konrad

Oaktrials, thanks for sharing your success story. Your description reinforces how I think the AAA cell in the Easy Start gets recharged. Originally, I thought it stole power from the stator's fuel pump winding (which provides the Flywheel Armed Condition). Later, I came to believe the AAA cell is recharged via the red and black wires because this is the only way an Easy Start could work when retrofitted to an older-model bike. I would bet your old AAA cell would still work now that you've fixed the wiring.

Are we all talking the same currency? Scotland is GBP. Indiana is USD.

Have you ever parted-out a complete motorcycle? I have not, but have sold various parts of motorcycles. The lower the price, the quicker they sell (if there's a market for them). You will probably have to ship internationally. My guess is that it could take years to sell 50% of an EFI OSSA. There are some parts that may never sell.

Breagh makes a perfectly reasonable argument. Selling the bike as a project would be infinitely easier than parting it out. But even selling it as a project may not be easy. The US market is small and it's unlikely you'll find a local buyer. Alternatively... graphics is a "don't care" issue for me. Make the bike functional and forego the appearance. I have a huge amount of time and effort in my EFI OSSAs. They return that investment by working exactly to my liking. (I just bought a 4RT for practice and will save the OSSAs for competition.) In the end, I love tinkering with bikes and if I have to make/repair or modify parts to keep the OSSAs running, I'll do exactly that. If the OSSA performs to your liking, fix it. If not, move on to something else.

Recently learned that although the home-made diagnostic cable works with K-Scan, you cannot load a map with it. Loading a map requires the official Kokusan Communication Unit shown below.

Can't hurt, but may not help. Does it run well other than difficult starting? If so, it's probably not the injector.

I just tested the compression on my 2016 4RT 260 (which runs flawlessly). I saw just over 200 psi on a cold engine after 16 kicks with a high-quality Snap-On gauge. I observed no increase in pressure after 20 kicks. These were not "fast" kicks, just normal kick-starting speed. Local atmospheric pressure will have a small effect on the reading, but I would say the decompressor (if it even exists) does not work as Montesa describes! P.S. I'll also add that although I appreciate the quality of the Montesa service manual, it appears Honda just "cut and pasted" some of the information directly from their motocross manuals. Rings every 6 months? Piston every year?

I make difficult-to-obtain O-rings from cord stock and join the ends with cyanoacrylate (Super Glue). To give you an idea, here's a source for such in the US: https://www.marcorubber.com/o-ring-cord.htm Try searching "o-ring cord stock" to find a local supplier.

True, but that will increase the pressure by a relatively small amount -- not from 65 to 200 psi. Did you try jimmyl's suggestion about setting tickover/idle speed? You need an accurate tachometer to accomplish this. I tried to set it with my digital timing light, but the reading was erratic. Ironically, this simple device measures rpm quite consistently: https://www.trailtech.net/tto P.S. I'm curious, what do other 4RT owners use to set their idle speed?

While testing compression are you kicking so rapidly that the decompressor behaves as though the engine is running? That would explain the the high pressure reading. I'm just guessing here, but typical kick-starting speed may be 250 rpm. The decompressor probably deactivates at around 1000 rpm.

The photos in the 4RT manual are not clear. Here is a photo of some of the decompressor parts on a CRF150RB. It may be similar to the 4RT. Does your compression gauge read directly in PSI? Maybe a units conversion error?

There is more to the decompressor than just a spring. There is a centrifugal mechanism to inhibit it from releasing compression when the engine is actually running. Americans call "tickover" the idle speed. There is an adjustment on the throttle body. It should be 1700 to 1900 rpm when the engine is up to temperature. Hard starting can result if set incorrectly. Also check that the valve clearances are set correctly. I see that you've done this already.

Sounds like your automatic decompressor (compression release) is not working. At kicking speeds, the exhaust valves are held open slightly. This system is very common on modern 4Ts. It allows a higher rotational speed for starting and easier kicking. Once the engine fires, the decompressor ceases to operate and the cylinder pressure returns to that of normal operation. The decompressor is built into the camshaft. See the service manual for more information.

Heffergm, did you solve your clutch problem? Your post prompted me to work on my Clake. I installed a new piston assembly and this was a magical fix. Nothing appears to be wrong with the old seals, however they may have grown excessively in diameter. It's a 9.5mm bore. The seal diameter measured about 10mm. Two other used piston seals I have measure 9.7 (from mineral oil) and 9.8mm (from DOT4). So maybe just a lot of seal drag in my case?

