my o.s. gurggling, please help.

[rrrunner]

hi guys,
i've been using o.s. tr for nearly 5 mth... since i'm new to nitro engines, i tried to tune it a bit here and there just to get the best performance out of it.. lately, everytime i run it, after 3-4 laps it will produce a strange sound (gurggle), and it will lose a bit of compression.. about 5%.Is it because of tuning or there is something wrong with the engine itself. I've asked a few experienced guy on this.. he said it is cause by the bearings.what is your opinion? thanks.

 

[lykan]

Answer a few questions for me.

How do you know it looses compression? Do you have a gauge? or are you turning it over by hand?

Did you mean it's loosing compression, or power?

When you let it idle, sitting on the pavement does it squirt, or spit out little doplets of fuel, or oil?

When it gurgles, how hot is it? If you don't have a temp gun do the spit test.

How long has it been since you have set the carb back to factory defaults?

Do you have a steady stream of smoke coming out when you hit the throttle from a stop, to a high speed? If so, how much smoke is coming out?

My suggestion without knowing the answer to my questions is to.
Set the carb back to factory defualts (check manual).

Start it up, and see how it runs with settings at stock. Adjust from there.

Possible problems-
#1 gurgling sometimes means you are runnin rich. It's possible that the fuel starts to build up after a while floodding the motor. This will kill your low end power. You will notice when you hit the gas, it stutters a bit, and then runs better at high rpm, or at high speed.

#2 You're running lean and after a bit of running the engine gets too hot, expands, looses compression and dies. It won't run right until it Cools. How to tell if your lean?
Hard to start, runs very well, and powerfull, jumps off the line faster. Dies and looses power after it heats up.

 

[rrrunner]

lykan,
sorry for the lack of info. firstly, i assume losing power are caused by losing compression. correct me if i'm wrong... i dont have any gauge. it is just my instinct, but i'm sure it loses 'pick-up'. it does squirt some fuel but not too much and my lhs tuned it for me when i bought it.. so i dont actually know the default factory settings. it's quite difficult to understand the manual because it didnt state any engine troubleshooting.

i did some spit test. when i drop a bead of water on the heat sink it will take about 2-3 seconds to fully evaporate.
Yes, i have a steady smoke but not too much ( i guess it's not too rich)
i dont even know whether I'm running too lean or too rich.
can u tell me how to basically tune my engine i.e how many turns from fully closed to open the high speed needle and etc..
usually in the first 3-4 laps, everything goes well, then it will start to lose pick up the moment i start to pull the throttle. it's like the timing/idling is too high but the top speed is still ok.for ur info i open my high speed needle 1 3/4 turn from fully closed. thanks for your attention, really appreciate it.

 

[lykan]

Which os motor do you have? I do not have an OS engine, so I can not tell you what the default settings are.

Do you do the spit test after a run? If so and the spit doesn't boil off quickly, your not too hot.

I really can't suggest what to do without knowin g the factory defualts hopefully somone will chime in.

If I could guess I would say you are running a little too rich on the low end, and a little too lean on the top end. Seeing as how you are new to tunning. I don't want to tell you to lean it out, and then have you overheat your motor.

I am however almost 100% sure that you have either an air leak, or your just not that good at tuning yet. (no offense)

Read through the manual Just look for the factory, or defualt settings for the

High speed needle valve (HSV)
and the Low Speed needle valve (LSN)

It Will tell you how many turns you need to take these out.

I would wait until somone tells you what the default settings are. You might be able to call O.S. and find out.

Maybe your LHS would tell you, but beware. Some don't really know as much as they let on, and some are in it for the sale.

#1 So which os motor do you have (so we can answer for ya)

#2 Check all your fuel lines, and make sure none have pin holes in them.

#3 Definetaly find your needle settings

#4 Compression is how much pressure the motor builds when it reaches top dead center. When you loose compression your motor looses power. When your motor looses too much compression, it won't run at all.

Loss of power, and compression are sometimes related but definetaly not the same thing.

If no one answers with the needle settings perhaps make a post titled "need factory settings for os XX" xx being your model hope this helps, for what it is worth I mam almost positive it is your tunning. These motors need to be tuned for outside temperature. What works great in 20 degree weather, doesn't work at all in 50 degree weather.

