ORIGINAL: 4u2nv-RCU
LOW nitro is key for that engine. I tried it on 10% and it ran lousy! Go to 5% or FAI and see what happens. If you want to run higher nitro you will then need a shim under the head to help reduce compression a bit. Good luck!!
One thing for sure, it does have compression. I have been using 15% full synthetic. what kind of a shim? I have about 10 gallons of 15% fuel as we buy it by the drum and all of my other engines do well with it.