04 Txt280 Blown Head Diagnosis. Need Help.

[tturvy]

Was out test riding my new to me 04 txt280 pro after replacing an o-ring that was causing gear oil to leak from around the water pump housing. The bike was idling a bit high so I put it in neutral, and went to check the throttle cable to see if it wasn't binding somewhere. In the process I pulled on the cable a bit to hard and the rubber cover at the carburetor pulled the cable housing out of its seat and then the bike went revving like crazy. I couldn't get the kill switch to work as there was an obvious large amount of current running through which didn't allow it to work. I thought of putting it in gear but didn't feel like sending the bike on a ghost ride. As I kept trying to free the cable the bike finally sputtered out on its own. This was after it had been stuck at full throttle open in neutral for a good 15 to 20 seconds. Once it stopped I allowed it to cool for a while and was able to get it to start but not idle. The compression is noticeably not what it was. I'm pretty sure that I have blown the top end and it will need complete replacement.

Just want to get opinions from others out there. It seems pretty clear to me but wanted to check just to make sure I didn't do something else or there's something that I'm not thinking of that could have happened.

Let me know what you think.

I'm thinking I need a new piston, head, rings, and ring bearings. Ouch!

[mark1984]

im not sure but if you are looking for a 280cc kit this guys is selling one on ebay

http://cgi.ebay.co.uk/gas-gas-txt-250-pro-...=item230796591f also them bikes have traction control aparently if you read his post

[laser1]

You will need to pull the top end and inspect it for damage. Usually, the biggest concern is what damage you do to the cylinder. You may be able to clean it up, or you may need to get it replated.

[jse]

You will need to pull the top end and inspect it for damage. Usually, the biggest concern is what damage you do to the cylinder. You may be able to clean it up, or you may need to get it replated.

A note for future reference, use a gloved hand to plug the exhaust end and the other to hold the kill switch. Two-strokes tend to auto-ignite at full chat in neutral, but plugging the exhaust will usually bring down the RPMs to the point where the killswitch will work.

Jon

[motomerlin]

Chances are it's smeared the alloy of the piston trapping the rings - so low compression.

Remove exhaust pipe & you can prob see this.

Iff really lucky a clean up of piston would get it going.

If not, plated bore may be damaged, so a piston & re-plate would be needed.

[tturvy]

Thanks for all of the helpful advice. I'll dig into the project tonight and get things looked at. Worst case it sounds like I will need to re-plate the cylinder and properly size a new piston and rings to match. Anyone out there know of a competent company that I can send off to for the re-plate if I need it. I had already checked with Rising Sun Imports here in the States regarding a swap out for a re-plated cylinder. They don't have any in stock and I thought I could save myself a few dollars by having it done by someone on my own. I would of course buy the piston and send it along with the barrel to be properly fitted.

I'd love to hear what you guys have to say about any reputable plating shops. I'm in Northern California, Santa Cruz County, so the closer to me the better.

Again, Thanks a bunch for the knowledge. It has been helpful.

tturvy

[jse]

Thanks for all of the helpful advice. I'll dig into the project tonight and get things looked at. Worst case it sounds like I will need to re-plate the cylinder and properly size a new piston and rings to match. Anyone out there know of a competent company that I can send off to for the re-plate if I need it. I had already checked with Rising Sun Imports here in the States regarding a swap out for a re-plated cylinder. They don't have any in stock and I thought I could save myself a few dollars by having it done by someone on my own. I would of course buy the piston and send it along with the barrel to be properly fitted.

I'd love to hear what you guys have to say about any reputable plating shops. I'm in Northern California, Santa Cruz County, so the closer to me the better.

Again, Thanks a bunch for the knowledge. It has been helpful.

tturvy

If you live in Santa Cruz, you might check in at Moore & Son's shop at 2-1431 East Cliff Drive. Johnny Moore is a Trials dealer for several brands, including GasGas and may have an idea of where you can send it that may be close. Tell him that Jon Stoodley sent you to him for his sage advice.

Jon

ps. Santa Cruz is my home town.....

[copemech]

I shall only add a bit of experience here, as you mileage may vary, but USUALLY, and that is a big word here, there will be some aluminum transfer to the cyl wall and some stuck rings here.

This will usually clean up nicely with a bit of muratic acid to eat the ali off the plated walls with a bit of agitation with scotchbrite. As the hard plated walls are very tough, there may be little to no damage, requireing no cyl repair at all or a light hone job(skillfully done) at best. The piston being the sacrificial unit.

It all needs to be closly evaluated, but even at worst, most local top MX shops are familiar with this type stuff, so I doubt you would need go far, add, as a trials bike mainly putting about, it does not really have to be perfect, as some wear and tear(before the incident) will be normally fine as long as you got a new and good piston and ring in her. All point being, cyl replate/replacement is the last resort and not usually neccessary.

Hope you find it repairable!