Well said! I like riding a variety of bikes and strive to improve all to match the strengths of the best. As Paul Thede says about suspension, "The best you've ridden is the best you know."

I'll suggest one final thing. I have a Clake OLC master cylinder. The free-play adjustment on that is critical. There's almost no range of adjustment between the clutch not slipping and it disengaging completely. And it can exhibit similar lever effects to those you mentioned.

I'm assuming the diaphragm clutch Shercos use mineral oil in the hydraulic system, so this thought is predicated on that being the case. If you're seeing a swelling of seals, this indicates a cross-contamination of fluids. Historically, Sherco used DOT4 in the clutch hydraulics. If, at some point in the bike's life, someone inadvertently put even a small about of DOT4 into a mineral oil system, I could see it causing symptoms like what you are experiencing. If it were me, I'd do a complete flush of the hydraulic system if I found swollen seals. I've also attached a page from Sherco's 2019 press release. Looks like they changed a lot since the prior model year. Can you find a specification for the clutch pack thickness? What does yours measure?

I'm new to the 4RT but often use an oil analysis service to make judgements like that. Here's a link to a service I use in the States: Blackstone Labs As you probably know, Honda says to change the oil & filter about every 15 hours. I imagine that is quite conservative, especially since the engine and gearbox use separate oil systems. I install hour-meters on all my off-road bikes for maintenance purposes. Trail Tech recently upgraded their hour-meter to make it even better! Trailtech TTO

You have to buy the entire connector, but here is a place to get the sealing gasket. http://www.cycleterminal.com/jae-mx23a.html

Seeing that corroded pin is really discouraging. The JAE connector used on the ECU is the sealed type. Is that connector's blue sealing gasket still present? Maybe Hawaii's environment (sea air) has something to do with it the failure? Prior to buying the OSSA, I weighed heavily the fact that most of its electronics were designed/manufactured in Japan (a huge plus in my opinion). P.S. I'm now wondering if the pin snapped off, and then corroded?

I'm feeling a bit sheepish now for having said the signal out of the ECU was unlikely to go bad (I was thinking of just the internal circuitry -- had not considered a broken pin). It's impossible to tell from the photo, but is that pin 17 or 18? (numbers are on the back of the mating convector). Pin 18 is for the injector, but pin 17 is switched 12VDC out of the ECU (which you may be able to work around). An obsolete electronics solder that contains lead would by my choice with a rosin-core flux (if it comes to that). P.S. If you destroy the ECU, don't throw it away. I've been wanting to get my hands on a dead one!

Am assuming diaphragm clutch. Gotta say, I'm not a fan. In my experience, seemingly small dimensional changes cause large changes in operation. I admired Sherco for sticking with what worked for so long.

Possibly the wrong seal for the fluid? The seals for DOT4 versus mineral oil are different. If the wrong seal for the fluid is used, swelling can result.

I now have about 3 hours, over 3 days of riding, on the Dexron-VI. At first I thought the Dexron-VI was a bit grabbier initially (before the fan runs the first time). Maybe the friction plates had to get fully saturated with the new fluid? Now I think that if there is any difference, the HTX 740 may be slightly worse in terms of range of clutch modulation. They seem to perform very similarly. To discern any real difference, I think you would have to ride the bike back-to back under exactly the same conditions with two sets of new friction plates that had only been in contact with the fluid to be tested.

Good diagnosis so far! 1. Yes. 2. Possible, but highly unlikely. 3. Likely nearly impossible to find. Plus it would have to be programmed for your bike. 4. Yes. 1000x more likely than just the injector signal out of the ECU going bad. Have you read my Notebook? https://www.trialscentral.com/forums/topic/69622-efi-ossa-notebook-formerly-tr280i-wiring-diagram-annotated-in-english/ Lots of relevant information there. The industry standard is to provide a "limp home mode" in which the vehicle runs (but very poorly) if one of the sensor inputs is bad. But I don't know if that is true of the OSSA. The ECU provides a ground to one side of the fuel injector when it is supposed to inject fuel (the other side of the injector is connected to +12VDC constantly). Remove the injector from the engine. Disconnect the injector from the bike's wiring and provide 12 VDC to it intermittently. (The injector is not polarity sensitive.) It should squirt fuel as long as there is fuel pressure. EDIT, I see you've already effectively done this test. At this point I would make sure the TPS is working properly.