Cold starting my Yamaha RD350YPVS

Goughie · L Plate Warrior Joined: 14 May 2011 Karma :

Hi all, not having had this two Yamaha two stroke bike before I've found cold starting to be a pain especially if not used for a day or so. I've replaced the fuel tap diaphragm with a replacement parts kit thinking it wasn't getting fuel. The tap has a prime position that I feel it tends to be needed to be left in for about 30 secs at least before trying to start and seems to need full choke. It ususally takes about six attempts minimum before I can catch it to allow me to snatch the throttle open to keep it going.
The carbs look either new replacements or have been professionally rebuilt. I don't really want to go back to the original seller for any advice. Plugs seem ok. Any tips anyone

Thanks.
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John speaking from the democratic republic of Stalybridge,Cheshire,UK

MarJay · But it's British! Joined: 15 Sep 2003 Karma :

Goughie · L Plate Warrior Joined: 14 May 2011 Karma :

Thanks, I'll try those suggestions and a good idea if I only end up with a spare set of plugs to begin with.

John
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John speaking from the democratic republic of Stalybridge,Cheshire,UK

Suntan Sid · World Chat Champion Joined: 07 May 2009 Karma :

Goughie · L Plate Warrior Joined: 14 May 2011 Karma :

Plugs and fresh petrol seem to have cured the problem. Also it seems to be better now it's been started more frequently.
Thanks for your help.
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John speaking from the democratic republic of Stalybridge,Cheshire,UK

steven_191 · Nearly there... Joined: 31 May 2009 Karma :

the prime on the tap wont over flow the carb. or rather it shouldnt.

all it means is that if you have removed the fuel supply or have an empty carb, switch it to prime and it will fill the fuel supply without running the engine. running the engine causes a vacuum to open the fuel tap diamphram.

in theory you can leave it on prime all the time. it shouldnt make a difference if everything works.

if i were you id see what happens if your leave it on prime and start it.
when running the engine the vacuum opens the fuel tap so prime will just bypass this. switch it back to on and see if the engine still runs ok.

and yeah if its a cold engine and a cold day, prime is usually needed for easy starting. and dont start it then open the throttle too much. let it tick over for a minute then slowly take the choke off. if its going to stall then crack open the throttle enough to keep it ticking over while th choke comes off., if your still have trouble then you may need to check things like carb settings, ignition timing and is it turning fast enough to produce a spark, possibly even things like air leaks in the engine or more serious stuff. but unless you have more serious issues this is probably fine.

just read you have sorted it.

andys675 · World Chat Champion Joined: 08 Feb 2007 Karma :

put some silkolene FST in mine, after doing a tank at 2% mix and and using that tankfull over about 8 days the bike would tickover on its own without being nursed to keep it running

Vincent · Banned Joined: 16 Oct 2006 Karma :

Might be worth checking the condition of the inside of the tank. They rot through on the bottom, give little warning and are difficult to replace cheaply. They can be treated to prevent this and it's well worth having done.

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

Remember not to kick it too hard. On a stroker it's more a case of pressing down on the lever so it gently tickles over rather than giving it a big boot. I see a lot of people giving their stroker the big welly when cold starting and flooding them.

The prime position on the tap shouldn't make a shite of difference unless the float bowls were totally empty but using it would eliminate any concerns you might have about the vacuum tap operating properly.

Mine used to like the throttle cracked open by the tiniest amount when starting but it was tuned off its nuts and was a total bastard to start anyway. Most bikes shouldn't need the throttle touching at all when starting.

Mine also liked the choke just off fully open, something I achieved by pulling the choke out, putting a plastic clothespeg under the choke plunger then pushing it in again (I kept it clipped to the clutch cable so it was handy).

It's more likely to be a spark problem than a fuelling problem.

EDIT: That said. If it's cold starting in 6 kicks, that's not necessarily all that bad. Especially if it's just being started and not ridden (not sure if you're giving it a run or just firing it up occasionally). Have you tried thrashing the arse off it? They tend to oil up if just started, reved for a bit then switched off again.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

Goughie · L Plate Warrior Joined: 14 May 2011 Karma :

Thanks to everbody for all the tips.
It seems to have all stemmed from a lack of use of the bike and me flooding the engine. Now it's had a good run I can start it easily on one or two kicks with little or no choke.

Easy when you know how?
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John speaking from the democratic republic of Stalybridge,Cheshire,UK