konrad

There's some practical information in my EFI OSSA Notebook in the first post here. Some of it might be helpful.

It's fairly common for people to elongate the stator plate mounting holes to alter ignition timing. The amount of elongation I see there would only be a few degrees. That should not prevent it from starting. I would use epoxy for repair. Have no idea if JB Weld epoxy is available where your are, but I recommend it. https://www.jbweld.com/collections/epoxy-adhesives/products/j-b-weld-twin-tube Really, almost any epoxy would work -- preferable with a 24-hour curing time. I've even used Fiberglas resin on stator plates. HOWEVER... I think those stators are a know electrical failure item on the small Polini motors (a friend had an MX version with that trouble). I suggest talking to your Polini importer.

Everything I saw has a minimum threaded length of 28mm. So if you needed, say, 25mm unthreaded, you would buy a 55mm fastener and cut off most of the threads. This example is stainless, with a 70 ksi tensile strength: https://www.mcmaster.com/92095a299 That's soft enough that, I think, you could cut more threads with a die. But that's generally frowned upon. And using a spacer under the head would would circumvent what you are trying to achieve with the button head. How about some sort of slippery plastic covering over the original bolt head?

Not sure I understand your question. The key size is based on the diameter. The tightening torque is a function of several parameters (e.g., grade, diameter, pitch) but length really does not enter into it. Are you looking for a specific bolt?

My mistake, I'll blame my poor English skills. In the US, McMaster-Carr https://www.mcmaster.com/standard-rounded-head-screws has been a great reference source for as long as I can remember. They say "fully threaded" or "partially threaded" (which is far less common).

They're very common in the US, often called "button-head cap screw" or "socket button head".

In the aircraft world it's called the "grip". http://spenceraircraft.com/hardware/fasteners-screws-bolts/airframe-bolt.html

Don't get too upset, that paper was written in 1996 and is from the point of view of manufacturers, not consumers.

"Monolayer-HDPE tanks offer long-term structural integrity but will not meet future permeation requirements." https://www.tms.org/pubs/journals/jom/9607/alvarado-9607.html

The plastic should be abbreviated on the underside of the tank.

If it is electrical, you should be able to feel that while riding. It will feel like it's missing combustion cycles.

My first trials bike was a 321. Letting off the throttle will not produce "spark knock" (detonation). I'd be wiggling bearings. Sometimes you can isolate the source of the noise with one end of a hose (maybe 3/4 - 1" ID) held to your ear and probing the engine with the other end. And yes, one side of the kill button goes to the chassis ground.

Chris, you can determine the volume of ethanol in a fuel with a simple test: Fill a syringe with 90cc fuel and 10cc water. Shake it well, then let it stand for 10 minutes. If the "water" portion increases from 10cc to, say 20cc, that indicates your fuel is 10% ethanol (by volume). As for ethanol's effects on plastic, I'm sure it depends on the particular plastic. (I would advise searching academic/industry research papers for a credible answer.) My red plastic fuel jugs are HDPE (high-density polyethylene). P.S. There are many ways to improve octane rating. I would say, in general, the less costly the fuel, the greater the ethanol percentage.

There seems to be quite a few topics related to fuels on this forum. I'll add my contribution here. The content of both these write-ups was posted on other forums as far back as 10 years ago. My thinking has not changed. Ethanol Technical Perspective.pdf Leaded Gasoline Technical Perspective.pdf

The owner's name is visible on the number board in the video. A search lead me to this: http://www.evalbum.com/3036

Given the diversity of bikes presented, beauty really is in the eye of the beholder. I'm a big believer in the idea that "form follows function." "That" was worth googling: https://en.wikipedia.org/wiki/Black_Versace_dress_of_Elizabeth_Hurley

Mecatecno Dragonfly. Since I don't own the photos, I'll just post the link: https://www.mecatecno.biz/

Yes. I think that is a good idea. You probably should have an electrolytic filter capacitor on that line as well.

