What Did You Do To Your Gas Gas Today?

[coops]

Agree on the carb spacer for the gasser ... best £20 spent on the bike! Makes life so much easier

[zippy]

Agree on the carb spacer for the gasser ... best £20 spent on the bike! Makes life so much easier

Those things should be fitted as standard from the factory!

[zippy]

You are OLD, bad knees, bad back, bad wrists!

Call up V-mar! He will make you an extension for your other toy!

yep getting to the older stage of life...........The reason I got the bad knees, bad back and bad wrists is because I still act like I am 18!

Why would I want to have the front forks of my bicycle longer????

[jse]

Those things should be fitted as standard from the factory!

I agree. The V-Mar adapter is like the rubber "donut" but a little longer and made from aluminum so you get a more positive seal. The dimensions of the carb/airbox boot area are a compromise in order to fit both the Dellorto and VHST/Keihin carbs. You can see the differences in spigot diameter, bell diameter and body length between the two types of carbs. Not usually a problem except for the confines of a Trials bike. The rubber "donut" adapter on the Dellorto seems just a little too short and flexible in some cases to make a solid, leak-free connection unless you are very careful and deliberate in installing the carb.

I don't have that problem with my 2002 280 Pro as the airbox boot fits the Dellorto perfectly, the adaptation components started in 2003 with the VHST carb used just that one year but also allowed for the Keihin PWK.

Hint: Install the carb/donut/airbox boot junction first and then lever the carb back into the manifold last. If you tighten the carb into the manifold first and then try to get the bell/donut back into the airbox boot, it can be an almost impossible task, in some cases, to get right.

Jon

[algreen]

Rebuilt my carb yesterday. My 2001 gasgas txt 280 is new to me last week, and I though it couldn't hurt to check the internals. Installed the Dellorto o-ring carb kit and checked the settings. Starts first kick every time and idles strong, but I'm hearing lots of popping, but no pinging, I think. Running 93 octane gas at 60:1. Jetting settings below:

36 pilot jet (30 stock)

118 main (120 stock)

270 Needle jet (270 stock)

D36 needle top clip position - leanest

Float set to 18.5mm under carb bottom

Plug is gapped properly. It looked like this after cleaning.

[jse]

Rebuilt my carb yesterday. My 2001 gasgas txt 280 is new to me last week, and I though it couldn't hurt to check the internals. Installed the Dellorto o-ring carb kit and checked the settings. Starts first kick every time and idles strong, but I'm hearing lots of popping, but no pinging, I think. Running 93 octane gas at 60:1. Jetting settings below:

36 pilot jet (30 stock)

118 main (120 stock)

270 Needle jet (270 stock)

D36 needle top clip position - leanest

Float set to 18.5mm under carb bottom

Plug is gapped properly. It looked like this after cleaning.

I'd say you are running a little fat on the main, which is why you have to compensate for it by the lean needle clip setting. I'd try a #116 (possible #114) main, needle clip 2nd groove from top. The pilot is fine and even a #38 would work. Start with the fuel screw about 3 turns out and then adjust it for ambient conditions (quickly "blip" throttle from idle and adjust screw in/out to get best response). Don't worry if your best fuel screw setting is different from your buddy's identical bike, each engine is different. I like to adjust the float arms level with carb base with carb upside down.

You can run 80:1, full-synthetic with no problem and you might want to check the reeds for any wear/damage.

Cheers.

Jon

[algreen]

Thanks for the quick response Jon. I just got off the phone with Jim Snell of Rising Sun Imports. He agreed that 99% of bikes run best on the second clip position from the top; only high altitude bikes use the top (leanest) position. All the other settings are close enough not to cause the popping I described. His recommendation was to dismantle and clean out the mid-pipe and repack the muffler as the previous owner was a novice, and likely spent a lot of time running near idle. He said carbon buildup could cause the symptoms. Since it starts first kick, idles strong, and pulls strong, the jetting likely isn't the issue. He also said that in general, some popping is typical on trials bikes.

Stupid question: Will the manifold remove with tearing the gasket, or do I have to replace after checking the reeds?

