WHAT THE PROPER PLUG GAP FOR 618
in 2 Stroke Technical Questions
14 years ago
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Re: WHAT THE PROPER PLUG GAP FOR 618
by bill martin » 14 years ago
Yanis,
The big screw is the idle speed screw. From the looks of the plugs, It appears that you are running rich on on the cylinder with the oily black plugs. Just be sure that both carb pistons are the same height at idle and they both begin to rise at the same time when the throttle is advanced. The fuel level in the carb bowl is controlled by the float valve. this valve has a small rubber tip which can become worn and cause the fuel level in the bowl to be too high. This results in a rich mixture. The valve can also have trash in it causing the fuel level to be too low. This causes a lean mixture. These are the things that would cause high or low EGTs throughout the throttle range.
If the EGT problem is only at idle, You need to check the idle jet, the idle air screw, and be sure the small idle ports in the carb are clean.
If the EGT problem is in the throttle mid range, Check the needle jets for wear and dirt, check the needles for worn spots and that the needle clips are in the same position in both carbs.
If the problem is at full throttle, check the main jet for cleanliness.
The jets and needles all have part numbers stamped in them and should be alike in both carbs.
The problem may be a single thing or it may be a combination of the above. If none of the things above work, we may want to look at ignition and compression. I'm also hoping someone else on the forum may have an idea that I missed.
Bill.
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Re: WHAT THE PROPER PLUG GAP FOR 618
by bill martin » 14 years ago
Yanis,
Just looking at the spark plugs again and noticed that two of them have the crush washers missing.
Bill.
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Re: WHAT THE PROPER PLUG GAP FOR 618
by bill martin » 14 years ago
Yanis,
Electrode gap and plug gap are the same thing.
I always left the washer on but I don't think it matters either way.
Bill.
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Re: WHAT THE PROPER PLUG GAP FOR 618
by yanis karvas » 14 years ago
Bill yes you are right I took them off onpurpuse,As these 2 sparkplugs have the CHT SENSORS ON, Should I put the double washers back? including the CHT sensor'swire ring?
I was also reading at the rotax 618 Manual and indicates that the ELECTRODE GAP should be 05.mm (.02") (Electrode gap that means the sparkplug gap right) I have the new sparkplugs set at 019
Yanis
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Re: WHAT THE PROPER PLUG GAP FOR 618
by yanis karvas » 14 years ago
Hello Bill and anyone that may read,
And regards from my smiling again 618 :lol:
I started all from the start, Balanced the slides, check the floats, 0ed the air screw and started with 1 turn and eventuall went to 1 1/2 a little more on the mag cylinder as it smoothed out better,
on the high RPM I may have about 50 degrees difference but still playing with the setup, Also a friend is visiting tomorrow which is more expert than me and he will be happy to look things over,
I thank you Bill for your assistance and input, I will report my frind assistance and end results,
Regards
Yanis :P
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