1996 XLT 600 SP cold starting and flooding

[mike bigger]

Hi all,
I have a 96 XLT 600 SP that I'm having issues with when it comes to cold starting/flooding. What I have done thus far:
- completely disasembled all three carbs and cleaned.
- replaced all three needles and seats.
- replaced all fuel lines, fuel filter, and checked fuel pickup in tank which was           fine.
- replaced all vacuum lines to carbs.
Is still hard starting and real finicky, but once running runs well after my arm is back in the socket. This doesn't make sense to me after all that I have done to correct the issue I started with. Can this be a choke problem as well?
Hotter plugs, different jetting?
There are 260 mains, 35 pilots in sled now which is what it came with.
This is really driving me nuts! Can someone help here?

[Vintagesleds.com]

[teamgreen2]

sounds like you have bad fuel.   I just worked on a 98 xc  700.   Thing started hard after I got done with the carbs.   we sucked all the fuel out.  Put fresh in it still started hard.    It would act like it would load right up.  Like it was flooded.  Could not get it started out side.  Finally switch plugs got in the shop put the old plugs in it cause all I had laying around was BR8es needs BR9ES.  Put the old plugs back in it started.   After it sat for a 1/2 in the warm shop.    Dumped some red Heat in it the red bottle.    Thing runs fine now.     I been nailed with bad gas about 4 times in the last 2 years.   Fresh stuff right out of the pump.      Add some heat and sea foam to it.   Get it running and ride it around see that helps. 

[Ski of Plenty]

Have you checked the throttle safety switch? When they fail it's usually an intermittent thing. While you flail away trying to start it I'm sure you occasionally operate the throttle...after that little switch plunger gets cycled a few times it starts making contact and the sled finally starts. I know it's a shot in the dark, but saw it happen a few years ago.  By the way, BR9ES is a colder plug than the B8's...almost any Polaris that runs that type of plug starts and runs better with the BR8ES. I personally run the NGK Iridiums in my trail sleds (BR8EIX I believe) and have never had one foul on me yet. The only downside is the electrode is so small that it's hard to do a plug reading if your playing around with jetting.

[mike bigger]

Regarding bad fuel, this sled was hard starting all last season with any fuel I put into it. But like everyone else just figured it was needles and seats. No matter what I do, the plugs are soaking wet with fuel when I pull them. Will misadjusted chokes create hard cold starting?

[chuck k]

Did you check the fuel pump pulse line for fuel in it.
I have had a bad diaphram cause this problem.
All my XLT's are sensitive to flooding when first started.
I have to shut the choke off right away.

[earnhardtnorth]

Air screws adjusted properly?

[TXLiquid]

Regarding bad fuel, this sled was hard starting all last season with any fuel I put into it. But like everyone else just figured it was needles and seats. No matter what I do, the plugs are soaking wet with fuel when I pull them. Will misadjusted chokes create hard cold starting?

Did you replace the needles and seats with OEM Mikuni parts?

[mike bigger]

I have not checked vacuum line coming off of crack case, but I will.
Yes I did replace needles and seats with Mikuni OEM. Air screws are
1 - turn out.

[teamgreen2]

You pull the fuel line in the tank??    If that is broke off it will start hard.   
   
Or the line gets soft and sucks shut trying to pump fuel.    Another thing  maybe you have a broken piston skirt.   I worked on a zrt 600 a few years back.  Thing would start hard.  Had good compression when the gauge was on it.   I pulled the pipes off to look in the cylinders from that way before starting to pull the engine a part.  A chunk of skirt was missing.  That will change the port timing make the sled push air back up through the intake.    A XLT you should be able to pull the Y pipes off and look at the pistons on the back side.  And you can pull the carbs and look at them from the front.
   Another thing do you have a plug exhaust.  Take the pipe off itself take a garden hose and run water through it.  If anything is in there it will push it out. 

[jettawreck]

Regarding bad fuel, this sled was hard starting all last season with any fuel I put into it. But like everyone else just figured it was needles and seats. No matter what I do, the plugs are soaking wet with fuel when I pull them. Will misadjusted chokes create hard cold starting?

The starting ritual for my '94 XLT SKS was this:
Full choke a pull or two (usually all it took) or until it first fired, even once. No choke after that until it started and then play with half choke (perhaps full choke flips on/off if it was really cold) until it idled on its own. This typically only took a minute or so.

Yes, if choke cables are set too tight it will lift the enrichment pistons(?) and cause flooding. Have you removed those enrichment pistons(?) and checked them? It's common for them to get corroded and they don't drop all the way down into the bores and create a rich condition even with choke "off". They don't move/lift in the bores very far.
They are a bit prone to flooding, but with the right starting procedure, most of them are excellent starters even in the very cold temps.
Sounds also like the float needle valve and/or seat may need polishing (even if new) or float level a bit too high. 

