Churns, coughs occasionally,won't start

[captainscarlet]

OK guys & gals. Suggestions needed. My Trixie, UK spec, 20k miles only, supremely reliable for the past 2 years gradually took longer and longer to start from cold until the fateful day when it just didn't.

Checked:
Spark - seems ok, plugs dry after trying to start so not flooding.
Petrol in tank (yup been caught there before...)

Took the tank off and the tap is dribbling when it shouldn't. Just wondered if anyone could say whether the TRX's fuel tap can die and the dribble of fuel is all the carbs get - which isn't enough...

Vacuum tube is connected- also to the scott oiler which still seemed to be working and the pipe seems to be free of holes.

Will get the tank off again and replace the tap assembly. Anyone else had similar issues? - p.s. before someone says emulsion tubes, I don't think they come into play when starting, only when on throttle - happy to be contradicted though...

Any thoughts & suggestions appreciated.

Final question - any good garages that can fix dead TRXs in the North West UK?

The Captain

[bubbaad]

Rig up an alternate fuel supply and if it still doesn't start or is difficult to start it will be worth checking the valve clearances.

[Snod Blatter]

The tank should serve fuel when under vacuum like normal, it just also gives a bit when it's not supposed to. Mine is the same, and it is also hard to start if I have left it standing for more than 3 weeks.

A silly suggestion maybe, but have you tried juggling the choke on and off while cranking it over? It's the only way mine will come back to life, a certain amount of choke at the right point does the trick.

Other than that, the real question is why won't it start? Have you ever had the valve clearances checked? D'oh, bubbaad beat me to it!

[zednine]

You say churns over ....... mine spins real quick .... bad earth ?

THe choke can seize on the shaft as well so make sure thats working

Chris

[Red Rex]

Mine can be a pig to start after sitting for a week in a cold garage.
It turns over real slow and will not fire.
Takes about 20 seconds worth of ever-more-slowly turning over without starting until all I get is a 'CLICK' from the solenoid.
Battery off and charge it up for 10 minutes and it fires up straight away.
Have you tried charging the battery ??

[bubbaad]

Yep, could be that simple......If you're lucky

[Kevtrx849]

If over a period of time it gets harder to start like you mentioned then i'd say definately your valve clearances have closed up.
OR if your fuel tap is dribbling in the on position then i'd say that your cylinders are filling with fuel which would account for the slow cranking. Check for fuel in your oil / increasing oil level.

[lenny]

Agree with Kev. Check valve clearances and do a compression check.

[fung]

+1.
but check your oil anyhow ,and if its fuelly get it out quickly cos it aint good no more
tap kits can be got thru the net.
search the forum for the thread.
cheers
fung

[zednine]

Hi there

Have you got it sorted ?

If not im in the north west and would be happy to give it a look at , got mostly all the spares for a swap and try session here

Chris

[captainscarlet]

Thanks to everyone who posted.

I've repaired the fuel tap. No problems there. To answer a couple of points, the starter spins the engine nice and quickly, I can hear the compression being released as the engine spins and it really does try and catch (you can hear it partially firing but not enough to actually start). The other day I persevered and it did actually start - once running it sounded fabulous - So - Not closed valve clearances or fuel supply issues. Next job (and I'm not looking forward to it) is to dismantle and clean the carbs - I suspect there may be some corrosion or dirt in there. Any advice on carb cleaning?

Cheers guys.

The Captain.

[zednine]

I have a spare set of carbs here you can try on

Chris

[captainscarlet]

Many thanks for all of the suggestions - however, it appears that I have solved the mystery with a 5 quid lawnmower fuel tap.

Basically, the main tap was still dribbling - actually it was more than just a dribble, even after the repair kit was fitted (and I did do it properly). The head of fuel in the tank was filling the float chambers to maximum so that when I tried to start the bike, it immediately flooded.

Test for this wasn't simply extracting a plug and looking for it - because it isn't immediately obvious if the plug is wet with petrol. Stick it on the gas stove and get it nice and warm at the tip and put it back in quickly (don't burn your fingers). If its a flooding problem, like mine, the bike will burst into life (on one cylinder at first).

Basically, I cut the fuel feed AFTER the pump - the pipe is easy to get at from the right hand side. I simply inserted the in-line fuel cock and secured it with a couple of jubilee clips and switched it OFF.

Next morning from stone cold it fired after barely turning once. One very happy TRX owner.

[captainscarlet]

Just one last technical note - a couple of replies suggested that the valve clearances may have closed up, causing the valve to be held open, thus losing compression. If you check the manuals, the cams act directly on shimmed cups, rather than via a rocker. Wear on the top of the cup / face of the cam will cause the valve to open to a smaller extent and to stay closed longer (surely?). As the bike has barely done 16,000 miles and I've serviced it myself, I'd be shocked if there was a lot of wear at the cam already.

Besides which, re-shimming the camshaft is a complete "engine out" job and I ain't got room for that.

Cheers,

The Captain.

[rogerc41]

Nice one captain. Glad to see that you got your problem sorted, think i'll remember that one for when my project is back together.

As far as valve clearances are concerned, yes clearances will close up over time. The reason is that bike engines in there nature are pretty hungry for revs when compared to the run of the mill production engines. The appetite for revs means that the valve is getting pulled into the valve seat at a hell of a rate and during time this in theory means that the valve will bash itself further into the head slightly. The top of the valve stem, with shim and bucket sitting on top then runs closer to the cam. It's maybe not such a problem on the TRX as its not as high revving as say an inline 4 but it will still occur. I've just done my valve clearances before puting the engine back in the frame. I had to re-shim 4 of the inlet valves as they had closed up (engine has approx 38K on it). Pretty sure you could reshim them with the engine in situ too, might have to drop the rad of though.