I wonder if there is a relationship between Pre-Mixing and the Marbles in a Can issue that some have? Could Pre-Mixing (without disconnecting the MOP) be contributing to the issue by causing more carbon buildup than usual?

or

Let the debate begin .

 

I can tell you that since premixing, I have a LOT less soot on the exhaust tips than I used to. It still gets dirty, but it's a light color, and very little, instead of pure black gunk.

 

My thought is that adding additional 2-cycle oil (albeit good synthetic oil with low ash content) into the combustion chamber with the oil that is already provided via the MOP will mean more total carbon is created during the combustion process.

More total carbon in the combustion chamber will cause more carbon deposits and/or carbon "marbles" being formed, leading to the "Marbles in the Can" syndrome. While MITC may also happen without pre-mixing, I would think it might make the problem worse.

There may be seal lubrication benefits by pre-mixing, but is it causing carbon buildup and MITC as well?

 

When I hear talk of marbles in a can, that sounds like detonation...

 

This may be true, but this is after the catalyst has dealt with much of what is in the exhaust - I am not sure this a very good representation.

My point is, I do not see how adding more oil to the combustion process can produce less carbon deposits. Other chemicals get rid of carbon (solvents, etc. that are used in fuel cleaners) but oil burning will just product more carbon.

 

Carbon buildup increases detonation issues in most issues.

 

which would lead to better sealing and complete burn. and less deposits on the tips?

beers

 

The only relationship I could imagine between detonation and pre-mixed two-stroke oil would be if your ratio was in the 2% range, or richer. (.....that would be a full quart of oil per tank!)

Most two-stroke oils have really sucky Octane ratings, and can bring the rating of a whole tank of fuel down, if it were used in ratios traditionally seen in lawn equipment.

I can't see any connection at the levels "rotary folk" would be using.

S

 

Its not and I just got a JVC high def digital cam. This sound is loud in my car on the driver side and sounds like fluid moving fast. Its real loud when my car is could too. I'll try to get some vid up but its just so hard to drown out the sound from the road when I place my cam on the floor board. I also hear a nother odd sound when my AT trans shifts but I think that one is normal.
I put the sound clips up when I get it mixed down.

Edit: I just had my engine replaced so I hope its not detonation.

 

I thought it was decided to be the heater core?

 

If you can post the sounds then Club Marbles can give our opinion.

 

I think at the very least our sound and Mike's is probably the heater core.

 

Marbles in a can is vague - it can also mean the SDAIS going nuts, like mine.

And I still don't know what the hell premix is.

 

Raptor, its when you a little bit of special oil into the gas tank before you fill up.

Thus gas arrives at the engine with oil already in it as opposed to picking up oil once inside the engine.

 

The best way to generate the "MIAC"and hear it very very clearly is to run the car on 1st/2nd gear to around 9500RPM and then let go of the throttle and let the revs come down slowly. You can hear the sound very clearly by itself without the roar of the exhaust noise.

maybe you can get a better recording that way.

 

i would like to know why such a few number of guys have added an OMP adapter to their 8's. i think that this might be the best mod for the 8 & it's only about $100.

 

That sounds like you're describing the light engine popping noises that the car makes normally.

 

It's just adding regular 2-stroke oil into your gas tank before filling it up with fuel. You'll likely only need to add 4 oz of oil. this will make sure your seals are properly lubricated.

You could also take it a step further, and disable your MOP completely, and only use premix, reason being that premix is nicer and cleaner than burning engine oil.

 

I have recently noticed what sounds more like sand in a can/blender. It appeared after I intalled my supercat. Is this likely the heater core noise? Have we decided if it is fixable?

The sand in a can noise was most obvious when I was running on a tank of 93 octane from a little rinky-dink gas station. I always run 93, but could it have been stale or diluted or something to maybe cause some detonation?

 

Great discussion - two questions.

Independent of the Marbles issue, does adding premix to an engine with the MOP on contribute to more carbon buildup,when this engine is already prone to it.

I do like the MOP modification idea, so that you can use 2 cycle oil only being fed into the engine - this could acually lubricate the seals better and reduce the carbon and other junk buildup in the engine. Does anyone make separate tank that you can hook up to the MOP and feed it clean 2-cycle oil only?

 

Richard Sohn sells an adapter for the renesis OMP. it can be found if you do a search. it sells for about $90. there is a DIY on the turborenesis website. check it out... real easy to do.

yesterday i began looking for some kind of auxiliary plastic fuel/oil tank that i could use for this mod. i had a hard timing coming up w/ decent search results. i tried motorcycle & moped online shops to no avail.
i refuse to give up my windshield washer tank!
can anyone help?
thanks

 

I did some searching, so to save everyone else time, here's a link for more info on the mod:

https://www.rx8club.com/series-i-tech-garage-22/oil-metering-pump-9772/

 

Another noob question - what's MOP? lol.

I'll search...maybe...

 

MOP/OMP = Metering Oil Pump or Oil Metering Pump

Rhythmic; so far we haven't found any cure for the noise. Where does your sound come from? Run a couple more tanks and see if the noise goes away; if it does it's most likely your gas. Also, feel free to join the party in the Marbles thread and post your observations. We've found that not everyone has the same marbles.

 

I wouldn't quite call them marbles, but I did have a buzzing sound from 5,700 rpm - 6,100 rpm and again right around 8,500 rpm - redline. I talked to Moon from Pettitt while he was at the Dragon in September. He moved with my secondary intake valve (I believe that's what it was) around a bit, and since then, haven't had a problem. Bad part is, at the same time I started running Pettitt's premix....so I can't definately say which one it was.