dan williams

Those dimples on the piston skirt say something's been bouncing around in there.

Unlike the Mikuni with its machined brass valve seat and Viton tipped needle the Keihin looks like just a steel needle on a machined surface in the carb body. One of the reasons I call the Keihin primitive. I'm a little suspicious of the seal this provides. The seal isn't a force issue either. The conical shape allows for the most opening with the smallest movement but again without a flexible sealing surface more pressure buys you nothing if there is dirt or a surface imperfection on either of the mating parts.

Mine makes the tail light come on.

Here's how I start my Beta. I take it off the stand and kick it. Then I kick it again, then again. Then I remember to turn on the gas. While the carb is filling I kick it a few more times out of impatience. Then I stop to rest and then kick it again after a moment and it starts. The 2008 was similar except for the unsticking of the kill switch.

<geek mode> It would be kinda neat to really tear a corroded Beta apart and find the other electrode the magnesium migrated to. </geek mode>

He's got a point. I've never seen anything on the Beta forums about dodgy clutches, flakey Keihins, dribbling Mikunis, cracking EVO frames, frying stators, crap kill switches, weak main bearings, clunky head bearings, corroded water pumps or strange grounding schemes. I guess we Beta riders just don't talk to each other much. They all have their foibles. The one thing I can't stand is when there is an issue and the deniers come out of the woodwork. I'd much rather a manufacturer just say, "Yup, we screwed up. Where do we send the new frame."

Possible suspects, Ignition, Shorting kill switch, plug fouled, ignition coil, CDI, Stator, intermittent connector Carburation, Bad gas, contamination in tank, blocked jet, air leak, blocked gas cap vent Mechanical, Broken reed, torn air boot Identify symptom Does engine run well at lower RPMs? Does engine run well at higher throttle settings when throttle is rolled on slowly? Does engine recover if allowed to cool off? Does engine recover if allowed t run at lower RPM for a while? Obviously you want to go for the cheaper solutions first. A good disassemble and clean of the carb and fresh gas is a good start. While the carb is out inspect the air boots and reeds to make sure all is well. All Beta stock kill switches are crap. Replace it. Make sure you can blow air through the gas cap vent. Throw a new plug in and ride again. If the problem isn't fixed it's probably about to get expensive. Try a new plug cap on the HT lead of the coil. If that doesn't fix it you may be looking at the dreaded stator failure. Diagnoses of ignition component failure is a swap and check deal. I'd love to tell you there was an easy way to test for failed components but there isn't. Metering the stator even with an LCR bridge is iffy at best. Good luck.

Billy's comments on viscous coupling are very good. I remember being told years ago not to fill the Beta gearbox all the way as it caused the clutch to drag and that the factory guys ran less than the spec oil level. I can also confirm on the new EVO I still have some low speed drag as well as very quick clutch engagement. Certainly quicker than I am used to compared to the '08 which has a clutch "like buttah". Gonna have to get me some of Billy's magic oil. He hasn't steered me wrong yet.

If the resistance of the kill switch is high or one of the contacts is through the head bearings as with the classic single wire kill switch a high revving engine can still generate enough voltage to trigger the CDI. Another scenario is the engine is running so fast it is acting like a diesel and just firing the mixture from the free radicals not scavenged by the previous combustion cycle. You could also have a drastically over heated plug or contaminant in the combustion chamber that is just lighting mixture on its own. The Zip-meister brings up a great point about revving I hadn't thought of. Heh heh the spell checker suggested "moister"

Did you polish the tabs on the friction plates?

I see the 2014 has a pinch bolt now.

Hmmmm, I sold my '05 with a fresh rebuild of the bottom end for $2500. $1800 for a 22 year old trials bike is rather optimistic. Look at prices around the web for used bikes to get a better idea of what the market is. One bit of advice is to go to local events. There's always a few bikes for sale that you can try out and you get to meet the people you'll be riding with and see what the sections look like.

Exeter has held several world rounds and many US national rounds. Great terrain and good spectating.

Hmmm I realize the ignition epiphany thread points to a dead link. Let's see if this upload stuff works. Beta_wiring.pdf

I run BelRay H1R at 100:1. If you tend to ride hard 80:1 is fine.

