Overheating

[beta_boi]

i have a 2000 beta rev3 270, and after about 1 hour of riding it starts to overheat and starts reving up with out the throttle, could this be caused by the silencer if in needs repacking, Thanks

Edited September 10, 2008 by beta_boi

[the addict]

How do you know its over heating? is it blowing water out of the rad? check your coolant level first and colour of your plug, if its white the bike is running to lean and needs re-jetting. I doubt its got anything to do with the exhaust packing.

[betarev3]

I'm no expert, but here goes....

You do not say whether fan is coming on when you think engine is overheating, so need to check this first.

Also, remove plastic rad cover and wash out rad fins to ensure no blockages.

Check air filter is clean, remove carb and give it a thorough clean out, checking float level at same time.

I would also repack silencer, as it only costs a few quid, and if it has not been done since 2000, then it is definitely overdue.

I have seen a couple of two strokes revving out for no apparent reason, and no one has fully explained this to me, but at the end of the day you need fuel, air and an ignition source to get combustion, so if you check these systems are working correctly then you will logically eliminate the problem. Therefore, lastly, I would remove the cylinder head and check for carbon deposit build up on piston crown - maybe excessive build up could lead to spurious detonation when engine gets to a critical temperature.

Hope this helps.

[firstgear]

First make sure your fan is coming on. If it is not remove the two wires from your thermostat and jump them together with alligator clips or anything. The fan should come on.

I you leave it like that to finish an event it is fine since the fan will be on 100% of the time.

If fan does not come on you either have a bad wire or a bad fan motor.

If fan does come on you just need a new thermostat.

Odds are it is a failed thermostat, this is not uncommon and is simple to replace.

Make sure you check your coolant level if you have boiled some out.

[beta_boi]

Thanks for the replys and the fan is coming on but not wen i would expect it to but ill check all these problems but it sounds like it is the thermostat.

[anotherfive]

I have had betas for 8 years now. Tackled various overheating probs but had a new one last night. Fan on, engine running hot, radiator full, mixture and supply fine. After a lot of thinking I took the water pump cover off to find the plastic impeller had lost its grip on the drive shaft so was not turning and pumping coolant around. Have one on order now and hope that will fix it.

[mad4it]

Thanks for the replys and the fan is coming on but not wen i would expect it to but ill check all these problems but it sounds like it is the thermostat.

WHAT YOU ARE REFERING TO IS NOT A THERMOSTAT BUT A COOLANT TEMPERATURE SWITCH !

[jse]

WHAT YOU ARE REFERING TO IS NOT A THERMOSTAT BUT A COOLANT TEMPERATURE SWITCH !

Though, not to get too pedantic, that's true. A "thermostat" in cooling systems is generally a mechanical, bi-metal, device that regulates coolant flow according to a preset temperature range. In just about all the Trials bikes I know, a "COOLANT TEMPERATURE SWITCH !" is sometimes known as a "thermocouple", and is a temperature sensor (on/off switch rather than say, a light dimmer, that "regulates" output, as a coolant "thermostat" might do) that monitors coolant temperature without interrupting flow of the fluid. The fan, when turned on by the thermocouple, is what does the added cooling by drawing more air over the radiator fins.

Jon

[dan williams]

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.

[jse]

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.

Thanks, Dan! I was misinformed and gonna give my engineer buddy who told me that a poke in the eye (even though I may have misunderstood, it's still fun to poke this guy in the eye...). Electronics is not his speciality, and obviously, not mine. Have you got the name a good basic book that I might obtain so that I can catch up on some of the basics? Something that would relate to a bike electronics would be helpful, especially in view of the more complex CDI and FI systems we are sure to encounter more often.

Jon

[dan williams]

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.

Edited September 19, 2008 by Dan Williams

[brian r]

So, is that thing on my wall I've been referring to as a THERMOSTAT now called a temp switch?

Dan, good job on the explanation of thermocouples, I'm just guessing, but I probably sell more of these than

anyone else on these boards. Plastic Hot Runner Supplier.

[jse]

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.

Thanks, Dan. When I lived in Silicon Valley, an MSEE was an arm's (or a handlebar's) reach away, but here in the Midwest, kinda hard to find.

Gordon Jenning's two-stroke tuner's handbook has been one of my favorites since it was released (1973) and I got mine in the early 70's and mine is well worn. They cost $5.95 then, but go for about $100 on Amazon now. Gordon's overall insights were way ahead of any body else for the most part and there was a lifetime of race tuning info packed into 156 pages.

I figure I should start researching since the trend is to electronic FI and my background is mechanical, though if you have any questions about Hillborn, Algon or Enderle injection systems ( or the old Rochester "doghouse" system on the 57' Vettes), let me know.....

Jon

[dan williams]

Thanks, Dan. When I lived in Silicon Valley, an MSEE was an arm's (or a handlebar's) reach away, but here in the Midwest, kinda hard to find.

Gordon Jenning's two-stroke tuner's handbook has been one of my favorites since it was released (1973) and I got mine in the early 70's and mine is well worn. They cost $5.95 then, but go for about $100 on Amazon now. Gordon's overall insights were way ahead of any body else for the most part and there was a lifetime of race tuning info packed into 156 pages.

Jon

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.

[jse]

i have a 2000 beta rev3 270, and after about 1 hour of riding it starts to overheat and starts reving up with out the throttle, could this be caused by the silencer if in needs repacking, Thanks

Hmmmmm,

Easy for me to get sidetracked.

Beta_boi, did you ever find out what the cause was?

Jon