Savage 25 - couple of questions.

[Timmyboy]

Hi everyone,

New to the hobby, so I know practically zilch other than what I've managed to read on various sites.

I bought an TT EB-4 a couple of weeks back out of the local paper, just because it was dirt cheap Had good fun with it and no problems with getting the engine running etc (pull start), right up until the time my father in law drove it into a curb.

Anyway, got some new suspension arms on order and bought a Savage 25 from the local paper for the same cheap reason - I've always wanted monster truck RC, it seems a bit more robust than the EB-4, it looks cool and is more suitable for the kind of areas I'll be using it in.

Anyway, I'm having a bit of trouble with it.

No problem getting the engine started using the rotostart. Original owner used 25% fuel so I've got some 25% ODonnel in it.

I've only tested it in my fairly small garden so far, and it is quite happy pottering around in circles and will continue to do so for as along as I like.

If I give it full throttle however (which I can only do for a couple of seconds due to space) it shoots forward ok, but as soon as I let the throttle go, it stalls.

I'm guessing the first sensible thing to do is to take everything back to stock settings and tune it from scratch, but is this a common problem anyone recognizes? Not sure how long it's been sitting around so perhaps it just needs a bit of running in?

Also, couple of easy ones:

1) Should I be using after run oil?
2) Got 4 rechargeable AA's in at the moment, so only 4.8V. Do I need 6v? If so, will the 6v savage hump packs I see on eBay fit? Only ask as I've got a 6v hump pack for the EB-4 made from AA batteries and it would never fit in the Savage.
3) I see the throttle has a return spring. I fitted an electric failsafe in the EB-4, is it wise to stick one in the savage in addition to the spring?
4) Is the reverse gear worth having, if so, is it a nightmare to fit?

Thanks in advance for any help, sorry to bombard on my first post

 

[NCNitro]

1) Should I be using after run oil?

Yes

2) Got 4 rechargeable AA's in at the moment, so only 4.8V. Do I need 6v? If so, will the 6v savage hump packs I see on eBay fit? Only ask as I've got a 6v hump pack for the EB-4 made from AA batteries and it would never fit in the Savage.

The hump packs for the savage use a different size cell than an AA, and in a 2/3 configuration will fit in the battery box

3) I see the throttle has a return spring. I fitted an electric failsafe in the EB-4, is it wise to stick one in the savage in addition to the spring?

I run both a failsafe and throttle return spring on my Savage SS, better safe than sorry

4) Is the reverse gear worth having, if so, is it a nightmare to fit?

I don't use reverse in any of my nitro rigs.

As far as your stalling issue, pull off the air filter, make sure when you apply the brake that the barrel remains open about 1-2mm, if it closes all the way when you hit the brake it will cause the engine to stall.

Hope this helps, and welcome to RCNT

 

[Timmyboy]

Thanks for the quick reply.

On the stalling issue, I'll check the barrel, but I'm not actually applying the brake when it stalls, just letting go of the throttle.

 

[NCNitro]

The barrel may still be closing all the way even without the brake. If that's not it it's possible the glow plug could be going bad as well.

 

[olds97_lss]

Or it could just be running really rich due to you not being able to really open it up. Putt Putt'ing around will cause it to load up the crank case with fuel in a short while which will then stall it out when the RPM's drop to idle.

Maybe try taking it to a park or somewhere where you can run it at a decent speed to clear the bugs out.

 

[Timmyboy]

Took it to a park today - it did the same thing a couple of times when applying full throttle, then seemed to sort itself out.

Spent 7 or 8 minutes flying around the park with no stalling and all seems fine, just a little... slow

When I run the EB-4, it leaves a nice trail of smoke on a wide throttle - there doesn't seem to be any smoke coming from the Savage - this is running too lean? It picks up nicely but is going far slower than the EB-4 does.

Does this explain why it's only gone though half a tank of fuel?

Also, should I be able to 'hear' the change in forward gears like you would on a normal car? e.g., when it shifts to second, will the RPM drop?

Continued thanks


Edit: forgot to say I checked the barrel, or at least what I thought I should be checking. Pulled off the air filter, can then see a metal rod in the carb - opened and shut the throttle a few times and the metal rod moves up and down, with a much thinner rod inside it - then at the bottom, this much thinner rod meets what I assume is the barrel - it is sticking out about 1mm from the bottom of the carb.

 

[olds97_lss]

If your not seeing smoke at all, then it is highly likely to be lean on the HSN.

You should hear it shift. You may want to try and tighten your slipper a bit. If it's slipping, when it shifts, it will slip and you may not hear it shift. Or, it's slipping too bad to actually shift.

 

[Timmyboy]

Ok, it's getting interesting now

Managed to find a suitably secluded area where I could give it a good tune without annoying people.

Took it back to stock settings, 4.5 turns on the HSN and 3 on the LSN.

First thing I noticed is that the idle has totally changed from before - need to have the trim right down on the transmitter or the revs are too high - more on this later.

Running like a dog at stock settings, the performance got better and better as I leaned it out until eventually the performance leveled out but the smoke almost disappeared at 2.75 turns - 3 appears therefore to be the sweet spot with a nice trail of smoke.

Very pleased, seems just as quick as the EB-4.

I then started with the LSN. Leaned from 3 turns to 2.75 and noticed an instant difference in off the line speed - it's basically wheel spinning now where it wasn't before and sets off a lot quicker.

However, right around this time the engine started to race on idle - a couple of times it literally got to full throttle (I then shut the car off) then it would consistently race each time I started it - not to full throttle, but enough to get some serious speed on the wheels and if I'd set the car down, it would have driven off. Trim is still at the zero point on the transmitter.

Any ideas on this latest issue? I take it nothing I've done today (fiddling with the HSN and LSN) will have affected the position of the barrel? It surely doesn't need adjusting further as it's barely showing 1mm.

I put the LSN back to 3 turns (i.e where it was when I finally got the HSN sorted out and running nicely) but still the same thing.

What I don't understand is why the idle point had changed so much from yesterday to today with me only touching the two needles.

Thanks olds97_lss for the replies.

 

[olds97_lss]

By changing the two needles, you are getting the tune closer to more accurate. By running a high idle (like it was probably doing before), it lets you run way too rich on the LSN and not realize it. When you lean the LSN out where it should be, your idle picks up quite a bit and you have to then readjust your idle for the leaner LSN.

Keep in mind that you can lean too far and your idle won't drop even with idle screw adjustment. It will go from high idle to off. If you end up at that point, richen the LSN a bit and try adjusting your idle again.

Glad your getting it sorted out.

 

[Timmyboy]

I think this thread will stand the test of time as being exactly what NOT to do to tune your savage!

So here it is. When I was tuning the LSN yesterday, well, erm, ahh, I was actually adjusting the idle. I looked at a diagram of the engine last night which pointed out the location of everything and realised I've been a muppet

God only knows how I managed to get it going yesterday, as it turns out I managed to adjust the IDLE back to stock LSN settings (!!), and yet it was fine for most of the afternoon. Somebody slap me.

Anyway, I had a play with the LSN today (indoors, not actually running) and was a bit confused as I set about gently turning it closed to see what setting it was currently running at how I did with the HSN, when I got to 8 turns I thought something was probably wrong.

From what I've read, it's quite hard to feel when the LSN is 'closed' as it will happily keep turning, so other threads have suggested setting the LSN flush with the casing and using this as a [probably rich] starting point. This is what I'll try but hopefully I'll get it all sorted at the next tuning session.

So, follow olds97_lss's advice and ignore everything I've said, you'll be up and running in no time