The McGlaughlin Oil Co, Ohio, Detonation and vibration

[multistrada1]

This is great information. Interesting about the spark timing, less timing causes less shock loads at the 3500rpm area but reduced power, so parts where developed simply to resist the shock load without failing.
I think this is why primary chain wear appears prevalent.

I see the ignition timing was changed from the M to A model, maybe to address this or it could be related to the removal of the secondary ignition points.

An interesting note on fuel. My A model always ran best on 87 fuel, compared to 91. I was concerned at the Ethanol content on almost everything we can buy now was a big issue. Therefore I would drain the carburetor
and fuel tank after every ride and run a small amount of fuel stabilizer all the time.

A friend who has numerous vintage bikes and several different Rotary motorcycles suggested I run 100 unleaded fuel from Union 76. No Ethanol and a 3 month recommended shelf life. I was dubious.

I did a 200 ride first on 100, then 87 fuel. The engine ran smoother and made best overall power on 100, and had less 3500 shudder. I could tell as soon as I filled up with 87, that things had changed.

I spoke with an Engineer at Union 76. He would not tell me the company they buy the fuel from but mentioned that the 100 unleaded had a lower flash point and worked well in rotary engines, even though they
required less energy to run well. A good ignition system was all that's needed, which the RE5 seems to have. He mentioned more performance and fuel stability might be found with a Motorsports 96 unlead fuel.

A plug check after running the 100 unlead showed no signs of fouling.

Lastly, in regards to oil. I've been running the recommended Castrol, but have seen the ash content has increased. I have found that Shell and Phillips 76 both sell zero ash airplane oil in Petroleum and Synthetic
10w40 and 20w50. These oils are developed for engines that don't use Catalyst, so they include some additives best suited to older engines.

I've used the Phillips AV oil the last couple times and use it in the injection tank as well. The spark plug seems have almost no carbon build up at this point.

Hope this helps, just my experience, yours could differ.

[Framitron]

Multistrada: Thanks for the info about the Union 76 ethanol-free 100 fuel. Sounds like a good experiment to try. I also looked up the Phillips aviation oil. Their datasheet for their X/C 20W-50 ashless oil states "nil" ash content for their SAE J-1787 test. It costs $9.50/quart through Aircraft Spruce, which is a US based small aircraft supply house.

Wayne: Thanks for digging up that document about the RE5 engine development. I am still struggling to get my mushy little brain around this uneven combustion problem that they describe. I can imagine that there can be a traveling flame front moving through the combustion chamber. The thing that puzzles me is how a small combustion region can exert a concentrated force on a small part of the rotor surface without that pressure just equalizing throughout the entire combustion chamber first. The inertia of gas is many orders of magnitude lower than the metallic rotor. I'm not a combustion engineer but I can only imagine this happening during detonation. Deflagration during typical engine operation is much slower than detonation and would probably just equalize. If they are fracturing stationary gear teeth it makes me think of detonation.

A knock sensor could be of use here...

Note: I'm not discounting the experiences of Suzuki engineers. There is definitely something interesting happening at ~3500rpm. I'll take a deeper look through the Norbye book and see what I can find.

[timpa136]

Another way to partially describe the combustion, in one of Suzukis primer books, imagine a teeter toter with

pretty equal loads. If the combustion happens at the middle for example, imagine the load on the fulcrum or in

this case, the poor internal stationary gear set.

[wayne]

Mar 28, 2024 9:04:15 GMT -5 Framitron said:

Multistrada: I'm not a combustion engineer but I can only imagine this happening during detonation. Deflagration during typical engine operation is much slower than detonation and would probably just equalize. If they are fracturing stationary gear teeth it makes me think of detonation.

Very interesting you say that Al. I had a private communication from a member with a solid background in race engines who also felt it may be detonation.

[Framitron]

Over the last two days I went through every page of Jan Norbye's 500+ page "The Wankel Engine" tome. A wonderful book but there was no discussion of a resonant or knocking behavior occurring at a fixed RPM range for any of the companies developing their Wankel engines. This includes Mazda. There was some discussion of detonation but that was at full load conditions. Sadly the Norbye book was published in 1971 so no reference to Suzuki/DKW/Norton, etc.

Wayne: What document were you referencing in your March 22 post? I'd love to dig through that.

[multistrada1]

Maybe knock is related to the shudder. It was barely noticeable on my A model running 100 octane unleaded. I would like to see someone else do an AB test.
Running a taller rear ICON shock and adjusting the chain slack on the tighter side also helped.

