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Thread: RTB-03 Cylinder head

  1. #1
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    RTB-03 Cylinder head

    I picked up a couple Predator motors today, I stripped the motors of tanks, tins, etc., and noticed one was an RTC-9 head, which is pretty typical. However, the other one had an RTB-03 cylinder head, I've not seen one of those before. Date on the box for the RTB head showed 12/30/16 so its a new motor. I didn't get a chance to tear the head off the motor yet, so I dont know what the valves look like, but was curious if anyone else has seen the RTB heads. These are California motors.

  2. #2
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    Let us know what size valves are in them, also are thee valves dished?

  3. #3
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    OK, so I pulled the head and compared to an RTC-9, and it looks identical in every way. Same valves, which are dished, the exhaust is stainless, intake is not. Ports, combustion chamber, valve springs, keepers, etc., everything looks exactly the same. So, it appears to be a new casting number, but its the same as the RTC-9, so it's a good head, with no downside that I can see.

  4. #4
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    Thanks - I will look for one.

  5. #5
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    Does it have 5.0MM valve stems or 5.5MM?

  6. #6
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    Got any stock air boxes you can part with?

  7. #7
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    Quote Originally Posted by kmc3420 View Post
    Does it have 5.0MM valve stems or 5.5MM?
    They have 5mm stems like the rtc heads do, same retainers also

  8. #8
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    I have quite a few spare air boxes, exhaust pips, gas tanks, carbs, throttle arms, etc. I build lots of motors, and strip the motors down completely, so anyone that needs brand new take offs, just send me a PM.

  9. #9
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    Quote Originally Posted by standup guy View Post
    I picked up a couple Predator motors today, I stripped the motors of tanks, tins, etc., and noticed one was an RTC-9 head, which is pretty typical. However, the other one had an RTB-03 cylinder head, I've not seen one of those before. Date on the box for the RTB head showed 12/30/16 so its a new motor. I didn't get a chance to tear the head off the motor yet, so I dont know what the valves look like, but was curious if anyone else has seen the RTB heads. These are California motors.
    what is the valve size? 27mm intake, 25mm exh? asking because i have been offered on of these heads. thanks

  10. #10
    4 Cycle Advanced User
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    Yea they are 27mm intake 25mm exhaust. I have one of these heads on my predator as well.it runs very well!

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