mcman56

A big bore kit was available from S3 for the Gas Gas 125 but I have never seen anything for the beta. Someone suggested that it was just a shortened 250 barrel but trying that on a beta would be a project. https://shop-s3.com/gb/cylinders/244-kit-cylinder-piston-gaskets-head-cover-gas-gas-tr-225cc.html?search_query=gas+gas+225&results=2

From a theoretical point of view, why would lighter springs create less drag? When you pull in the clutch, the pressure plate moves back a fixed distance creating space for the clutch plates to move apart. When fully disengaged, why would it make a difference if there was 5 lb force or 500 lb force trying to push that pressure plate back in?

I would like to inspect the impeller on a 2016 4t. The manual makes it look like there is a gasket rather than an oring sealing the cover. Is the gasket reusable or should I order another before pulling off?

I had a somewhat similar problem on an MR50. It ran fine until under a load but at this point I don't remember if it stalled or simply ran poorly. I found a wire under the flywheel that had rubbed on the flywheel so was kind of bare. It may have been to the points. I taped and moved the wire to eliminate the issue. My theory was that as compression pressure went up, voltage required to spark went up and the voltage would arc to the flywheel.

I don't know if this helps but I once bought a used Beta that had a round steel ball under the bleed screw of the rear caliper. At the time I did not know if it was OEM or not. I suspect a PO had a hard time getting the screw to seal so added the ball. It did work. I would think the challenge to re-threading the caliper would be ensuring the that the threads were perfectly perpendicular to the sealing surface at the bottom. A ball may help if it was a little off.

The non adjustable needle was the only smog compromise to the carb. I have not seen one with a cap over the pilot jet like some other street legal bikes. As I remember the carb was exactly the same a a tl125 when viewed side by side at least the us models

Can you detail the gear box differences? Where do they fit in? Do you have numbers? Carb works fine when tuned properly. All that is needed is a richer pilot jet and adjustable needle. Needle is available from carb rebuilds kits on ebay. Carb on the reflex is the same as TL125 and other 125s like SL125, etc. Although they do not seem as readily available as they once were https://www.ebay.com/itm/HONDA-SL125-SL125S-Carburetor-repair-Kit-KEYSTER-KH-0047/253694458093?hash=item3b115e38ed:g:bOYAAOSw6EhUNWk1

I believe the internal gearbox ratios are the same. Only the final drive is different. The trials TLR200 came with larger diameter forks, aluminum rims and a much better skid plate plus the lightweight seat/ tank. I think the front brake is different too. The Reflex came with all of the street legal equipment but it can be removed. The larger Reflex gas tank and seat make it a good choice for trails like the Rubicon.

I agree that it has a plugged pilot jet. It is only about .014" in diameter so plugs fairly easily. Drilling out to about 0.016" (#78) will get rid of the pop and stall. They take an odd pilot jet so sizes other than original can be hard to find. Multiple people in this area ride a Reflex in trials. I have done it too. They are no modern bike but are fun to ride and very quiet. The only change really needed is lower gearing. A 9 tooth front with the OEM rear works well. But in addition to old technology, they are about 50 pounds heavier than a modern bike.

That is what mine does. I think many bikes do it to some extent but mine was the worst. Advice on line suggests an air leak in the exhaust system allowing air into the pipe that then causes un burnt fuel to ignite in the pipe. I went as far as bubble testing the pipe under water and fixing all pin holes but it still does it. I also notice a little pinking when rolling along with the throttle barely cracked open and suspect these are related. It does not pink under any other conditions and other wise runs fine. It did the same thing with a mikuni and keihin jetted rich or lean although rich jetting did reduce the popping. It sounds like some KTMs do something similar It looks like you are missing the skid plate.

I had a 130 main so went to 25 and 130. Clip is at 4th position. Spring looks silver. What spring is OEM? What is the blue spring for? It is lighter for quicker opening? I have ridden at sea level and 5500 feet and ti seem sOK

I have been through the carb and tried different jetting plus have the adjuster screw. Initially, I had to run a rich idle to prevent bogging. Once I raised the needle, the bog tendency went away so I leaned out the idle. I'm now running a 22.5 pilot and since the symptom is lean will go up one size to see if improves.

