3 different MCs but all years use the same slave so I suspect all of the MCs have the same bore size, I suspect the changes in MCs has to do with vendors. My 04 uses AJP hydraulics.
I don't know the brand of the other MCs but others may post, and there are aftermarket kits for most brands.
I also don't like the difficulty in finding the Elf oil or its high price. So I did some research on oils:
Crankcase lube oils are risky to use in a wet clutch because anti friction additives can cause clutch slippage. ATF oils are gear oils for wet clutches.
Montesa recommends Elf HTX740, which is a very thin synthetic gear oil. Elf cautions to not use this oil in a wet clutch. EBC and others recommend not using synthetic oils in wet clutches. Go figure!!
Dextron ATF provides much smoother clutch engagement than "F" type ATF.
Synthetic ATFs are much thinner at typical ambient temps than Dino based ATFs (see chart below). Thicker oils cause more clutch drag, thinner oils quicker lockup
Cork friction discs provide the smoothest engagement, paper the grabbiest. EBC claims smooth engagement with their sintered cork and Carbon Fiber frictions.
I tried a Valvoline synthetic Dextron VI ATF in my 315R with good results. A little more drag at cold startup than the Elf, slightly longer range of engagement, and smoother lockup. The slight increase in drag was fixed with a bit of adjustment at the lever.
Here is a table of gear oil viscosities at 40C and 100C, the dino oils are very much thicker at 40C than the syns You can see the Valvoline syn is closer to the Elf than the other ATF oils.
Honda #22201-KZ3-730 frictions used on 84-07 CR250Rs, plus some others.
Honda # 22321-KA4-741 discs used on 84-07 CR250R, plus some others.
The clutch in my 315 is the best clutch of any bike I've owned.. I use to run the Elf oil but it is expensive and hard to find so I searched for substitutes.
my research:
Crankcase lube oils are risky to use in a wet clutch because anti friction additives can cause clutch slippage.
Montesa recommends Elf HTX740, which is a very thin synthetic gear oil. Elf cautions not using this oil in wet clutches. EBC and others recommend not using synthetic oils in wet clutches. Go figure!!
Dextron ATF provides much smoother clutch engagement than "F" ATF.
Synthetic ATFs are much thinner at typical ambient temps than Dyno based ATFs (see chart below). Thicker oils cause more drag.
Cork friction discs provide the smoothest engagement, paper the grabbiest. EBC claims smooth engagement with their sintered cork and Carbon Fiber frictions.
I tried a Valvoline synthetic Dextron VI ATF in my 315R with good results. A little more drag when cold, slightly longer range of engagement, and smoother lockup. But how much was new oil versus old oil, or different brand? The increase in drag was fixed with a bit of adjustment at the lever.
The head bearings are generic Honda used on a couple of hundred different models. The bearing is based on a a standard 25x47x15 metric tapered roller bearing (#32005), but the Monty stem OD is 26mm, so Honda/Montesa use a special inner.
Check the ID of the bearing it should be 26mm and should fit easily over the threads and then a light push fit on the upper bearing journal.
If the bearing ID is 25mm then you have the standard metric inner and not the Honda inner. Go to a Honda dealer and order part no 91015-425-832, which is the correct bearing set.
If you search for an aftermarket bearing the NACHI part number is 32005JS/26 (the "/26" indicates the non standard ID of 26mm). The outer is 32005J.
I think the 4 pots are AJP calipers like my 04, but I don't know if the mounting bolt pattern is the same as the 2 pot caliper.
Some aftermarket pads have a higher coefficient of friction than OEM so would provide lighter lever pull. After market rotors also may have a different coefficient of friction than OEM. Also a smaller bore MC would lighten lever pull.
I have the opposite problem on my 04 with aftermarket pads; the low speed braking is very grabby, at low speeds the bike stops with very light peddle pressure.
Tenth digit of the VIN is the model year code and also applies to other bikes and cars, but letters are used for years other than 01-09, here is a list.