 

[rrrunner]

lykan,
my engine is o.s. .12 tr(p) (in malaysia we call it os 5 port turbo), u r right, i'm not good at tuning at all...
if i'm too lean, in general it means that i close the high end too much, am i right? and in that case the engine will overheat and sooner or later stalls.. but my engine never stalls before.
i agree with u saying that i'm too lean on the low end and too rich on the high end. that is the most possible answer.
if i want to richen the low end this is what i should do, please correct me if i'm wrong: i will have to turn the lower needle (spring tension screw) OUT a bit (about 1/8 at a time), am i right? Can u suggest any site with good tips on basic tuning guide?
however i would do like what u suggested, getting the factory default settings.. thanks for ur advise, i'll get back to u when it is done.Thanks again.

 

[lykan]

"if i'm too lean, in general it means that i close the high end too much, am i right?" Yes you are right.

Ok I will list some symptoms, then some ideas for you.

The low speed needle is for adjusting the amount of fuel the engine has at idle (no throttle) and for the change between a stop, and high speed.

The high speed needle is just that. It controlls the amount of fuel that is allowed into the engine at half thottle and above.

This is where the confusion starts. After the carbuerator, the fuel goes into the crankcase. This part of the engine stores some fuel.

So when you adjust one of the needles it won't make a difference right away. The engine needs time to burn off that exra fuel. When adjusting the the carb, yuo will have to run the car for a bit, and wait for your new settings to take effect.

I suggest you do a google search on OS engine tunning. You will find a lot more articles with a clearer explination of how to tune. I have found several between those articles and this board I learned how to tune.


Here's a link to a decent tuning guide.

http://www.nitrorc.com/reference/etuning.asp

Any help from our more experienced members?

 

[olds97_lss]

Just out of curiosity, how much fuel do you have through the engine?

They only last so long before you need a rebuild. Again, it may just be a tuning issue, but the symptoms are close to that of a worn out piston/sleeve.

 

[rrrunner]

hi guys,
i have already ran about...15 litres through the engine.. and so far it never stalls.
i went to the track just now and try to richen the high end a bit and lean the low end a bit(base on lykan's advice) i realize that after 3-4 laps the car still performs well and the gurggling sound is still there but reduced a bit.when i richen the high end, i must have been making it too rich that my car does not shift or hardly shift into 2nd gear, so i lean it a bit.
it happened that our lhs owner was racing there too. i told him the problem and seek for advice. he said the engine is fine, it has been tuned perfectly, thanks for ur advice. he said that maybe the sound came from the pipe and he noticed that the pipe hole(the small hole where the smoke came of) is a bit crumpled making it smaller by 30%.. i used THS tuned pipe. to me, a pipe is considered in a good condition as long as there is no hole on it , not crumpled and still in shape.is there any chance of the inside part of the pipe to spoilt without any visible bad sign outside.. my tuned pipe looks good to me. anyway, i'll try to use another pipe to determine whether that is the problem. thanks a lot guys.

 

[lykan]

I found this link to the product manuals.

http://www.osengines.com/manuals/index.html

I don't know if this is the same motor , but what I found on the

O.S. max-12TR series

For this motor.
The high speed needle valve (needle vlave in manual) reuires 2 full turns out from fully closed.

For the 10 j carbuerator on this motor. Pull the mixture needle (low speed valve) flush with the carbuerator body. The turn the screw in 2.5 turns.

For the 10M carb, pull the LSV out flush with the carb body, and screw it in 1/5 turns.

I suggest you click this linkhere and read for yourself to get a beter understanding. The correct settings are on page 17

 

[rrrunner]

after a few testing.. i beleive it's not the engine. sorry guys, i'm new and still can't 'read' the symptoms. yesterday somebody hit my car, the muffler and pipe joint loosen up, i heard the gurggling sound obviously.when i lift my car head down the sound dissapear, that's because the pipe is in straight direction.. i noticed the funny sound appear since my muffler was banged 3 wks ago.. before that it was ok.. thanks a lot for ur help on this, learned a lot of lesson on this.

 

[lykan]

So it is your muffler or the joint?

It would still bea good idea to find your defualt settings for the needle.

 

[rrrunner]

the muffler and the pipe should be in a straight line position. in my case it's a bit bent causing an air leak at the bottom.. that's where the sound came.

it's the joint, the rubber thing...