Thanks for the responses, it seems like this means lean.

I have a 2016 300 with the standard pipe and muffler. I have adjusted the jetting and it runs great with one exception. Occasionally, when opening the throttle from idle it will stall. It does not pop through the intake but instead you hear what sounds like fuel burning in the exhaust. It sounds very similar to a gas barbecue being lit. This happens at lower idle settings, below 1200 rpm. At higher settings up above 1400 it does not happen. Is this rich or lean?

I ran a 26 mm OKO on a 250 REV 3. I bought it from the same place. It worked well and the supplier was helpful.

Does anyone make polypropylene or polyethylene full length fork guards? I think the carbon fiber looking ones are ABS and they break way too easily.

The popping I can get from mine is like adding up 5 or 10 of those pops. It only happens when winding up the engine and chopping the throttle off.

I don't know if they would fit but 1992 PW80 forks were very smooth with nice dampening. I assume all PW80 forks are the same. Looking on line, they even sell Chinese copies for very low prices but the OEM Yamaha ones were surprisingly good for such an entry level bike. As I remember the front brake was good also. I found this at http://www.pro50parts.com/buy/pw221-pw80-front-fork-set/PW221 Size Spec: 63.50cm in Length, 26mm in fork leg diameter, 10mm in wheel axle. Leg Diameter -- 26.0mm/34.3mm The same site has dimensions for PW50 forks.

I have a rev 3 that will pop in the exhaust when chopping the throttle off, sort of a Pop...Pop...Pop I chased/ tried everything you can imagine to eliminate the issue but it is still there. I tried all different fuels including race gas by the can. Other bikes I have ridden will do that occasionally but mine does it a lot. Otherwise, it works fine. It was sold as a 200 and I put a 250 top end on it. The top end is from a different year so maybe that has something to do with it. When Beta sold 270 kits, I noticed that there were different kits for different years but I could never find out was was different.

If an original carb is not easy to find an OKO from Mid Atlantic Trials would be an option. I assume they could supply a throttle and tube also.

What exactly is a flame out

I have a 2016 300 4t and it runs OK but sometimes spits and dies when opening the throttle. Yesterday, i even got a very serious spit back through the carb, (80 degrees F). I have had bikes spit the carb right off the manifold with spit backs like that. I pulled the carb today to check jetting and noticed that the big vent for the vacuum slide was not capped off like it should be. There was a little dust up there like it had been off for a while. Could missing the cap create issues I have seen? Otherwise the carb looked clean, 27.5 pilot, 120 main, idle mix 2 1/2 turns out, needle 3 positions from top, standard quiet muffler, I don't know how to tell the difference between slide springs but assume it is the original. I have no other 4t to compare it to but the fan does seem to run a lot and sometimes it is finicky to start when hot so I thought it may be lean. The bike does have extremely low hours so maybe that is why the fan runs a lot. I'll install an adjustable idle mix screw. It seems like the only other option is to raise the needle. Are there any recommendations?

I have run X ring chains on a number of trials bikes including a Rev3 and Evo 2t. A standard O-ring chain fit on a 2002 Sherco. They need little lubrication, no adjusting and seem to last forever so are very convenient. You can buy wider chain tensioners to accommodate. I did not notice any power loss but none of the bikes were under-powered. Anyway, rider skill limits my riding infinitely more than power. But, there is little clearance between sprocket and engine case on the 4t so I'll give the WD40 method a try.

Has anyone run an o ring chain on a 4t? Does it rub on the cases? What front sprocket size do you run? I have a 9 tooth and there is very little clearance between chain and engine case with a non o ring chain. I had a short piece of the skinny RK X ring chain and if I put it on the sprocket and push in on the chain, I can feel it drag on the case when turning the sprocket. The X ring chain is about 0.045" wider than the non o-ring chain (at the link plates not pins)

To clarify, does the Amal 80/200 throttle tube fit into the stock 4T throttle assembly or do you need a complete Amal 80/200 throttle assembly?