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Old 01-19-2013, 10:22 PM   #256
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Engine is performing flawlessly!! It likes to be around 230* with the big head, anything over that and power drops off. Short shifting it really improves acceleration , it s a bullet through the infield. I will say that i am not seeing anything special about the mileage though.

Engine doesnt seem to like hot plugs either! in the finals I made a dumb mistake and put a new 7 plug in while i had been running 8 and it ran like crap no matter how i tuned it, probably cost me a place or two but i consider it a lesson learned!

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Old 01-23-2013, 01:14 AM   #257
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What is the latest version of the O.S. Speed 21 Engine called?
Also do you use the RP7 or the RP8 Plug?

Last edited by mrlahey; 01-23-2013 at 02:28 AM.
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Old 01-23-2013, 09:10 AM   #258
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What is the latest version of the O.S. Speed 21 Engine called?
Also do you use the RP7 or the RP8 Plug?


XZ-R, Mine ran better with the 8
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Old 01-23-2013, 10:07 AM   #259
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XZ-R, Mine ran better with the 8
Mine runs RP7 under 30-35 Celcius / 65-75% humidity with Byron Gen II 25%/11.(0.6mm head clearance) Lots of torque and good top speed. (OS T-2080 pipe)

Never runs over 96 C temp and the plug lasts very long.

By the way it is very easy to tune, idles perfectly and fires up with just few turns, my starter box battery last days with this engine because I just touch the rubber wheel and it starts so easily.

Last edited by sm4100; 01-23-2013 at 10:20 AM.
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Old 01-23-2013, 11:34 AM   #260
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Has there been more than one version of the Speed 21 XZ-R?
Like an updated version 2012 model?
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Old 01-23-2013, 04:41 PM   #261
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Mine runs RP7 under 30-35 Celcius / 65-75% humidity with Byron Gen II 25%/11.(0.6mm head clearance) Lots of torque and good top speed. (OS T-2080 pipe)

Never runs over 96 C temp and the plug lasts very long.

By the way it is very easy to tune, idles perfectly and fires up with just few turns, my starter box battery last days with this engine because I just touch the rubber wheel and it starts so easily.
+1 mine is really running good especially since it is finally fully broken in, first bump and its going and very easy to tune.
here it is with an 8 and Nova "bat" pipe!
http://www.youtube.com/user/Mantisworx?feature=mhee

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Has there been more than one version of the Speed 21 XZ-R?
Like an updated version 2012 model?
Well I will say that the liner that was in my new motor is not the same as the extra one i ordered a month later, new one is much nicer, broke in much better and just runs better in general, I have a little over two gallons and the pinch is till nice and tight.
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Old 01-23-2013, 06:02 PM   #262
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Does anyone change the rear bearing to ceramic? Could I use the buggy one?
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Old 03-12-2013, 05:40 PM   #263
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Here are some side to side differences between the XZ-R VII and the speed liners.




I accidentally ordered the wrong piston combo, so after measuring i noticed that there are some differences. the VII piston has cooling/lubrication holes and the pin to piston top height is also not the same, the pin on the VII sits lower than the SPEED and the lip on the liner is .013" thicker than the SPEED. So i started thinking about Frankensteining something together. according to my measurements if you use the SPEED piston with the VII liner you should have advanced timing but you have to shim down the head to get the compression back to where it needs to be. So i ported the VII liner, got it together and fired it up! sounds really good and is very responsive, will get to the track thursday and see how it feels on the track.
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Old 03-13-2013, 02:46 AM   #264
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Very interesting; thanks for sharing.
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Old 03-16-2013, 08:08 PM   #265
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so if u used the v2 piston and sleeve and just put a capricorn 1mm shim under the sleeve then u wouldnt have to use the v1 piston to get advanced timing?
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Old 03-17-2013, 06:48 PM   #266
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so if u used the v2 piston and sleeve and just put a capricorn 1mm shim under the sleeve then u wouldnt have to use the v1 piston to get advanced timing?
I do not know the dimensions of the V1 piston to tell you. All i have is a Speed and V2 piston. The difference between the two pistons i have is .013" If you add that many shims under the liner you have to figure out how to get the compression where it suppose to be via the shims under the head. If you shim the liner you lose compression so you cant shim it more than you can remove from the head and to seal properly you need to have at least one copper shim.

I May have stumbled onto something here, this engine RIPS!! WOW it is so freakin fast, insane top end and literally roast the tires at the top of first gear, when it goes into 2nd the back of the car drops and it rolls out! Mileage seems to be a little better but i didnt time it today i was too busy driving it! tune wise i did make some changes: leaned out LSN a bit, 3rd needle 3hrs lean and HSN 2hrs rich. It feels best around 240
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Old 03-20-2013, 07:32 AM   #267
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does anyone know the new part numbers for the piston and sleeve i cant find any info on os site.
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Old 03-20-2013, 08:09 AM   #268
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Originally Posted by ralphierace13 View Post
does anyone know the new part numbers for the piston and sleeve i cant find any info on os site.
http://www3.towerhobbies.com/cgi-bin...I=OSMG2041&P=Z
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Old 03-22-2013, 02:07 PM   #269
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does anyone know what offroad tuned pipe works for OS XZ- R for a 1/8 GT
thanks
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Old 03-22-2013, 03:35 PM   #270
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does anyone know what offroad tuned pipe works for OS XZ- R for a 1/8 GT
thanks
I run the 9886 and short Nova header, perfect combo! i suggest putting a large offroad head on it, tends to run hot if you dont.
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