mcman56

The lower legs can be modified to accept standard size bushings.

With light oil and teflon coated bushes in the lower legs, I find the stock TY175 forks to work pretty well.

My Beta once ran the same exact way. It would idle nicely and doing tight turns was fine but if you tried to rev it up, it sputtered rich. I had left a rag in the air filter after washing the bike. You could inspect the air box. https://www.frankmxparts.com/rebuild-repair-kit-MK-BSR33-79-Mikuni-BSR-33-carburetor-2008-2022-Beta-EVO-300-4T-Trial IIRC, that model carb is also used on a 400cc quad. If you search the model number of the carb you should find what else it fits.

Interesting comment. Then, what would be the 4t technique for a basic double blip over a log? I went one tooth down on the front sprocket and that feels pretty good.

I have a 2018 300 with black throttle tube. It looks just like the 2T throttle. Is a slower one available? I have a 2016 Beta 300 4T standard model and the throttle has much more resolution for small blips, maybe 100% more resolution that makes throttle control much easier.

I compared riding position on the Beta 4t to the 4RT and the handlebars were 1" further forward on the 4RT (compared to the pegs). I think this put more weight on the bars promoting the nose feel heavy. 30 mm riser additions brought them back to be more like the Beta. It also looked like the forks had not been serviced in a long time and fresh oil made them perform much better. With these two changes, it feels much better and the nose dive feeling is gone..

Did you measure how much squat was in the back? I added some spring preload to the forks plus more rebound damping to the shock and it feels better. Still, the shock feels stiffer than the forks. This bike has a fork compression damping adjustment on the bottom of the left fork leg. The manul implies it is only effective when the forks are bottoming.

Not as pretty as yours but this should work. Thanks for the details. Do you have a recommendation for a home use hobby level TIG machine?

engine braking - maybe but rolling on and off the throttle in first gear, my beta feels like it has more engine braking

Engine performance is very strong. This is in first gear, clutch out, double blip. I'm an old guy with damaged hands so more clutch usage would not be a good solution. To rephrase my question, what can make a bike nose dive on the back side of a log. I have not been on a modern or vintage bike that did this.

I got out for a ride on a new to me 4RT and it is quite different from my Beta 300 4t. This is a 300RR version, 2018. Power is much sharper than the Beta but it seems like power is cut much quicker than on the Beta. The front wheel really slams down on the backside of logs, even a small 10 inch diameter log.. I tend to double blip most any obstacle. I'll do a second blip when the tire is on the front of the log or on top, chop the throttle, bikes roll over and set the front end down. This 4RT just drops the front wheel like a rock hitting the ground pretty hard on the back side. I'm wondering if this is the way fuel injection works or could it be something else. Could it have less flywheel weight than the Beta for less run on? I put the electric start kit on but the flywheel is still very close in weight to the OEM flywheel so I don't think the starter has an effect. Simply bouncing up and down on the suspension seems OK but I wonder if too little sag, too much compression damping or too little rebound damping makes the rear tire slam in causing the front tire to slam down. Or is the Montesa just like that.

Has anyone successfully replaced the drive chain tensioner bushings? Mine is a 2018 and appears to have a solid bush but the replacements (with the correct part number) arrived as a compressed split bush. They also look a little too large. When I look at them, the chance of getting them installed, round and fixed in the swingarm to work with the tensioner seems small. Has anyone done it? Does it work? It does not look good.

I did heat the hub but was not careful with the old bearing. It is marked SKF France.

I disassembled the second bearing and the inner race is cracked. You can also see stress marks in the ball area of the matching outer race so maybe the cracked race allowed things to move around. I did use an expanding anchor to try and remove one of the bearings so possibly could have cracked the race but that would not explain the stressed out race. I have never seen a crack like this before.

Per my measurements, the non counterbored spacer is the correct width for this particular hub. I have ordered a new one and will verify its size. That brings up the question of how the counterbores got pressed in. I do not think an inner race could be moved 0.016" without destroying the bearing. Even if it did not destroy the bearing, I would expect it to fail immediately. The ring of interface between the bearing inner race and spacer is only about 1 mm wide. I would like to understand before installing all new parts and having it lock up. I have high confidence in my measurements but they may not be perfect. I could get an outside mic on the hub and used a depth mic for the bearing counterbores. They are rather thin and have a corner radius so not easy to measure but the number I found was the same width as the bearing. Maybe something is wrong with one of the bearings. To get this apart, I had to rip the cages from one bearing to remove the balls and inner race but I can take a look.

From your answer, I take it that the spacer should be a simple tube so I ordered a new one. It seems odd that the issue just showed up now. I use a torque wrench. It has over 200 hours on the bike. Maybe an original crush at the factory plus tiny moves at the axle tightening finally made it tight on the axle. I took some measurements and the spacer without counterbore is the correct length. The pressed in counterbores are 0.016" deep each. It seems odd that a bearing would take that kind of side load for a long time. The bearings are pretty small. The shoulder on the inner race is particularly small in area where is presses on the spacer.. The spacer does look like some kind of extrusion and I was tempted to make one of 6061 but I would have to order material for that too. Do you think the manufacturers all make their own wheels? Most of the bikes come from a small part of the globe so I wonder if they all get their wheels made at tahsame place.

