The second 151 was run today. As a reminder, this is a twin to the first one this thread is created from, but it is running a stock head with a cam and was running a VM20 carb. This one runs the Trailbikes V2 roller rocker head with the big 27/23 valves, a VM26 carb and an aluminum oil sling to take the weight off the rotating assembly and a lightened flywheel. Running the same exhaust and same gearing.
Well, as our friend Racerx would say...you can feel it by the "seat of the pants dyno" and it is a little more than that. You feel it by the throwing you backward as you accelerate. It started on the second kick and idled pretty nicely. The VM26 is jetted 22.5/190 from factory and I'll be within 1 main and two pilots till we are done, so it was a good starting point to let it be.
The engine is crisp on the kickstand, but it has a dead spot in the midrange under load. I have not really ridden it yet as I just ran it through the neighborhood as a first heat cycle. Pleased to see there are no leaks.
A twist of the throttle and you can tell immediately that this is a different animal. It is louder, revs up faster, and clearly accelerates faster. I wouldn't be surprised if this has at least 4 HP more than the other setup. I'm predicting that this will have 17 RWHP when its all done which will be good for just shy of 80mph on this particular bike. You cannot lug it like the other one...that probably has a lot to do with the lightened rotating assembly and also the cam on the roller rocker is more of a mid-upper range cam, whereas the cam I put in the stock head has big lift but mild rotation giving great off throttle torque.
I'll be heat cycling it over the next few days and hopefully we will have decent weather for me to take it out for a pass on the test route.
More than likely, this is the same head combination I am going to put on top of the Dry Clutch build too. Takegawa has discontinued the 2V Superhead +R and only has the 4 valve. I Don't see any advantage of the 4 valve setup after having having a Takegawa 2v+4, Takegawa 4v+r, Trailebikes 2v Roller and the Kitaco 4v DOHC setups. The only exception is the Takegawa 2V+r I have that is reworked to a 30/25 valves on the 176.