4 replies to this topic

[colin1212]

My son was out on his bike today and as soon as he tryed to kickstart it he knew there was a problem. took 8 kicks to get it going but as soon as he put it in gear it just stalled. It happened again twice so he had to do pritty much full revs to keep it going.He was half way down the field when the bike just backfired and just halted to a stop, (Sounded like a gun being fired), He tryed starting it but no luck. Checked the bike everythings fine, full tank, oils fine. I don't know anything about trials bikes so I have no idea what to do with it. Any tips on how to maintain a trials bike would be appreciated.

[JSE]

colin1212, on Jun 12 2010, 08:25 PM, said:

My son was out on his bike today and as soon as he tryed to kickstart it he knew there was a problem. took 8 kicks to get it going but as soon as he put it in gear it just stalled. It happened again twice so he had to do pritty much full revs to keep it going.He was half way down the field when the bike just backfired and just halted to a stop, (Sounded like a gun being fired), He tryed starting it but no luck. Checked the bike everythings fine, full tank, oils fine. I don't know anything about trials bikes so I have no idea what to do with it. Any tips on how to maintain a trials bike would be appreciated.

My first guess is that the flywheel hub has slipped on the crank stub and sheared the Woodruff key. This will throw the ignition timing off and can cause the symptoms you describe.

You'll need to pull the flywheel off and check the key (a half moon shaped piece of metal that fits in a special groove in the crank stub) to see if that's the cause.

What model and year is your son's bike?


Jon

[colin1212]

JSE, on Jun 13 2010, 03:51 AM, said:

My first guess is that the flywheel hub has slipped on the crank stub and sheared the Woodruff key. This will throw the ignition timing off and can cause the symptoms you describe.

You'll need to pull the flywheel off and check the key (a half moon shaped piece of metal that fits in a special groove in the crank stub) to see if that's the cause.

What model and year is your son's bike?


Jon

Its a 2004 TXT Pro 280, is that a common problem and is it hard to fix?

thanks

[JSE]

colin1212, on Jun 13 2010, 10:54 AM, said:

Its a 2004 TXT Pro 280, is that a common problem and is it hard to fix?
thanks

Actually not too bad to fix. You'll probably need a flywheel puller (from your dealer, they are special to this type of ignition),
a new woodruff key and a torque wrench. Take the flywheel off using the puller, take out any of the old key pieces, install new
key, put on flywheel and use a little Loctite on the bolt threads. Torque flywheel bolt to 32 ft lbs (42 Nm) and you should be set.

This is not an uncommon problem in Trials engines of just about any year or brand. The bolt/nut is torqued at the factory during
initial assembly but after a few heat cycles tends to loosen a little (like new spokes). With the large mass flywheels and drivetrain
shocks that are normal to Trials, the flywheel will often slip after a while and shear the key. It's always a good idea to check the flywheel
fastener on a new bike after a time, and a re-Loctite and re-torque will usually prevent this in the future.

Jon

[bigfoot]

Jon could well be right and its a good starting point but it the key is intact try swapping out the voltage regulator module. They aren't that expensive and I've had two go on a 2004 and 2006 bike. They did exactly what you describe. Basically water gets in between the potting and the electronics and start shorting out until the short blows the electronics up. If won't start after that or if it does it will only run a few seconds and electrically break down again.

Gas Gas UK will have the regulators in stock.