Mr.No1

Okay.
I have got some problems.
I've been using my engine for 2-2.5 litres 25%nitro 18%oil.
Running a medium plug.
I am using the stock shims.
It is 13-17celsius.
The problem is, when I am firing up my engine it works just fine. But when I am applying WOT it just shuts off it is not 4-stroking.
My needle settings are 5.5turns on the LSN and 3turns on the HSN. If I am using less turns at the LSN it wont start.
What can cause this problem?

Thanks.

dino.tw

18% oil is a bit too much to a breaking in finished engine. If you wanna ues it for a long time,12% is enough. 15% is good for break-in a engine. 18% is too sticky.
13-17c,you can use a hot plug. med plug still ok but the stock shims a bit too much. You can try 25% nitro with 0.3mm shim. If the plug be burned then add 0.1mm shim.
The front bearing is 7x19 (#607)
The rear bearing is 14x25 (#2514)
regards,
Dino

speedy2

iTrader: (1)

just had to open low needle 1/6 th turn

Laterilus

Hey everyone,

Just today I happened to see this thread after being on this forum for a long time! Don't know how it slipped by me! Anyways, I've become very curious in these STS engines after reading through the entire thread.. especially due to the price and having someone aboard that is very well experienced with them.

Speaking of which, Dino, how is the rear exhaust 3-port gas truck engine? 99$ is a steal for a high quality .12. I'm currently running Picco's 3 port gas truck engine, but I'd really like to see some more top end speed without having to spend 180$ or more to get it. The picco has more than enough torque, but I get burned in the straights by all who use the novas and sirios in their trucks. How would you rate the torque and overall speed of your gas truck .12 engine? I'm also assuming it is a ROAR legal engine?

Lastly, I've never seen so much discussion over some of the minor details of engine tuning (head shim size/amount used, different nitro/oil % for different conditions, etc...). Anyways, I am really curious how you go about breaking in your engines. Can you write out your break-in process here? How many gallons do your engines usually last? Thanks in advance for your answers.

Either way, I'm too curious not to try out your engines. I'll definitely have to try out both the gas truck and 1/8 buggy engines the next time I need new ones for my cars.

afm

[QUOTE=Laterilus]Hey everyone,.............................
Lastly, I've never seen so much discussion over some of the minor details of engine tuning (head shim size/amount used, different nitro/oil % for different conditions, etc...). Anyways, I am really curious how you go about breaking in your engines. Can you write out your break-in process here? How many gallons do your engines usually last? Thanks in advance for your answers.........
QUOTE]

BREAK-IN PROCEDURE
＊1. Install a new conical type glow-plug (Hotter rated plugs will be better for the rich settings used during break-in)
＊2. Use high castor (12% or above) and low nitro rated glow fuel, 5%~15% nitro is best.
＊3. First tank of fuel: Start your engine, idle for 2 minutes with rich air/fuel mixture setting (some raw fuel is spitting from the exhaust)then stop and let it cool down. When your engine is stopped, make sure the piston is NOT at Top Dead Center (TDC) by rotating the flywheel. Let it cool down and repeat the “start-idle cycle” 6 to 8 times. If idle rpm is too high, adjust the Idle/air-screw. Make sure the temperature is under 80 oC (176 F).
＊4. Next several tanks of fuel: run the car on the track at low speed (50% to 80% throttle). Avoid using a constant throttle position; keep blipping the throttle to vary the rpm, slow-fast-slow-fast etc. Check the temperature regularly and keep it between 80 oC (176 F) and 100oC (212 F), if you can not measure temps make sure the engine is running at heavy smoke from the tuned pipe.
＊5. When your engine is still being run-in, higher running temperature is expected. As time goes on, running temperature will be lowered. At this point you may lean the engine by turning the main needle clockwise incrementally and keep the engine running temperature at or below 100oC (212 F). After about 1~2 liter fuel through it, take out the glow plug and turn the flywheel by hand, let the piston pass the top dead center in the sleeve. When you don't have any significant friction or just a little snug, you can start leaning the main needle incrementally in small steps, and keep it around 100~120 oC (212~248 F).

