'94 XP hard to start after running

[biggsy]

Hi all I have bought 2 94 XP's and have had a lot of issues with them. I finally seem to be getting somewhere now but after I ride one of them and take a break for 1/2 an hour or so it is very hard to get restarted - it seems the engine is flooded - I need to hold the throttle full open for quite a time whilst cranking and I've read on here you shouldnt crank for very long. So I am just wondering if anyone has an idea what would be causing this. Any help is greatly appreciated. Cheers
Nigel

 

[Bills86e]

Carb needle & seat

What do the *plugs look like? If wet, more than likely than not the carb(s) needles & seats are leaking fuel into the cylinders when the motor is hot.

If cold hard starting, the following may apply.
The carb filters can be clogged with goo minerals & moisture oxidation particles.
Yes the Rotary Valve O-ring could be leaking air into the cases.
The carbs may not be sealed/bolted down tight.

Describe each cylinder's piston top & plug observation & smell.

A common cause is a carburetor needle(s) & seat(s) leaking fuel into the cylinders. How can gas get past a needle valve other than what I have talked about? One way is if the fuel tank pressure release check valve in the OUT vent line is not functioning. The fuel pressure in the tank overcomes the spring tension on the needle valve and gas is FORCED past it. The ski's fuel pump & the gas movement are further pressurizing the tank. Bills86e

 

[biggsy]

Ok - thanks for the info. The engine starts fine when cold. Like I said after i have rested it is then a bitch to start. It seems to be flooded - but being a twin carb setup i thought it might be too much of a coincidence for both needle & seats to be suspect. Also I am not sure of the reasoning behind a poor needle and seat - doesnt fuel only flow while the engine is running or does gravity continue to push fuel through the carby's after the engine has stopped? I just re-read your post - maybe its the pressure release check valve - how do i test that?

Addressing your other points:

I've cleaned the carb filters and replaced the fuel lines (I suspect this was the reason one cylinders rings seized before i had to have it repaired!). It's a new rotary valve o'ring so that should be fine.

The carbies are attached firmly.

 

[Dr Honda]

this is becoming a common problem.

like you said... both needles going bad at the same time is highly improbable. I bet if you open the carbs up... you will find non-Mikuni diaphragms in them. It seems like the aftermarket diaphragms aren't as flexible, and preses on the needle arm as soon as you tighten the cover.