Microlighters

As you know, I have the technical knowledge of a dungbeetle. So please have a look at this pic of my (trike's) plugs and tell me what I need to know!

Well you`re sure as hell not going to fly there`s no spark

Serious now- Maybe a bit oily but nothing to worry about:?:I dont think:!:or am I completely off Duckkie and kie:?:

Maybe a tad rich

Well, thank you sir. Oh, you mean the fuel.

And I am going to fix that how?.....

Gert,

You've flown this aerie now for 300+ hrs I suppose and she was serviced every 25 - 40 hrs at which time the plugs were replaced as well. The plugs has at least then been replaced 8 - 10 times before

a. Did they look like this on all the previous occasions?
b. Have you changed any mixture settings on the carbs recently, last service? or whoever services your aerie?
c. Are you using same 2-stroke oil? ie. Castrol Superchain
d. Was your last mixture ratio correct? Can also be too much 2-stroke oil

gertcoetzee wrote:

Maybe a tad rich

Well, thank you sir. Oh, you mean the fuel.

And I am going to fix that how?.....

You can buy a GT450 for a start.....

1)Check that you have the right main jets for the altitude you fly at, from Aviation Engines. Carbon build-up on the plugs and head is caused by a to rich fuel mixture.

Maybe also consider using another oil? Are you using "Castrol Super Chainsaw oil"?

You've flown this aerie now for 300+ hrs I suppose and she was serviced every 25 - 40 hrs at which time the plugs were replaced as well. The plugs has at least then been replaced 8 - 10 times before

a. Did they look like this on all the previous occasions?
b. Have you changed any mixture settings on the carbs recently, last service? or whoever services your aerie?
c. Are you using same 2-stroke oil? ie. Castrol Superchain
d. Was your last mixture ratio correct? Can also be too much 2-stroke oil

Thanks.

(a) No, the previous I changed it they were not this "oily". That was 60hs ago. Was changed since that change by AP for the 300hr (rather 275hr) service.
(b) I have not. Will ask AP.
(c) Yes same for past 300hrs - Total
(d) Automix

1)Check that you have the right main jets for the altitude you fly at, from Aviation Engines. Carbon build-up on the plugs and head is caused by a to rich fuel mixture.

I have had same jets since the start.

Any of the Wintervogel gang going to be there on Saturday? Would like to have someone in the know look at carbs and other bits.

Hi Gert, hope you are well !

It does look a bit rich, could be an adjustment on the oil injection that has changed/moved or, my guess, is that you have worn needles ! (Have they been replaced?) They wear, mostly due too vibration, making them thinner, letting more fuel through and thus you get a richer mixture.

The bad thing is this can result in more carbon buildup causing rings to stick.

Good luck with the investigation !
Regards,
Rudi

Hi Gert,

Colour looks fine for approx. 60 hours. 2-strokes are notoriously “dirty”. Gaps not the same perhaps. Should be 0.5mm.

As you might know, our trikes are identical. I encounter hard-starting after 30 hours on a set of plugs – not worth it – I change every 25 hours now.

Regards
John ZU-CIB

Yes, John is correct, 60 hours is a bit much, should be around 25 hours according to Rotax for their 2 strokes !

Rudi

Sorry what I meant was the previous set I changed was 60 hours ago, then they were changed again (not me, serviced AP) about 30 hours ago [now you have got me thinking - will check that they were indeed changed]. Now I have changed them again.

That GAP - maybe because the one is turned on the pic. I think they were all the same! Will check.

Thanks, this is why I love this forum. You know that UK TV series, "I know notink, I am from Barcelona?"

hard-starting

meaning? I have had to pullstart a couple of times - thought my battery is going. Was going to sort that out next....a link between the two? No, please tell more...

Gert

Looking at plugs from a 2 stroke that you allowed to idle (even for a short while) and then stopped may be deceiving, and does not tell you a hell of a lot. If you really wanted an accurate indication of the mixture setting by looking at plug condition, you have to stop the engine with the mags at high rpm. This of course is not a good idea in itself.

Someone mentioned worn jet needles. This is the first thing I would check, and its easy, even if you have 10 left thumbs. Unscrew the 2 screws on top of each carburetter. The cable is lightly spring loaded, and it pops out when last screw comes out of its threads. Hold the carb lid down lightly to ensure the screws don't go flying out. Pull the piston out, the needle is attached to the bottom of it. If it has signs of wear, or even shiny spots on it anywhere it is worn. Run your thumb nail down the side of it, the smallest little ridge can be felt rather than seen with the naked eye. Replace jet needles and the needle jets they fit into if you notice any signs of wear. The needle tends to wear the jet it fits into as well. If you look through the white plastic cap inside the carb piston, you should be able to see if a small O-ring is visible on the top of the needle. This is a rather recent Rotax mod. If you don't have it, fit them when you replace these parts. I gather your trike is relatively new, you should have these.

When you replace the pistons into the carbs, they only go in one way, there is a slot on the side of each, and a little pin in the carb body that you have to align. The lids also go back one way only.

Before you even start thinking of leaning your engine out, I would highly recommend that you fit accurate EGTs. MGL's gauges are probably the best money can buy. These cheap analog Chinese gauges are useless, and I would not trust them for this purpose. Without EGTs you are running totally blind, and stand a good chance of wrecking your engine.

If you want more info on how to do this, let me know.

gertcoetzee wrote: ...hard-starting meaning? I have had to pullstart a couple of times - thought my battery is going. Was going to sort that out next....a link between the two? No, please tell more...

Yes Gert,

The main reason we change at 25 hours is for ease of starting. No point in wanting to fly but first having to pull and for 15 minutes - interspersed with colourful language.

Keep a spare set of plugs pre-gapped (0.5mm) with a light coat of copper-slip on the threads in the hanger together with a torque wrench pre-set to 27Nm.

Tip No. 1

Don’t remove the plugs with the torque wrench – use a plug spanner with adequate leverage.

Tip No. 2

If you intend to only use the torque wrench for plugs (set at 27Nm), then use an appropriate socket and bolt fixing in the hanger to “crack” the torque wrench a few times before engaging the spark plugs.

Regards
John ZU-CIB

Further to the discussion, changed my plugs this morning after 25 hours.

I am quite happy with what I found - see picture below.

Regards
John ZU-CIB

Dumb question(s)

What is the standard gap size, as supplied,

Why grease?

Is'nt fasten the same as 'boppa',.i.e till the spanner don't turn no more, is a torque wrench essential?

Delta VV wrote:What is the standard gap size, as supplied?

Anything from 0.0mm if they were bumped closed up to 1.5mm which probably wouldn’t spark.

Delta VV wrote:Why grease?

Actually – not any grease – only copper slip or copper grease should be used.

These products are heat resistant, prevent metal migration and will alleviate the torque required to remove plugs.

Delta VV wrote:Isn’t fasten the same as 'boppa', i.e. till the spanner don't turn no more, is a torque wrench essential?

Aluminium head means “soft threads” – “boppa” means stripped threads resulting in heli-coils having to be fitted by an engineering shop – expensive mistake.

27Nm will not strip the threads. However, with experience, 27Nm is not hard to feel – just enough to squash the compression washer.

Regards
John ZU-CIB