Foxtrap

Ok....Savage .25...with "HPI .25 3.5" written on the side of the motor....

I've tuned smaller buggy engines before with no problem,,,,But for some reason, when I try to return this one to factory settings...correct me if i've researched wrong....4 turns-counter clock wise-out from all the way in on the HSN....and 3 turns-counter clock wise- out from all the way in on the LSN?.....

When i do this the opening in the carb on the slider is way too big to correct with the idle srcew!!


its the LSN that seems crazy to me....when I screw it all the way inthe opening is huge...I'm sure there is something wrong here...maybe I'm tuning for the wrong engine?....or missing a step?....the order has to be specific for these engines?....I dunno...please tell me U do...wanna go for a Raz tomorrow...long weekend!!

The truck was running in the first couple minute that I had it the other day...It is an E-Bay Purchasethat seems to be in good order...

I just wanted to get it back to factory and tune it myself from there.

Thanks In Advance
Stephen_

rclugnut10

My Feedback: (1)

if you go to factory it'll be crazy rich so lean it 1 turn on the HSN, and just ignore factory idle and set it so when you push the slide closed you see a 1mm gap, and then tune your hsn then lsn from there

the lug

Foxtrap

Thanks for the quick reply...

But I'm still confused about the LSN....its wide open at 3 turns out from all the way in...and the idle screw doesn't come handy to fixing that...

any thoughts?

Foxtrap

I CAN produce that couple mm/credit card opening in the carb with the LSN....but only by backing the LSN out like 10 turns from all in?!?!

Can I take the slider assembly apart to see that all is Koscher?...or is that over the top?

rclugnut10

My Feedback: (1)

http://www.hpiracing.com/instructions/#Kits

engine manuals are near the bottom...
that should help a lot...
i dunno about you but i LOVE exploded views

the lug

Foxtrap

OK...How come when I do some googleing for factory settings of the savage 25...I get the settings that some people are saying here (4 turns out for HSN..and 3-4 turns out for the LSN) and other sites say that its about flush with both collars for both needles.....seems like the latter is the one that gets me at a desired carb opening!?!?!......

Do I have a different carb slider/adjustment on my .23/3.5 than most of you guys running 4.6/5.9's?

Must be....any way...I'm gonna go for a test run...its -30 here in NL...I guess that will not help tuning either hey!!!?


Lol


Thanks for the help guys
Stephen_

BudBud

Your idle screw should set your gap for you, the high and low needles should not affect that at all.



That screw on the side is the idle screw.



The screw in the middle of the end is your low speed needle... it sets the fuel mixture, not the idle speed. While it may change your idle speed, you can correct it with the top photo.



That screw in the top of the brass tube is the high speed needle, again, it just sets the fuel mixture at high speed. When tuning, always get the optimal performance at high speed first, then adjust the low speed needle. You may have to adjust the idle setting accordingly. I think you may have just misunderstood the terms a little.

The factory settings are just close, they were never intended to be a tuning reference, just a rich starting point and the opening at idle will probably be less than recommended when you get done, it almost always is.

I apologize for the dirty carburetor. It was in a bunch of junk that some guy dumped in with a used Picco I recently bought, so it was handy. Not that I do not have my fair share of dirty carbs laying about from my own salvage. Glen

Edited for spullin isssuuuuues...

3-172IN MTN

My Mistake

fxrs

when the savage first came out it had a .21 cid or 3.5 cc engine.
When HPI upgraded the savage it went to a .25 cid or 4.1 cc
engine called the nitrostar S25 . The settings for that are
4 1/2 turns out from fully closed for the HS do not over tighten and 3
turns out from fully closed for the LS needle. When the Savage X came
out they upgraded the Nitrostar and called it the F4.1.
The factory settings for F4.1 are flush for both HS And LS needles as a start point.
You need to turn Low speed needle back out and then hold
slide closed and then turn needle back in untill it bottoms out, do not over tighten
and then back out 3 turns . You must hold slide closed while turning needle screw in
or slide will just keep opening more each turn of the screw.

