Spark Plug Color

[Martinvt]

Hi There,

Can anybody maybe help my with some advise on these spark plugs.

I am using a Rotax 503 and these plugs were taken out yesterday and were found with this almost white color.

is this a sign of the engin running lean? I found that my feul pump is not pump as well as it should. What else can cause this?

At times when the engin idle, it will back fire through there rear carb but at hi rpm it runs fine.

I am planning to replace the pump, Socket rubbers between the carbs and engin and the plugs as well.

I do have the correct jets fitted in the carbs.

Any advise will be greatly appreciated.

[Duck Rogers]

Martin, that thing is running lean and you risk burning a hole in the piston if you continue running it like that.
You may have a number of things wrong there like fuel mixture too lean, faulty ignition system (causing the backfire) air leak in the rubber sockets or somewhere else on the crankcase, dirty carb, sticking rings, worn out floats (wrong level)...........there are literally tens of things that could be wrong. Bottom line: It's too lean. DO NOT run it again before you find the fault, it could be costly...

[Martinvt]

Thanks Duck,

I am going to fit new socket rubber bescause the is n bit loose. Iam also going to clean the carbs today and replace the feul pump because it is not pumping anymore I suspect that the pump was never pumping at full capacity. Iam also thinking af replacing all the jets.

Will defnitly make sure before i run it again.

[Tailspin]

Martin, it could be costly...

Hi Martin

Duck is right and read that as "It WILL be Costly"

[Gaylord Focker]

Pick your needles up one notch too

[weedy]

The 2 on the left look the leanest, is this from the backfiring side? If backfiring is on the darker ones then check ignition system, if on the lighter ones then you may need new nozel and metering needle on that carb, but first do as you plan, carb rubbers, pump and plugs run it and check after a few hours.

[Martinvt]

Hi,

Yes the lighter ones is from the backfiring cylinder.

I found that the rubber socket on that carb was leaking and replaced with the new Silicon type available from Oom Alex.

Will test and check the plugs after a circuit or two this afternoon if the weather permits.

Thanks for all the advice. It is much appreciated.

[Leprachaun]

Too late cooked!!!

[Jean Crous]

Too late cooked!!!

Hi Alex, what got cooked?
Jean.

[Kalahari]

The backfire is in my opinion a sign that it is too late already and the damage is done, there might have been a moth in the cylinder eating a hole in the piston. Cooked seem to be an under statement. Hope I am wrong but not very positive.

[Leprachaun]

What got cooked????? the engine el heat seizo , now pilot his barcly card , she is cooked

[Jean Crous]

OWAHA, not nice at all, tip to the pilot.......DONT take a bite of that coocked Barclay-card coocked plastic , she dont taste so good

[Martinvt]

Hi There,

Jip. Not nice at all

But I found the real cause of the problem after fitting a loan engin from Oom Alex.

I was using a Optifuel fuel floe system and for some reason the turbine unit did not allow enough flow and caused the engin to run lean at high rpm.

Was using the system from august last year. And was using the new sensor with Aluminium body. Will send the unit back to Optifuel for in spection.

But I think I am going without it from now.

[nicow]

Ek haal my Optifuel ook nou uit...