TDM850 Tickover problem - Jetwash?

[Spezza]

Hi - I popped my 2000 TDM850 over to the local garage saturday and used the jet wash being very careful not to point it anywhere vital. Afterwards all was well (and clean), I lubed the chain, and took it out for a run and didnt have any problems. Didnt use it Sunday but this morning I started it with choke which normally runs the engine at an extra 500-1000rpm depending on how much choke. But...after about a minute, and without touching the choke, the engine slowed to normal idle. Once it warmed up I took the choke off and it sounded like it was running on one cylinder only and had to use the throttle to keep it running on both cylinders. I figured if it was moisture, the run to work would clear it, but still wouldnt tickover at work. So in short - once warmed up - its running on 1 cylinder at idle revs and stops.

Any suggestions? (apart from dont use a f*****g jet-wash!)

cheers

[Spezza]

Update - suspected a sticky choke....figured if one choke sticking then wouldnt idle on that cylinder but still open up okay.....took the tank and airbox off and slide is operating both choke stems so reckon thats good enough.....could be further inside carb but thats as far as I can delve without losing bits!

[Airhead]

try opening the carb bowl drain screws in case theres water in a bowl,

but first you may be able to identify which cylinder is causing trouble by touching the exhaust header with a damp cloth...the problem one wont get so hot...try to use as little choke as necessary to allow it to run or it may mask the problem

[Spezza]

Thanks Old Git! I'll have another go tomorrow eve. The tank and airbox comes off in 5 mins so can get to the carbs easily. Presume the drain screws are round the bottom of carbs somewhere?!? Was reading another post on AVRider forum with very similar symtons and poster replaced cracked diaphrams - is that likely to cause these symtons and the Jet-wash is just a coincidence?

[Airhead]

maybe i have have no experience of diaphragm cabs though.......

yes i suppose you will see drain screws at the bottom but thats just a guess

[Spezza]

AirHead? sure it said OldGitOnaBike yesterday! apologies if i'm wrong.

Taking bike over to friends this eve who has the right tools for the job - were gonna have a closer look at the carbs

cheers

[mervin]

Yes he has gone from OGOB to Airhead it is the same person

[Spezza]

Couldnt get bike started last night so hope to organise a van to get to workshop this evening - had to catch a frigging train today :-(

[pilninggas]

My TDM did this (riding in a jetwash-type downpour), the coils/leads/plugs were too blame (they are a little exposed in extreme wet), I replaced was fine afterwards.

[Spezza]

Coils/leads/plugs? sounds extreme (and pricey) ! but got to admit though, my mate John knows a thing about bikes and has got him scatching his head. Symptoms are pointing at carbs but hes had those off, in a bath, clean as a whistle. He replaced them, tested it and worked a treat. He gave me a call Thursday, went over in the evening and the symtoms returned. It starts with no choke, warms up, then wont idle. It will keep going on the throttle but definately not right! We considered dodgy fuel but figured that would be consistant. I'll have a closer look at electrics and check the spark - that would explain unburnt fuel and on/off symtoms - cheers!

[Airhead]

how about a temperature related ignition problem?

like pulser coils breaking down when warm, or perhaps water in the coils area of the engine...WD40 here?

[pilninggas]

Coils/leads/plugs? sounds extreme (and pricey) ! but got to admit though, my mate John knows a thing about bikes and has got him scatching his head. Symptoms are pointing at carbs but hes had those off, in a bath, clean as a whistle. He replaced them, tested it and worked a treat. He gave me a call Thursday, went over in the evening and the symtoms returned. It starts with no choke, warms up, then wont idle. It will keep going on the throttle but definately not right! We considered dodgy fuel but figured that would be consistant. I'll have a closer look at electrics and check the spark - that would explain unburnt fuel and on/off symtoms - cheers!

Coils with leads, plug caps and plugs ran me £45 all in.

But starting with no idle and then going bad when warm is a classic problem with the mikuni family of CV carbs fitted to these bikes. The problem is that the emulsion tubes have worn (needle jets). This permits fuel to flow, in addition to the metered idle quantity and the bike is over-fuelled (hence why it starts without choke). This is an absolutely known problem and is fixed by replacing the tubes - sadly something you cannot do on a 2000 model tdm850 (the tubes are not removable),

you have a few options that i am aware of:

1) fit carbs from a 96-98 4TX, these have replaceable tubes.

2) lower the fuel level; remember that if you are doing this on the bench, using the factory pro technique (google it), that it will be back 'back to front' when you bend the tangs - will work but may make the bike lean at high load (dodgy).

3) Drop the needles a few notches - if you can, sometimes works.

You need to go on the carpe forum for a full run down on the problem. I bet your electrics are still iffy though and what you are observing is the combined effects of both problems. I have had these issues on both my old TDM and my FZR - i could rebuild one of those mikuni set-ups eyes-closed. This is a reason, that often big, old yams change hands over and over with the seller tellin the buyer "it just needs a new air filter and plugs", when they really meaning they never figured it out, and can't be arsed any longer.

[Spezza]

hey PilningGas you were spot on. My man John fitted a carb kit and I'm cured! Running much happier now and a tank of fuel lasts all week. And yea, it cost a few quid but should pay for itself in fuel by time I sell the bike.