As mentioned above, my bike has always been difficult to start if left for more than a day or two - in really cold weather (like -4C + it's a real pain and quite a strain on the starter and battery.
I know it's trite but maybe riding it more, or at least starting the bike once every few days would be options.
I've lived in a warm climate for many years now, and even here it's not easy to start if left for more than a few days.
Sprock's ideas are spot on - maybe fitting a set of 1000RR coils may help, but I think it's more to do with fuel evaporating from the float bowls and the diaphragm on the vacuum fuel control may not be allowing full flow. That's what it sounds like on my bike.
HOLD the starter on until it's firing properly - you won't do the starter any harm, and it's easier on the battery than making it start the engine from a static position.
A dose of starting fluid into the air intakes may help when turning the engine over - just don't get it on the paint...............it's mostly ether I think.
Hope this helps.

 

Mine had the same starting symptoms until I replaced the starter clutch... but if yours fires up OK when warm it's probably not that.

 

I cannot find any reference to a 1989 model being sold in the States. Are they more akin to the MkI's?

The reason I'm asking is that I don't recall having a similar issue when I was running with the fuel pump installed. Now that I run a gravity feed the same happens to me if the bike sits for a couple of days. My bike will eventually start right up. I gave three or four short stabs at the starter, then a longish one and voila', she's good.

Are you running gravity feed on your bike?

 

I second the motion to put a shot of your favorite carb cleaner in the tank and go for a long ride. Then when you need to fuel up again, run another shot through. It might help and can't hurt.

 

Second that.

Give her the "Italian tune-up". Make sure she's safe and then go out flog the crap out of her.

Run her up and down the revs

Look in the mirrors for any bad emissions

Report back

 

Thanks one and all for your input. I'll probably try the easy way out first with a carb cleaner in the fuel, though think Ive tried that one before. Failing that will look into a carb re-build. Yep pretty expensive parts. Whilst you can get away with generic rings, the OEM kit come with the float bowl gasket, do you reckon the float bowl gasket stands up to the test of time? or probably needs changing so have to go for the kit.

Also if overhaul carbs. why not change jets to Carb Stage 1-3 Jet Kit by Sigma, anyone tried that?

And lastly would the needles need changing. Trying to ascertain costs of a carb rebuild.

Cheers

 

I have an '89 Australian model and I think it's the same as the US of A '90 model.

 

I've recently been using a Lithium Iron battery in the cold weather and it starts the bike quicker than any other - more or less instantly. Before I fitted it, it was sitting in the garage for weeks and stayed at a constant 13.2V - without trickle charging. An expensive but possible alternative for those in colder climes.