I'm not talking about any one part in particular i guess.. ALL the parts aren't of the same quality as their OS counterparts. Do a test. Dismantle both engines completely and lay out the parts next to each other on the table. Then go get your wife/sister/mum or whoever knows nothing about nitro engines ;). Ask them to pick which parts look the best quality. You will end up with a pile of OS parts and all the arrow parts leftover.

I'm not totally concerned with appearances though but these things need more attention for me: The groove in the slide, the inside of the cooling head, the exhaust port in the case. Also i'm not sure what the slide is made from but it I think its aluminium whereas the OS one is steel(could be wrong about that).

I'm not trying to "eat my own" as you put it. Just pointing out that while the arrow shares many of the dimensions of the vspec, it doesn't share it's build quality. Don't get me wrong I quite like my arrow.. But if they want to sell big numbers and compete with companies like Alpha and Go, they will need to improve the overall finish.

i dont think arrow was trying to do exact copy if the vspec and it has a few different things. thats why the compression on the arrow will last way longer than the vspec. it has a oiling whole on the rod where os messed up at and so on. i agree with you they could made a lil better. but i still really like running this engine

Yeh well I'm with you there. They have done some things better than the original. And if I had to choose between how it looks and how it runs then I'd go with how it runs ten times out of ten. Just don't put your finger inside the cooling head.. It will come out like grated cheese:)

mine cooling head is not like that. is the one you have 1st or 2nd version?

No sharp edges? I thought the cooling head is the same on the 2nd version. Only the case and o-rings are different?

Just looking at it now.. It seems like the Arrow carb needles will fit into the OS body... I know people have been complaining about the new short needle carb on the xzb.. Maybe you could transplant the arrow needles into the xzb carb?

they should be but mine is not sharp. arrow does have the long needles like the old os carbs did

Finally, got to run the engine. Thumbs up.
The 6.5 mm venturi did the trick. Got 11 to 12 mins now.
Tq for the tips. Solid performance.

How many gallons before I should remove the shim ?

as far as I know ( I've been wrong before :D ) You cannot interchange needles from a carb made for short needles, with long needles, nor vica-versa

odd as guys running the xzb vspecs are changing out the needles on the carb for the old carb needles as they are short needles on the new carb and long on the old....

I think they confirmed in the xzb thread that the body, slide and hsn etc were the same part numbers.. only the lsn and mid needle were different. So if the OS long needle and mid needle fit then it looks like the arrow ones will too... Totally untested of course so don't take my word for it. I do know the arrow needles screw into the 21J body ok.

Needles have to thread into something, wouldnt the thread count and sizes of the carb have to be different? If you use a 5mm screw in a part made for a 8mm screw what happens? I have seen and heard people changing out the whole carb but just the needles?

I uses a nova plastics venturi. How good is a metal one compare with the plastic one ?

Both are the same in my opinion. i have tryed both and didnt notice anything

from the o.s thread ^^^

I believe you Ryan, it just seems strange to me that a carb designed for long tuning needles works just fine with shorter ones. I would think that would cause all the settings to be completely out of whack and the needle would have to be cranked down way to much, but if it works than that's great. Thanks for the info