, produced better torque and a little bit more at the top then the AF SS1 cam.
Both cams relatively good lift and not too long duration.
Do not waste money on 5mm valve kit. My set worked for 20.000 km, then were the bronze guides worn out, the upper part. The skinny 5mm valve stem is very flimsy and bent during operation.
(Racers that need light valves and constant very high rpm might need it.)
That head got CycleX SS valves 34/28 mm. I do not know if they still have in stock. Plus their guides for higher lifting cams.
The K6 engine has 970cc right now, 104.7whp DIN earlier this year on dyno.
Cam Megacycle 125-75 with a very even power from ground and up. Stable idle at 1100-1200 rpm as my stock bike has too.
Maybe this cam match more displacement better.
It has a JMR Billet block 1005cc too, now waiting to be used. That measured similar power. But it had thicker base gasket then so a few hp less due to lower compression.
Compression is important to get the extra power. It can make the difference of 92whp or 101whp as I saw with 1005cc.
836cc can use stock rods if not racing.
It will cost much more when rods needs to be replaced with Carillo or CycleX Super rods.
Undercutgears, 2-4.
My bike use the harder Barnett springs for smaller CB's, 66ft lbs version.
Their CB750 spring has 56 ft lbs and is not that hard. Glass beaded clutch plates, EBC fibers.
When 836, even the cheap Cruzinimage clutch with Barnett CB750 springs worked fine.
Still glass beaded metal plates.
Bigger bore like 970-1000cc produce much more torque so clutch can slip.
Make alternator lighter another thing. Charging works fine on my bike.
Mike Rieck (JMR Porting) is the guy how knows what you need and can make it happen if still working.
MRieck is his forum name.
JE 836 pistons, DP295 and a JMR stage 3 head will give your bike around 80whp with good bottom torque.
Undercutted gears are a relatively cheap improvement.
