dan williams

That idle mixture screw is a pain in the A** isn't it. I have a whole bunch of long flat blade screw drivers ground to size and scattered all over my car and garage just so I have one handy at all times. I tried one of the Jitsie mixture screws but it was worse than the stock one. The older bikes had a screw soldered to a cable but I guess Beta gave up on that idea. The carbon reeds won't seem snappier but they will let you pull a gear higher without stalling. It actually will come off idle a bit cleaner because the carbon reeds open and close faster because they weigh less so they will enhance the fuel air charge in the crankcase at low rpm. At high rpm the reeds could be made of lead and it wouldn't make any difference because they just stay open anyway. I always love to read someone bragging about how carbon reeds make their bike faster. Goes along with the, "My bike is faster because it has the RED powerband"

One thing to consider is the current required to start the fan going is considerably more than the current required to keep it going. When the switch first closes you can get an inrush current to the fan above ten amps as the motor builds up a magnetic field in the windings. After the initial demand the operating current usually drops to less than an amp. I know this because I worked on motor control chips for a bit but mostly because I was troubleshooting a fan and put it on a current limited power supply and it wouldn't start up until I cranked the amperage. The problem is usually the thermoswitch. If it is operating normally it will have resistance in the milliohms. As the switch ages the contacts can build up oxides and carbon and pits on the surfaces due to the initial arc when the switch closes. This can cause the switch to gradually start degrading so even when closed it can read several ohms. Doesn't seem like a problem except it will degrade to a point where the required inrush current can't be provided reliably. So maybe you're cranking along and the lighting coils are putting out full voltage, enough to overcome the contact resistance, and the fan starts. Or you're sitting in line at a section with the engine idling and the fan just can't get enough current to start. Comes down to when is an on/off switch not an on/off switch. So yeah you may read the switch as turning on and off but check the on resistance and you may find it's sufficiently higher than a new switch. Just back of the envelope type of calculation, say your switch has got 5 Ohms of contact resistance and your lighting coil puts out 12 Volts. E = I x R (Volts = Current x Resistance) Assuming the inrush current looks like a dead short across the fan motor, which is pretty close to reality when starting, then I = E/R (Current = Volts / Resistance) Current = 12/5 or 2.4 Amps. If the motor needs an instantaneous 10 Amps to start then the lighting coils can't push enough current through the switch to get the fan spinning. Or there might be almost enough current and you end up with an intermittent failure like you have. Keep in mind that resistance in a connector or ground will cause the same symptoms. So the practical takeaway is those few ohms that you normally just ignore on a meter are actually pretty significant when large currents are involved. Even for a very short period of time.

Excellent. I've never thought the thicker plates were anything more than a solution looking for a problem or at least a hail mary attempt to fix what is easily fixed with the fix. Last sentence brought to you by the department of redundancy department.

Dumb luck. Conditions were just right to keep it dieseling along. There could be a weakness in your kill switch or wiring. When an engine is running full blat the ignition coils are putting out significant current and any resistance in the wiring that shunts the current to ground will keep some current flowing into the CDI. This is why I like to run the ground wire of the kill switch back to a hard ground on the frame. Usually one of the screws that mount the ignition coil. Years ago most bikes had a one wire kill switch. Ground was achieved by shorting to the handlebar. Good in theory but bad in practice because a runaway engine would pump out enough current to overwhelm the contact through the steering head bearings and not only not shut the motor down but electrify the handlebars in the process. Was great fun in the rain since hundreds of volts occur in the primary ignition circuit. Take a look at the wiring for your kill switch and if the ground doesn't come from a hard point on the frame you need to correct it by running another wire back down through the harness to a good frame connection. Beta's not known for their wiring prowess.

Ok guys think this through. Keihins don't have plated slides, just anodized aluminum. He parked the bike to walk a section so the engine was warm so no ice. A bike can't run on fuel in the crankcase without air mixed in the proper ratio. The bike ran well before and after so the needle holder and needle jet were in correctly. It is possible to put the needle jet in upside down in the Keihin but the bike won't run. That leaves dirt in the slide causing it to stick to which the Keihin is very resistant. Strong spring, small slide. Pretty much narrows it down to throttle sticking or cable pulled out. Both fairly common. All you have to do is momentarily catch a piece of clothing on the throttle cable to yank it out of the twist grip or carb noodle not to mention the excitement of hooking a branch on the loop trail. On the Beta you also have the potential of pulling the cable out of place by moving the wire bundle that comes up through the top plastic cover. I don't think this is anything unusual Simon. You just hooked a cable and now it's got you a bit freaked out. Happens to everybody at some point.

