Rc engine low speed needle tuning

[Daniel J]

Hello everybody. My rc car low speed needle is all the way screwed in and still run very very rich. I know this because there is a ton of smoke and it pulls away very slowly with aalot of smoke. Using 20% nitro in .21 engine. The car is a nanda NRB-5. Thanks in advsnce

 

[Rolex]

There are 2 needles, high speed and low speed. There's also an idle screw. These 3 need to play together.

https://www.rctalk.com/forum/threads/nitro-tuning-tips-and-tuning-flow-chart.60832/

 

[sv250]

Something is wrong. If its all the way in, it should not get any fuel at low speed. Think of it as a hose. The hsn is the spiket and the lsn is the nozzel. Even if the spiket is wide open, no water comes out of a closed nozzel

I think your orings are shot. Each needle all 3 have orings on them. They do go bad. New rings with a touch of grease and start over with factory settings

 

[Daniel J]

Something is wrong. If its all the way in, it should not get any fuel at low speed. Think of it as a hose. The hsn is the spiket and the lsn is the nozzel. Even if the spiket is wide open, no water comes out of a closed nozzel

I think your orings are shot. Each needle all 3 have orings on them. They do go bad. New rings with a touch of grease and start over with factory settings

Ok thanks mate. It's a new engine and it came very rich with only 1 and a half turn out. I will try that. Maybe seal the engine?

I

There are 2 needles, high speed and low speed. There's also an idle screw. These 3 need to play together.

https://www.rctalk.com/forum/threads/nitro-tuning-tips-and-tuning-flow-chart.60832/

Have tuned the high speed but the low speed is still rich. Takes like 8 secs to quit on pinching the fuel line

 

[Hristo Al]

Hi, I have the exact same car, the exact same problem. Top needle is set on the lean side, even when I overdo it and it bogs asking for more fuel (almost dies from fuel starvation), the bottom is screwed in all the way in, still incredibly rich. It so rich that on a fully warmed up engine, after some WOT runs, if I let it idle for 30 sec and then hit the throttle (not even the whole way, just before the middle) it's just drowning in fuel and it goes out. So I have no options to tune it, the HSN is too lean and the bottom is way too rich.

 

[Daniel J]

Hi, I have the exact same car, the exact same problem. Top needle is set on the lean side, even when I overdo it and it bogs asking for more fuel (almost dies from fuel starvation), the bottom is screwed in all the way in, still incredibly rich. It so rich that on a fully warmed up engine, after some WOT runs, if I let it idle for 30 sec and then hit the throttle (not even the whole way, just before the middle) it's just drowning in fuel and it goes out. So I have no options to tune it, the HSN is too lean and the bottom is way too rich.

Try different fuel I'm trying it. Tell me if you fix it.

 

[Hristo Al]

Something is wrong. If its all the way in, it should not get any fuel at low speed. Think of it as a hose. The hsn is the spiket and the lsn is the nozzel. Even if the spiket is wide open, no water comes out of a closed nozzel

I think your orings are shot. Each needle all 3 have orings on them. They do go bad. New rings with a touch of grease and start over with factory settings

Hi sv250, sorry if this is a stupid question but what leads you to believe it's the 0-rings?

 

[cbaker65]

Hi sv250, sorry if this is a stupid question but what leads you to believe it's the 0-rings?

The needles them self could also be damaged ,they tell you not to over tighten them ,the hsn needle rides inside
the lsn.
When I adjust mine ,I try to throttle my carb at the same time of adjustment so it doesn't strain or wear on the
needles!

Try taking the needle out an rub some vasoline on the O-rings ,if that makes any difference ,
then your o-ring or needle is bad or worn out!...

 

[sv250]

Hi sv250, sorry if this is a stupid question but what leads you to believe it's the 0-rings?

Because fuel is getting by a closed needle. That shouldnt happen

 

[olds97_lss]

What engine is it? Got a link? Then we aren't guessing what you have and making the wrong assumptions.

