Yamaha XT600 Cold Starting

Bat · Nova Slayer Joined: 11 Aug 2008 Karma :

Hi all,

I have just bought an '89 XT600 Tenere. I've replaced the battery and the bike has recently been serviced, but it's very reluctant to start from cold. When warm it starts instantly but from cold it takes a good 20 seconds of turning the starter over with some choke, then taking the choke down and giving it some throttle.

Any suggestions as to what will be the likely cause?

Many thanks,

iooi · Super Spammer Joined: 14 Jan 2007 Karma :

Could try changing the spark plug.

Other than that its a case of trying diffrent ways to see if it will start better.
Each bike seems to have its own idea of what it needs to get it going....

Just think yourself luckey its got a starter and its not kick start only.... Laughing

____________________
Just because my bike was A DIVVY, does not mean i am......

Bat · Nova Slayer Joined: 11 Aug 2008 Karma :

finpos · World Chat Champion Joined: 13 Sep 2005 Karma :

you should check the choke (actually enrichment device, I would imagine) is working, 20 secs of turning over generally dumps enough unburnt fuel about the place that it will evaporate and enrich the mix enough to start the engine without the choke.

f.

Gawain · Nitrous Nuisance Joined: 06 Dec 2008 Karma :

Dont touch the throttle when starting. Big singles dont like it IMO. New plug also cant hurt things.

Bat · Nova Slayer Joined: 11 Aug 2008 Karma :

Bat · Nova Slayer Joined: 11 Aug 2008 Karma :

finpos · World Chat Champion Joined: 13 Sep 2005 Karma :

... The throttle thing is interesting. a quick google says your carb has an accelerator pump. And that means your choke almost certainly isn't working.

When you go to start it tomorrow, before you do anything else, quickly open and close the throttle two or three times. Said pump will dump a load of petrol into the engine inlet. Again, that will evaporate and sufficiently riches the mixture which will make up for the (assuming broken) choke.

f.

Bat · Nova Slayer Joined: 11 Aug 2008 Karma :

Bat · Nova Slayer Joined: 11 Aug 2008 Karma :

Hmm that seemed to improve things. I still had to give it some throttle before it fired up, but it took less than 10 seconds.

Gawain · Nitrous Nuisance Joined: 06 Dec 2008 Karma :

The xt carb accelerator pump is vacuum driven... If the engine is off its not going to do anything.

Im not sure of your fuel tap arrangement but try priming the carb before starting, only every done good things for me.

finpos · World Chat Champion Joined: 13 Sep 2005 Karma :

this wouldn't have one of those hideously complex mikuni carbs, would it?

f.

Gawain · Nitrous Nuisance Joined: 06 Dec 2008 Karma :

Nope. More complicated than that (probably)! Its a teikei, primary carb is a standard piston carb with enricher choke, the secondary carb is a cv carb that parasites the primary carbs float bowl and which butterfly only starts opening at part throttle. Accelerator pump works of the cv inlet vacuum. Yamaha duel intake system YDIS.

finpos · World Chat Champion Joined: 13 Sep 2005 Karma :

Found a picture of one, what a nightmare Smile

I asked because the Mikuni carb (don't remember the model) had 2 interesting "features":

1. It had a mechanical accelerator pump which was disabled by a vacuum operated valve.
2. The choke/enrichment circuit was blocked if the throttle was open.

What this meant was that if it was set up a bit wrong, and by that I mean it was set up with the throttle slightly open so the damn engine would start when it was hot, then the choke/enrichment never kicked in and you had to pump the throttle like an angry monkey whilst also furiously kicking the engine over to get the bike to start. It did not look cool.

I'm guessing something similar is happening to Bat, especially if it starts so well hot...

f.

Gawain · Nitrous Nuisance Joined: 06 Dec 2008 Karma :

Xt's shouldnt be that hard to start, its not a common problem even with the kick only ones. My srx4 was a pain cold but warm was one kick. I turned her into a 1st kick starter 90% with a carb clean.

Bat · Nova Slayer Joined: 11 Aug 2008 Karma :

Interesing info cheers guys. I should mention that a previous owner apparently changed the carbs for later post 89 ones. Although my bike is registered in 89 it's an 88 model with the bigger tank, kick start and no windscreen.

The sodding thing took forever to start this morning. Had to give it loads of throttle and it still kept dying.

Ah loving the news that you sorted a crappy cold starter with a carb clean Gawain. As Tesco seem to be doing Redex for 90p a bottle at the moment I have chuck a load of that in the tank. Will do the same with the next tank and change the plug at the weekend.

Actually what I did do different was tutn the fuel taps off last night and on before starting this morning. This did not help matters.

Thanks for all your advice!