Couple of questions help please

[funwheels1]

hey,
I'm still a newb to nitro rc. I'm not sure if its me, or my engine, but i can't get my savage going worth nething. My hobby shop can, i mean there like experts. Anyways, its bone stock except for a motorsavers air filter, venom temp guage, and some heavy duty fuel line. The few times i get it running, it only runs half a tank! What i was asking is if you would suggest keeping this and maybe getting the s-25 engine or maybe selling it and buying a friends rc10 gt. Please post comments. Also, any tips on starting ur stock .21bb engine with pull start would be great. THank you for your time.

Drew

 

[RoadRunner]

just relax... if you r new to nitro, u will need to go through some going pains and a learning curve.. read the instructions 2 times.....if not 3..follow them exactly as written. dont lose your cool.. the results r rewarding....enjoy!

 

[indyjohnny]

All I can tell you is what works for me... make sure your needle settings are back to factory (original) position.. Make sure your glow plug is good. make sure your glow plug ingitor is charged or has a new battery in it.. fuel up your tank, carefully remove the pressure line from your exhaust pipe.. gently blow into the line until you see fuel make it all the way to the carb (replace the pressure line to the pipe).. give it a couple of pulls.. you may want to hold your throttle approx. 1/4 to 1/3 of the way open while pulling.. all this works for me everytime.. good luck.. Peace

 

[funwheels1]

hey,
I'm not trying to lose my cool but about 3 months and still can't operate it? My dads buddy that uses them thinks I'm a complete idiot lol. Anyways, thanks for the advice so far.

 

[LarryA]

The carb is the biggest problem wit hthe 21BB engine. I couldn't get mine to run the same two days in a row with the stock carb. I hate HPI carbs! I have two HPI R/C's (one on-road and a Savage) and both have had the carbs replaced with other manufacture ones. My Savage now has a carb from an SH engine (Megatek <- spelling?) and it now starts fairly easy and runs real good. I use a roto start so I can't say how many pulls to itwould take and I removed the tank primer. I went nuts with the stock carb and was about to tune the engine with a hammer! I've been doing this nitro stuff for about 10 years and the HPI carbs are one of the worst I've seen. It seems to be the midrange setting and the way it can easily move that screws things up. Both of my replacement carbs have only the top and bottom end that are adjustable. The midrange is not supposed to be changed anyway, so why even have it adjustable?

 

[Error401]

Lol, no offense Larry, but I put a 21BB carb on my Picco .26 and it screams. The only beef I have with that carb is that it's full metal and conducts heat.

One thing I can say is that if the LHS guys can get it to run, then it's not screwed up. Big block nitro is a bit harder to lean than the small block engines, but it's not impossible. A couple of things that come to mind regarding your problem are, first, don't flood it. If ya use the primer botton, pump it until the fuel gets to the carb, then one or two more times should do it (the book reccomends 4 or 5 more). Any more and it'll flood. Do you run a fuel filter? If you don't, the HSN (high speed needle) will get crap in it and make it run lean (if at all). Make sure your plug is good. My engines start up within a couple of pulls, and if they don't the first thing I check is the plug. Factory settings on the 21BB are slobbering rich, but the engine will run (not too good, but it will run) and it's a good startng point for tuning. Do a search here on RCNT for "engine tuning savage", "engine tuning", etc or just look thru the archives in the savage section on the nitro engine section. There have been some relly good techniques written up on the very problem you're having. Don't give up, and don't take crap off your dad's buddy. The savage is a solid truck, ya just gotta listen to it.

Whitt....

 

[Zipperfish]

couple of growing pains that I can share... I got rid of the pull start and went with the roto start and I love it! Before I had the roto start though my knucles got all jacked up from pull that thing. Starting the truck on a sturdy stand may help, this way you can get better leverage while pulling the starter. AJS machine makes a sweet stand,

http://www.ajsmachine.com/rc/products.php

You'll know when you've flooded your engine because it will be very hard to pull and the sound of the piston moving will be very muffled as apposed to a crisper, less muffled sound when it's about to fire. If you do flood the engine, follow the instructions and clear out any excess fuel. I too had problems with it only staying running on half a tank. I fixed that with a new tnk set up, as shown in this link.

https://www.rcnitrotalk.com/forum/showthread.php?s=&threadid=4653

Here's a good tuning link too, https://www.rcnitrotalk.com/forum/showthread.php?s=&postid=70067#post70067

Good luck!

 

[LarryA]

error401: The "lol" could have been done without. I had nothing but problems with the HPI carbs and that's a fact. Switching carbs cured my problems and they have not returned since. Otherwise after three months or so of not being able to tune the engine would not changed by just switching carbs. I was just sharing what I've found so there was no need for the "lol" and then the "no offense". These two staments in the same sentance contradict themselves.

