Bike not working

[mbanham]

Hi guys,

Have never really posted on here, just kind of read what everyone else says.

Right I have a 1998 Yamaha Thundercat which will not start, it sounds like the engine is turning over but is not catching, it has stood still for a couple of months (If this will make a difference). Also should note the battery is fine.

Does anyone have any suggestions what may be wrong or maybe a list of what to check first (have only had this/ my first bike for about 4 months so a bit clueless)

Thanks in advance

Mark

[crankedup]

Drain out the fuel and refill with fresh petrol, modern fuel has an nasty habit of going stale very quickly and this will, if its the case, stop the engine from starting.
You have made double sure that all immobilizers are inactivated I assume.

Spray the plug leads and inside caps with a moisture repellent.

Let us know how you get on.

Edited by crankedup on Friday 11th January 14:06

[mbanham]

Cheers, I take it this is simple?!?

I have a Haynes manual at home so will have a look, I need to improve my none existant mechanical skills anyway

Thanks for the reply.

[podman]

TBH id it has just been a matter of 2 months the fuel wouldnt have gone off enough to stop it from starting, it does take around 6 months to end up terribly stale , after that it starts to solidify into almost a varnish which really gums up components.

Id go down the moisture route to start with, myabe you have flooded it as well? can you smell fuel around it?

If you dont have any luck there, id say try go down the fuel route.

Drain out the fuel from the carbs by un doing the drain screws on the bottom of the float bowls.

You can either syphon off the fuel in the tank or take it off and undo the fuel tap.

Keep us posted

[Carl-H]

Kill switch? Fuel tap?

[Silver993tt]

spray some easy start into the air intake/air box. That will get the engine running for a few seconds enough to clear the plugs and for the fuel system to get going

[mbanham]

Cheers guys, all good stuff to look in to.

As mentioned the engine just doesn't seem to catch.

Could the spark plugs be corroded, could that be a possibility?

Will be busy this weekend then!

[Brite spark]

I know you think the battery is fine, but how do you know this? has it been on an optimate keeping the charge?
a very small drop in the battery will prevent the bike from starting, especially as it has been stood for a while.

have you tried bump starting the bike to get it going?

always the lazy option if you have breakdown cover with home start

[mbanham]

Yes mate, optimate and a volt meter so I know once the optimate is turned off it is still holding it's charge.

See where your coming from though, try the easy things first!

[robstvr]

I had this problem, siphoned the fuel, and put in some silkolene pro boost. Did the trick but, man, does petrol give you sore guts. And as for lighting your farts - just don't. :-)

[mbanham]

So remember the mints and stay away from the gas fire...Got it!!

[crankedup]

Yes as I mentioned earlier stale petrol can cause problems. I do agree that 2 months standing in a tank that the fuel should still be OK but time and again stale fuel is the problem. Engine management systems are very fussy but even vintage engines sometimes struggle to start on old fuel.

[paul_tim2000]

Suggestion.

If its fitted with carbs (which I think it is) and it's been standing then the fuel evaporates, and if it is a vacuum fuel tap it can take a long time for the bowls to refil with petrol before it fires, think it was my old TDM that always did this (or maybe Suzuki, cant really recall)
If it's got a "prime" or similar fuel tap setting try that (doesn't need the inlet vacuum).

[bimsb6]

drain the carbs ! i've had bikes in the past that wouldn't start on the button after a week without the carbs being drained first (yam xj600) my evo harley and the mrs buells always need the carbs draining if left for a few weeks .

[podman]

bimsb6 said:

drain the carbs ! i've had bikes in the past that wouldn't start on the button after a week without the carbs being drained first (yam xj600) my evo harley and the mrs buells always need the carbs draining if left for a few weeks .

If you have a bike that wont start for just 21 let alone 7 days with out the carbs needing draining something else is amiss...or you just like the smell of un leaded?

No way would 3 week old fuel stop a bike from starting

Did you get it started this w'end mate?

[bimsb6]

podman said:

bimsb6 said:

drain the carbs ! i've had bikes in the past that wouldn't start on the button after a week without the carbs being drained first (yam xj600) my evo harley and the mrs buells always need the carbs draining if left for a few weeks .

If you have a bike that wont start for just 21 let alone 7 days with out the carbs needing draining something else is amiss...or you just like the smell of un leaded?

No way would 3 week old fuel stop a bike from starting

Did you get it started this w'end mate?

you obviously know better than me how to start my bikes ! this is from EXPERIENCE not my imagination .

Edited by bimsb6 on Sunday 13th January 16:52

[Silver993tt]

bimsb6 said:

drain the carbs ! i've had bikes in the past that wouldn't start on the button after a week without the carbs being drained first (yam xj600) my evo harley and the mrs buells always need the carbs draining if left for a few weeks .

my bikes sit 5-6months in the garage over winter and they always start first touch of the button. I never have to drain the fuel or touch anything except I do keep them on battery maintainers.

[bimsb6]

Silver993tt said:

bimsb6 said:

drain the carbs ! i've had bikes in the past that wouldn't start on the button after a week without the carbs being drained first (yam xj600) my evo harley and the mrs buells always need the carbs draining if left for a few weeks .

my bikes sit 5-6months in the garage over winter and they always start first touch of the button. I never have to drain the fuel or touch anything except I do keep them on battery maintainers.

it does depend on the bike ,i have an old xt500 which will start if left a very long time ,the damn xj600 did it from new that was in 1986 .my harley and buells if left for any amount of time won't fire up until the carb has been drained .

[TeZREX]

Depending on what type of fuel you use the fuel could have gone off. How long did you try to start if for? if it didnt fire pretty quickly you could have flooded the engine. Try turning the choke off and firing the bike with the throttle fully open to try to clear the fuel in the cylinders.
You may even have to remove the plugs if you are really unlucky, which cabn become a bit involved (Tank off airfilter off no doubt some plastics as well. It was for my old ZZR600!)
If not you may have to drain the carbs if you are really unlucky.
Also check that the petrol tap has its vacuum hose still attached!
If the battery starts to die due to attempted starts then a car battery has a bit more ooomph with a set of jump leads connected to the bikes battery..
Good luck!

Tez

[mbanham]

Hi,

Have replaced the spark plugs as the others were really dirty, guess that means the carbs need draining? Can't see where the drain plug is so any pictures would be appreciated???

Battery def fine, have made sure it has new fuel in and an additive.

So if I try and repeatidly start with choke off would this clear it and then be ready to fire up?