• Welcome to RCTalk! 🚀

    Join the #1 RC community where hobbyists connect, share, and get expert advice on RC cars, trucks, boats, drones, and more!

    • ✓ Friendly & passionate RC enthusiasts
    • ✓ RC tips & troubleshooting
    • ✓ Buy, sell & trade RC gear
    • ✓ Share builds & upgrades

Big problem tuning with new pipe and air filter

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, and others.
R

RCgangsta

RC Newbie
Messages
12
Reaction score
0
Points
0
RC Driving Style
Hi,
I am ready to throw this truck off a cliff. I have a savage 25 rtr and it ran perfectly, it was so much fun!! The engine never turned off and it never over heated. Now 2 days ago I bought the HPI ribbed pipe and Motor Savers air filter and it will not stay running no matter how much I tune it. I adjusted the low and high speed needels so much but nothing helped. Its starts no problem but after like 15 seconds of running it shuts off, no bogging or stuttering, it just stops dead. If I am lucky enough to run it a little it wont go over 1/4 throttle for more than 3 seconds without stopping. I am experieneced with Nitro, I have many cars and trucks but this just baffles me. Any help would be greatly appreciated. Thanks
 
I had the same problem when I went to the ribbed pipe. I am still having problems myself. My current thoughts are that it is not providing enough force through the pressure line to the gas tank as my temps have soared and I have to run extremely rich (10-11 turns out) jsut to keep it running. Here are the things I've fixed so far:

-larger exhaust gasket... was not making a good seal to the pipe
-new header springs
-shortened fuel tubing from pipe to tank to only 8 inches (was 14)
-Went to a COLD plug
-richened the HSN consoderably.
 
All I have ever ran is the ribbed pipe since both my savages are SS trim. I have a big ass Ofna filter that compares to the Motorsaver. My high speed is no where near 10 turns out? I think you guys may need to hunt for air leaks. But the shorted pressure tube, cold plug and header/pipe gasket are good starting points.
 
I agree with jones, it sounds like you might have created an air leak somewhere. Try getting a larger header gasket and a new header spring. Also, make sure your zipties on the header to pipe coupler are tight. If you have a leak in the exhaust, your not getting sufficient pressure to push fuel into the engine.

Did you maybe tear the pressure line somewhere when installing the new pipe?
 
Hey, thanks for the responses. Could you please supply me with some links from tower hobbies. What kind of Header springs do I need? I checked all the fuel line which is brand new, I replaced it with the new pipe and air filter. This kills me cause my truck was always the truck that ran the best, never a problem but now mine is the most trouble out of all my friends. Thanks again.
 
Last edited:
Here is the link for the replacement parts on the Savage.
http://www2.towerhobbies.com/cgi-bin/wti0005p?&I=HPIC1832&P=Z
3/4 down the page or so.
I would get the book out and go back to factory settings on the carb. (not trying to be a smart-a..) The larger air cleaner will make it run lean. I think I ended up about a turn to the rich side on mine.

If that doesn't do it, you may take the carb apart. Got a little bit of dirt in it when you changed lines?
Check your pressure tap on the pipe. May be something in it from the manufacturing process? Put your other pipe on and try it.
Good luck. Let us know what the problem was.
 
I've learned the hard way to change ONE thing at a time, and retune. When it's running great, add the next. A while back I added a tuned pipe, larger cooling head, and a bigger air filter and couldn't believe how much I had to change both needles to make it behave.
Try going back to the stock pipe, and get it running right. If it will, at least you have eliminated one problem. Then add the new pipe, and see what you run into.
 
I know, I should have done one part at a time but now I don't feel like changing things back. What needle whould I adjust first, the LSN or HSN?
 
Here's the system that works for me all the time. I end up tuning engines every time I'm at the track. Guys show up with cars that quit running, or cars they just bought used and know nothing about, and I always get them to run. It's not always a quickie, sometimes it takes a few extra tweeks, but they always leave happy.


