mcman56

This is the float valve in the carb I have. It is marked 270 on the brass part.

I happen to have one of those carbs that came off a good running 315, maybe a 2000. It has a 45 slide, 46 pilot and 114 main. I don't think that second slow jet is there. The manual says float height is 18.5 mm. A quick look on line suggests that 315s came with a 46 pilot so a 33 would make it quite lean. I would try a a 46 pilot or at least something bigger than what you have. I don't know how sensitive the bike would be to slide changes but that should just affect the transition off of idle as the slide lifts. Stock Jetting A manual is here. http://montesatrials.com.au/store/wp-content/uploads/bsk-pdf-manager/Montesa_315R_02_2002_2.pdf

It sounds lean. Have you tried adjusting the idle mixture screw to make it richer? I believe turning the screw clockwise makes the mixture richer on that bike. Clean the carb again. Check float height and take a good look at the idle circuit and pilot jet again.

I found it, thanks. There are two springs and a couple of sealing spots in the cap. If things get out of shape, I wonder if it can sort of become a pump. I cleaned and reassembled and will see what happens.

Are you saying fuel normally comes up out the tube? I can be sitting on the bike not moving and watch it bubbling. What would push the fuel up? For something to flow out it, there would have to be expansion or some kind of flow in. I looked up CSP caps and only see them for 2018+. They do not include a vent line. I believe 2018+ has a vent line connected to the tank directly. Mine is a 2016 and would need a vent.

During the last few rides on my 2016 Beta 300 4t, I started smelling fuel. I have a clear tank vent line and I can actually see gas bubbling up the line. A 1/4" or so of air will be followed by a 1/4" of fuel and so on. It sort of slowly oozes out the top of the vent line. A long time ago I put on a long vent line because fuel will spill when pointing sharply down hill and ran this a long time before this issue. See picture. The fuel line is not too near the exhaust. The bike is not overheating and the tank did not feel particularly warm when I put my hand on it. The tank does not have to be full for it to happen. It does it with and without the vent fitting on the end and with the tube facing up and the tube facing down. The hot start line was touching or just about touching the exhaust. I have corrected but not tested and don't see how that could create this issue anyway. The bike runs well but can somethings be finicky to start. Are there any ideas on this?

You are rarely in high traction situations in trials so I don't find the TY brakes to be an issue. The TY is also not that heavy at around 175 lbs. The Honda 4t is listed at 170 lbs so not much difference at all. As an amusing example... I had been just riding my TY for a while and commonly riding over a log about 12" diameter with the top maybe 18" off the ground. One day I went to the same exact place on a 280 Beta. I lifted the front wheel and anticipated the front wheel hitting the log so I could apply the second blip but the back wheel was instantly on top so I was over the log before I knew what happened.

I believe the answer is related to your talent level and type of stuff you ride. I'm an average 65 year old with a modern Beta and a TY175. On any modern bike, I am constantly on all of the controls; throttle, front brake, clutch and back brake. My TY is geared quite low so I get some engine braking and can mostly ride with just the throttle. I find it much much easier to manage one input vs. four. (For a talented rider this probably does not matter.) Brakes are weak so when you do use them you don't have to worry about stalling the engine with the back brake or easily washing out the front wheel with the front brake. Power is soft so you don't have to worry much about using too much and things happen slower so reflexes do not have to be so sharp. (This may be the definition of forgiving.) It is short so some people say they can turn tighter on a TY175 than they can on a modern bike. Overall, it can be much easier to ride in many moderate sections. However, there are a few situations where there is no comparison. Due to lack of suspension, the TY feels like the ball in a pin ball machine in anything like a rocky creek bed. The lack of abrupt power makes it difficult or impossible to get up bigger obstacles if there is no run at it. (Riders skilled with firing the clutch would not have this issue,) The third thing I notice is that the TY clutch out riding style sort of commits you to a certain line in a tight turn. If that line does not work out, there is a dab. On a modern bike, I can pull in the clutch to regroup and make corrections mid turn.

I had a 2014 Evo 300 2t Factory and now have a 2016 Evo 300 4t. They have very different power curves. The 2t was quite soft on the bottom with a grunty type of power that was very easy to modulate. However, at higher rpms it became quite powerful. If the throttle ever "gets away from you", it would not be a good beginner bike. My 4t is not so soft right off the bottom (particularly just as you let the clutch out). It is really only noticeable on full lock turns. However, the rest of the power curve is very smooth, almost feeling kind of fluffy. You can be much less precise with the the throttle from mid range on up. Other brands are likely different. If you are a lightweight, older Beta 300s required a pretty firm kick to start them. I have read that the newer ones are easier to kick. Timdog Does the Amal 80/200 smooth out that initial cracking open of the throttle? Does it use the same cable? I would like to smooth out that little part but would not want a slower throttle anywhere else or have to twist it farther. I have read that newer 4ts come with a different/ smoother throttle but don't know how they compare. I wonder if that initial little surge is throttle related or more related to inertia of the slide when it first lifts. Do the Hondas so that? I prefer a slow idle around 1300 rpms and suspect it would not be noticeable with a higher idle.

The evo 300 4t with standard muffler is the quietest trials bike I have seen by far, even quieter than a Reflex. I was warming up mine the other day. It was on the other side of a sliding glass door and I had to listen very carefully to tell it was running. I have heard that other mufflers give it much more power and much more noise. I do think the evo 2t clutch is a little more progressive than the 4t clutch but not a huge difference. The 4t is vey easy to kick over.

https://betausa.com/content/SUPPORT_PDF's/2008 Rev 125-270 2 stroke owners manual.pdf Be sure to drain the cartridge. After filling, be sure to then pump the air out of the cartridge.

