Jørgen's H2 Performance Mods
(click any pic for full size)
Below is my new project. 72 H2, 72 Gold paint, with 73 decals.
Tuned for street, using billet SSO heads, TMX39,2 carbs, a lot of portwork incl crankcase. Silicone tube inlets (100mm). (I can give full throttle from idle in fifth gear now. Before the tubes, I needed 3000+ rpm. 70mm Ramair attached to the tubes (not pictured) A fifth gear launch without clutch abuse is absolutely NO problem, as seen on the youtube vid, here: (same cylinders, but on my caferacer using Jollymoto WITHOUT the silicone tubes. https://www.youtube.com/watch?v=BgztkGq_1K0
I modified the pipes for a more upward position. They are 10mm shorter than stock Denco.
I use Ralf Schipmann lock-up clutch.
I have attached the latest dyno sheet as well. As you can see, the power below powerband (5600 rpm) is almost as good as a bone stock H2 using stock pipes and 30mm carbs.
I did an overlay with 2 stock H2's. One with air silencer attached on top of air box, and the other without. Red is with the silencer, blue is without. Green is the tuned H2 as pictured.
The power is greater than an H2 using VM34's/Denco with stock cylinders. That's interesting, since a set up like that gives about 78 rwhp, or close to 25 rwhp less than this set-up.
This is the strongest set-up I have ported ever, regarding low and midrange. Not a great powerband on this one compared to previous set-ups, but one has to consider using my mighty Jollymoto pipes adds 12-15 more rwhp, at same peak power rpm. And that is also interesting: The power increase here is done by torque increase, not by rpm increase (it gets the 100+ rwhp at just only approximately 4-500 rpm more rpm than a vm34/Denco/stock cylinders set-up)
Lot's of work regarding crankcase portwork, transfer duct portwork, transfer windows portwork, perpendicular to bore (with a VERY short intake tract) carb position, and off course the exhaust portwork where also the "hump" is removed.
Cylinders are lifted 1,5mm. Decked. No head gaskets. 0,8mm squish. Only 188 degrees exhaust duration. Stock ignition.
Below: HP Comparison & Torque/hp curves:
Torque flattens out in the 5000 to 5500 rpm area, but at least not a severe torque/hp dip. And as you see, Jim's pipes is absolutely amazing regarding street tuned H2's. It THE BEST old school pipes for that purpose, in my opinion. (even better than the Figaroli pipes that I have)
My cylinders machine work, done by PK: (NO welding)
Transfers: (128 degrees)
Think she is ready for my trip to Norway west coast as seen below, next summer