Never tried it. I was told many years ago by a pro engine moder that the mid range should be set so it is flush and the hole in the mid needle lines up with the high end needle. So on every engine I have ever used since then, I unscrew the high end assembly and turn the mid range until the hole lines up. Then put a drop of thread loc on the assembly and reinstall. Then I mark the carb with an exacto so if my pit man accidentally changes it, I can set it back to where it should be.

Also, Arrow Racing recommends that if you are having any tuning issues and using 30% nitro fuel, to use the extra head shim. An engine with lower compression is easier to tune, will increase fuel mileage, and run cooler.

Has anyone ran this motor in truggy? Just wondering how the power is in truggy.

Gene, you should post that Unique break in method that Arrow recommends.

This is the latest break in proceedure recommended by Arrow-Racing. I had already broken in both of mine before they emailed me this so I have not tried it yet but will on my next engine or rebuild.

Upside Down Engine Break in:
If you already own a break-in bench, during break-in please turn the whole bench with the engine upside-down to assist with extra lubrication at the "Top-Dead-End". After the end of each tank (125.cc) of running on the bench, turn the flywheel to the "Bottom-Dead-End" position to allow the piston to cool at the most bottom position of the sleeve. Start the break-in process again only after the temperature has dropped to less than 45˚ Celsius. Continue with this break-in process for at least 1 to 1.5 liter (3/4 of a gallon) of 25% - 30% Nitro fuel before actual running on the vehicle. We use about 2 liters of 30% Nitro fuel for running-in on the bench with the engine running UPSIDE DOWN!
When the engine is on its first run on the vehicle, it is a common sense to richen the fuel on both the low-speed needle and high-speed needle with slightly higher idle speed! Your vehicle should sound like a 4-stroke engine. However, at the same time, you should also check the temperature and try to keep it up at between 80˚ and 90˚ Celsius to maintain a good break-in temperature to ensure proper expansion of the sleeve.
After 5 to 6 (125c.c) tanks of fuel running on the vehicle, remove the glow plug and check the compression by turning flywheel. If the flywheel stops turning before the piston reaching the TOP-DEAD-END, this means that the piston/sleeve is NOT YET broken-in. This also means that you SHOULD NOT run your engine at FULL THROTTLE for a prolonged period of time (we're talking about 2 to 3 seconds only)!!! Continue with the break-in process until you find maximum compression while turning the flywheel with a slight bite between the piston & sleeve. This usually takes another 3/4 of a gallon.

So Arrow recommends 1.5 gallons of fuel to break in. When done this way, the rod, piston & sleeve will last 8+ gallons of fuel. Since the GTR has a very strong pinch, racing the engine before the 1.5 gallon mark will put more stress on the rod and piston/sleeve so the life will be reduced. The mechanical pinch should be gone when an engine is fully broken in. To check it, remove the plug while the egnien is warm and turn the flywheel over. If it gets stuck at TDC, then it still needs more break in.

This should be easy to do with cars that have a clunk style fuel tank like the Agama, losi, and Hot Bodies if you don't have a breakin stand.

New Version 2 Arrow crankcase.

Received my Arrow GTR 2 motor, looks impressive. Tried heat, loosened plug a 1/2 turn, trying to start on Ofna Chrome top box so I know I should have enough power to crank this motor over. Added the extra break in Head shim, any tips on starting up a New Extra Tight motor ?

Heat the motor up to 200 degrees, if it still won't turn over maybe go a little hotter. It should turn over if the engine is warm enough, I also like to rap some tin foil around the head to hold in the heat

Finally got it, a little extra heat did the trick, Thanks. Ran the first tank thru no problems, had a good idle. I hope it gets a little easier to start. I have a big race next weekend, need to get a few more tanks run in.

put at least 3/4 of a gallon before running it on the track.

+ YouTube Video

Andrew Smolnik testing the Arrow-Racing GTR-21 engine in an Agama A8 buggy at Revelation Raceway. Fuel mileage was 11:30 first day at the track.

My Arrows GTR21 only just came alive after 1 1/4 Gallons. It is an absolute beast now with what seems like an endless top end and silky smooth bottom end.

I have to date had GO engines and Novarossi's and I would say it has a little less bottom end than a plus 4 team, but a lot more top end. The GO engines don't even compare in my opinion.

I thought i was running lean it was so quick on the straight but it tempted at 220 after 10 mins hard running. And it is pretty fuel efficient, doing about 8 mins per tank at the moment and I will put a smaller venturi in it to see if I can do 10. Then I am laughing!

I just put a old ninja carb and crankshaft in my arrow. Im running it in my buggy this weekend with a OS 2050 pipe on 25% nitro with P3 plug. It will be interesting to see the run times i get, as i found whilst throwing a tune on it in the back yard the 2050 pipe made the engine sound like it was running rich yet when i leaned it off a liitle to tune to the sound it would bog down (too lean). It seems to run better with the changes (but maybe its all in my head). I also put a arrow piston/sleeve in another old ninja motor to give it a new life. I threw an old GRP (novarossi brand) ninja pipe on it and it went crazy, It will also be interesting to see what run times it gives with this pipe.
Has anyone else messed with these engines and crossed over carbs/rods/crankshafts from old ninja/os motors. Ive been going to do this for a while just only got motivated enough today to get the hex drivers out and pull them apart
Im interested to hear opinions on this, im not trying to re invent the wheel but like most racers have alot of old OS/ninja engine parts laying around and the cash is too tight to throw around for club races

What pipe is suggested for this engine? I have a few to choose from the OS 2060 or the Losi RE11. Is there any other I may want to try for small to med sized tracks?