Set the needles to factory specs, if you know what they are. If you don't, follow this procedure.
Put the nose of the truck against something firm so it can't get away from you. If you have an EZ start, keep it running while moving your LSN slowly, one way or the other till it starts to run. If it's a pull start, it's easier to have someone else pull, so you can concentrate on the needles.
Adjust your LSN and idle screw till it idles well and will run up to half throttle. (get it to running temp before you finalize any settings) When it idles properly, throttle it to half and see if it stalls or bogs down. If it stalls, it's too lean. If it bogs, it's too rich. When it goes to half throttle nicely, put it on the ground.
Now go to full throttle. This is when you adjust your HSN. Same thing. If it bogs, it's too rich, stalls, it's too lean.
When it seems to be running good, pinch the fuel line. It should speed up slightly and then stall within 3 - 4 seconds. If it stops quickly, your LSN is too lean. If it takes longer, the LSN is too rich.
Drive it for a while and then take a temp check to make sure it's at the proper temp. If it's too hot, richen the HSN.
You will have to make small adjustments on the HSN almost daily to compensate for outside temperature and humidity.

By the way, the factory settings are for break in, or a starting point if you really messed things up. Once an engine is broken in, don't expect it to run right by going to those settings.
 
This may be a stupid question
but did you think to try a new plug before you started changing the needles?
I have been running the same combo you are running for some time now and it works very well for me.
I am also using Mc Coy -9 plugs .


Tim K
 
I finally went out today to try and fix the tuning problem and now the truck is running awesome!! Heres what I did:

1. Went back to factory settings.(I followed HPI's instructions this time to properly set the needels.)

2. Proped up the truck so the wheels were off the ground and spun freely.

3. Got the engine started.

4. Adjusted the LSN with very small turns until the engine kept running. (I had to lean the HSN a little because 4.5 was just way to rich to even keep the engine running to adjust the LSN)

5. Then I adjusted the HSN till I could rev the engine without it dieing.

6. Then I let the engine heat up to running temperature.

7. I then put the truck on the ground, Fine tuned the HSN and richened the LSN a little because the engine was cold when I was adjusting it.


As you can see I pieced together everybody's methods into one that worked for me. Now the truck runs better than ever. Thanks a lot guys!!!!
 
Do not attempt to tune the motor when it is cold. FWIW I am in your area (L.I.) and with the MotorSaver and Ribbed pipe my S-25 ran great with the needles very close to the factory settings.

Warm the motor up. Tune the HSN before touching the LSN. Richen the HSN till the motor bogs and then lean it a bit just until it stops bogging. After that do a few high speed passes and then immediately do an idle pinch test. This will tell you if the LSN is close. Fine tune the LSN by watching the way the motor runs off the line. Keep your tune on the rich side, expecially with the cold N/E weather.
 
Both needles are very rich and pretty close to factory. The engine has a hard time starting at first because it so rich, I can hear it almost bog out but once it gets hot it runs well.
 
When do we get computer controlled, fuel injected nitro motors? This sounds like what a 1:1 car forum would sounded like from the 1970's and 80's. :)

This may sound nuts, but I tune mine cold and OFF. I simply run a tank and determine what needs to be done, and make small adjustments.

I tuned my 4.6 for the polished pipe before I ever started it after the install. Guessing the difference in backpressure which affects the air into the carb and making the adjustments. It was perfect and had more power than before.

I currently have a truck that wheelies on demand and runs about 230 degrees at the highest. (2nd half of stock tank of course. OFNA coming to the rescue soon)

*
 
Last edited:
*cough cough* Wow, a dusty topic, lol.

While I applaud your search skills, young Jedi, I'm afraid the topic is 3+ years old.
 
Rolex, you ought to write a book. The way you described it makes soooo much sense it makes me feel stupid........lol
 

RC Builds

Back
Top