The Elf HTX740 is the Montesa recommended gearbox oil, it is a very thin synthetic gear oil not recommended for clutches by Elf, go figure. Thin oils provide quicker clutch take up and less drag so I started looking for a cheaper thin gear oil. ATFs are gear oil designed to work with wet clutches, exactly what our gear boxes have and the closest oil to the Elf for viscosity is Valvoline synthetic Dextron VI, I like the clutch action better than the Elf oil. The non-Dextron or "F" type ATFs are a bit grabbier if you want faster clutch take up. All of the other oils that I checked were thicker at 40C. So try some different oil and you will find one that suits you.
Repeated hits on the sump guard knock some of the curve out of it so it no longer has the correct bend to fit the frame, not good for the frame. Get a new 1mm thicker guard and you will have less problems, or take you guard to a sheet metal shop and have them use their sheet metal brake to add back in some bend.
+1 on the above. My friend's 4RT has a terrible clutch and my 315R a great clutch, because of the differences we started looking for causes; same size clutch, different plate materials. Also found different oils had an impact on shifting and clutch action. The tranny gears shear breakdown the oil viscosity causing hard shifting when hot so fresh oil is a good start. You won't like the price of Montesa's recommended oil, they recommend Elf HTX740, a very thin synthetic gear oil. I found a very close substitute in Valvoline Dextron VI ATF, also a thin synthetic gear oil at a fraction of the price. And the clutch action is smoother than with the Elf oil.
are they as easy to ride as a 315 i have one (315) but would like to change it for a 4rt but il struggle to ride it if its harder im a poor rider on the 315
I have a 315R and a friend has a 4RT. But to understand my comments you need to know that we have been trail riding for 40 years and our bikes of choice for trail riding have almost always been 4Ts.
My 315R has the smoothest clutch action of any bike I have owned or ridden, my friend 4RT has one of the worst clutches I've ever ridden, yet these clutches are the same size as the CR125/250 clutch, just different frictions. Go figure.
The EFI of the 4RT is golden, always the same hot or cold. I'm in the process of replacing the Delorto 315 carb with a Keihin PWK carb. The 4RT is harder starting than the 315R.
Power delivery of both bikes are classic 2T or 4T. In spite of the Delorto carb issues my 315 doesn't flame out on a slow steep technical section. And is easier to start.
The 315R is lighter, with a lower CG, and has a smoother bottom end response than the 4RT and that does influence your ability to get thru a section.
Other than the above the chassis and suspension appear to be the same. I'll opine that the chassis is more rigid than some other Trials bikes, the suspension is adjustable cartridge Showa, and the quality of components better than others. It is a Honda, if that means anything.
I'm keeping my 315R and my friend is talking about a 2T Trials bike, but he will continue using the 4Ts with a long ride kit for technical trails.
So for me the 315R is easier to ride and a better Trials bike than the 4RT.
the clutch cover can leak IF the skid plate rubber pad is crushed up against it. If so you may need a new skid plate and clutch cover gasket.
Exactly my problem, the skid plate had been bashed too many times and was putting pressure on the side case causing an oil leak. I bought a new aftermarket HD plate from Lewissport, end of problem. You could take your plate to a sheet metal shop and see if the could put some more curve back into it.
You don't need the liner, add a strip of closed cell foam weather strip across the top of the air box to seal the gap to the fender, also an extra piece in the wiring slot.
I have two friends with 4RTs. I had trouble starting them and was told that starting is more reliable with a slow steady kick, I tried it and it works. Next time I tried a harder faster kick like I'd use on a 4T and it wouldn't start. I suspect there is something in the EFI system that switches to a starting mixture below a certain speed.
315 Clutch Hydraulics
in Montesa
Posted
3 different MCs but all years use the same slave so I suspect all of the MCs have the same bore size, I suspect the changes in MCs has to do with vendors. My 04 uses AJP hydraulics.
I don't know the brand of the other MCs but others may post, and there are aftermarket kits for most brands.