jrsunt

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.

I presume you’re uk based, the street legal or ED and 2ED bikes weren’t really ordered by dealers in the uk as there isn’t a market for them, the 4ride filled that market. The 3ED and 4ED are the competition versions that came more or less ready for trials without having to swap parts. The 4 ride (2ED) does come with the road legal front pipe as well as a 3ED/4ED front pipe in a kit. It was generally swapped for the 3ED parts as it made the bike a lot better. This is only a 26mm pipe as with all the 260’s. The parts list shown by lemur is from a 2005/2006 bike. Which only had to fulfill Euro4 requirements. The restrictor was a very basic top hat design, something that could easily be fabricated to fit the 300 pipe. It may be worth looking in to. If you could find one off the original 4rt it would fit, the cylinder head is exactly the same from the 1st 250’s right through to the current 301rr

I’m not sure you will get a Mont to feel like a Beta. The injection vs carb response is very noticeable. Mapping would be the way to do it, getting hold of a HRC (fully programmable) throttle body may be impossible though. But, it has been done before with various header pipe set ups, there were some posts on here a few years ago. It would be worth a read. I think the standard 250 and 260 header is 26mm and the 301 is about 30mm. There should be plenty of standard 250/260’s available second hand fairly cheap. The 250 pipes did change around 2009 they are slightly longer to accommodate the newer style silencers. Aftermarket headers are about 28mm. Getting the right gasket to fit the combinations might be tricky.

A 125 would work well, they have enough bottom end to pull away without having to use the clutch excessively and as she progresses the 125 is more than capable when you start exploiting the power at the top of the RPM. 125’s enjoy been ridden hard, if she’s confident with throttle, clutch and brake timings a 125 is a lot of fun. I enjoy riding my lads Gas Gas 125, it’s highly manoeuvrable and a lot lighter than the Mont. It only lacks power on the really big stuff. The 200cc bikes do tend to ride more like a 250 than a 125, a little more flywheel and inertia keeps everything moving forward a little easier.

I’d be checking the internal diameter of the con rod small end. Even with the slightest play it will give a knocking noise. The piston doesn’t do much other than support the rings, which do all the hard work and wear considerably. If the con rod is slightly out of specification everything will wear as it won’t be runnng true and it will do the same again

Take it all off, it’s just stuff for homologation purposes. All the vapours and fluids end back in the air box, not what a competition engine needs. (The bike will empty the contents of the crankcase back into the air box when upside down) Remove at the air box and bung the hole. Firstly start with the petrol cap breather, cut it to about 6” and tuck it into where the throttle cable goes. The cylinder head breather can be shortened and tucked in down the left side of the radiator/frame legs as can the ht coil wiring. (Loosening the bolts and front engine mount helps get them in) The fuel pump breather down the right side of the radiator. The crankcase breather runs on to the sump guard at the rear. The electrics on top of the crank cases can be made much neater, do away with the bank angle sensor nearest the shock. Unplug it from the rubber boot and put a link wire connecting the outside terminals together ( i think there’s a yellow, white and green in there). The relay wiring comes down from under the headstock and sits under the exhaust. Now that you’ve got room under the tank from removing the junk, the relay wire can be shortened and attached under the headstock using the fluid catch can bracket. I have the Mitani condenser, it’s very small which allows it to go into the rubber boot. I’ve removed the bank angle sensor connector which makes more space in there. The only thing I have left is the rectifier and rear brake reservoir so I made my own carbon fibre bracket to hold them rather than the hefty steel one. Hope this helps

I also think it would slip when removing springs. The 4rt clutch is quite grabby compared to other models, Elf and light gear oils emphasise the issue more so. The early ones with the small master cylinder were particularly bad. Setting the lever up correctly is quite important and the dimpled plates really do help, much more progressive and will not slip, ever. The Mitani clutch pack is awesome, starts in 1st gear and is quite a bit lighter…. expensive too, but a good investment. I believe there are titanium springs for these, not sure if they give a different feel or are just purely for weight saving

They give a little more leverage for the shock, it’s hard to explain how it feels, but the shock feels a lot more responsive to rider input. There isn’t much difference when you line them up side by side but it does feel better to ride with. I prefer the feel of the Showa shock compared to the RCV thingy and run with about 7 threads showing below the lock ring. Be careful though as it can be a little more prone to throwing you over the bars until you are used to it. Make sure your bearings and bushes are good. 1mm of play in the linkage turns in to a lot at the rear wheel. Don’t skrimp and buy the all balls kit, Always get the genuine Honda bushes and most importantly the spherical bearing, it’s a world apart from all balls quality

I used a bum bag for a couple of years but found they wriggle around too much. Last year I used a fender bag and it was nice to have the bike carry tools instead of me. They are a bit limited for room so you’ve got to be ruthless with what you put in them I don’t carry a drink for me but 250ml for the bike instead. The rucksack allows plenty of room for everything you need but it’s easy to go overboard and end up carrying too much weight, Make sure tools are wrapped in a cloth or something and don’t move, otherwise they’ll rub a hole in your back

The 10w40 should be more than up to the job unless it’s very poor quality. These things will happily change up and down without the clutch just by matching the revs. My gearbox is 20 years old and never been touched!! I have always found 10w40 to stand up better to heat and more abuse than Elf and light gear oils. The lights ALWAYS give a better clutch when cold but they get very grabby and snatchy when working hard. I run Motul 300v factory line for both engine and gear box. **** when cold, but isn’t affected by heat and hard riding. Another thing with the Mont clutch is that you generally need full pull of the lever to find neutral. Any fingers between the lever and bars makes finding neutral tricky. Using the short lever helps, then it’s just 1 finger right at end next to the ball.