[Framitron]

Hi Multistrada: I am running the Koni shocks and have tried every possible chain tension. Those alterations have not changed the grinding for me at least. However I have not tried different fuels. That is easy test to conduct and I'll get a few gallons the next time that I am near the race track.

The primary chain will possibly get swapped out as I bought one of the chains from David. This spring/summer I'll pull the clutch cover and measure the amount of stretch of the existing chain and decide if I want to permanently install the replacement. But it makes sense to do the simpler fuel (and any other) tests first.

I also reached out to the Wiznorton guys and asked them if they experience the grinding with their other Wankel bikes. Not sure if they are regularly checking this forum but it was worth a try.

[multistrada1]

My bike had a new primary chain installed when the Rotor proper unit was replaced. Maybe that makes the grinding less prevalent.
I don't want to spread any dis-information. Just my experience, yours could differ.

[wayne]

Mar 30, 2024 10:17:19 GMT -5 Framitron said:

Wayne: What document were you referencing in your March 22 post? I'd love to dig through that.

I've sent you the article by email Al.

Cheers,
Wayne

[ap951]

When I graduated high school (1979) my best friend started working at a large motorcycle dealership in Denver. His first job was to remove new motorcycles from shipping crates & assemble them. He told me that it was dealership policy to put a half gallon of aviation (101 octane) gas into the tanks of the new motorcycles. He said a bike can sit (unsold) for a long time & aviation gas will never go bad so the bike will always start. This is when I began taking many many trips to the local small airport & filling up my gas cans with Avgas. I put it in everything, motorcycles, lawn mower, chainsaws. It always works very well but over many years I experienced some things. When I purchased my first house I was gifted a worn-out lawn mower. It ran OK with regular low octane gas but when I would put Avgas in the tank it would become very hard to start. (I checked and the compression was extremely low) High octane gas needs compression to combust. I live in Denver (mile high city) and the thin air lowers compression. I have a 1977 GT750 and if I fill the tank off with Avgas and ride it up to mount Evens (12,000 feet) at some point the motorcycle will hardly run. This is a low compression motor that has even less at altitude. If I fill up the tank with low octane pump gas and take the same ride its operation will not be affected by the high altitude.

It's my understanding that high octane gas was developed for engines with high compression/forced air induction & it's slower to detonate (to prevent pre-detonation)

With regards to the rotary grinding what Wayne says: "a member with a solid background in race engines who also felt it may be detonation." makes sense to me.

I always ran my RE5 on Avgas and the ginding/shuttering problem was almost non-existent although I had also replaced all of the bearings in the transmission & my RE5 had very good compression.

As multistrada1 says: "I don't want to spread any dis-information. Just my experience, yours could differ."

I feel the same way & my lack of expertise always makes me hesitant to share

[Framitron]

Multistrada: I can imagine that a stretched and looser chain could cause the tensioner to extend beyond its typical range and therefore have less spring pressure (thus tension) on the primary chain. The short Youtube video that David put up a few months ago could support that idea.

Wayne:
Thanks for the article! Looking forward to reading it.

P.S.: I seem to have completely derailed this thread from McLaughlin oil to drivetrain resonance. Sorry about that!

[timpa136]

Mar 30, 2024 20:39:30 GMT -5 Framitron said:

Multistrada: I can imagine that a stretched and looser chain could cause the tensioner to extend beyond its typical range and therefore have less spring pressure (thus tension) on the primary chain. The short Youtube video that David put up a few months ago could support that idea.

Wayne:
Thanks for the article! Looking forward to reading it.

P.S.: I seem to have completely derailed this thread from McLaughlin oil to drivetrain resonance. Sorry about that!

Not a problem with me . Interesting turn of discussion.

Perhaps Wayne will authorize a search code or add a search term to the subject?

I am sure we are not done with the RE5 characteristic.

Tim

[Framitron]

Hi AP951: What is interesting is that if it is detonating, it is happening at part loading rather than throttle wide open and maximum load. But it is possible that at a certain rotor speed and charge density the combustion does weird things. But this is just wild ideas at this point.
Good point to mention the compression of your engine. I'll confirm my compression when I run the fuel experiment.

Al

[wayne]

Mar 30, 2024 20:50:25 GMT -5 timpa136 said:

Perhaps Wayne will authorize a search code or add a search term to the subject?

Tim

Good tip Tim, search terms added.