The engines run best with the Radical pipe (best mileage/power) you can also use an 053, I have never used the 053, but have been told it works very well. always alwasy always use an OS P3 plug, the engine seems to run far better and cooler, engine temps should be around 185 to 200, if your running much hotter than that you more than likely not getting the full potential out of your engine.

I good starting point for the carb is 2.5 turns IN from flush on the bottom, 2.0 to 2.5 out from closed on the top. this should get you in the ballpark, the most important is the bottom.

The one down side of these engine are that they will run even if they are way out of tune. I have spent countless hours testing and tuning these engines, they tune a bit differently than most other eninges on the market today. but once you find the sweet spot you will be amazed.

Truely awesome mills....+ 1000000000000000 on previous post.

Yes the uses of the P3 plug was a surprize to me. Since most 21-up use med to cold plug the old saying was bigblocks med to cold plugs smallblocks hot to med plugs. But I'm seeing alot of .21 using hot plugs now how things change

Keller, its funny we were talking about these engines at Nitro Fever and BOOM here they are.

I had seen a thread on here a few weeks back about someone carrying them....maybe we can get the ball rolling a little faster.


Cause you really need a new engine.

Ouch man LOL

That wasn't a stab....he really does need a new engine.

I know it wasn't a stab LOL. Yes the radical are very nice engines

Ok guys,
I'm proud to announce that I will be working with Radical again, this time we will be doing things the right way. I have spent alot of time working with Dave in the past, and we have talked at length about the future of Radical and Gotnitroonline.com. Dave and I will be working our tails off to bring you the best engines and support in the business. Please be patient as you all know there will be some bugs that we will have to work out but rest assured we will do our best to make sure everybody will have access to one of the best engines on the market RADICAL!!!

For the time being please feel free to contact me by email [email protected]

For all of you that our interested, we are accepting resumes for the Radical Race Team. If you are interetsed in being sponsored by Radical please email your resume to me. We can not sponsor everybody, but we will consider all.

Thanks for your time!!!

Get Radical!!!

That's awesome dude!!


I knew you wouldn't stay away for long.

I will say that the motor is good, real good. But the customer support is not all that. Had a bushing go out in the 621p and tried emailing and no reponse, so I think they need to work on it !!! thats whats going to kill them.

Was this recently?

how long ago did that happen? Radical was purchased by a new company recently. The old company went out of business.

best i have ran love them wb