Just picked up a used TT 91 and the choke venturi is missing, I've heard these engines won't run well without it so I need to find one, Looked everywhere and can't find anyone selling one so if you have a dead TT and want to part with the venturi I'd be happy to buy it from you. Search did not bring up much either other than these engines like to have them.

Thanks
Dauntae

http://www.paulsmodelsupply.com/

I would check your parts listing or call Ace first. I think it has been reported that the newer engines have been replaced with a smaller bore carb and don't need the venturi / choke.

How would I be able to figure out how old this one is, It was strapped on the front of a Pica Waco I got at auction for $125 with radio gear RTF so to speak, Can you believe it. The plane looks old and the guy I got it from said he got the plane used himself but I'm not sure when the engine was put on. I have a Magnum 91 I'm going to put on because I know how well it works and almost never had a deadstick on it but would love to get this TT going, Looks clean with no scrapes or damaged fins but no idea of how much flight time on it, It's a little gummed up but every thing still moves... just a little slower than a clean one but I'm sure it's not a newer one.

Thanks for the input guys
Dauntae

I would have doubt about this engine being new enough to have the new smaller carb.

Ok, the older carbs with the venturi had a good sized bore. Maybe about the same as a TT .46. I think someone said the carb was change about a year ago. Not that they knew it was changed a year ago, just that they had one with a smaller bore and they reported this about a year ago. Mine is about 4 yeas old and has the large bore carb. With the venturi they are very reliable with lots of power. However, because of the large carb and venturi they do not have a liner response. Most people do not know this but the reason four strokes have more controlability on throttle is because of the smaller carb. The TT .91 FS is actually worse about this than any engine I have had including all two strokes. There is almost no differance in power from 3/4 throttle to full open, in fact I think it runs better if you don't fully open the carb.

Heck, I work in a machine shop and might have to make one up if someone has some of the measurments to go by such as the length and dia. of the hole in it, The worst thing that could happen is it won't work right which is where I am now so if someone has one post some pics of it with a few dementions and I can begin to play with all those fun machines I have acsess to at work HEHE


I love my job
Dauntae

A venturi insert would probably work better. Just make it the same or slightly larger diameter as your Magnum and the outside diameter to match the TT carb. This would give better throttle response.

Also some have pointed out that it does not need the venturi if you are using a pump or regulator. The super cheap and easy solution is to simply not open the carb past 5/8 to 3/4 open.