 

[Hristo Al]

What engine is it? Got a link? Then we aren't guessing what you have and making the wrong assumptions.

Yes, it's a SH.21 engine, less than 3 liters of 16% fuel old.
Disassembled the carb today, cleaned it, o-rings looked fine. Lubed them, put everything back together, there is no change whatsoever.

 

[cbaker65]

How cold is it getting in your area?

16 % seems low ,I run 30 % .an have a few gallons through them ,my engines
are getting up to 10 years old ,some are older!

Your engine may not be burning the fuel right do to cold weather ,low nitro count ,
fouling plug ,or even leaky head or carb.!
I would seal carb an make sure the head screws are tight ,sometimes the head screws
will loosen up!...

 

[Daniel J]

What engine is it? Got a link? Then we aren't guessing what you have and making the wrong assumptions.

itm/SH-ENGINES-Model-Blue-21-Nitro-Engine-3-48cc-RC-Car-Buggy-Truck-Truggy-EG635/253395403034?ul_ref=http://rover.ebay.com/rover/1/710-5...Banner=1&_rdt=1&ul_noapp=true&epid=1843129429

 

[Daniel J]

How cold is it getting in your area?

16 % seems low ,I run 30 % .an have a few gallons through them ,my engines
are getting up to 10 years old ,some are older!

Your engine may not be burning the fuel right do to cold weather ,low nitro count ,
fouling plug ,or even leaky head or carb.!
I would seal carb an make sure the head screws are tight ,sometimes the head screws
will loosen up!...

All my screws are very tight. Puzzled right now

 

[Daniel J]

How cold is it getting in your area?

16 % seems low ,I run 30 % .an have a few gallons through them ,my engines
are getting up to 10 years old ,some are older!

Your engine may not be burning the fuel right do to cold weather ,low nitro count ,
fouling plug ,or even leaky head or carb.!
I would seal carb an make sure the head screws are tight ,sometimes the head screws
will loosen up!...

I use 20% nitro

 

[Daniel J]

How cold is it getting in your area?

16 % seems low ,I run 30 % .an have a few gallons through them ,my engines
are getting up to 10 years old ,some are older!

Your engine may not be burning the fuel right do to cold weather ,low nitro count ,
fouling plug ,or even leaky head or carb.!
I would seal carb an make sure the head screws are tight ,sometimes the head screws
will loosen up!...

Do I need to remove a shim under the head it only has 1 shim right now stock

 

[cbaker65]

Do I need to remove a shim under the head it only has 1 shim right now stock

I'm not sure how that works ,I've never removed shims before ,but have heard about shims
being removed for different % fuel I think ,its been years since I read about it!!

Also ,the type of glow plug matters as well ,the temp rating on the glow-plug!

 

[Daniel J]

I'm not sure how that works ,I've never removed shims before ,but have heard about shims
being removed for different % fuel I think ,its been years since I read about it!!

Also ,the type of glow plug matters as well ,the temp rating on the glow-plug!

Ok thanks! I took out the carb and rubbed Vaseline all over the o rings hope that makes a difference

 

[Daniel J]

I'm not sure how that works ,I've never removed shims before ,but have heard about shims
being removed for different % fuel I think ,its been years since I read about it!!

Also ,the type of glow plug matters as well ,the temp rating on the glow-plug!

Should I run 25% nitro or 30% i don't want to blow it up

 

[cbaker65]

Should I run 25% nitro or 30% i don't want to blow it up

Well ,I'm in warm sunny California an always ran 30% ,I've tried a 20% 0ne time an my stuff just wouldnt
run worth a hoot ,some of the engines I run are size Os 18 ,Ofna hyper 21 , an 2 Hpi 5.9's!

An I also try to run my engines a little on the rich side to acomidate any type of heat or an accidental
lean out!...
I would like to try 25% nitro myself ,but ,30% should be ok if you reset to factory an retune with a new
glo-plug!....