super Tigre 90 problem accelerating
 

My ST90 worked like a charm for about 3 month. After the last time I flew, I cleaned the engine and it has sat there in the garage for about 2 months. I started it today and it started right up. We then took it to the field where we noticed that it sputtered when accellerating quickly. I was unable to adjust the needle valve so as to fix the problem What are the steps I need to take to get it running great again? I appreciate your help.

Best regards

Gene

super Tigre 90 problem accelerating
 

Gene,

Usually, a rich midrange can be adjusted by leaning the idle mixture a bit, increasing the idle RPM a bit, and readjusting the high-speed needle.

A bit of richness in the midrange is normal, but is should not be so bad that the engine almost quits.

Check your glowplug. After a breakin, glow plugs are usually contaminated by the small amount of metal worn off the engine's parts as they wear in.

If your engine hasn't been run for a while, the fuel in your main container could have been contaminated with moisture from the air. That will also affect acceleration.

When the weather over the seasons changes, all carb settings may need to be changed. Winter settings can be quite a bit different from Spring and Summer settings. Usually, though, only the high-speed needle needs to be changed.

Super Tigre 90
 

Since sending the original message I have gone full circle. I have had all kinds of advice from "replacing the carburator with a Chapman carb to changing to synthetic fuel to adjusting and re adjusting the high speed and low speed needle valves to changing the glow plug (2 or 3 times at least) I still have the same problem.. that is , basically I can run the engine on a test stand or on the plane and get it to the right richness by the pinch test but 8 out of 10 times after the taxi I try to accelerate and it stall on the runway . Is there a place I can send it for setup and testing? If so how long will it take and how much will it cost? Any help will be appreciated.

Cheers!

Gene.

super Tigre 90 problem accelerating
 

If the engine tends to quit when you're accelerating for takeoff, it's usually not the engine. The most common problem is a clunk that's too close to the rear of the fuel tank. The closeness of the clunk allows it to be rammed full of fuel when the fuel rushes to the back of the tank when you apply throttle. This gives the engine a severely-rich mixture, which can cause the engine to falter.

Remember, if an engine will run all day on a test stand, or in a static situation on the ground, but not in the moving model, the problem's almost always NOT the engine, but something in the system of engine/mount/tank/lines/airframe. You have to go through all components to locate the difficulty.

super Tigre 90 problem accelerating
 

Thanks Bill,

I just got back inside from my latest troubleshooting. I followed the engine and carburator setup procedures for High Speed, Idle and midrange .. I bought a tachometer and changed my prop to 13x6 from 14x6. I am using a PSP Mfg stand with a 6 oz fuel tank. When the engine is running at high speed the max rpm I could get the gobie tach to register is 7200 rpm at the very leanest setting. I backed the high speed needle off a few clicks until I got and used the pinch test to get it sorted to flight setting. I only got about 3-4 minutes of open throttle running with the smaller tank but it ran ok at high speed. I tried it again and this time afte about 1 minute at high speed I backed it off to about 1/2 throttle. It ran at that speed for a minute or so and then sputtered a bit and died. I could start it up again and run it at high speed but every time I moved the throttle back to 1/3 to 1/2 it died. I am using synthetic fuel (green) 10 % nitro. it looks like the fuel is boiling while the enging running. I will check the clunk on my plane (Joss Stick) . I am new to this rc stuff and don't have too many other resources I can ask for help. On my previous email I asked how long and how much it would cost to send it to Tigre for repair? .. Any thoughts?

best Regards

Gene

super Tigre 90 problem accelerating
 

Gene,

We hope you're discussing a new G90, or an S-90K.

If your engine's turning only 7,200 RPM, we'd sugges that there's something very wrong. We use an APC 12 x 8 propeller, Omega 10% nitro fuel, and an OS #8 glow plug and expect to see 12,000 RPM or so. Some have been as high as 12,300 RPM.

7,200 RPM would be considered much too low, and you're operating nowhere near the engine's power potential.

If you have an older engine, it may be worn out, especially if you got it second-hand. It may be time to consider a serious rebuild or replacement.

Sounds Like my problem
 

This thread sounds exactly like the problems I'm having. I don't have a tack but I'm sure I'm no where close to 12,000 RPM. I'm running a 14x6 prop on a Goldberg Ultimate using 10% fuel. I've had the engine for about seven years, but it doesn't have a lot of time on it. I loved the engine when it was working good but it's been a real headache lately. I think I need a rebuild too.

Where is a good place to send it?

RE: Super Tigre 90
 

wow!.. i have the exact same problem... almost to the letter... and i have no idea what to do!!!!