 

[Error401]

Appologies, that probably was out of line.

I just have a hard time believing that the stock 21BB carb is a bad product in general. This point has been voiced in a number of threads by more than one person, so I'm not pointing fingers. I have used and tuned alot of engines, mostly aircraft engines, but also a fair number of car engines too. Yes, I have seen some really crappy carbs. Yes, I have seen some really solid ones too. The 21BB carb has it's problems, but it does work. The biggest problem is that it is all metal and soaks up heat and thus causes fuel flow and restart problems. The intake venturi is rough cast and could use some polishing. There is a "MRN", but it's there more for fuel jet design than for any kind of tuning. By no means is it the best carb in the world, but there are some that are worse.

All I can say is that I have had 2 stock 21BB's, a modified a 21BB carb that I installed on a Picco 26, and have tuned a number of stock 21BB's for friends here. All of these I have gotten to run reliably with the stock carbs. My point was that if properly tuned, the 21BB carb will work.

And on top of it all, funwheels posted this truck in the forsale section the day before he started this thread.

 

[SkyMaxx]

When you say it only runs for a half a tank and then quits, that indicates one of two possible problems to me (and the carb isn't necessarily the material source of the problem).

The first one would be a cracked tank or an air leak from the tank. Do you notice any fuel on the shelf beneath the tank or any excess grime on the outside of the tank when you run it? If so, you just might need a new tank.

The second reason could be that the engine is just plain overheating. Do you run it WOT for great lengths of time? Do you know what your needle settings are (the indirect ref to the carb...bad carb or not)? If you run excessively lean and/or run WOT for great lengths of time, you can easily overheat the engine by half tank and it will quit...and it won't want to restart until it cools down. Another question...have you properly ventilated the body to allow air flow over the engine? If not, this can also contribute to an overheating engine.

Not saying that the coversation on the values of one carb over another doesn't bear an investigation of your carb's condition, but let's look at the basics first. Once you have removed those two possibilities, then you can start looking at the carb for issues.

 

[funwheels1]

Well....I finally got it running. YES ME ON MY OWN. I was inspecting the engine when i noticed the pulstart was loose. I took out the engine and tightened it, and it stayed running long enough to tune. It runs like poop when its cold but once it gets to 200+ it screams. Any advice on how to make a tank last longer?

 

[Error401]

They all run a little funny until they get to 200+, that's normal.

Once ya tweak it in, the fuel will last a bit longer, but don't get it too lean. Letting off the throttle once in a while helps stretch the mileage also. Just kidding. Leaning it up will make a difference, but it's gonna burn X ammount no matter what. feeding a 26 is even worse than the 21's.

Glad ya got it working. Also, put some loctite on the backplate screws, or else it'll happen again.

 

[Mugen-Racer]

Congrats on getting it running. Glad you stuck with it... And I do believe if you let off the throttle, you will get better mileage.. The bad thing is, it just sits there. I can't have that... I gotta have mine go. hehehehe...

 

[funwheels1]

haha. I am planning on breaking the primer pieces out and putting a machine screw with lots of silicone in place just in case i do have an air leak. I figure that with an air leak i might have enough pressure for it to run at a full tank, but by the time its at half a tank with a air leak its just gonna have no pruessure. Also, i just got some new fuel line. I dont think the fuel line was an issue but the stock broke real easy and was hard to see through. Also, i put a lot of old fuel line under the tank to absorb vibrations. I'm hoping all this will enable me to get a whole tank. However, is it NORMAL for a savage to run roughly a half a tank? Its not really rich or SUPER lean. I made sure it had a nice blue mist and i could see the exhaust. No blubbering but not over 300 either. Neway, i figure if it is normal to have only half a tank i might invest in the ofna 125cc fuel tank until a better savage one is out. I figure 125cc is better than a 160 dived by 2. Thanks for all your help. Maybe some day i will get an action shot of this.....someday.

Drew

 

[Zipperfish]

I sent my original tank back to HPI along with a note describing similar symptoms you're having, I simply said there must be a leak in the primer button and asked for a new tank. They sent me a brand new tank, no questions asked, rather quickly. Go ton their website for required documentation to send along with the tank if you decide to send it back. Something to think about before you start plugging the primer with silicone.

 

[funwheels1]

that sounds pretty smart but from what i hear and understand is that no matter what, a tank with a primer is prone to air leaks. However, i heard that the new savage ss tank is supposidly upgraded and that they have fixed the bugs. I might just stick with silicon and a screw because a new one is only 10 dollars

 

[RatzoRC]

I had trouble with the roto start when the motor was new. the battery got so hot, that it melted the pack