BudBud

If he has it running, I would recommend not going back to bottoming out the screw. I see more carburetor damage from this practice than anything else, the guys bottom out the needle, I guess with some authority to make sure it is all the way in and they groove the needle in the seat. Once damaged, it is very hard to get it in tune again as the gap at the seat has been compromised and the needle no longer has a smooth flow surface. I have seen some pretty ugly stuff from returning the needle to fully closed and counting the turns out.

Foxtrap

OHHHHH....KKKKK


thats what the problem was!!!

I found a pic somewhere online that was telling me that the idle screw was the LSN!!!!

oh the internet and its faux info

Thanks again!!

Stephen.

Foxtrap

Ok I am still confused...

Just so I am clear ....the screw with the purple rubber boot on it is the LSN...? Right?...because as I said before...when I adjust that, it opens the gap in the carb as an idle screw should....

and FXRS said that there was a .21 - 3.5 engine....mine says .25 on it, and 3.5 not 4.1

is that an odd ball,,,,,or is he wrong in his conversion?....or am I reading this all wrong?

if mine is the .25cid 3.5cc engine....what are the factory settings for it?

Thanks Guys!

Stephen_

BudBud

That is the low speed mixture screw, if you are opening the slide with it, you have it completely bottomed out against its seat and and probably damaging the needle and the seat. It is true that you can push the slide open by screwing the needle all the way in, but that is supposed to be a finely finished surface for the fuel to be drawn past. If you manage to bell the seat and groove the needle, it is next to impossible to get a decent tune out of it.

Glen

Foxtrap

hmmm

Great....I hope thats not the case...

I can just replace that slide assembly seperate from the motor pretty cheap I guess?

fxrs

Ok

.21 cid is same as 3.5 cc

.25cid is same as 4.1 cc

Savage X f4.1 cc is same as saying .25 cubic inch displacememt.

To end your confusion if your engine block looks like the picture below
you have nitrostar S 25. look close at the picture and you will see
a decimal point to the left of the 2 so its .25 cubic inch displacement or 4.1 cc.

The picture below is not the f4.1 that was in the Savage X.

Go to this link to get the Nitrostar S25 manual in pdf format.

http://www.hpiracing.com/graphics/in...gines/1406.pdf

Foxtrap

No I'm not confused about the metric to imperial Conversion (although I wish the world standardized all that ish years ago!!)....

I wish that i had a camera with a macro setting on it so i could take a picture of the side of that little motor....

MY MOTOR SAYS IN THIS ORDER...

.25
HPI
3.5


?....See ...thats what I;m confused about....this was an ebay buy,,,,So i have no idea what the history of this rig is....love to know whats up ...and where this motor came from...

Thanks again all for lookin and helpin'

Stephen.

fxrs

How about this picture!

Foxtrap

Nope...that one says .21 3.5

Mine says .25 3.5

???

I have the Carb off now....and the only logical setting that I can see for the LSN is keeping the screw flush with the collar that it screws in...there is no way that it is all the way in and then 4 turns out for my carb assembly ...

I'm going to put it back together now.. try that and see what happens...

I must have an odd carb or something?...it looks like the carb in the pics first posted above....it doesn't have a screw on the opposite side of the LSN screw like some of the 4.6's and others i've seen....just a flush plate.

fxrs

I would really like to see picture of that engine!

Foxtrap

Ok...I'm on it.....one sec

Foxtrap

Here you go....









everything else looks pretty much the same......but it is a .25 3.5 ???


is this the reason that the factory settings are not at all right for this motor?.,....I guess the carb is different....like I said above....flush with the inside collar (not the linkage arm surround part) seems to be closer to what should be right....not 3-4 turns out...thats wayyyy off!!


I just went out and tried to start it set up this way...(flush on LSN and -4 on the HSN) and it gave an offer...but did not start....my roto was not charged fully so i had to quit.


any help/links to what I need will be rewarded (offer subject to change depending on what you call "reward" lol)

Cheers
Stephen_

fxrs

Wow, Maybe thats a collectors item. I wonder if on the early .25's
the engine manufacturer didn't get the memo to remove the 3.5.
It can't be both. Anyway looking at your 2nd picture down from the top
that low speed needle is in way to far. Bring it out at least flush and then
start retuning from there. As stated above factory settings are
just a starting point.

fxrs

Also the info below came from this forum a few years back. I did not wright it two
other members did but it helps.

