HOLY SHIT! Glad I didn't push the button...

[R6_kid:Me]

Recently I've been having a little bit of trouble with the TRX - on two previous occasions I've gone out to the garage to find that there is fuel leaking from the bottom of the exhaust headers where it joins from 2-1 So as you would, I take out the plugs, turn the motor over and fuel splurts out of one of the cylinders... on one other occasion I couldn't see any fuel but it 'hydrolocked' and thankfully didn't fire - I've heard/seen that you can bend/snap rods/cranks/valves if it fires up and the other cylinder hyrdro-locks.

Well today it was a bit worse than that. I walked out to the bike to check if the problem had gone away after fitting an inline fuel filter. There was fuel in a puddle underneath the bike, and the engine was covered in fuel as well. I took the tank off and my stomach tied itself in a knot - the right hand cylinder has about 1L of fuel sitting in it, all the way up to the needle in the flat slide carbs... unfortunately my camera doesn't do justice to what I can see

I'm about to rip the carbs off and check all the seals as well as cleaning out the float bowls.

So much for studying!!!

[White trash]

Fuck me! Petrol's expensive too. Fucken Yamama's........

[bungbung]

Clean out the float needle valve seat(s) and check the needle(s) itself for corrosion or unroundness.

[p.dath]

Sounds like a great anti-theft device. If someone took your bike you could locate them by the colour of their underwear.

[slofox]

Sounds like a great anti-theft device. If someone took your bike you could locate them by the colour of their underwear.

And the pile of smoking debris...

[t3mp0r4ry nzr]

yup check out your floats.
not sure if the starter motor would have had the juice to "compress" the fuel. probabley wouldnt have bent a rod, but wouldnt like to test this!

[kwaka_crasher]

Clean out the float needle valve seat(s) and check the needle(s) itself for corrosion or unroundness.

and sticking float pivots. Since you're there, check & reset the float heights as required.

[AllanB]

Has it a fuel tap?

Did you or some evil bastard set it to 'prime' and leave it there?

Prime setting is designed to flow fuel in to the carbs.

If it is left on this setting it will continue to flow fuel into the carbs and then through the intake valve (ones bound to be open a bit), into the cylinder, seeping past the rings into the sump, mixing with the oil. Apparently this stuffs the oil and can quickly cause bearing failure if used.

Apart from that I'd not be too worried ........

[R6_kid:Me]

It has a fuel pump (external from tank) AFTER the fuel tap (which is a vaccum tap) so it shouldn't be leaking THIS much fuel! Also it only ever seems to dump fuel into one cylinder, everytime I've taken the plugs out to pump out the gas the right cylinder is wet, but the left cylinder is not.

I've just bought a new oil filter and oil as it is HIGHLY likely that fuel has made it past the valve seals and/or rings and is diluting and breaking down the oil. I'm just using mineral oil this time through and will replace it in just under 600km (when it was supposed to be due) with the usual Motul 5100.

I took the carbs off and went down to Holeshot, the workshop manager said "go home and sort out the tap first, I don't want to charge you $90 for an hours labour and not fix the problem" then they came up with the idea of fitting an inline on/off fuel tap (the standard tap is on/prime/reserve) to see if it's just pressure from the tank that's pushing the fuel through, or if it is in fact the carb(s) that are leaking on their own.

Had to go down to Hauraki Mowers and Cycles to get the inline tap which will be showing up tomorrow.

You've gotta love problem solving by elimination!

Thanks for all the tips - no I don't leave it on PRIME, it's only ever on ON or RESERVE. Also the floats are not adjustable - the carbs are Keihin FCR's. The float bowls were clean as a whistle and the float valves are in good condition too.

I think I'll take the head off in the near future (after exams) and check that the valves are still seating properly and that the pistons are still making full-stroke. The bike runs fine otherwise, there are no extra vibrations or funny noises, and I haven't noticed any loss of power. From what I've read as long as it doesn't happen at speed (i.e through water induction), or if the other cylinder fires while the other cylinder is on the compression stroke it should be ok.

And to think the warranty only ran out 2 weeks ago

[imdying]

Prime shouldn't actually matter, the needle and seat should be able to stem the flow adequately.

[R6_kid:Me]

That was my thoughts...

Would a needle stuck open allow fuel to drain even if the floats are closed??

[quickbuck]

Also the floats are not adjustable - the carbs are Keihin FCR's.

Why not??????
You know you just bend the tab to get the correct height eh?

Also if you have been using Ethanol Blend fuel, check your Float Needle valve rubber... Conjure has it that this stuff drys out the rubber these are made from and shrinks it.... Causing the leak.

So, Fuel will not flow through the carb if the needle is open under normal circumstances.... as the float chamber will be full and the float needle will seal off the fuel

HOWEVER if the float needle is stuffed, then there will be fuel still flowing through.

Have a surf around This Site....

[R6_kid:Me]

Cheers, I don't think I've been anywhere near Gull with this bike, but can't be 100% sure...

The float needle valve rubber was fine, I'm pretty sure the whole float was plastic though - so no tab to bend. My old CB650 carbs were exactly the same.

[k14]

I'm just using mineral oil this time through and will replace it in just under 600km (when it was supposed to be due) with the usual Motul 5100.

Why would you do that?? Just dump out the old oil and put in some new motul. Not worth it for 600km

[R6_kid:Me]

The oil that came out was a lot thinner than anything I've put in, I just want to make sure that any fuel that may be left circulating in the system isn't mixed with good oil. I'll keep an eye on the oil and may leave it in there if need be, it's Motul 3000 so not entirely 'bad'.