Edited August 8, 2013 by algreen

[jse]

Thanks for the quick response Jon. I just got off the phone with Jim Snell of Rising Sun Imports. He agreed that 99% of bikes run best on the second clip position from the top; only high altitude bikes use the top (leanest) position. All the other settings are close enough not to cause the popping I described. His recommendation was to dismantle and clean out the mid-pipe and repack the muffler as the previous owner was a novice, and likely spent a lot of time running near idle. He said carbon buildup could cause the symptoms. Since it starts first kick, idles strong, and pulls strong, the jetting likely isn't the issue. He also said that in general, some popping is typical on trials bikes.

Stupid question: Will the manifold remove with tearing the gasket, or do I have to replace after checking the reeds?

Jim, as usual, is spot on and I'd follow his advice. If I think that the jetting is off a little (not unusual for a used bike) I like to fix that first and then go on to other possibilities, like the exhaust system, but starting at either end works. If you are careful when taking the manifold off, the gaskets can be re-used, although using new gaskets is always a better idea. Sometimes a razor blade will help ease them off without splitting. You can use a very light coat of gasket sealing compound on the old gaskets to avoid leaks.

On the reeds, look for a rough, frayed tip at the outer ends. Also check as to how far the tips stand off from the sealing surface and if it's more than about .010/.015", I'd replace them. Boyesen dual-stage reeds work really well in this engine.

Jon

ps. Not to worry, there are no "stupid questions", you are going through the same process we all went through and we all realize it takes a little courage to ask in the first place.

[algreen]

Want to thank everyone for their feedback. I rode my 280TXT yesterday for about 40min and it rode great. Started easy, idled normally, and the low end throttle was strong. I guess I'm not used to the sound and feel of a trials bike compared to my 2011 KTM XCW.

On a separate note, I removed the exhaust per Jim's recommendation and the header had some moderate carbon buildup. With the the header removed, I noticed some nasty looking scoring on the piston. How mad do you think it is?

http://lh3.googleusercontent.com/-i3YZ6-LP3fs/UgwylHSuIKI/AAAAAAAAGRw/aZdfO_CVvf0/s1024-no-k/IMAGE_42.jpeg

Edited August 15, 2013 by algreen

[sting32]

did you feel it? I just wondered though... over the "exhaust port" isnt it likely there might be some 'scratching' which might scare a guy and yet be normal? Sorry I can't say if that looks bad or normal, haven't had pipe off the last 4 or 5 bikes I have owned.

[lineaway]

She`s been stuck before! Not good, but if it is running fine you will get by for awhile! New (re-chromed cylinder) and new piston is not cheap.

[purplebeast]

Replaced the normal push button kill switch with a magnetic lanyard based on on my '02 TXT Pro.

So she should be feeling good with the extra bit of attention! I've been ignorring the trials bike for too many weeks, and instead riding the enduro bike....gotta fix that this weekend.

Also picked up some 5.5' diameter tractor tires to replace the smaller ones I have in my obstacle course. That's gonna take some serious digging, 'cause their going in endurocross-style...vertical! Also need to arrange for 10 cubic yards of dirt to fill and finish the splatter training wall too.

[shyted]

Installed new grips , stripped linkages and greased , new oil , new tyres ,new chain and sprockets , front rim in really bad shape , is actually starting to split at the through point on the tyre clamp where some DH has over tightened the nut . Just goes to show , when people leave bikes standing for a while ( This bike was left for two years before it came to me without turning a wheel ) how the metal moth starts to munch through where it can . riding in a trial on Monday .

Edited August 24, 2013 by shyted

[shipdamite]

http://stores.ebay.c..._fsub=367442419

http://www.demon-tweeks.co.uk/Product.do?method=view&n=2079&p=425233&c=215&utm_source=Google&utm_medium=Base&utm_campaign=Grease&gclid=CPe2hZaVlrkCFVMPtAod6EoAGw

I have been using this for a while now - top grease for all those wheel and chassis jobs. I also use the red rubber grease on inner tubes to prevent snake bite / compression type punctures. This is good grease for caliper pins too (the rubber boot doesnt rot)

Edited August 24, 2013 by shipdamite

[shyted]

Hello ship . I use similar stuff . The red rubber grease i use is just made by Silkoline and clear plumbers silicon grease from local plumbers shop . Also cheap nasty LM grease for the chain but castrol LM 2 for those bearings etc . One you want to try is Molly Cote . Not cheap but had one tube for over 2 years . It's like the SAS of thread coatings . Sticks like poo to a blanket !