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Old 05-03-2010, 11:29 AM
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Default O.S. Speed question

Im kind of a newb with nitro motors so heres a few queations

Just bought a used OS speed Magnesium head with "2gal" on it.

Whats the difference between MAG head and worlds - is it inferior?, are there things that need to be replaced?


Just wondering how do I tell what needs to be replaced? Ive heard the speeds still run well even without great pinch

I kind of know how to take the motor apart an check for slip between the rod and crank but how do i tell if the bearings are good? - what else should i look for when checking the condiditon of the motor - specifically in teh carb which i know nothing about

are tko cermaics good for this motor

Is it ok to "re-pinch" or should i get a new piston sleeve

Im thinking about getting a ninja 5 port piston sleeve combo for it - is this a good idea for my mbx6 buggy. Do i also need the ninja rod and pins?

what kind of spares should i get for the os motors, O-rings? carb parts? what goes out alot?

thankyou so much to anyone who can answer any of these questions
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Old 05-03-2010, 12:16 PM
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If its really only 2 gallons on it, and it was broken in properly and ran decent, its just now getting fully broken in. You should not have to replace anything.
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Old 05-03-2010, 02:13 PM
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Speed magnesium has the older carb.
Worlds (if you meant the Hara edition) has the newer carb.
no difference in tuning, except for different sized venturis.

Magnesium head was designed for lighter weight and cooler temps.
I'd advise you to replace the mag head, it gets brittle at high temp and the fins will break if you flip your bug too often.
Although the head allows for cooler temps, this might not always be a good thing.
Better to use an aluminium head, either the blue head or a speed alu head.

No way to check the bearings unless you take it out of the crankcase.
(except maybe if you remove the p/s/r and spin the crankshaft and feel for grittiness..)
If you're unsure of the bearings, just replace it. TKO ceramics are good.

Don't worry about wanting to pinch the p/s.
Your 2gal Speed might be good to go.
See if there's any metal pinch left. If yes, the engine is good. Just need abit more runtime to finish breaking in process. (but this shouldn't be the case if it really had 2gal of fuel..)
If not, see how much compression is left.

If engine idles steadily and makes power both bottom and top then you've gotten a good deal!

A lot of guys have done the frankenspec motor mod, either 3port v-spec liner in a ninja case or 5port ninja liner in a v-spec case, do a search in the forums.

Ninja rod and pins are the same as the Speed's.
Don't need to keep spares, motor should last you a long time if you take good care of it. Perhaps only rod change after every 3-4gal..

Best mod for the speed?
Go find Tony's Screws..
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Old 05-03-2010, 04:36 PM
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Originally Posted by Shuming
If its really only 2 gallons on it, and it was broken in properly and ran decent, its just now getting fully broken in. You should not have to replace anything.
....except the rod.

I generally replace the rod in my motor after a couple of gallons, just to be safe, since it gets so stressed during break in. Could be overkill, but I figure it's an inexpensive insurance policy. Beyond that, just run it.

I bought my Speed with 1.5 gal on it, and did nothing except replace the rod, and put in some new TKO ceramics (front and rear). I did the bearings simply so I'd know the condition from the start. If yours feel smooth, not gritty, then go ahead and keep running them.

I've got another 2 gal. on my motor since I bought it, and it's still running nice and strong.
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Old 05-03-2010, 05:15 PM
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it won't matter if you put a speed/vspec or ninja P/S. You won't be able to tell the difference.


buy tko front and rear ceramic bearings, a new rod and get a pinch. 100 bucks rebuilt.

But none of us know if there is even anything wrong with it.
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Old 05-03-2010, 05:20 PM
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Originally Posted by dreaux
it won't matter if you put a speed/vspec or ninja P/S. You won't be able to tell the difference.
speed and blue head vspec is a big difference..... blue head top end flattens out while the speed keeps on revvvving to the moon and the speed is tons smoother...... i love my speed, its allows you to clear jumps that other guys dont attempt because they dont have enough grunt.....
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Old 05-03-2010, 05:27 PM
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Originally Posted by Teccmoney
speed and blue head vspec is a big difference..... blue head top end flattens out while the speed keeps on revvvving to the moon and the speed is tons smoother...... i love my speed, its allows you to clear jumps that other guys dont attempt because they dont have enough grunt.....
i am talking about the piston and sleeve only. just about all the differences are in the crank/rod/case. That is pretty much it.

and lmao about a vspec not being able to clear anything.
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Old 05-03-2010, 05:47 PM
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Originally Posted by dreaux
i am talking about the piston and sleeve only. just about all the differences are in the crank/rod/case. That is pretty much it.

and lmao about a vspec not being able to clear anything.

ummmmmmm....... never said blue head vspec couldnt clear anything, i own one so i know it can clear almost anything but when its loamy and traction is an issue and the run up to a big triple is short, i will put on my speed to have no worries about clearing the triple, well to be frank over clearing the triple
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Old 05-03-2010, 05:55 PM
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I have been getting 2 p/s/r sets out of my speed engines before they need too much too make it not worth rebuilding. Around 8 gallons I replace the p/s/r carb boot and rear o-ring and then run it once the 2nd p/s/r is done then they are pretty much parts because it costs too much to rebuild and better to just buy new. I replace bearings as needed with TKO ceramic and thats it.
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Old 05-03-2010, 06:02 PM
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Originally Posted by Frank L
I have been getting 2 p/s/r sets out of my speed engines before they need too much too make it not worth rebuilding. Around 8 gallons I replace the p/s/r carb boot and rear o-ring and then run it once the 2nd p/s/r is done then they are pretty much parts because it costs too much to rebuild and better to just buy new. I replace bearings as needed with TKO ceramic and thats it.
whats up frank..... revoracer from cvr...... havent got to that point with my worlds speeds..... but i have 3 gallons on one that is running great and 4.5 on one that started acting up at round 2 at riverfront r/c.... it had a air leak on the carb boot and it was making my low end go lean and burn up glow plugs..... had a tiny bit of dirt inside from the leak on the dust boot, but no visible internal damage, im hoping for the best after i put this new 21j carb on it and put her back together......
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Old 05-03-2010, 06:03 PM
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Originally Posted by wstuart
Im kind of a newb with nitro motors so heres a few queations

Just bought a used OS speed Magnesium head with "2gal" on it.

Whats the difference between MAG head and worlds - is it inferior?, are there things that need to be replaced?


Just wondering how do I tell what needs to be replaced? Ive heard the speeds still run well even without great pinch

I kind of know how to take the motor apart an check for slip between the rod and crank but how do i tell if the bearings are good? - what else should i look for when checking the condiditon of the motor - specifically in teh carb which i know nothing about

are tko cermaics good for this motor

Is it ok to "re-pinch" or should i get a new piston sleeve

Im thinking about getting a ninja 5 port piston sleeve combo for it - is this a good idea for my mbx6 buggy. Do i also need the ninja rod and pins?

what kind of spares should i get for the os motors, O-rings? carb parts? what goes out alot?

thankyou so much to anyone who can answer any of these questions

YGPM
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