konrad

An inexpensive thing to try is replacing the spark plug cap (which do go bad). My favorite 2T spark plug cap is the NGK TB05EMA. It is a nice waterproof cap with a 5K-ohm resistance. Although your spark plug has an internal resistor, I think it's a good idea to use a resistor cap as well. Resistance in the high-tension circuit lengthens the rise-time of the spark event which helps minimize radiated electromagnetic interference that can upset the workings of the CDI.

Hmmm, I think mcman makes a good point about gearing the bike shorter that I had not considered. I'd say gear the bike taller so it has less driving force, but gearing it shorter means a slower ground speed before running out of revs. Use whatever works for you. My opinion is that learning to use the clutch proficiently is always your best protection against a "too much" mishap. The best advice I got when starting out in trials was, "One finger, and one finger only, always, always, always on the clutch lever."

If you are looking for an inexpensive option to a low-compression head, consider installing a thicker base gasket. This decreases the compression ratio by increasing the clearance volume, however it also changes the port timing. But in your case that may help achieve your goal by moving the torque up the rpm range slightly. Increasing the thickness of the base gasket by 0.5mm will have a very noticeable effect. Ideally, you would measure your current base gasket first, but a lazy person might just order a 1mm gasket and test the result. See: https://www.thehellteam.com/products/gas-gas-genuine-parts/gaskets/ I've written some basic information about heads here: https://www.ossa-efi.com/home/engine/heads If you have access to a lathe, a zero-cost option would be to increase the combustion chamber's blend radius. This will slow the rate of combustion and thereby make a less aggressive power delivery.

Welcome to the board. I don't know anything about your bike specifically, but decreasing the compression ratio will both help starting and reduce the motor's torque. Other things to try would be retarding the ignition timing and making the low-speed jetting richer. Both of those things will likely make it easier to start too. Also, try riding in a higher gear (or gear the bike taller). A flywheel weight will decrease the motor's rate of acceleration, but only if you have excellent clutch skills. Otherwise, that mod may just get you into more trouble.

The older EMs (5.7 / sport) require that the battery switch be on during charging. The BMS detects voltage at the charge port and enables the charge relay instead of the discharge relay.

That's strange behavior. The LED display is an autonomous voltmeter that is not being controlled by the BMS. There are two relevant pages on my EM website. This one describes the 5.7's battery in some detail: https://www.electricmotiontech.com/home/em-5-7/5-7-battery This one shows two inexpensive power meters (one for the DC side, and one for the AC side of the charger) that have helped me understand the charger's progress: https://www.electricmotiontech.com/home/em-5-7/10-amp-charger

Re-plating the cylinder may be less costly than replacing it. If it's a light seizure, it's possible a diamond hone and new piston may be all that's needed. It's not typical for the head to be damaged due to a seizure, and even then it may be repairable. You don't say where you are located but if in North America, try https://millennium-technologies.com/

After one year of owning an EM Race, I agree. Yesterday I rode my EM and my OSSA in the same areas. The EM is a fabulous trail bike, but the OSSA is a better trials bike (for me). The EM's complete lack of vibration and minimal noise coupled with no need to start it make for a much less fatiguing riding experience. The bike's forte seems to be climbing. But I'm unwilling to attempt my most difficult obstacles with it. I find it really difficult to generate lift without velocity.

From what I've observed over the years, not all trials bike manufacturers follow the convention of encoding the model year in the 10th character of the VIN. If I'm not mistaken, 2002 was the first year for the Pro model. 40mm forks started about 2005.

If the bike in question supports EM Connect, it will have an additional electrical module near the rear master cylinder reservoir. The module has a QR code that uniquely identifies the bike.

Try this company in The Netherlands: https://nonstopmotoren.com/?s=ossa&post_type=product At one time they rebuilt OSSA gearboxes. They will only deal with EU countries.

Wow, this is only the second TR125i I have heard about! Do you mind telling us where you live (country)? Please don't throw the bike in the trash! The OSSA TRi gearbox is unique and gears from other manufacturers won't fit. In fact, it's much more difficult to disassemble than a typical geqrbox. Some information may be found here: https://www.ossa-efi.com/home/engine/gearbox All the EFI OSSAs use the same gearbox. Some spare parts were available, but it may be easier to find a complete gearbox.

Some engines have required me to make an extension for my dial indicator. All timing specifications assume that you "zero" the dial indicator when the piston reaches TDC.

