S-25 wont rev?

[NitroNick]

I took out my savage 25 (S-25 engine) for the first run this summer and at first it seemed fine. After about 1/2 tank it started to really struggle revving up to max rpm. It seemed like it would stop around 20k or so, so still a while to go. It would get to high first and into second but then just be a complete dog.

I know about the lean effect so I kept making it richer but the problem persisted. I then took of the air filter because I though it could be clogged, but it ran the same. I then took it off completely and checked to see If I was getting full throttle from the carb and servo, and again I was.

Any help would be greatly appreciated!

 

[Edwarj1795]

How long was it sitting before?

 

[NitroNick]

Its been sitting since August so about 9 months. (School) You think that would have an effect on it?

 

[Edwarj1795]

Its been sitting since August so about 9 months. (School) You think that would have an effect on it?

Well, it depends. Did you use after run oil. Did you leave old fuel in the lines and tank. Maybe there is a small clog in the fuel line and when the engine is screaming and requiring more fuel...it can't get what it needs and bogs. Maybe there is a pin hole In one of those lines, and you are getting air leaks. Also maybe you are too rich on the top end and you are bogging it down. Have you checked the glow plug? Was your fuel stored properly?

So first thing I would do is, check lines for holes and leaks, then make sure glow plug is good. You can try returning needles back to factory settings and starting over. Maybe remove the fuel tank and lines and clean them real good.

Let me know and we can go from there bud.

 

[NitroNick]

Thanks bro thats some great advice I will check all of that out when I get home this weekend and let you know!

I do know for sure there was no old fuel in the lines/tank and no I do not run after run oil, I should probably start doing that. I used to when I just got my X but Ive never in the 25.

 

[Edwarj1795]

Okay cool, since you don't use after run oil, maybe open her up and check the sleeve....see if there is a gummy buildup on it. Check the transfer ports too. If they are dirty, don't scrub or scrape them. Use mineral spirits or something. These are things I would check. Maybe someone with more knowledge can school us both. Let me know what happens when you run it this weekend.

 

[EUGENE477]

With fuel line being so cheap, why not replace it for good measure? Do you have a local hobby shop that's near by?

 

[Edwarj1795]

I agree, make sure you get a good high temp fuel line. Don't be like me and try hardware store line that melts when it gets hot and can't handle chemicles without getting gummy.

 

[NitroNick]

Thanks! All good advice and I will. I do have a LHS not too far, thats a good idea, I'm currently building a VTA 1/10 car so money has been tight for the trucks lol

 

[Edwarj1795]

Yeah, good luck. In my experience, an engine wants to run once it starts. At its most basic level, it is just an air pump. I am sure the engine (block, piston, and sleeve) are just fine. You just need to check all the other players and see where your issue is.

 

[NitroNick]

So I got home today and looked at some of the stuff you guys told me about. I took the fuel lines off and cleaned them with WD40. I also put some in the engine and cranked it a few times to lubricate it. I don't think there is an air leak on the tubing after all of this, I will try and run it tomorrow to see if anything changed!

 

[Edwarj1795]

So did you get it worked out?

 

[Grumpy1822]

I think its just rich. Fire it up and get it warmed up. Then with whelks off the ground give it throttle. When it stops reving hold the throttle and lean the hsn and see if it revs higher.

 

[NitroNick]

Update: Went to my local HobbytownUSA to see what they thought about my truck, and I was making some rookie mistakes. I have been told to not touch the LSN and only the HSN from when I got into Nitros nearly 10 years ago. Basically he told me to adjust BOTH (what a novel concept) needles and get it tuned right because it was a tuning problem.

I went back home, fired it up, did exactly what Grumpy1822 said and its honestly never ran better, it was amazing. I guess it just needed to be tuned. Thanks for all the help though guys, I will be buying some extra fuel line and after run oil in the near future!!

 

[Edwarj1795]

Sweet, yeah the carb needs a total tuning. Well have fun with it, hope you get many gallons out of it. Glad you got it running well man.

 

[olds97_lss]

Typically, if you have a 3 needle carb (not including the idle screw), you don't mess with the screw that opposes the carb slide. That screw adjusts where the LSN needle seat is and where the fuel dumps down the carb throat. The other two screws (HSN/LSN) both need adjustments based on weather, fuel, ambient temps and terrain.

Can check out this thread from a guy who really knows a thing or two about tuning:
http://www.rctech.net/forum/onroad-nitro-engine-zone/295490-tuning-bible.html

 

[Edwarj1795]

Typically, if you have a 3 needle carb (not including the idle screw), you don't mess with the screw that opposes the carb slide. That screw adjusts where the LSN needle seat is and where the fuel dumps down the carb throat. The other two screws (HSN/LSN) both need adjustments based on weather, fuel, ambient temps and terrain.

Can check out this thread from a guy who really knows a thing or two about tuning:
http://www.rctech.net/forum/onroad-nitro-engine-zone/295490-tuning-bible.html

That's a good thread, read it many times

 

[olds97_lss]

That's a good thread, read it many times

Ron Paris really knew his stuff.

 

[Edwarj1795]

Ron Paris really knew his stuff.

Yeah for sure, back when I first started I use to Do the idle method....but after I gained experience, it's been all heat cycle. I noticed a huge difference.