FUEL: This engine should ONLY be used with fuel particular blended for R/C model car. Never run this motor with gasoline! The choice of fuel is very important, it should contain a minimum of 10% castor and/or synthetic oil by volume. Regarding the percentage of nitro: more nitro content (higher %) will provide more explosive power from your engine, but it will also shorten the engine’s life. For average use, we recommend 15~25% nitro fuels.

GLOW-PLUG:Check your glow-plug regularly. When the glow-wire becomes dull or mat and the engine stalls without reason, change the glow plug. A new glow-plug will keep the engine idle stable and optimize its performance. An old glow- plug is prone to glow-wire broken, melted or missing. If you keep on using an old grow-plug, you may damage your engine. Please avoid this situation and check the plug regularly.

These are some other important considerations.

For .21/.28 Series:
*Do not forget to install the proper number of head shims. We suggest that you use at least 0.3 mm head shims. You may need to adjust the thickness of head shim for best performance. These are our guidelines.
FUEL Total thickness of head shim
- Under 20% Nitro 0.3 mm
- 25% Nitro 0.4 mm (±0.1 mm)
- 30% Nitro 0.5 mm (±0.1 mm)

For .12 series
*Do not forget to install the proper number of head shims. We suggest that you use at least 0.3 mm head shims. You may need to adjust the thickness of head shim for best performance. These are our guidelines.
FUEL Total thickness of head shim
- Under 16% Nitro 0.3 mm
- 20% Nitro 0.4 mm (±0.1 mm)
- More Than 25% Nitro 0.5 mm (±0.1 mm)

Hope it is clear enough

AFM
GPP Model Racing
www.gppmodelracing.com
South American
STS Distributor

BigBadJabba

hi.

is there a modified and non-modified version of this engine?

if so how do i tell the difference between the two?

thanks

dino.tw

No. There is only one version so far.

BigBadJabba

hey dino r u low on engines? mushroom has been out of stock of d21b's for a while now! yet it is on theire front page all the time

speedy2

iTrader: (1)

hi... I have some trouble with my D21B engine on a buggy
I run it in nicely very very rich for 1/2 gallon/ 2,5 liters

now I closing the high needle for 1 liter already
and the engine is giving the RB and p5 a run for their money already...

my problem : after 2 tanks the engine is shutting up each time a few seconds or so, after putting it on the track and it continues like this so I just can't run anymore, even if I give full trottle at the beginning to clear excess fuel from starting or whatever, everything is ok , till I put it on the track and drive a few meters, it seems something exstingises the plug (new) after that , some residu of oil in the motorblock????

I run always a bit rich also bottom but this issue is ridicules
what can be the problem ???? help !!!
could it be a clutched airfilter ?must I clean it every time?

dino.tw

Check the clutch shoes,springs and bearings,rebuild it may help.

speedy2

iTrader: (1)

thanks
I run stock shimms with 25% nitro is that alright , I had no problems till now..
but as I am leaning out, piston can come higher in the sleeve , no?
2 first tanks being full power in the straight with no issues

by the way this motor is real good as you know.....

dino.tw

Stock shims with 25% is no problem. But once the compression become less,the output power will become less,too. So I suggest people to remove some shims after break-in process. You can remove 0.1mm out then feel its different. After you remove some shims,you need to rich the HSN.
No,the stroke still the same.
If the clutch has no problem,check the engine temp. If enging temp is too high,the engine will snuff out,too. Try to rich the HSN 1/4 turn,if it becomes better that means engine overheat.

speedy2

iTrader: (1)

no overheating
it's at the start
I run 1 tank and rest a bit, and so on

I think I have first to try with a cleaned airfilter as our track is real dusty
and I didn't clean it last time
and see from there on...

dino.tw

ok,remember to try to remove some shims. Bigger compression has better idle also better acceleration.

BigBadJabba

HEY DINO. is there a difference in D21B the engine without any markings on the top of the head?