Ignition coils for CDIs are neither 6 volt nor 12 volt. CDI coils work on a completely different principle than "induction coils". The capacitor inside the CDI gets charged to on the order of 200 - 300 volts, and then is discharged into the ignition coil. Technically, such ignition coils are "pulse transformers". They typically have somewhere around a 1 : 100 (primary : secondary) turns ratio. Their primary resistance is very low (usually under 1 ohm). I just searched "CDI ignition coil" on eBay and found something for $8.25 USD shipped from China. Better yet: https://www.ebay.com/itm/IGNITION-COIL-YAMAHA-TTR125-TTR125L-TT-R125-TT-R125LE-2000-2009-2011-MOTORCYCLE/281087430819?hash=item41721dd0a3:g:iFIAAOSwDk5T1Lw~:sc:USPSFirstClass!55066!US!-1

Regarding item #7 (I called it a "beauty cover"). Perhaps a better name could be "access cover" or "body cover" or just "cover"? It's called "airbox cover" in the OSSA parts book. But that's not a good translation. They call the actual airbox cover the "air filter manifold". Although it's desirable to keep item #7 installed, I suggested testing without it. I rode my bike for an entire day without that cover (which made getting to the diagnostic port easier on the 2011 model). I can tell you the fan was loud, very loud, objectionably loud! Also, the 2014 cover has louvered openings whereas the 2011 cover does not. So I think the cover must have some affect on cooling.

I think it's both. Item 7 below is what I am calling the "beauty cover". I see what you mean about VR wire! I was told by a knowledgeable person that works with Arctic Cat snowmobiles (also uses similar Kokusan Denki ECU) the fuel pump is powered separately. A lot of what I found lead me to agree with that. But I'm not so sure now. I don't have a running bike right now to investigate further. When you run K-Scan, "pump voltage" and "battery voltage" are reported separately. P.S. I recently found out that the OSSA fuel pump is a standard part used in other motorcycles. This makes me think it odd not to just run it from 12V (battery) power.

Possible, yes. But risky too. Power comes from the stator, but rectification/regulation happens inside the ECU. This additional load could cause that part of the ECU to fail, or create enough extra heat inside the ECU to cause something else to fail. If the additional load of the fan caused a drop in voltage, the fuel pump pressure would be decreased which would have an effect on fuel injection volume. I have a couple other thoughts... Does the boiling occur as you are riding or when stopped and the fan stops? (Install a small clear "catch bottle" on the radiator overflow to see when fluid loss occurs.) Maybe it's better to ride around slowly after a steep assent? What happens if you remove the plastic "beauty cover" that goes over the airbox/fan/ecu area? Does that improve airflow enough to decrease the operating temperature? I would install a temperature gauge so you know what help/hurts.

Some (slight) fluid loss due to thermal expansion of the coolant is normal. I was going to suggest using a 1.6 bar Kawasaki radiator cap, but just tested this and it does not fit my radiator. Still, you can probably find a higher pressure cap than standard (which is 1.2 bar) that will fit. You can use distilled water instead of antifreeze (coolant). Pure water has better heat transfer properties than antifreeze and this will lower the system operating temperature somewhat. But using pure water has drawbacks, namely: lower boiling point; no corrosion protection; no freeze protection. I use Motul's MoCool to provide some corrosion protection. The recommend concentration is 5%. You can unplug the coolant temperature sensor. This will make the fan run 100% of the time. As you mentioned, running the fan at a higher voltage (maybe fabricate a DC-to-DC boost converter?) would make it turn faster, but would probably also decrease its life. P.S. you can also use K-Scan to enrich the A/F mixture up to 5%, but this will likely have a detrimental affect on power (but you may be able to tolerate a few percent).

Great tip, thanks! I'll order one. That photo was taken even before I used flywheel weights. I ended up just heating and bending the stock levers to clear. (Also slid the levers out on the splined shaft a bit, too). Not shown in that photo is a Nylon washer I machined that goes between the engine case and the shift lever. I'm hoping this will prevents the shifting mechanism from being damaged if/when I crash the lever into a rock. The OSSA's entire shift mechanism looks quite fragile. I would have sacrificed some weight there for durability.

Pindie, you don't need to remove the cover completely. Just loosen the screws and pull the cover away from the engine case slightly. But this makes a mess! I made this little extension specifically for trials bikes to keep the mess at bay. Works fine on the 2011, but I can't get anywhere near all the oil out of the 2014 via the drain plug alone. Anyone know why this is? Does the locker shaft have something to do with it? My 2014 has some additional machining that allows clutch cavity oil to drain by removing one case screw.