Started a spare parts list

[BrendAn]

1 minute ago, Red said:

The whole point (according to Rotax) is for heat transfer purposes.

 

i think its a bit over the top. i just give my plugs a squirt of oil or crc and have never had a problem.  as nev says correct torque is the most important thing, thats what we were taught at trade school.

[Red]

1 minute ago, BrendAn said:

i think its a bit over the top. i just give my plugs a squirt of oil or crc and have never had a problem.  as nev says correct torque is the most important thing, thats what we were taught at trade school.

As I said, Rotax insists its about heat transfer not anti seize, apparently they consider that an important factor in their engine.

 

[BrendAn]

i know its not an issue, each to his own i suppose.

[Red]

Back to the purpose of this thread..... a year or so ago I found that the engine mount rubbers for the Jab engine were actually an old Aussie car part and as a friend was currently over there I had him get me some, it was far far cheaper than going through the UK dealer for Jab (their prices for most things are beyond a joke)

here is the part.......

 

[skippydiesel]

33 minutes ago, Red said:

The whole point (according to Rotax) is for heat transfer purposes.

 

Heat & electrical conductivity.

[BrendAn]

24 minutes ago, Red said:

Back to the purpose of this thread..... a year or so ago I found that the engine mount rubbers for the Jab engine were actually an old Aussie car part and as a friend was currently over there I had him get me some, it was far far cheaper than going through the UK dealer for Jab (their prices for most things are beyond a joke)

here is the part.......

 

they are good value. buy them over the counter here. early mustang is the same as well.  

there is a good jabiru alternative supplier list online compiled by someone in the uk.

Edited June 6 by BrendAn

[skippydiesel]

It's amazing how conversations on this Forum can dive down unexpected, often entertaining/instructive "rabbit holes".

 

This is not one of those beneficial digressions - there are certain people who have voiced opinions, completely unrelated to the maintenance of Rotax 9 engines regarding the installation of spark plugs.

 

I warn Rotax maintainers against these opinions (anti size and unspecified lubricants) -  they have no application  in the installation of spark plugs in Rotax 9 engines. 

 

Rotax, MAINTENANCE MANUAL LINE, Chapter 12-20-00, Page 57

 

"...................... Apply heat conduction compound sparingly and do not apply to the first three threads.
Apply small amount of heat conduction compound to spark plug thread and tighten spark plug to 16 Nm (142 in. lb) on the cold engine

 

[facthunter]

If the alloy picks up you will completely ruin the thread or break the threaded part off trying to take the plug out. Every aircraft mechanic KNOWS this.  Nev

[facthunter]

Another stuck  one above. Posted anyhow.

        With the threads and the washer compressed heat transfer is a NON ISSUE as it's more than adequately coped with. You want PREDICTABLE results. The only plugs that will overheat the entire plug are loose ones. The centre electrode has to get to the right temp to keep carbon from depositing on it and shorting it out.. If it gets too hot the risk of detonation increases on higher output settings. Extended idling will often deposit soot on plugs. (taxiiing) Running on may be  a result also but might also be  a bit of carbon incandescing. ' I would not be satisfied of the silicone preforming predictably at Higher temps. It's more for electrical  situations where a heat sink is needed..Diodes rectifiers regulators etc.  It won't conduct electricity.   Nev

[BurnieM]

Replacing plugs on motorcyces (40-50 sets replaced);

I have never used a heat compound of any type

I have never used an anti-seize compound

I have never torqued a plug

I have never stripped the thread on a head or plug

I have never had a plug come lose or been unable to be removed.

 

I have seen helicoils used in motorcycles including racing motorcycles running at high revs/temps.

The plugs/heilcoils did not fail altho other engine components did (perhaps not a good test).

 

While motorcyles rarely sit on constant revs for any period of time they frequently go above 5,800 rpm.

 

I acknowledge motorcycles have a different use to more constant speed aero engines but I would like to understand the technical justification for Rotaxs requirements.

 

[facthunter]

Helicoils in plug situations are NOT a good fix. they usually leak a bit and can dislodge.. IF you don't use Anti seize and are a licenced Lame you should be sacked. It's standard practice. Advisable on all engines. If it's a fairly oily type of engine you might get away with it.. Anti seize has to be applied sparingly as excess can short the plug out...  Nev

[skippydiesel]

Factunter/BurnieM

I have no issue with your advice, for all ground based vehicles and indeed for all non Rotax 9 aircraft engines (of which I know nothing about maintenance). Indeed I pretty well practise what you are preaching BUT when it comes to Rotax 9 aircraft engines - the Rotax Maintenance Manuals are my bible and I would advise others to follow only Rotax advice.

[facthunter]

You are not consistent there when you look for different oils and parts. starters etc. Nev

[facthunter]

 Silicone is an excellent Heat insulation Material. Look it up. It can stand high temps. Behaves as a non metal.  Nev

[BurnieM]

1 hour ago, skippydiesel said:

Factunter/BurnieM

I have no issue with your advice, for all ground based vehicles and indeed for all non Rotax 9 aircraft engines (of which I know nothing about maintenance). Indeed I pretty well practise what you are preaching BUT when it comes to Rotax 9 aircraft engines - the Rotax Maintenance Manuals are my bible and I would advise others to follow only Rotax advice.

Its not advice, simply what works on a range of motorcycles.

Some manufacturers agree and others disagree, often on almost identical engine configurations.

 

When a manufacturer says do it this way and later says do it another way I question the justification for both methods.

 

I am a data based guy; tell me why.

I know you cannot.

I find it disappointing that Rotax will not.

