mcman56

I put in a new tensioner today. First it was noisier so I manually pressed on the plunger while rotating the engine a few times. I reinstalled the spring and let it warm up. I think it is OK but as you listen to noises in an engine you can start to hear (imagine?) all sorts of things and I don't have another to listen to.. I made another video with the microphone not as close and out of an echo area. That specific noise is still there but it seems more in line with the other noises. Even when it was louder it went away or blended in as the rpms were bought ut to mid range. The tensioner is a ratchet design and tightens in steps. It seems logical it would get noisier as the chain wears but then quieter as the chain loosened enough for the tensioner to get out one more tooth. That could explain the difference between two bikes. The video is kind of vague because all you need to to to make it sound bad is turn up the volume.

Clearances were spot on. I rotated and looked at all parts of cam chain and it looked ok so I’m down to suspecting the cam chain tensioner. I hear the tap/ sound at idle but when I bring rpms up slowly to mid range, the sound is less noticeable or goes away.

I appreciate all of the input. I did notice it oddly hard to kick over at least once. I pulled the valve cover and see nothing obvious. The decompressor spring does not look broken and the decompressor is free to rotate. Surface finish of the decompressor shaft is not that great and looks like it was worked on with a file. If it was stuck, I guess it is possible it got unstuck during disassembly. The spring force is very very weak but it is a tiny spring. Locked in the TDC position, it feels like the weight of the lever looking part provides the force for returning. I can't rotate the cam so assume that means the cam chain is tight. Looking down from the top I can see red guides are there but no detail. Cam sprocket feels bolted tight to gear. Rocker arms have some end play but otherwise feel tight. Rollers that run on cam feel OK as does the little pieces that meet the valve stems. I did not check clearances before pulling the valve cover but, by feel, nothing was grossly loose. There were a couple of very tiny flakes on the magnetic drain plug. Oil looked good. Nothing was in the two plastic oil filters. Any other suggestions? I'll look again but all I can think of is to loctite the gear to sprocket bolts, set the clearances and see what it sounds like before going deeper.

I pulled the tensioner out. Teeth look ok and spring has enough tension to push out the plunger when off the bike. When it was out, I tried pushing on the red guide. It felt solid but I don’t know what it should feel like. It does sound much like a klx250 with bad tensioner I heard recently

I have a 2016 300 4T with maybe 75 hours on it, almost 35 since valve adjustment. It runs fine and starts easy. On the last few rides, I noticed that the top end seems to be noisier than before. Nothing sounds horrible but there is some "clitter clatter". Probing the head area with a mechanics stethoscope, it seems a little louder at the cam chain tensioner. Is this normal? See the video. It does seem to sound worse in the video than in person. The deep sound that comes and goes is it quieting down a little when pulling in the clutch. The engine was cold but I think it sounds the same hot. If not normal, any ideas? https://youtu.be/gk9x64aulWQ

I go up to 100 psi with tire lube

It sounds like the throttle is barely opening. Could it be too much play or some kind of binding. You could pull the carb boot off to verify full opening or even pull the slide out to verify. Other issues should have different symptoms.

I may have had it easy. It was a 6 volt points controlled ignition that was already 25 years old at the time. The coil had 2 leads that fired two plugs at the same time. Modern ignitions must have a lot more zap.

Comedy Central - I was once riding a V twin motorcycle with no insulation at the spark plug cap while wearing shorts. I lost my balance at a stop, planted my foot on the ground and the bike laid against my leg. Continuous high voltage shocks zapped my leg while I fought to regain balance and get the bike off of my leg. So, I can say from experience you would know. (This was prior to Youtube.)

I had a similar issue with a fantic 80. I had to use a hydraulic press to press the axle out. It took a surprising amount of force but did not damage anything. They are called shop presses here but seem like one of those things that may have another name elsewhere. Something like this. https://www.harborfreight.com/20-ton-h-frame-industrial-heavy-duty-floor-shop-press-60603.html

My 4t usually has a very steady idle but sometimes it will step down about 200 rpm and stay there. The idle does not wander like a lean 2t. It may not do it for a couple of rides and then do it consistently. Otherwise runs fine. I fiddle with the mixture screw and it does not seem to help. I do ride at different temperatures and when it started today, it was maybe 20 degrees cooler than it has been. 25 pilot, screw 2 turns out, needle one step rich from mid, 125 main. The plug is black but does anyone get a tan plug on any beta? Beta seems to run cold plugs and I never got a tan plug on a Beta 2T either. Can a blackish plug in itself cause idling issues?

Does the 130 produce any black smoke when full reved up in neutral? I have a 125 in mine and get just a hint of black smoke at full throttle in neutral. I don't know if it does that under load.

From my understanding, a common failure of CDIs is that the advance function fails. They could get stuck in a retarded mode or advanced mode that could explain crappy running but not really a dying engine. If you have a flywheel puller, you could try fully advancing the timing to see what happens. That is assuming your model has an advance curve. I checked a 97 techno that had about 20 or 25 degrees of advance from idle to full scream. I have a 2008 REV 3 that only has about 6 degrees of advance through that range. 6 degrees is likely due to higher voltages making things happen a little sooner rather than an actually designed in curve. Beta must do something different with the port timing for engines with and without advance. I wish I understood what.

Are the available rings compatible with Nikasil? I thought rings were developed for specific bore materials.

I had a rev 3 that acted like that as the stator failed. It seemed exactly like a carb issue. Possibly it did not produce enough voltage as the compression pressure went up. It started out intermittent and got worse.

This does nto really answer your question but I ran bultaco leading axle forks with the Bultaco yolks on a BSA C15 and it turned quite nicely.

Have you tried starting with the throttle fully open?

Lampkins have a couple of pages of recommendations for SSDT preparations. One of these is a piece of foam pushed down between frame and front of air box by the top of the shock on an evo. This will cause it to touch the top of the muffler. How do you ensure it does not melt or catch fire?

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