Wednesday, September 13, 2006

STS engine D28M / 21B

This is the engine I won the O'Donnell Off-road Championship with. What is interesting is that through a broken diff that was binding the drive train at a big race, I had what seemed like no power, so I kept telling my pit man to lean it out ( main event ) and he did so... until it got very hot indeed. It got up to over 400 degrees and was still running well. We thought it would have trashed the engine but we were wrong. With NO rebuild at all, that is the very same motor that won the O'Donnell. Now that same motor has won AGAIN, the RD Logics Off-road Championships in the Expert Truggy Class. These motors are so well made and such quality it is just amazing.

Quote from racernine driver

D28M (#2801*)
Monster Truck Engine
Cylinder Contents 4.66cc
Bore: 18.80mm / Stroke:16.80mm
Crankshaft : 14mm SG type
Carburetor: 2 Needles Slide 9 mm
Piston / Sleeve: ABC 3P
Glow-plug : Standard
Use : 1/8 buggy;1/8 Monster Truck

#2801 Pull-Start Version*
#2804 Shaft-Start Version
#2805 Standard Version

D21B (#2101)
Buggy Competition Engine
Cylinder Contents : 3.48cc
Bore: 16.20mm / Stroke:16.80mm
Crankshaft : 14mm SG type
Carburetor : 2 Needles Slide 8 mm
Piston / Sleeve : ABC 5P
Glow-plug : Standard / Turbo
Use : 1/8 buggy

STS Racing Taiwan 21B

*** .28 & .21 use the same Carburator!

Factory needle setting

HSN 2T out
LSN 3T out

Running needle setting

HSN 1.5 to 2T out (others will say u running lean but ignore them!)
LSN 3 to 4T out (even sometimes 5T ... this carb like to be rich at LSN)

Temperature Guideline

When the air temp. is lower than 5C,stay at home.
When the air temp. is 5~15C (41~59F) Keep the engine temp around 80C(176F)
When the air temp. is 15~25C(59~77F) Keep the engine temp around 100C(212F)
When the air temp. is 25~35C (77~95F) Keep the engine temp around 120C(248F)
When the air temp. is more than 35C (95F) Keep the engine temp around 140C(284F)

If your engine works just fine and you feel the power is enough,you don't need to worry about the shim's setting. All STS engine shimmed for 30% nitro,if you are running 20% or 15%,you may need to remove some shims for getting the most power.

Pullstart problem

This is what Dino said in the sts .28 rctech forum regarding how to pullstart.
Page 7, post #209.

We talk about the bleeding blisters first!
when you operate the pull-start system,there are some tips.

1)Before you start the engine,pull the line out fully. Then you know the total length of the line. Don't over pull it out! With a strong arm you will damage the pull-start system.

2)Why you got some bleeding blisters is because your finger touch the heat sink(cooling head). So it is important that you don't need to pull the starter from the start. You can pull the starter around 10cm out slowly,then just start to pull the starter between 10cm to 40cm distance continuous. Then your finger or hand should not touch the heat sink.

3)ok let us try to start the engine. Use your knee press on the tyres to fix your monster truck. Right hand pull the starter line out around 10cm. Left hand finger block the pipe then pull the starter line several times. Make sure the fuel be pumped into the carburetor. It not,that means the LSN is too lean or even cut the fuel supply at idle position already. Or the carb is close fully and no air bypass.

4)Put on the igniter and make sure the idle opened. Start to pull the starter between 10cm to 40cm distance continuous. After several time pulling,the engine should be started.

5)If it still not work,it most have some thing wrong. Stop to keep on trying. Try to find anything wrong. Check if the plug is fine and the igniter battery. Check if the fuel enter the carb already. Check if the idle is open enough. If you can see a lot of fuel flow out from the tuned pipe,that means the HSN is too rich.

6)After the engine started,don't loosen your hand suddenly and let the starter line return very fast. That is not cool! It may snap the return spring. You should let the inner spring return the line slowly.

Above process is what I start mine D28M. Hope you understand my poor english. For you information..

Dino advice to newbie:

It is not because of the small gears,it is because our engine has too big compression. It may happen when your engine use not more than one gallon of fuel. When the first gallon,the compression is too big. Everytime you start the engine,you need to loosen the grow plug a little. About half turn is enough. Then try to start the engine. Once the engine is started,tighten the plug soon. I'm sorry because we want to produce a race level pull start engine,so we give you the race level piston/sleeve set. We want your engine lasting longer under serious situation. But it do make the engine hard to start no matter pull-start or roto-start. Remember to loosen the plug would help. We just don't want to produce RTR level engine,it's not our style. You can check your engine,when you remove the plug it is very smooth. Once the plug installed it is unbelievable tight! It is a standard of a race engine. Maybe we should give you more shims but a lot of people don't know they need to remove shims after break-in....that's why we don't give you extra shims lately...but the gears issue pop-out.... Best Regards, Dino

Horsepower comparison:

check this link from my friend, Ryan of
comparing engines from HPI .28, RB TM7 .28, Infinity .28, Sirio 27S.
STS .28 got the most horsepower!!!!!!!! at a very reasonable price!!! How can u beat that!

STS Dealers

These are my friends ...
David Aw of from Johor Bahru, Malaysia
Ryan of Utah, USA.

Must links:

STS own website from Taiwan
STS 28 engine Rctech Forum (first page)

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