 

 

 

[skippydiesel]

1 hour ago, facthunter said:

You are not consistent there when you look for different oils and parts. starters etc. Nev

I understand that you might think this, however my search for alternative service items is ALWAYS with the proviso that they meet/exceed Rotax specifications.

When it comes to matters of maintenance technique & specification - I follow the book.

 

1 hour ago, facthunter said:

 Silicone is an excellent Heat insulation Material. Look it up. It can stand high temps. Behaves as a non metal.  Nev

I agree. 

 

I think it likly that the heatsink paste, selected by Rotax, has a high zinc (metal) content, presumably to counter the insulating properties of the silicon. Further speculation, the combination of zinc & silicon is likly to have much to do with raising the melting point of the paste, so that it persists/remains in position doing its job.

 

I note that pastes of this nature are prevalent in the electronic world for use with heat sink systems. I presume that the specification that product Rotax has selected has an appropriate mix/ratio of insulating silicon: zinc for the purpose intended.

 

"Properties Specific features • Thermally conductive

Technical data General Characteristics Property Condition Value Method

Appearance - white -

Bleeding (at 200°C/30h) - max. 0.4 % FED-STD 791 M 321

Density 23 °C 2.1 g/cm³ DIN EN ISO 1183-1 A

Dielectric strength - 10 kV/mm IEC 60243-1

Dissipation factor 50 Hz 9 x 10⁻³ IEC 62631-2-1

Loss of weight⁽¹⁾ - max. 1.2 % FED-STD 791 M 321

Operating temperature range - -40 - 200 °C -

Penetration (unworked)⁽²⁾ - 194 - 238 1/10mm DIN ISO 2137

Permittivity 50 Hz 3.5 IEC 62631-2-1

Solidifying point - approx. -45 °C -

Thermal conductivity - 0.6 - 0.8 W/m.K ASTM D 5470-12"

 

[facthunter]

You are trying to fix a problem that does not exist. The sealing washer seals it and conducts heat well and at least 1/2 the thread area is in close contact. It's just another engine after all and they all have spark plugs.. Bits of silicone block small oilways too. I stopped using it as a sealant years ago.  Unless parts are scrupulously clean it does not stick. Nev

[skippydiesel]

20 minutes ago, facthunter said:

You are trying to fix a problem that does not exist. The sealing washer seals it and conducts heat well and at least 1/2 the thread area is in close contact. It's just another engine after all and they all have spark plugs..Bits of silicone block small oilways too . I stopped using it as a sealant years ago.  Unless parts are scrupulously clean it does not stick. Nev

Nev;

What problem??

When you have your own Rotax 9 you may do as you wish with it.

I choose to  follow Rotax instructions, for the maintenance of their engines.

 

" Bits of silicone block small oilways too. I stopped using it as a sealant years ago.  I stopped using it as a sealant years ago".

What on earth has silicon sealant got to do with the use of thermal/conductive paste on spark plug thread ????

 

[facthunter]

I now have to have a Rotax to be able to comment??  Get  real . It's just another motor and the heat transfer problem doesn't exist in any peculiar way for the Rotax relating to spark plugs. If anything it's probably less of a problem that it is with air-cooled motors. Nev

[skippydiesel]

31 minutes ago, facthunter said:

I now have to have a Rotax to be able to comment??  .............................Nev

The master of the out of context comment and the non sequential tangent - in your words "get real"

 

 

[kgwilson]

Unless using a specific product voids the warranty (if there is one) I'd use whatever works. Manufacturers often have commercial agreements with other organistations and get a good deal if they recommend their product. There are usually a number of others that are just as good often less expensive and sometimes better. After all the Rotax is just a glorified Skidoo motor.

[skippydiesel]

21 minutes ago, kgwilson said:

Unless using a specific product voids the warranty (if there is one) I'd use whatever works. Manufacturers often have commercial agreements with other organistations and get a good deal if they recommend their product. There are usually a number of others that are just as good often less expensive and sometimes better. After all the Rotax is just a glorified Skidoo motor.

I suggest you go back at least a page, possibly two - this is not about a specific product or its cost (I have suggested an alternative, lower cost, more readily available (in AU) product, that still meets/exceeds Rotax specification). 

 

It seems to have descended into a debate about the merits of the manufacturer (Rotax),  recommended service/maintenance procedure, with regard to using a type of conductive (heat sink) paste on the threads of the plug.

 

There are those who advocate anti-seize, oil and no conductive past at all in this procedure - all at variance to Rotax recommendation.

[Red]

5 hours ago, BurnieM said:

Replacing plugs on motorcyces (40-50 sets replaced);

I have never used a heat compound of any type

I have never used an anti-seize compound

I have never torqued a plug

I have never stripped the thread on a head or plug

I have never had a plug come lose or been unable to be removed.

 

I have seen helicoils used in motorcycles including racing motorcycles running at high revs/temps.

The plugs/heilcoils did not fail altho other engine components did (perhaps not a good test).

 

While motorcyles rarely sit on constant revs for any period of time they frequently go above 5,800 rpm.

 

I acknowledge motorcycles have a different use to more constant speed aero engines but I would like to understand the technical justification for Rotaxs requirements.

 

Burnie, It's my understanding that the water cooled heads fitted to 912 engines are so efficient at cooling that there can be a greater temperature gradient between the plug and head than most other engines we use, the heat transfer paste helps reduce this temperature gradient.

 

I'm not going to advise on whether its use is warranted or whether Rotax know whats good for their engines🙃

[BurnieM]

For clarification;

almost all motorcycles today have watercooled heads and barrels including single cylinder dirt bikes.

 

[Red]

4 minutes ago, BurnieM said:

For clarification;

almost all motorcycles today have watercooled heads and barrels including single cylinder dirt bikes.

 

Like the one Im racing in my profile pic?🤣