The TL250 has an external grease fitting for a the clutch actuator on the left side cover. This does not look like a standard grease fitting and the standard tool does not fit. See picture. How do you fill it? I thought about threading in a standard fitting but it would stick out farther and would be easy to tear off.

Maybe these guys can help. . http://www.ajpamerica.com/calipers.html

I have been thinking about a slower turn throttle and have heard the newer Beta 4ts come with a slower throttle. Do you know how the Amal 80/200 compares to that? I would just like to smooth out the initial opening of the throttle....if that is possible. When doing tight turns, the initial cracking of the throttle can be abrupt. This is particularly a problem when going back and forth from 2t to 4t. On that same note, how does the 4rt compare in that situation where you just barely open the throttle? Do they really have no engine braking? Does that make it easier to go back and forth from 2t to 4t? But....don't they require a high idle speed?

I have had some success bonding to plastics like PE and PP with a product called marine goop. Goop is the brand and marine is the flavor.

Thanks for the info but how can you be sure to get a Taiwanese version? Do you run a 22 mm or 24 mm? Did you find a spigot mount carb or adapt a flange mount type? How did you adapt? Sorry for so many questions but it seems difficult to find something that will fit with the stock air box.

Details state that OKOs do not work with stock air box

Does anyone have experience with the Chinese Keihin copies of 22 and/ or 24 mm size for TLR200s or similar? Is there a brand to recommend? I'm looking for something to run on a TL250 with stock air box. Most other carbs are bigger.

This is also a TL250. Out of curiosity, what carb do you run on your TL250? This bike came to me with no carb and there do not seem to be any great options. OEM is not available. OKO is larger and does not seem to fit with stock air box. I often ride in very dusty condition so really want to keep the stock air box. I have a Mikuni VM and Delorto 26 mm but they are also pretty long plus have large entrance mouths like the OKO. China reproductions of an original Keihin 22 are 24 are available but I wonder how they work. I would also have to adapt from flange to spigot mount but that is doable.

I have an old aluminium gas tank that looks like it was not used for many years. I poured out some stinky gas, filled with fresh gas and shook it periodical for a couple of weeks to clean it out. After draining and drying, I can see sort of a layer of solidified gas lining some of the bottom. The petcock must have had a slow leak because it is covered with what looks more like dried tree sap than dried gas. Are there any solvents that will remove this? A non hazardous one would be nice but not required. I can also see that there are a couple of pin holes close together. Has anyone had luck with using epoxy to spot treat pin holes?

A flywheel weight really helps slow down the engine response. I believe all UK bikes come with them but someone may have taken it off. Pull the cover and take a look. They look like the picture below and are mounted to the outside of the flywheel. Also take a look at how many teeth are on your front sprocket. It is counter intuitive but lower gearing (less teeth on the front) slows response by reducing the transition from clutch in to clutch out. The bike will go slower in first gear. Lower gearing also makes it harder for the bike to totally get away from you because it will run out of rpms before too long. Many Betas come with an 11 tooth front. I ended up with a 10 but a 9 is even better for the situation you describe. A 9 kills come of the response to get over an obstacle but that may be exactly what you want plus you can always use 2nd gear. Front sprockets are also cheap. I also agree on comparison with another bike.

Looking at self etching primers, none show as heat resistant to go with engine paints. On top of that, engine paints seem desirable due to resistance to fuel. Are there any specific recommendations?

This is an interesting comment. I also noticed some odd looking rust on the bottom frame rails that were probably under the skid plate. The rust is protruding up from the surface, sort of like crystals growing on the surface. There is not much but it does look odd. I was planning to remove rust and paint this area. Other areas of the frame just look a little rusted and similar to what is found on other bikes this age. Are you suggesting that the frame should be totally rust free? The skid plate is also steel and will get cleaned and painted.

This is an interesting comment. I also noticed some odd looking rust on the bottom frame rails that were probably under the skid plate. The rust is protruding up from the surface, sort of like crystals growing on the surface. There is not much but it does look odd. I was planning to remove rust and paint this area. Other areas of the frame just look a little rusted and similar to what is found on other bikes this age. Are you suggesting that the frame should be totally rust free? The skid plate is also steel and will get cleaned and painted.

I have a 76 TL250 with pretty severe pitting on the outside of both magnesium engine side covers. They are structurally sound and this is not a restoration so I'm not concerned with a cosmetic repair. However, I would like to prevent further corrosion. For better or worse, they are both now bead blasted clean. This is an air cooled bike but must have spent some time parked near water. I'm in a mostly dry climate so there should be no significant moisture exposure. Some on line sources say that Alodine or some other "conversion" prep is needed first to prevent corrosion. Other sources say that Alodine will actually promote corrosion in magnesium and make it so paint will not adhere well. These chemicals do not seem readily available or cost effective plus can be hazardous so are not desirable. I do think I saw some gold tint on a cover when blasting but if it was Alodine, it did not help the original finish. All sources seem to agree on a self etch primer but it looks like these are mostly lacquer based except maybe the Rustoleum brand. They also come in different colors like green and gray which must signify some difference. Is one better than another for this purpose? I plan to top coat with some enamel roughly matching the original Honda paint color. Does anyone have experience with something like this?