I don't have the factory 300 just the regular. I did the clutch tab polish as they were still pretty rough but I skipped the glue removal since they were loads better than what they used to be on the older bikes. The washers on my bike were stepped so there is about a 2mm difference in spring preload depending on the way they are installed. It probably didn't make much difference but it was free and I had the thing apart anyway so... If you're getting pins and needles in your hands you are putting too much pressure on your hands. You need to fix that before you damage the nerves in your wrists. Check your bar position and make sure you have gloves with proper padding. Bars too far back will make you lean forward to compensate especially when you get tired. I think the EVO position is slightly different from the Rev3 and when I'm tied I start to feel like I'm falling forward. The riding gets really sloppy when that starts to happen. I think the stock grips aren't as good as Renthals but I haven't changed mine yet. Too lazy and/or cheap.

Ah back from visiting the in-laws. Glad to be back at work where I can relax, sort of. You have no option but to jet to the available fuel. You can jet rich to eliminate a pre-ignition mostly because the extra evaporating fuel cools the combustion chamber but it isn't optimum. Another gasket under the cylinder to slightly reduce the compression is also an option. This reduces the pressure in the cylinder to something a bit more in line with the lower octane rated fuel.

Lesson noted.

Betas ping without race gas. Carb will stop peeing fuel if you nip a hole in the float bowl vent tubes about halfway up the carb body.

You are missing a ground connection. There is a big black wire that connects to the top triple clamp behind the headlight. Reroute it down by the ignition coil and hard ground it to the frame. See if you can find my post on the same thing on my 08. Ignition epiphany or something like that. I'll post more when I can because I'm away from home at the moment.

That's an '02 and yes the fix is intended for just that problem. At least the deglue part. The tab polishing makes the clutch more linear.

Hey Scotty, on the 300 you can flip the washers around to lighten up the pull. If they're the same as on my bike. I haven't taken any springs out of the 300 though I did do the clutch tabs. The '08 is slipping a bit now 5 years after the clutch mod on four springs so I guess it's time to put the other two back in. Might as well I don't ride it anymore.

Yeah what he said. Be careful when you pull the pressure plate off not to drop the thrust bearing that'll be stuck to it. It helps as you disassemble to have a nice clean spot to put the parts like a table with paper towels on it. They are greasy parts after all. You can get the clutch pack out by hand but it's a pain. I used to use a small screwdriver with a bent end until I realized the toolbox held some of the bent dentist picks. Those stainless picks are one of those tools you pick up on a whim and just keep finding uses for. I'll just take two and stick them under the clutch pack and it comes right out. Don't worry too much it really is pretty simple. Oh yeah one other thing to be careful of is the o-ring under the cover can be a pain to get situated back in the groove. Be patient and if it remains intractable a few dabs of lithium grease will keep it in place. I also just lay the bike over. Also wash the bike first. No point in getting the innards dirty. ...and one more thing, don't over tighten the bolts that hold the springs. they are held in place as much by the spring pressure as bolt torque. If worried put a dab of Loctite on. Too much torque can snap off the studs from the basket. Been there, done that.

I'm afraid the best course of action is the usual, take it apart and do the fixes/adjustments/cleaning and then put it back together and see how it runs knowing at least the carb is sorted. All else is speculation. Idle changing from lean angle is a little weird but I'd suspect float level. The water bubble in the exit hole of the pilot circuit is not really variable. When it happens the bike runs awful in the lower throttle range all the time until it's cleared.

What was funny is I was dreading the shock spring change. I pulled the back wheel and airbox off and crawled under the bike on a stand to get at the bottom shock bolt but it really was pretty easy. The forks that I thought would take me 5 mins took a lot longer as the adjuster was solid in the fork cap. Even with a big wrench and breaker bar on the allen bolt it wouldn't free up. I had to lay into it with a big propane torch which carbonized the small o-ring in the cap. Only when it was really hot could I move it at all. When I finally got it all the way out it wasn't the threads of the adjuster that were jammed. (surprise) It was where the adjuster shaft with the allen socket goes through the cap that was so tight. Dremel tool with a grinder bit and a new o-ring sorted it out but man was that a bear to get apart. I've only ridden the new springs once but it was immediately apparent it was a good choice. The bike has lost none of it's stability but seems to be easier to time over obstacles. It's a little more enthusiastic about rotating the front end up when I hit somthing with the front end.