posted
Hi Rody, Just break-in the X12 3-port Turbo...and the engine is running sweet and starts smoothly each time.
However, when i remove the plug, i notice some burn marks on the piston head surface...It looks like something stick onto the piston's hot surface during engine operation and result the burn marks...! Or is this normal for all the Pistons to look this way?
Secondly, i'm trying to tune the engine myself but am worry the engine gets overheated. Basically, when i try to open the throttle from idle, then the engine seems choke and dies. This, i closed the low-end needle until when it doesn't stall when initial throttle is applied. Is this right?
When the engine gets running at about 1/2 throttle open, the engine dies. So i thought the main needle is a little rich because the engine choked and died during the 2nd half of the throttle which means this is controlled by the main needle where too much fuel had gone into the carb and choked the combustion at plug point. So, i started to closed the main needle until a stage where i can open the throttle all the way from idle without stalling the engine. Is this correct?
Am i tuning the engine correctly? Now, the main needle is about 4 turns from closed and the low-end needle is about 3/4 from closed. I know that by judging from the no. of turns for these needles might not be correct as there are many factors affecting it (eg. fuel, weather, & etc...)
Despite the above, i still would like to find out would i be overheating the engine for the above tuning/setting as i dont have anything to read the temp of the engine.
Thanks Rody and awits your kind reply.
Posts: 12 | From: Australia | Registered: Mar 2003
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posted
The burned marks on the top of the piston is probably the oil which burns on high temperatures, this is normal.
Seems your engine is indeed still very rich and you can notice this because there must be quite some smoke coming out of the pipe and also the engine does not run clean.
As for the overheating, as long as you do not run the engine too lean with high rpm's it will not overheat, so no real worries.
If you are not sure about all this, please ask at Hobby Link, I am sure they can give you the advice you need.
posted
When would you rebuild your engine or change the rod. What are the symptoms of it needing a rod or piston and sleeve? Sometimes it is not easy remembering how much gas has been run through your engine is the reason I am asking.
posted
Most important is to change the rod when you have burned 5 liters of fuel through your engine, or 1 1/4 gallon. You should know that sometimes the conrod can be stressed and this is not visible, the only thing which is visible is excessive play and if you notice this on the conrod you also need to check the big-end of the crankshaft.
As for the piston/liner, when your piston/liner wears out it does not hold its compression and your idle is very unstable and your engine dies easily at idle.
If you want to know how much fuel you have burned through your engine, we suggest you write this down somewhere.
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