Espritmodel.com Telemetry Radio
Reply
Thread Tools
Old Sep 10, 2013, 10:51 AM
Chess club geek with wings
blunight's Avatar
Brainerd, MN
Joined Aug 2008
1,052 Posts
Help!
First nitro motor

I just bought a used Thunder Tiger 40 Pro off of Ebay...this is my first nitro motor in a VERY long time (last one was 1989!) so I'm a real noob when it comes to nitro.

My question is: What is the best way for me to assess the condition of this motor?

I'm mechanically inclined so taking it apart is not a big deal - I just need to know what to look for as far as signs of abuse. If the motor has serious problems I intend on returning it.

I'm also going to bench test it. I know I need a 9x6 APC but is the "Sport" prop?
Also, what should a non-modified motor tach out at? I believe there are some tuning tricks such as taking out a needle spring - removing the head shim etc that make these motors even faster but I'm just trying to assess if I bought a decent beginners motor.
I intend on getting a brand new motor when I get serious about racing.
Thanks!
blunight is offline Find More Posts by blunight
Reply With Quote
Sign up now
to remove ads between posts
Old Sep 10, 2013, 11:13 AM
Tampa,Fl
Dale 813's Avatar
United States, FL, Tampa
Joined Jan 2007
1,470 Posts
APC 9X6 sport prop. Should tack between 15.5-17K RPM's at peak.

Take the glow plug out. Soak the top of the piston with after run oil. With the carb open soak it too. Then. With a prop on. Turn it Round and round. Several times. Put glow plug back in. Turn prop between compressions. Should feel smooth. Compression should feel strong. Put on bench and fire.

On the test stand. I wrap a craft wire through the carb linkage an around the exuast to keep the carb wide open. Open your high end needle rich until you start it. Then you can start closing the needle. Do you know how to pinch/Tune the motor ?
Dale 813 is offline Find More Posts by Dale 813
Last edited by Dale 813; Sep 10, 2013 at 11:26 AM.
Reply With Quote
Old Sep 10, 2013, 12:41 PM
Chess club geek with wings
blunight's Avatar
Brainerd, MN
Joined Aug 2008
1,052 Posts
Thank you Dale, I'll follow your instructions to the letter.
Warning...stupid question alert....

Is there a locally available product I can use as an after run oil - something like Marvel Mystery Oil?


"Do you know how to pinch/Tune the motor?"

I only have a vague idea, what do you recommend? I don't want to run it too lean and overheat it. The good news is I do have a tach
blunight is offline Find More Posts by blunight
Reply With Quote
Old Sep 10, 2013, 02:17 PM
Registered User
cpaine's Avatar
Canada, ON, Paris
Joined Mar 2007
174 Posts
Quote:
Originally Posted by blunight View Post
Thank you Dale, I'll follow your instructions to the letter.
Warning...stupid question alert....

Is there a locally available product I can use as an after run oil - something like Marvel Mystery Oil?


"Do you know how to pinch/Tune the motor?"

I only have a vague idea, what do you recommend? I don't want to run it too lean and overheat it. The good news is I do have a tach
Pinch/Tune..... I think he means this....its what most do, basically... when the needle is close to "Peak" give a quick pinch of the fuel line. That leans it out for a split second. you can here it jump up in RPM and sound. If it and sags off instead, then its to close to the lean side..... now that you heard it jump up in RPM, sneak the needle in until the motor is matched to that "pinch"
my 2cents
cpaine is online now Find More Posts by cpaine
Reply With Quote
Old Sep 10, 2013, 06:05 PM
Tampa,Fl
Dale 813's Avatar
United States, FL, Tampa
Joined Jan 2007
1,470 Posts
Exactly what Cpaine said except we like to stay about 300 rpm below peak. Well. Maybe closer to 150 if its during a Race

A good running Motor will turn 16.6K RPMs. A buddy of mine tells me I'm too hung up on RPMs . He's probably right. Recently I was disappointed with one that wouldn't turn past 16.2. So I changed the rear bearing and now it's at 16.7. That's what I shoot for. Once a bearing gets worked in. The RPMs may increase.
Dale 813 is offline Find More Posts by Dale 813
Last edited by Dale 813; Sep 10, 2013 at 08:02 PM.
Reply With Quote
Old Sep 11, 2013, 11:35 AM
Registered User
United States, KS, Overland Park
Joined Jun 2007
413 Posts
Marvel air tool oil - I get mine at O'Reilly auto. Makes good after run oil.
fizzwater2 is online now Find More Posts by fizzwater2
Reply With Quote
Old Sep 11, 2013, 11:59 AM
Chess club geek with wings
blunight's Avatar
Brainerd, MN
Joined Aug 2008
1,052 Posts
Quote:
Originally Posted by Dale 813 View Post
Exactly what Cpaine said except we like to stay about 300 rpm below peak. Well. Maybe closer to 150 if its during a Race

A good running Motor will turn 16.6K RPMs. A buddy of mine tells me I'm too hung up on RPMs . He's probably right. Recently I was disappointed with one that wouldn't turn past 16.2. So I changed the rear bearing and now it's at 16.7. That's what I shoot for. Once a bearing gets worked in. The RPMs may increase.
Quote:
Originally Posted by fizzwater2 View Post
Marvel air tool oil - I get mine at O'Reilly auto. Makes good after run oil.
Thanks for the replies, cant wait to get my hands on it. If you don't mind I may have some additional questions for you guys.
blunight is offline Find More Posts by blunight
Reply With Quote
Old Sep 11, 2013, 12:24 PM
Tampa,Fl
Dale 813's Avatar
United States, FL, Tampa
Joined Jan 2007
1,470 Posts
Quote:
Originally Posted by blunight View Post
Thanks for the replies, cant wait to get my hands on it. If you don't mind I may have some additional questions for you guys.
Don't mind at all. Keep the questions coming.
Dale 813 is offline Find More Posts by Dale 813
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion brand new to nitro just got my first nitro heli a few days ago... old stuff man Fuel Heli Talk 47 May 06, 2013 03:07 PM
For Sale Nitro plane motors and brushless motor! thefogecig Aircraft - Fuel - Airplanes (FS/W) 0 Mar 25, 2013 12:45 PM
Discussion Advice on first nitro build Atomic Skull Fuel Heli Talk 13 Feb 13, 2013 07:10 PM
Help! HBX Wildfire- first Nitro Rc angermgnt Off-road Cars 5 Feb 11, 2013 07:48 PM