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There is a reason the hrc machines use a different clutch.

The 4RT 301RR makes a pathetic 16.3 HP , 1 HP more than a VERTIGO 125 but the 301RR puts out 15.1 ft/lbs torque , where as the VERTIGO 125 makes 8.8 ft/lbs . With that much torque output of the 301 it may be better leaving it with the stock clutch spring set up. 4RT 260 makes 15.6 HP and 13.4 ft/lbs torque

Personally I think you are trying to improve the best clutch in the industry. Hasn't been mentioned yet but there are 2 types of friction plates in the Cota clutch, 3 corks and 2 paper, the consensus was the paper plate gives the clutch more bite, or absorbs less oil and exhibits less compression, depending how you look at it. Key to making the clutch pull lighter is not to weaken the clutch but to improve your clutch actuator leverage at the levers, the further you hold the lever out from the pivot point the more leverage you have against the hydraulics and the greater your friction range is.

The plate holds the springs straight. They other wise rub on the towers. The springs are much lighter. Available from Webike.

There are springs and plate available which improves the clutch feel. of course it`s only available in Japan.

It is a chamber but will never be an expansion chamber like we found on enduro motorcycles simply because the shape and position is not right.

I managed to rip it out, turns out the baffle tube is titanium just like the outer. Took about 4 hours of hammer, lever bar and brute force. NOT FOR THE FAINT HEARTED! I repacked the silencer while I was at it. Started the bike up in the shed and very crisp note, slightly louder. I'm interested to see what it rides like potentially utilising the expansion chamber shape for the first time ever...!

like you said it works the reverse way, the springs push the plates out to the pressure plate on the end, when operated the pressure plate pushes toward the engine and releases the clutch. I've only ridden a few 4RT's and found the clutch to be of a light action so I would compare yours to others before adjusting the springs. It may be you have another issue

Thanks for the clarification. I was installing some spacers to reduce spring preload. I planned to pop the plates out to see if it had dimpled plates but was surprised that the plates could not just slip out. It is sort of the reverse of every other bike clutch I have ever had apart. I learned something new.

Well unless you want to let out all of the packing behind that baffle I wouldn't recommend it. I can't say for sure on the beta but all of the 2T bikes I have worked on have behind the baffle is one of a few different kinds of packing... Video of an older Sherco getting a re-pack.

Take a look from 4-42 to 4-45 of the service manual. should help enlighten how the clutch works. (2020 301 RR service manual: https://www.montesa.com/wp-content/uploads/2020/03/OSM-301RR-2020-EN-Web_V04.pdf )

Cool thanks for posting. Gee haven't ridden. Rain on last trial and a few other bikes needed thier wheels rotated every other sunday in the manner of which they demanded and I am but their humble servant. Edit, sorry ever other made it sound 2 weekly. I meant every Sunday other than the rained out Trial. But Sunday looks good to have a proper test at a low key trial, ideal.

You can use a Gas Gas Belville spring there a little softer I took the Belville spring and ground it thinner it worked great

Sorry, im no help. Now I know what's inside that front triangle section anyway. I know you can buy a more conventionally shaped aftermarket front pipe from s3 or the likes for the beta, that I guess doesn't have the baffle

Beta Evo 300 2013 factory

What bike is it?

This is an amazing technical resource for Electric Motion motorcycles! Terrific work konrad!! As he stated, use the search tool on the site, great way to find all info relating to your topic of interest. Mark 2017 Escape rider

Not unusual really, same as TLR's albeit they are cable operated......

I had the clutch cover off and am struggling to understand how the clutch actuator works. Every bike I remember controls the bike from the opposite side of the engine. A rod goes through and pushes the pressure plate out to create clearance and release the clutch. On this bike, the slave cylinder pushes in the opposite direction. So, is the movable pressure plate on the back side of the clutch pack when compared to other bikes? The parts list looks like that.

Hi all, has anybody removed the baffle from their modern 2 stroke trials expansion chamber? Seems a bit odd as it's the worst place for trapping unburned fuel/oil mix, and kinda negates the point of an expansion chamber in the first place?

Or this one? https://www.ebay.co.uk/itm/376665968838?chn=ps&_ul=GB&var=645264625710&_trkparms=ispr%3D1&amdata=enc%3A1kL_m6yi5R4-BWruA4BSmVA13&norover=1&mkevt=1&mkrid=710-173151-921626-2&mkcid=2&mkscid=101&itemid=645264625710_376665968838&targetid=2448003509029&device=c&mktype=pla&googleloc=9190959&poi=&campaignid=22924815337&mkgroupid=183371074490&rlsatarget=aud-2317547358629:pla-2448003509029&abcId=10425036&merchantid=5631438962&gad_source=1&gad_campaignid=22924815337&gbraid=0AAAAAD_Lr1dnIkdoNdVfCbDEXvX4OtSA_&gclid=CjwKCAiA2svIBhB-EiwARWDPjn8ILoYjk45RuGuHPej4d8KMDBmpi9uoV9sY6kEm_GYT4-8VSWNfthoCeHEQAvD_BwE Why the massive price difference?

Hey I've got the same issue with my Bing 84 - not able to find replacement O-rings, choke rubber and gasket kit which have all perished. Is the below link what I should go for, for a straight swap? It's for a Sherpa T 350 1975 https://www.ebay.co.uk/itm/301495710655

Thanks guys this is all I need. A new Dellorto from In Motion it is! Over and out

Mikuni or Keihin or OKO or Dell Orto are all a better option. Keihin most expensive. OKO least expensive.