GK73a Advise Needed Float Height & How To Install The Airbox

[Mazzerdod]

Hi All!

I hope someone can help... basically I've stripped and rebuilt the carbs on a 1989 SP this went well new o'rings etc runs lovely revs fine and ticks over as it should.

However when I took her out she is really holding back doesn't want to pull at higher revs at anything more that 1/3rd throttle.

I set the float heights at 14.6mm and I feel that it's fuel starvation that's the problem.... forget the book what float heights work i.e. should i lower the float to allow more fuel into the float bowl?

Second problem for love nor money could I get the airbox onto the carbs... no!

The airbox rubbers are in good nick, not disfigured and plyable, I tried using rubber lube to help and tipping the carbs but it won't go on.

The airbox sits on the frame at the back because it's such a tight fit, this is subsquently tips the airbox forward and pulls he airbox off the carbs.

Hope that made sense.... any advise would be a big help!

[Variablevalves suck]

You must fit the carbs to the air box BEFORE fitting the carbs to the motor, it only works this way around.
By going the other way you cause the air box to leak around the rubber airbox trumpets and the bike will run crap.
Reseal the airbox trumpets/rubbers to the plastic air box with gule and then fit to carbs before fitting airbox and carbs.

[Mazzerdod]

Most awsome advise seems like it could be fiddley but it certainly won't go on any other way so I'll give it a try!

Thanks fella if it wasn't for your help I wouldn't have been as far along as I am

[Variablevalves suck]

LOL- it seems strange until you start to work this and then it makes sense.
Problem is when people force the airbox with the carbs attached they cause the rubbers to laek air and the bike dont run right, other thing to check is the rubber flap is still fitted between the rad and frame spars, if this is missing (people think it will get more power) the bike will have flat spots. Im sure the VFR guys will tell you the problems you get when you remove it from the V4.

[Mazzerdod]

Yes it does make sense when you think about it!

The rubber flap you refer is intact.

Any idea regards float heights mate?

[Variablevalves suck]

Running mine at 15mm from gasket surface.

[Mazzerdod]

Hmmm interesting..... I wonder if the tanks is gummed up preventing the float bowls from filling at the rate required at road going speeds?

The bike has been stood for 5-6 yrs and I haven't checked the tank.

I have to get the carbs off to install the airbox so I will double check the float heights and strip the tank, also I have some of that something something acid crystals that I'll use to soak the tank to ensure I remove any gunk.

I will post the results when I'm done fingers crossed it's the tank!

[Mazzerdod]

Oh one thing you may have some advise on... what would the stock needle setting be?

The bike is currently set at the 3rd groove from the top and I put a small 1/2mm washer on followed by the small nylon spacer.

[Variablevalves suck]

If its SP its 2nd groove and if standard its 3rd groove. Small washer then needle and finally the large plastic spring seat.

[Mazzerdod]

Yes it's the SP I checked all jets and needles against the part numbers you gave me and everything checks out.

So I will also drop the needle one notch back to stock i.e. place the clip on the 2nd groove from the top?