jrsunt

I wasn’t aware of this happening, perhaps it’s more prevalent on the 300’s and 301’s due to the extra power. Maybe this is what was happening to Andy12343 in a recent previous post. Mitani do know their stuff and do quality products, I’ve used them for many years. Mark at H&D Racing knows their products well. He may have come across and fixed these before

Shouldn’t have come apart like that. A new one won’t be cheap but a 2nd hand one may be worth a try. I would think Richard Allen trials spares would have some. If you’re really stuck I have one on a spare engine.

Do you mean large gear that engages with the primary drive? Isn’t that pressed into the aluminium basket with rivets?

Lemur, you don’t experience the drag because you are using a similar viscosity to the HTX which works perfectly on a cold engine. If you’ve never experienced the clutch failing due to heat and stress then you haven’t reached the limit. It is a common issue for the expert riders that require the clutch to do more work. Montesa301 has asked why he has a particular problem when the bike is hot using new oil and a new clutch plate kit. This problem is experienced when using particular oils

Light oil/thin oil is the problem, the HTX is too thin at 46 viscosity when the bike is working hard. I don’t know the science behind it. The ONLY reason HTX is recommended in the manual is so the average rider doesn’t have clutch drag when starting up from cold and it will start in gear. Most riders will never have a problem with HTX. When we were doing the European and some World Championship events, the clutch would be completely useless by section 2, 10w40 engine oil was the answer Different level of riders require their clutch to operate differently, mine drags and is a bitch to start in gear when cold, but I know it’ll work properly when i need it to.

A multigrade oil is not necessary, but something like the Motul 300v is also designed for wet clutches in sports bikes which is perfect for the Mont. None of the light gear oils can handle the 4rt when they are ridden hard, big climbs, steps or prolonged slipping and feathering then the clutch becomes grabby, snatchy and eventually it’s hard to change gear. The light/thin oils are perfect for clubman riders, but anything more it’s just not up to the job.

Get rid of the Elf, it’s great when the bike is cold but can’t handle the heat of a properly used 4rt. Use the same 10w40 that you use in the engine. I also run the Mitani clutch. Try that first, if it doesn’t help then something else isn’t right.

It is unusual for the pump to fail, particularly the older style, they were pretty reliable. Yeah that pump should do the job

It will be difficult to pin point the noise without a bit of investigation. If you don’t mind a bit of spanner work there’s a few things you can try. Get a workshop manual if you don’t already have one, they are very useful. Firstly, take the chain off to see if taking load off the gearbox sprocket makes any difference. If not, put chain back on, you’ll need it on later. Drain the Gear oil and coolant Now you need to take the full right side canckcase cover off by removing the brake pedal and kickstart. The kickstart can be very tight on the shaft and can take some prying off. The bolts for the cover are various lengths so make a note or plan of what goes where. Be careful when lifting the case off, use the pry tabs. There is a shim/washer on the water pump shaft and kickstart shaft that like to disappear. They usually stick to the cover. Take the clutch apart and basket off, ideally you need clutch holder and impact gun to get the 36mm nut off the basket. (it can be done without with some improvisation) If the sound is still there when spinning the rear wheel it will likely be gearbox related and possibly an engine split. If the sound has stopped, it’s in something you’ve taken off. Good luck

Drain the gearbox oil and check for metal. The flywheel is on the left side. It would be unusual to have clutch related noise there. Could it be output shaft, gearbox sprocket or chain related? Does it only happen when the bike is moving in gear or does it also happen when moving but in neutral? Does the sound not happen at all when stationary? Is the bike new to you or have you owned it a while? Just looking for a bit more information

Wish I understood the data, I have no idea what the red or blue lines indicate 🤣( X axis crank degrees and time? Y axis voltage?) That was from my 250 manual. Looks like Honda freak was also been testing the 250.

Does this have any relevance to anyone’s data: Intake valve opens 6 degrees before TDC Intake valve closes 27 degrees after BDC Exhaust valve opens 30 degrees before BDC Exhaust valve closes 1 degree after TDC

It appears to be that the 4rt was the first bike with batteryless fuel injection and the test bed for everything else. With regards to your tests and findings, why is the high tick over so critical for the starting procedure?

This is a fascinating read, mostly beyond my understanding but it somewhat makes sense. It baffles me how all this was conceived in the first place. Was it by clever men in sheds smoking a pipe jotting things down or was it all computer simulations? Even if it was computer simulations, getting it to work in real world trials senarios completely reliable and virtually unchanged for 20 odd years is something else. Carry on with the good work

That is interesting Konrad. What ECU have you managed to connect to? On the silver sticker with the part number there is also a 2ED, 3ED and HRC. The early Repsol 4rt’s were all fitted with the HRC version which was programmable. Due to customers fiddling without proper knowledge of what they were doing some ECU’s were causing headaches for the dealers which in turn resulted in future ECUs becoming locked and then the 2 map switch as a compromise. There are also a few “works” ECU’s about from factory bikes. They connect to the software via a 9 pin plug rather than the usual 4.