dan williams

Looks like a Fantic 301 to me

I eventually got tired of the DellOrto on my '95 and changed it out for a Mikuni. Best fix I ever made. It's probably different now but when that bike came out the DellOrto on it was a new design with a two piece pilot jet. Unfortunately parts weren't available so I could never get the thing jetted properly. Sorry if that's no help but the Mikuni really made the bike much easier to ride.

Ah yes the Can-Ams. First year I believe was '83 with a red frame called the CMT 310 with a Hiro motor. Next year same bike, white frame called the CMT 320. After that the 350 Rotax based SWM Jumbo clone in '85. Very scary to ride at least for me and then the 270cc aluminum framed mono the 300AT in '87. My 350's frame number was 853200001. Not sure but I think that meant I had bike number 1. Not sure what the '86 bike was since I didn't own one and my buddys had moved on to Beta by then.

See here http://www.jackscycles.com/lpse.html

Just wiring the kill switch ground through the steering head bearing violates bike wiring 101. When I started building bikes long ago as a kid (only way I could afford a bike) I read time and time again that you don't do that. Adding the lighting circuit ground to the same lug is just insanity. The diode in the kill switch circuit on later bikes proved that Beta suspected something similar. Unfortunately changing the lighting circuit to ac negates the diode fix. I doubt it's the coil insulation. That's a technology that's been proven for 150 years and a coil simply doesn't fail unless you pump too much current into it or feed it a voltage that breaks down the insulating goo which has to be in the megavolts or you mechanically damage it. The semiconductors is another matter though and all of the modern ones are much more prone to damage then their predecessors. The reason for this is the shinking of feature geometry. This is done for three reasons. Smaller transistors switch faster (hence your 3GHz pentiums), they use less power and they can make many more parts per wafer bringing the manufacturing cost down. This is true even for power semiconductors as used in the ignition system so they are a lot less tolerant of reverse voltage/over voltage conditions then a semiconductor of the '70s & '80s. I can see two probable failure mechanisms. It's not a stretch to theorize damage to the semiconductors in the CDI system from the primary voltage of the ignition system. If you've ever been tickled by the kill switch on a wet day you know there's a lot more then 12V running through that puppy. Likewise it doesn't take a rocket scientist to know that an 85 watt rated lighting system with a 12V output is capable of considerable amperage. Possibly enough to burn out the primary coil of the ignition system. The starting current for the fan alone with the radiator face down on the bench was on the order of 6.5 amps. This explains what I believe to be the two most common failure mechanisms one stator coil and one CDI box. Mixing those two systems together on one ground lug is just plain crazy. I've loved every one of my Betas and I love the '08 but the exploration into the stock wiring was an eye opener to be sure. There are Beta faithful that are mad at me for bringing this up but it's such a simple fix for such a drastic problem that I can't understand why every local Beta dealer and rider isn't pulling their buddy's aside and saying, "Pssst... let's take a look at your wiring for a minute. I'm just going to snip this kill switch ground wire, move it down here and reconnect it under the coil." That's been pretty much normal procedure in the US and certainly here in the northeast and I haven't seen an ignition failure yet. Then again we don't need lights here so it may be serendipity that the fix is just part of good grounding procedure. If I had a full schematic of the CDI internals I could tell you with a pretty high degree of certainty what component failed. Then again I'm a product engineer at a semiconductor company so I've spent 25 years probing and debugging ICs. I doubt Beta (or any other manufacturer has anyone on staff who has that kind of experiance. I'm sure they've been back to their supplier umteen times demanding an answer why their product is failing and the ignition manufacturer has hooked it up proper and been unable to find a failure. That reminds me of a story I heard years ago... The A-10 Warthog tank killer aircraft had been in service for a number of years and was suffering a high rate of engine bearing failures. The US Air Force was beating on the engine supplier GE Lynn for an explaination. GE took several of the A-10 engines and beat the hell out of them running at 120% power for days on end and doing all kinds of abusive things and the engines just would not die. Finally producing a 6" report on the testing and results which needless to say didn't satisfy the Air Force one bit. As one of the GE engineers was leaving the A-10 base he looked up to see an A-10 doing a slow roll. Ding! The light went on! The A-10 uses a modified commercial engine that was never intended for inverted flight. The bearings were lubricated with a half bearing cup type of deal. When the aircraft was inverted for more then a few seconds the oil drained out of the bearing and damaged the bearing. The fix was a retrofit to an enclosed bearing and the engine failures stopped. I used to live in Lynn and could hear the GE plant when they were testing. Call me a motor head but I loved the sound. Then again I lived a few miles away.

Yeah after years of Baldrige awards and "Six Sigma" quality control BS some have finally started to realize that the best quality control is the guy on the assembly line who knows what he's doing putting it together the way he knows it should be done. Unfortunately so little has been done to capture that knowledge because it didn't come from an MBA that the idea of craftsmanship in a mass production environment has all but been abandoned. Hence the nostalgic feeling of finding some 50 year old piece of kit that still works perfectly while your fancy new whatever breaks 10 meters from the store.

Careful you don't break off a screw or crack the hub. All disks are now floating type and have some freeplay. Just as a rule of thumb, if you're nervous you're tightening too much you are. None of the modern machines has much metal behind that bolt no matter where it is on the bike with the possible exception of the crankshaft. Most disks have some type of finger washer on both sides to approximately center the disk.