The only thing that will make an engine run away like that is something that holds the throttle slide in the carb open. A couple of common scenarios occur, Throttle tube sticking due to a fall or grip rubbing on end of handle bar. You may have noticed a lot of riders use "bar ends". Those things that sit in the hole at the end of the bar and require you to cut open the ends of your grips. These are popular for two reasons, First is you tend not to rip up grips as quickly. Second, in a fall the bar end takes the hit and you are less likely to mash the throttle tube further into the bar or even damage it so it doesn't turn freely. I highly recommend you get a set of bar ends and open the end of your grips. The other thing that is common with any bike is the cable getting pulled out of either the throttle housing at the top or, in the case of the Beta, the "noodle" that comes out of the top of the carb. Here's where it's important to get into the habit of before you start the bike twist the throttle and let it go and listen for the "thwock" sound that comes from the carb as the slide hits the idle adjust bolt. If you don't hear it DON'T start it. Fix it by making sure the grip is loose and the cable hasn't pulled out. Make it a habit. I don't even think about it anymore I just do it by reflex and it's kept me from the full throttle start a few times. It also has the tendency to seat a cable that isn't fully seated if you twist to the full throttle position. Now as for not being able to kill a runaway engine at full throttle that is a fairly common experience. At that speed there is more than enough heat and free radical chemical compounds to keep an engine going without any spark. As for pulling the plug wire, I did it once. Never again, I actually felt my heart stop until the engine wound down. Scary as S***. As the wise folks above said stuff something over the exhaust. A glove a boot whatever. It will usually kill or slow down the engine enough for the kill switch to work again.

Nothing like an engineer with a new bike.

Betas do whine a bit. Dammit why can't you guys all live near me so I can see these things in person. That's what it sounds like when I whine.

Oh and in a pinch one of those cans of compressed air from a camera shop can be used to blow out a carb.

I like how Beta paints the reeds black to look like carbon fiber but under a microscope the fibers are clear so fiberglass. Small amounts of water can get into an engine all kinds of different ways so it's not a great indicator of leaks. Certainly not intake tract.

Just another thought. Chewy posted measurements of his basket and hub runout. I wonder if there is some eccentricity in your clutch assembly. Perhaps a bearing is bad? That could also cause a whine but only with the clutch out and the tranny input shaft driven.

Ooooh the whining noise doesn't sound good. Usually indicates a missing or chipped gear tooth. Check your tranny drain bolt. As for the clutch going to hell after sitting that is not something I've experianced after the fix. Once the excess glue is removed the time to cold flow becomes irrelevant. Do you have the 4 thin 2 thick fiber configuration? Are you using any additives that might swell the fibers? Do you have any bent plates? I think a disassemble and inspect is in order. Nothing in the fix should cause what you are describing. Something is definately in need of attention.

Carbon reeds do help the low end torque. I put VForce reeds on any new bike I get but the carb clean is the place to start. If that doesn't fix it you can look for an air leak. Typically done by spraying small amounts of hot start fluid around the cases of an idling engine and listening for a change of speed. This is of course dangerous as hell so must be done in tiny shots with an extinguisher at hand. You do have access to the jets without removing the tower and you can blow air through enough holes to clear out the pilot circuit with the tower still on.

My experiance with the Keihin carbs is the pilot circuit gets blocked because the exit oriface behind the slide is TINY. Even a droplet of water is enough to seal it off. When that happens the whole carb should be taken off, disassembled and blown out with compressed air. If you take the jet tower off (requires security torx bit) be VERY careful not to damage or lose the rubber ring gasket at the base of the tower. What you describe could very well be a blocked pilot circuit. Typically the bike starts running sluggish off idle so you turn the idle speed up which keeps the engine running but makes for some inconsistant behavior at low rpm.

Usually just to direct overflow to back of cases. If it's missing there shouldn't be any issues unless you spend a lot of time in deep water. Since it won't siphon like the vent lines length is not an issue.

Honda just wants to win. Trials bike sales is chump change to their bottom line. Beta just wants to sell bikes and they know the market is good for them and the world champ is irrelevant because most won't buy Honda because of price and most still prefer two strokes. If Honda released a competitive low price two stroke and Toni won on it there'd be a problem for Beta as market share could seriously erode.

No but if you get the chance to see Jake Shimabukuro play While My Ukelele Gently Weeps it'll change your perception of what can be done with four strings.

Yeah I got some but waeyonwan and clabber threw me.

Well since I intend to go see Trainspotting 2 tomorrow I better get my head into it.

Could be. I haven't seen it in a long time but I just hate that things are made dangerous to make it spectacular for the proles.

Usually I go back to the mounting point on the ignition coil. Any clean point (no paint) on the chassis is good as it is still a big piece of aluminum. I'm not sure of the wire on the new ones but it doesn't hurt to add extra wires if in doubt and you're right about small wires not being optimum for reasons of current/resistance voltage drop especially for high frequency ground bounce which can theoretically affect the microcontroller in the CDI box. On my 2008 I took the thick wire from the top of the loom and pulled it back down out of the loom and attached it to the lug that mounted the regulator to the frame. I ran another wire from the same lug over to the coil attachment and another back up through the loom for the kill switch. The 2013 appears to be wired correctly so I didn't touch it.

I'm glad you guys understand this. Thought I was having a stroke!

A former expert champion in New England died while playing on his bike during 4th of July holiday several years ago. That one hurt. George Tormey was the nicest guy. Always a smile and a good word for everybody. We also had a rider almost die when playing after an event. Took a big fall off something that was above his ability. Had to have his heart restarted on the way to hospital and survived. Yes it is the safest motor sport but nothing and nobody is perfect and we are all mortal. I was called "Helmet Nazi" when I was NETA president for strictly enforcing the helmet rule. I have no regret for that. A $300 carbon fiber helmet might as well be a plastic baggie if it isn't on your head.

This is what I hated about indoor trials. I still think if Kenichi Kuroyama hadn't broken both wrists in a serious indoors crash he would have been world champion.

No fish or shoes