We are putting a Thunder Tiger 75 in a Reactor 46. Engine Fits pretty good in cowling. Couple questions for you folks 1) Will the OS 90 degree inside header pipe work in the Thunder Tiger, Specs seem to be the same 10mm outside diameter, 8 mm inside diameter? 2) How is the best way to entend the needle valve thru the side of the cowling? Have seen pictures of wire type extensions but dont know how they are attached to standard needle valve.

Thanks to any who can help, please send pictures if possible. Bill

Don't know about the header, but...

Your needle should have a little set screw in it, or at least a threaded hole where one would go. My engines have all come with a braided wire, a set screw, and a round disc to put at the end of the wire for easy turning. The wire can be cut to any length.

An alternate method is to use either a piece of music wire bent into an L shape, or use a spare allen wrench, held in by that little set screw. I like the allen wrench method as it has flat sides for the set screw to grip, has a perfect pre-bent shape, and is fairly rigid.

Here's some pics. Sorry they are blurry; I'm a better pilot than photographer.

Thanks Joe, on my way to the basement to take a look at the stock needle adjuster knob. My son does not like the idea of the wire permanently out the side of his cowl so we are thinking of ending the extension just inside the cowl with an allen head, this way we can stick the allen wrench in to adjust when necessary, ever seen that done?

just added pics.

haven't seen that done, but i still have a lot to see. personally I have the needle accessible at all times. it's for the good of your engine.

Well that was embarrassing. As you said, it has an allen head to hold whatever a body wanted to put in the hole to extend the needle valve. Thanks so much Joe

You're welcome. Wish I could be more of a help for the header. Can you post a link?

That little set screw Joe told you about is designed just for that reason. What you were asking about is in the photos I'm posting for you. When I set up an engine that is cowled I like to keep the needle valve hidden and just have a small hole in the cowl. I drill out the NV hole and tap it for 4-40 then use a hex head screw in there plus the set screw Joe showed you just to keep it tight. I don't have any photos of one but most the time I use a 22 rifle shell that I drill out and have the set screw running through it. That way I just have to run my hex head wrench into the shell case when the engine is running and the screw head is easy to locate and the wrench doesn't pop out due to vibration when I'm adjusting the high end. You could probably use a 2-56 screw but I had a lot of 4-40s in my box over the years and used that size. It's clean looking and works well. Just another way of doing things. A bit more work though.

Another way I've seen done is to cut down a T-pin and insert it into needle valve, being held by set screw and simply slot a wooden dowl to go through a 1/4 inch hole through cowel to adjust. The only problem with this is not misplacing the dowel when your not using it. Hope this helps.

TF96