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Engine basics => Engine set up tips => Topic started by: Geoff Goodworth on January 21, 2013, 03:44:41 PM

Title: Piston and cylinders for .25s
Post by: Geoff Goodworth on January 21, 2013, 03:44:41 PM

Some time ago there was a discussion about using LA 25 pistons and cylinders in other engines. As I had a rather tired Thunder Tiger GP 25 lying around, I bought a couple of LA 25 assemblies—just in case.

Last week I replaced the TT piston and liner with the LA 25 assembly—fits were spot on, and there is no boost port. I ran the engine yesterday for a total of 20 minutes. Initial start took some time due to having to find the correct needle setting. Once found, after that, the start routine was finger over the venturi for one turn, flick twice, add power to the glow plug, start second flick.

Configuration for the TT GP 25-LA: Scott Riese venturi—excellent work, thanks Scott—Randy Smith NVA, OS E-2030 muffler.

Title: Re: Piston and cylinders for .25s
Post by: Andrew Tinsley on January 24, 2013, 12:17:44 PM

Hello Geoff,
Is there a problem with getting TT GP25 spares? It is the only reason that I can think of for anyone wanting to swop from a good quality TT P/L and substitute an OS P/L. The Thunder Tiger P/Ls are a much better product with thicker and harder nickel plating.

Andrew.

Title: Re: Piston and cylinders for .25s
Post by: Geoff Goodworth on January 24, 2013, 03:44:53 PM

Good question Andrew. There wasn't a Thunder Tiger source when I bought the LA parts. Thundertiger4you had disappeared but Tower was not supplying at that time.

Tower has them available now—limited stock—and for LA 25 users, they list aluminium backplates for $4.99 and gasket sets—which include the thrust washer—for $2.69.

Title: Re: Piston and cylinders for .25s
Post by: Dick Pacini on January 24, 2013, 11:31:38 PM

Quote from: Geoff Goodworth on January 24, 2013, 03:44:53 PM

Good question Andrew.

Tower has them available now—limited stock—and for LA 25 users, they list aluminium backplates for $4.99 and gasket sets—which include the thrust washer—for $2.69.

Geoff, I couldn't find these on the Tower website.  Can you post a link?

Title: Re: Piston and cylinders for .25s
Post by: Geoff Goodworth on January 25, 2013, 02:37:39 PM

Here Dick, http://www3.towerhobbies.com/cgi-bin/wti0095p?FVPROFIL=&FVSEARCH=thunder+tiger+gp+25&search=Go  H^^

Title: Re: Piston and cylinders for .25s
Post by: Timothy Payne on January 30, 2013, 02:59:43 PM

I wish I'd have known about this before I just went and rebuilt my rather worn Thunder Tiger 25! I've even been contemplating sticking a 28 piston and liner in there. Got three of em now, (at least one is a branny!).

Love em! - They go for ever and are pretty unburstable.


Cheers Geoff!


ps Don't suppose you know where I can get a spray bar for one of these from?

Title: Re: Piston and cylinders for .25s
Post by: Geoff Goodworth on January 30, 2013, 05:21:49 PM

Tim, the hole in the Thunder Tiger crankcase accepts a 4mm spraybar. The Super Tigre-type NVAs from several sources—including Randy Smith—will fit and that's what's in my rebuilt TT 25. I believe that the Enys NVA is 4mm as well. Again, the only one that I have is in a Randy Smith modified engine so that's where to get the Enya or the PA needle assemblies.

For reference. the venturi is 0.136" ID from Scott Riese and the needle is open about 2 1/4 turns.

Title: Re: Piston and cylinders for .25s
Post by: Chris Wilson on January 31, 2013, 06:02:52 PM

Geoff,
          would you know if the Thunder Tiger GP 15 would be similar to the OS Max 15 piston and liner?

Thanks.

Title: Re: Piston and cylinders for .25s
Post by: Geoff Goodworth on February 01, 2013, 03:37:52 PM

No idea, Chris.