It's really important to fix the wiring by moving the ground reference from the steering stem to the chassis. I firmly believe that will stop the majority of blown ignitions. The time to do it is before the bike suffers a failure. http://www.newenglandtrials.org/Beta_wiring.pdf

Haven't done a top end since my '95 but... Before bike seemed to run OK but a bit hard starting. After felt like a new bike. My guess is you just need rings. The piston and cylinder don't wear very fast with the hard surface coating on the current engines. Try just rings first and I think you'll be a happy camper.

As George Carlin said, "Save the planet? If the planet wants to get rid of us it will flick us off like a bad case of fleas!"

I got to ride an event up there some years ago. Hugo and the rest of the ATAQ guys are good people. The ATAQ (L'Association des trialistes amateurs du Qu

If your Beta has a lighting system on it you should read this. http://www.newenglandtrials.org/Beta_wiring.pdf

Classic illustration of a fundamental problem. If you want people to participate you must make the information accessible. I googled the following terms (Dudley Trial 5th Oct) and the only hit that was relative was this thread. Think about it.

Welcome to the wonderful world of web hosting. I put a notice up on the front page of newenglandtrials.org. Some of the NY and VT guys will probably check it out.

If you're on your way down the east coast through New England there's still a few events to go. Let me know and a Beta is yours to play with. http://www.newenglandtrials.org/ October 5 Exeter RI RITC Sam Singer/Joe Antonelli October 11 Northville NY CATRA Pete Lacagnina October 12 Northville NY CATRA Pete Lacagnina October 26 Meriden CT Meriden Motorcycle Club George Eddy

Yeah but once we're all on the dole think of the riding time we'll have.

See this http://www.newenglandtrials.org/Beta_wiring.pdf

Check out http://www.betamotor.com/system/attachment...evisione_03.pdf page 5 POS 23 part number 29-07314-8 scroll down to footnote at bottom of list. If you look at the 00-06 parts manuals you'll see the extra weight is on the 270 Yes I can see it through the sight glass on my 05 270. No I can't see it through the sight glass on my 08 270 No I couldn't see it through the sight glass on my buddy's 05 250. Not the first trials engine I've seen with an additional weight on the primary side of the crank. My old Bultacos also had an additional weight on the primary side of the crank.

Heh heh I'm up to my ass in MSEEs from MIT here. One of the best things about the two-stroke tuner's handbook is that it taught me the concept of wave propagation at a young age. Something that is the basis of transmission line theory which I have to use designing circuit boards to work with data streams in the GHz region. It was also useful in doing pro-audio work as the theory translates directly to accoustics and how sound behaves in speaker enclosures. I owe a lot to Gordon Jennings.

One thing you might want to consider is before '07 the 270s had an additional flywheel weight on the primary drive side of the crankshaft. The 250s didn't have that and as a consequence felt quicker. The '07/'08 bikes are reversed with the additional weight on the 250 and not on the 270. If you feel the need for a little quicker revving then you might want to take a look to see if yours is equipped with the weight. You can see it through the gearbox oil sight glass.

Ya know Jon damn near everything you could need to know is on Wikipedia somewhere. There is one huge tome called the Art of Electronics but it's probably massive overkill. Hey one cool thing I've recently discovered around Boston is a used book place called "Got Books". I wanted a book on PHP programming and typically I'd go into a Barnes and Noble and plunk down $30-$50 but I picked up a slightly used one for $3.50. Might be worth looking around for a used book shop. Maybe pick up something at a local college book store that sells used text books. I'd love to find a cherry copy of the two stroke tuner's handbook. I just remembered something cool. Way off topic but cool anyway. Did you ever wonder why some deep space probes have this long arm sticking way out from the rest of the probe? It's where a fission pile sits generating heat as the radioactive material decays. Unlike a ship where that heat is used to make steam that turns turbines to make power, spacecraft have big arrays of thermocouples that sit near the hot nuclear material generating electricity.

Ooohh can I get pedantic too? The temp switch is indeed a switch. A thermocouple is different. A thermocouple is a sensor made of two dissimilar metals that generates a voltage when there is a temperature difference between two similar junctions. Very commonly used to measure temperature.

Depends on fuel octane, jetting, compression (rings, cylinder condition, carbon buildup), riding style, air temperature... Like any other tuning technique the only way to really know is to try it and measure the results in your specific application. I know that's not the answer you wanted but it's safer then giving an answer that causes you to seize your motor. Try gradually increasing the advance a small amount at a time and note the results. Soon you'll know more about how that engine responds to ignition advance then the guys who designed it.

Er... trials bikes are pretty much tuned about as good as they can be especially when compared to other racing machines. At best you might improve power by a few percent with port matching and such but there isn't a whole lot you can do that won't fundamentally change the nature of the engine. Your avatar says you've got an '08 125. Sherco used to make 200cc bikes and it's possible the cylinder/piston from a 200 would fit your bike. The stroke is the same. Other then that there's not much else you can or should do. It's gonna be expensive though.

Partially blocked pilot jets will do this sometimes as the bike starts fine with choke but has an issue when hot as it is too lean to start. First thing I'd do is strip down the carb and blow out all the holes with compressed air. Also make sure the gas cap vent is clear and that the vent tubing on the carb is open. Also look to make sure the kill switch isn't partally shorting causing a weak or dead spark. After that hard starting can mean it's time for a set of rings. They do wear and if the bike is three or four years old it can be time to throw in a new set. Even though it seems to run strong once the bike fires up you'll be surprised at just how much spunkier it'll run with new rings. I wouldn't bother doing anything to the cylinder just throw the rings in and it's done. Edit: I should note that lean jetting will also cause hard starting and we are getting to the time of year when going up one size on the pilot and main are useful due to the colder, denser air.