dan williams

Check out the Mikuni thread sticky'd to the top of the forum. Float level and travel should be adjusted and a 27.5 pilot jet is used around here for operation at sea level. Check to make sure your choke circuit is closing all the way.

I bought a set from Saunders Extreme for my '08. Expensive but good quality and they looked great.

I think the simplest answer is the most likely. Somebody played motocrosser on a trials bike. Probably with straight gas once the tank ran out of whatever you had put in. The kind of cascade failure you are all trying to diagnose is pretty rare unless an engine is going like hell when it fails.

Did you do the clutch fix? Polishing the tabs helps with the slip as it allows the fibers to properly re-engage under torque. Another thing to look for is to make sure your adjustment on the bars lets the lever return far enough to uncover the reservoir port in the master cylinder. When the lever doesn't return all the way the heating of the hydraulic fluid causes expansion that would normally just flow into the reservoir. If the hole is blocked though the fluid pressurizes the system slightly disengaging the clutch. I think the springs are probably fine. You'd have smoked the transmission fluid before you reach the temperature necessary to take the temper out of the springs.

Mine did too at first. I moved them forward and that helped. You can get used to them but they do take some getting used to if you're coming off a Rev3.

Oh yeah, that does make you the cool kid on the block.

Since they were going with "right side up" forks the next year any prototype USD forks would likely just get bolted to a production machine once the decision was made on the '96. My guess is you got one of those, "Hey, Mario, wadda ya want to do with these prototypes?" "Bolt them to a bike. We've got no other use for 'em."

I'm still thinking you got factory forks there bucko.

Yeah Beta did that on my 08. Really poor grounding scheme as it caused the kill switch and lighting circuits to cross feed when the ground went intermittant.

peterh, That's interesting that you went the other way jetting with the Boyesens. I can't find MC1 anywhere around here. All I see is the H1R Bel-Ray which I run at 100-1 with VP C12 race gas.

Not that I remember but it's been a while.

As a guy who chases pico-amps for a living I maintain you can never have too many grounds. The earth on the coil is probably best as you are not relying on the frame but a direct connection through a wire back to the summing node in the stator. Personally I prefer to ground things in several places so when one fails I don't have to push out of the woods or even know for that matter. I am a strong believer in different grounds for ignition and lighting systems.

Anything grounded to the frame has to have the anodizing ground off to make good contact. I also use conductive thermal grease to keep the aluminum from reoxidizing.

Merry Christmas to all my fellow Betazoids. And a completely crash free new year.

Consistent fuel is great but there's often an advantage to tweaking the jets just a bit. On the mikuni equipped Betas I've owned dropping the pilot to a 27.5 was pretty standard around here for the '08 Stock jetting was fine with a needle adjustment. The '13 was a bit of a surprise. It felt a bit boggy off the bottom so I dropped the pilot to a 45 and it got worse. Going up to a 50 from the stock 48 cleaned it right up. Easy starting is not always the sign of perfect jetting. For example if the bike starts easy without choke on a cold day the pilot is probably a bit too large.

I drop to a ten tooth engine sprocket. As far as being obsessive for jetting it really is necessary. Jetting is all about test, tweak, test, tweak. It takes patience but the reward is a bike that pulls like a steam engine yet jumps like a scalded cat when you twist the grip.

I put VForce carbon reeds on all my bikes to smooth them out.. Boyesens would probably have the same effect of increasing crank pressure at low RPM and therefore increasing torque. Proper carb jetting is essential to get a smooth transition between the different circuits in the carb. I also drop one tooth on the countershaft sprocket which I find better matches the power and of the engine to my meager skills. You may want to disassemble and clean the carb with compressed air as the pilot circuit on the Keihin is notorious for getting blocked with dirt or even water. That will make the throttle response seem abrupt as the bike comes off the malfunctioning pilot onto another jet circuit and suddenly wakes up. Can make a bike very hard to ride.

Yeah, I've been dropping a tooth on my countershaft sprocket since '02 which has the same effect. The gearing change shouldn't affect the clutch at all. I don't think I posted to this thread but I replaced the thicker fiber plates on my '13 with a cleaned up fiber set from the '08 and flipped the step washers around. The clutch is much less abrupt, more progressive and has less hydraulic drag. The pros like the abrupt clutch action but for a permanent novice like me the old plates, properly prepped are much better. I didn't have to leave springs off for light pull either as the stepped washers let me use all six. It's really good now!

Get a good two wire kill switch. Lanyard or pushbutton. Make sure the ground connection is properly tied to a hard point on the frame not through the triple clamps or bars. Yeah I had the seals in the exhaust of a Rev3 blown out by a "friend" jokingly putting a hand over the exhaust. Still better than pulling a plug wire. I've also tried killing a WFO engine by pulling the plug wire. NOT DOING THAT AGAIN!!! Not keen on that feeling of waiting for my heart to restart. Funny story, my nephew wrote a piece for school on his experience doing the same. He didn't want to show me because it was on my bike but when I read it, it was brilliant. The spark burned through his leather riding glove and the leather knee pad on his pants where they were touching the frame. His friend told him he had never heard anyone scream that loud but Greg said he couldn't hear himself scream because of the buzzing in his head from the current.

