hard start

[ejonira]

I'm new to this site. I have a 1994 750 Katana and can't get it to start. It was sitting for 3 years when I tried starting it up. The gas had dried and varnish built up in the carbs. I took it apart and thoroughly soaked them, put them back together and tried starting it again. The bike would briefly fire up but can't get up on the revs to hold idle. I've adjusted the pilot screw, float height and bench sync the carbs. It seems there is not enough fuel going through the carb bore and into the cylinders to bring the revs up.
Does the float height make a huge difference? The float was set below 14.6mm (around 10 mm) before I brought them up. What effects does raising or lower the float have on the idle circuit?
Also, it took 4 turns out on the pilot screw to just get it to fire up, setting it at 2.5 turns shows no signs of firing up.
Any help would be appreciated.

[Jerkeife]

hmm the gas dried up...is fuel flowing freely from the petcock?

[ejonira]

Yes, it flows fine.

[akarob]

I would bet money that the tiny holes in your emulsion tubes are not clean. You need to poke a .020 diameter wire through those holes to make SURE they are fully open.
Seeing carb cleaner spray through them is not good enough.
Holding them and seeing light through them is not good enough.

Also, the cars are very sensitive to vacuum leaks. Make sure you have all the tiny o-rings in place - the ones unter the top caps that seal the sync ports.

After you get it back together, you need to sync the carbs using a vacuum gage. A lot of people have good results with a home made gage (or manometer), or there are also many good ones for sale. If you make your own, use a thick oil. I used 10w and it worked but it would have been easier if the oil was thicker.

This is all part of regular maintenance and I bet the bike runs like a dream after you do these things.

[ejonira]

Thank you for the advice. I'll look into it ASAP. I reused all of the old rubber seals and they were flatten.

Do you know the correct size of the rubber washers I'll need?

Can you tell me what differences the float height will make to performance?

[akarob]

Float height differences will result in differences in fuel mixtures. They should be within 1mm of each other I think, maybe less. I doubt that is your issue but it's good to check.

Also, if you soak your o-rings in oil for a few days, they'll come back to life. As long as they aren't torn at all, you can salvage them if you're on a budget.

[ejonira]

Thanks for the advice.