Is the front wheel bearing spacer on a 2016 Evo just a simple tube or are there countersinks on the ends. The pics I see on line look like simple tubes. Would anyone know the exact length? Mine has countersinks on the ends that match the inner ring and sort of a bulging ring on the ends of the ID. Could this be correct? See pictures. To pull the front wheel from my Evo for a tire change, I had to use a hammer to get the axle out of the wheel. I never had to do that on this bike before and there is no corrosion. The bearings were crunchy feeling but there was no place to use a driver so I had to remove the inner race from one side to drive the bearings out. These are the original bearings, made in France. The bearings were greased so not a rusty failure mode. The spacer still will not slide over the axle from either direction. It does not look like the bulges on the ID were machined. It sort of looks like the countersinks on the ends and the bulges were formed by crushing the spacer but is that even possible? Strange

Curiosity made me look and I found this. It suggests that there is/ was a racing head available. However, it shows the racing head making more top end power and from my understanding more compression should make more low end while choking off the top. Is yours a 280 or 300? Could someone have put a 250 head on a 280/ 300 or a 280 on a 300? I would expect that to drive the compression way up. Does the engine knock (pink?) a lot when running. https://www.ossa-efi.com/home/engine/heads I had a Rev3 270 that was hard to kick and had very sharp power right off of idle. Adding 1 mm of base gasket in addition to the original made it easier to kick while softening the off idle power. It was a common practice, easy to do and easily reversible. I was told that someone used to make head spacers for Gas Gas to do the same thing so I once made one for a 250 Techno when trying to make it so my 100 lb daughter could start it. It was simply a 1/16" piece of sheet aluminium cut to match the head/ cylinder interface. One side sealed with the OEM o-ring. The other side was just flat surface to flat surface with a little silicone. IIRC, it was still too hard to kick but ran leak free long after it was owned by someone else.

A new to me 2018 4rt has a plastic guard mounted between the frame and bash plate that extends back to protect the suspension link. It seems like a good idea but also limits the torque that can be applied to the rear bash plate mounting bolts. If the bash plate is considered part of the frame, this seems like a really bad idea. I don't see it on the parts list. However, in addition to the front rubber pad above the bask plate, I see a secondary "pad" that I do not have on the parts list. Could the plastic piece I have be that secondary pad? Is the piece in the picture OEM? What came from the factory?

Solved The instructions are a bit misleading. They show the new harness plugging into a connector that is capped off. They must show the model with lights. The only capped off connector is in the boot in my picture. The new harness actually plugs into the map switch connector in the front boot. When this is done, putting the harness in place is OK and it also aligns with the OEM wiring diagram.

I'm installing the S3 E start on a 4RT. Near the end of the under fender install, a rubber boot with a number of connectors inside is supposed to get pushed down between the throttle body and frame. This is pretty much the same as the OEM setup but one connector accepts an addition to the harness so there is maybe a little more wire. The problem is that this boot with connectors looks to be twice the size of the space it is supposed to go into and I'm not getting it in place. (The estart kit adds the battery under this area so not as roomy as OEM but I didn't get a good picture of the OEM set up of this area before disassembly.) I have pulled the airbox off again but still no joy. Is here a trick or could I have some cabling routed in the wrong way? As it is, the cable that is supposed to connect to the estart button also looks too short.

Thanks for the pictures and details. I looked at mine again and stand correctly. The mount bracket looks the same as yours and is highly magnetic. It is an odd color and I just assumed aluminium. Since it is highly magnetic, could I assume it is just basic steel. IIRC, 300 series stainless is only mildly magnetic. 400 series is also somethat magnetic but I don't remember how much. I have no idea what they use for casting. I can mig weld some. Do you think standard steel wire would work?

Is this a 260 swingarm? I recently bought a 2018 300 4rt that has a cast aluminium kick stand that does not work very well. It is sort self retracting. The pin that locates the top part of the spring looks not positioned well to properly overcenter the pivot and stay in the down position. The other day I saw a 260 rt with what looked like an OEM welded up steel tube kick stand that worked better as in not auto retract. It looked like your picture. Are they interchangeable? So, If I could find one, could it be mounted to the 2018 300? Both parts of my 300 kickstand are aluminium and I don't weld aluminium. I can weld steel so if both parts of the 260 kickstand are steel, I could also bend and weld to suit. Does anyone have one for sale? I'm in the US.

Are there any secrets to removing the chain tensioner pivot bolt on a 2018 300 4rt? So far I have tried penetrating oil, heat and a few heat cycles. Does a steel bolt thread right into an aluminium pivot?

Has anyone done this? Could the Evo 4T share cases with any other Beta models so it may be possible with factory parts?