Yeah common problem. Do what the smart people above suggest. Annoying that vibration through the lever ain't it.

Usually if it pops into gear that means it wasn't in the actual neutral in the first place. You can get a false neutral between gears in almost any box. That is because there has to be enough spacing between the gears engaging to prevent more than one from engaging at the same time. Happened to me in a Hyundai once. It was entertaining to the firemen sitting outside the fire station watching me slide by mashed into the steering wheel. I was less entertained. With a trials bike having such close ratios in the first three gears it's easy to think you are in the real neutral. That's why you'll see experienced riders furiously stomping down to first and then clicking up to the gear they want before riding a section. Most gear boxes are set up with a detented cam attached to the shifter cylinder that controls the position of sliding gears on two gear shafts. There is a spring plunger that sits in the detents that indexes the shift cylinder into the proper position for each gear. Proper neutral has its own detent but when you are in false neutral you are between gear detents and slight movement of the shift cylinder can cause the spring loaded plunger to rotate the shift cylinder into one of the gear detents "popping" the bike into gear. Check out the exploded parts diagrams from the Beta website and look for an access bolt on the engine for the detent plunger spring and then check on your motor to make sure that bolt hasn't backed out. If the bike isn't spontaneously changing gears as well this probably isn't the issue but hey it's not a lot of work to look at a bolt. Now if the bike was dropped on its shifter or the shifter saw a wonking big hit then the shifter forks that shuffle the gears back and forth can be bent but that usually manifests as difficult shifting and really isn't all that common on a Beta. One thing that is common to Betas is notchy shifting which I attribute to the long aluminum shift lever because it is very flexy. Good thing too as a friend of a friend, who I was assured was an experienced rider, was "test riding" one of my bikes stood on the shifter and jumped. When those of us watching got over the initial shock and asked, "What the *&$# are you doing?" He looked at us with the classic "well DUH" expression and said, "Trying to start it of course." He didn't buy it. Probably thought it was too hard to start.

Not necessary but it couldn't hurt.

Easy to misunderstand what you are describing here. I think the key statement is that it is acting like the front brake. The clutch is about as simple an actuating mechanism as you can get. That means the problem is simple to diagnose so no panic. The main difference between the brake and clutch is the clutch is supposed to have sufficient travel in the slave cylinder to take all the fluid the master cylinder can give it. On the brake that slave cylinder's travel is limited so that there is resistance before the master cylinder can be completely emptied of fluid. So if your clutch is acting like the brake something is stopping the slave cylinder before it can absorb all the master cylinder fluid. Two things can cause this, 1. The slave cylinder travel is offset because the spacing between the actuator and the pressure plate is too short and the slave cylinder has treid to compensate by using some of its travel and you are running into the end of the the slave cylinder's travel. This is the most likely scenario and is because some piece got left out or replaced with the wrong piece. Often the ball bearing that decouples the spin of the clutch mechanism from the non-rotating slave cylinder. Other possibilities are missing/ misassembled thrust washers/bearings on the pressure plate. 2. Something is binding in the clutch actuator mechanism. If you pull the clutch cover off make sure the pressure plate is fully engaged with the clutch pack. Actuate the clutch and see if the pressure plate moves. These two things indicate the mechanism is free. Time to disassemble and make sure all the parts are where they belong. My guess is you'll find something not where it is supposed to be.

It doesn't sound familiar to me. Maybe you've got some factory prototype forks?

Expert doesn't sound very expert. If the crank seal on the primary side fails you will get transmission oil coming into the bottom of the crank and get a smokey exhaust and a fairly distinct smell of burning tranny fluid. A leaky seal on the other side will lean out the air fuel mixture causing pinging and loss of power. Neither will give the symptoms you describe unless oil is fouling the plug. The problem with Beta stators is pretty well known to be an issue with the trigger coils. Often they will put out a marginal pulse that is enough to trigger the CDI until the coil warms and the output drops below where it can fire the CDI. As described a blocked pilot circuit can look like this if using the choke. Bike will essentially run on the choke circuit and then die when it warms up and the choke is flipped off. If you can start the bike at 1/4 throttle or with the choke on that's a good indication of a blocked pilot jet. Fuel starvation is another possibility and that is where the tank vent in the fuel cap comes in. Water in the fuel also comes to mind. Modern pump gas has ethanol in it which absorbs water (displacing oil in the process, bad for two strokes) however water that gets into the tank and isn't absorbed will sit in the lowest part of the tank and can get sucked into the fuel system gagging the carb. As my esteemed colleagues have noted above start with (inexpensive) basics. Drain fuel tank and put in fresh premix. Disassemble carb and clean out with compressed air. Check condition of reed petals to be sure none are broken. Make sure fuel is freely flowing in fuel line and that fuel cap vent is open. Fresh plug and check plug cap, possibly replace in case plug cap resistor has broken down. Throw a compression tester on and kick a few times with the throttle open just to make sure you have adequate compression. Low compression will make a bike harder to start. I'm not sure but I think the last time I did the compression experiment I was seeing about 140PSI on the '08. If that doesn't explain the failure I'm still thinking stator.