I've not investigated the fuel level sensor but have been told it's a thermistor -- which seems really, really weird to me. If it is, you can construct a table of resistance versus temperature and compare that to commercially available thermistors. Of course, you may also have to manufacture a housing too. That's what I had to do for a failed coolant temperature sensor.

K-Scan works for me under Windows 10 (Pro x64 is the only version I've tried). My new favorite USB to RS-232 converter is made by Okiwan. It uses the FTDI chip. Here is an example: https://www.amazon.com/Serial-Adapter-Chipset-Supports-Windows/dp/B08B5M1KBZ P.S. K-Scan can only see COM1 through COM10 (I think). So you may have to reassign your serial ports using Device Manager. P.P.S. Just noticed that I had initially linked an Okiwan converter with a female DB-9 connector. You need a male DB-9 to mate with the Kokusan Communications Unit. Link is now correct.

If you were happy with it in the wet, I predict you will like it even better in dry conditions.

Nope, and I'll admit I'm stupid for not having one.

A stuck throttle is a safety concern on all motorcycles. The photo illustrates three things I do to pretty much all my bikes. White plastic "doughnut" between grip and throttle housing. Grip cut well back so as not to interfere with my very robust homemade bar-end slider. And a fourth: there's a dry graphite-based lubricant between the bar and the throttle tube. And even a fifth: frequent testing to assure easy self-closing action.

Lemur, I will provide a counterpoint to your comments about TKO. I have not ridden a bike with TKO, but skilled competitors who have told me it's a game-changer. TKO is no more dangerous on an electric bike than any traditional ICE bike (with the exception of a child's bike having a centrifugal clutch). I see two immediate benefits: improved gyroscopic stability (improved static balancing) and a reduction in lag time when the throttle is applied. One disadvantage is increased power consumption. If anything, the ePure Race is geared too tall. Considering driving force at the rear wheel, it's similar to riding a powerful ICE bike in 3rd gear. The clutch itself is the same diaphragm type used on other trials bikes. Perhaps you can adjust the lever more to your liking? Choice of clutch/primary gear fluid has an effect on engagement feel. Trapezeartist, learning to use the clutch well is an important part of modern (non-vintage) trials.

The website is an outgrowth of my personal need for technical documentation. In some spots the writing is pedantic, in others it's purposely vague. Those skilled in the art will find sufficient information to conduct their own investigations. There is definitely different firmware in the controller for different model years. It would not surprise me to learn that there are multiple firmware versions within a model year or for different markets/countries.

You are correct. In fact, I tried that exact approach. I called it the hybrid design. Have just added a photo to the write-up. Here is a direct link: https://www.electricmotiontech.com/home/em-epure-race/regen-experiments#h.mz8dt9a6u3e

That's great! When an EFI OSSA works well, it's a fantastic bike. Owning more than one officially makes you an addict. 😁

Thanks, Chris. It's fixed now.

Many sections have been subtly revised. Several new sections have been added. EM Connect: https://www.electricmotiontech.com/home/em-epure-race/controller/em-connect Adding Flywheel Inertia: https://www.electricmotiontech.com/home/em-epure-race/my-modifications/adding-flywheel-inertia Controller Thermal Management: https://www.electricmotiontech.com/home/em-epure-race/controller#h.caepne62t36l Preferred Regen Solution: https://www.electricmotiontech.com/home/em-epure-race/regen-experiments#h.wkoy7uqx2hr Mecatecno Dragonfly: https://www.electricmotiontech.com/home/mecatecno-dragonfly Battery Care and Feeding: https://www.electricmotiontech.com/home/ev-tech-101/battery-care-and-feeding

I'm not sure the USA is actually excluded. Google Play auto-detected my location and I was able to load the app on an Android phone (but not an Android tablet). I was not willing to give EM my phone number just for a "look-around." You can get a pretty good idea what the app does from the sample screens. My real curiosity is about the hardware. The 2023 controller has a different part number than earlier models. I'm wondering if Bluetooth capability has been integrated into the controller or if an external dongle will be required? The controller has a 3-pin CAN bus connector and a 4-pin USB connector that are presently unused. My guess is that for marketing reasons EM will only make it available on the 2024 Comp model for now, and then possibly make it available to other models later. I also wonder if the present exclusions have to do with working out data privacy or other legal issues for certain counties?