Here is Tuning 101:

HSN TUNING 101 by Nitronutt
To tune your HSN, you need some open space, your truck and your ears.
Begin by running your truck to get up to operating temperature.
Once you do, make a high speed pass (50-75 feet) at WOT (Wide open throttle).
How did it sound? How did it perform? Pay special attention to the
highest rpm your truck reaches. Try turning the HSN 1/8 turn counter
clockwise (More rich). Repeat the above pass. Did the RPM’s get higher?
If so turn 1/8 again in the same direction. If not, turn ¼ turn clockwise.
Better? Keep going. Find the exact setting that gives you the highest rpm
that your truck will reach. Once you find it, turn the HSN 1/32-1/16 turn counter clockwise.
This is the optimal HSN setting. Verify the temperature after you have
finished tuning to be sure that it is within the 235-275 degree range.
Proceed to LSN tuning.

LSN TUNING 101 by Frost

Tune for performance, forget the gimmicks, go with what works.

If you are already getting good top end and you are running at 250F or so
(if you haven't bought a 20 dollar temp-taker DO IT) here is what to do to get
SNAPPY response, this is what pulls wheels and gives you that GREAT take-off:

1. Since off the line "snap" can be given or taken away by being lean OR rich
on the LSN the first move is a guess (well it won't be after you get a feel for it,
but this will get you going quickly)...

2. Pull the truck up in front of you and let it idle for 8 seconds.
Then pull the trigger to WOT... Did it scream and take off? If no:

3. You have to go one way or the other...
choose richer or leaner (suprisingly to many beginners,
off the line stutters can be caused by too lean conditions
just as easily as too rich) and turn the LSN in that direction 1/16th of a turn.
Make a short pass at medium to high throttle and return the truck to in front of you.

4. Let it idle 8 seconds and floor the throttle. Did it take off better or worse?
If better, turn it a 1/16 in the same direction, if it got worse,
turn it 1/8th the OPPOSITE way. Either direction you started in,
now you will be going one way based on whether it got better or not... either richer or leaner.

5. Make another short pass at medium to full throttle (AFTER you made the change to the LSN)
and return the truck to you. Let it idle 8 seconds and floor it. Is it still getting better?
If so, continue to lean or richen using the pass/idle 8 seconds method
until you lose preformance and back up a step...

If your temps are in range this is how to quickly get your
truck to "explode" off of the line... Always make the pass to
clear out the engine and then let it idle 8 seconds.
The idling will allow it to either lean out or load up,
depending on which way the current settings are off...
Get the hang of this and your truck can really take off.
If you end up leaning the LSN out excessively make sure to
keep an eye on temps, your top end needle may need a bit of enrichment.

Note on idle speed: You often need to adjust the idle speed
screw to compensate for the LSN needle change.
If you find that you cannot idle, or the truck stalls around turns etc,
the idle needs to be raised. If you need to chase after your
truck because the idle is too high after an adjustment,
then obviously it needs to be lowered.

_____________________________

Foxtrap

yeah...weird hey...

Well When I upgrade the motor I'll put it on ebay as a rare factory misprint to pay for my 5.9!!


lol


Thanks for the tuning guide....

I'll try putting the lsn out level with the linkage clip...I did notice that it was a little hard priming like that....so maybe that'll be a help.


but like I said...the normal factory setting for the lsn is wayyy off what i need for this slide carb....so its hard to say what is right...I'll have to be careful while tuning...to avoid damage at this rate.

Thanks again...
I might post a spin off thread of this one to see if anyone knows what motor I have....or what the story is on the misprint!!

Cheers\
Stephen__

Foxtrap

Well!!!


After all the confusion...I tuned the engine with logic instead of "factory settings"....I took the carb apart to look for any problems...found nothing odd or damaged....backed the lsn out to the collar....set the HSN to a couple turns below the collar....and tuned the idle to a mm er 2 from stall....and it stared up with a blip of the roto starter....

a nice healthy stream of blue/grey smoke out of the exhaust as it ripped down the alley behind my house!! (after letting it warm up at idle for a couple minutes of course !)

Thanks all for the help....

Looks like I've got a weird, 1 off motor,,,,but it seems to run fine, despite its funny markings.


Cheers
Stephen_