[mike bigger]

Thank you to all for the tips here.
I will check everything you guys have suggested one at
a time as a process of elimination starting with fuel in the
impulse line. I did pull fuel pickup line out and examined
it well and it appeared fine. Other than the pickup line, I replaced
all fuel hose from shutoff to pump and to each carb.
Right now I know the choke lever is tight against the dash
with no play. I will go through all of the easier potential issues first.
How does one know if the float levers need to be bent a bit as to not
allow fuel bowls not to overfill, as well as
how much to bend if it comes down to this? I did disassemble the entire
exhaust system as I blasted and repainted but I did make sure that all
blast media was cleaned well prior to reinstalling.

[mike bigger]

Also how do you polish these tiny needles and how
does one know if they are in fact leaking, shut fuel off
and leave it overnight?

[vtg]

First off, the XLT Specials and the monoblock XCRs usually had 38 mm carbs as opposed to the 34 mm carbs used on the standard XLT models. The 34 mm equipped ones were always considerably easier to start than the 38 mm carbed versions. But having said that, cold starting was not usually an issue with either version. It was when you had shut the sled off for about 15-30 minutes, that the 38 mm carbed XLTs were a bit stubborn to get fired up again. And you mention that you are having problems starting yours cold? Cold starting should not be a problem at all. You described the things you have checked thus far. Here are a few other things to look at if you haven't figured out the problem yet:

1) Check that the hose inside the tank has not swelled up causing it to be loose on the fitting that screws into the tank. This happens OFTEN and is easily overlooked. If the hose swells and becomes loose on the fitting, the fuel pump will be sucking some air and not much fuel. If the hard starting only occurs when the fuel tank level is somewhat low (as in below the level of the fuel tank outlet fitting), then this is very likely the problem. You did state that you looked at the pick up line but it can look perfect and still be loose on the fitting. The only real way to know is to drain the tank and screw out the tank outlet fitting.

2) You mentioned you changed some fuel lines but it's unclear if you changed all of them? If your XLT had the black rubber fuel lines, make certain you change all of the lines. Those black rubber hoses can look perfect on the outside but the crap gas we buy today will attack the inside of the hoses and small black particles of rubber will eventually wind up in the fuel pump and in the carburetors. So also dismantle the fuel pump and make certain there is no rubber debris in it and clean the carbs again if you suspect the fuel hoses are deteriorating. Those little black specs of rubber will end up lodged in the inlet needle valves causing the needles to not seat properly and the carb will flood.
 
3) What is your idle speed set at? I'm not sure of the exact setting but if it is anything higher than about 2000 RPMs, the chokes will not function properly.

[jettawreck]

Quote:
"Right now I know the choke lever is tight against the dash
with no play. "
That's too tight.
Check that out and the other great recommendations.

[mike bigger]

First off, the XLT Specials and the monoblock XCRs usually had 38 mm carbs as opposed to the 34 mm carbs used on the standard XLT models. The 34 mm equipped ones were always considerably easier to start than the 38 mm carbed versions. But having said that, cold starting was not usually an issue with either version. It was when you had shut the sled off for about 15-30 minutes, that the 38 mm carbed XLTs were a bit stubborn to get fired up again. And you mention that you are having problems starting yours cold? Cold starting should not be a problem at all. You described the things you have checked thus far. Here are a few other things to look at if you haven't figured out the problem yet:

1) Check that the hose inside the tank has not swelled up causing it to be loose on the fitting that screws into the tank. This happens OFTEN and is easily overlooked. If the hose swells and becomes loose on the fitting, the fuel pump will be sucking some air and not much fuel. If the hard starting only occurs when the fuel tank level is somewhat low (as in below the level of the fuel tank outlet fitting), then this is very likely the problem. You did state that you looked at the pick up line but it can look perfect and still be loose on the fitting. The only real way to know is to drain the tank and screw out the tank outlet fitting.

I did pull pick up line and filter out and inspected. The pick up filter actually had band on the hose as to not fall off, but I will drain gas and reinspect. I do have a new pick up so I'm going to change that as well as the clear hose (pick up line).

2) You mentioned you changed some fuel lines but it's unclear if you changed all of them? If your XLT had the black rubber fuel lines, make certain you change all of the lines. Those black rubber hoses can look perfect on the outside but the crap gas we buy today will attack the inside of the hoses and small black particles of rubber will eventually wind up in the fuel pump and in the carburetors. So also dismantle the fuel pump and make certain there is no rubber debris in it and clean the carbs again if you suspect the fuel hoses are deteriorating. Those little black specs of rubber will end up lodged in the inlet needle valves causing the needles to not seat properly and the carb will flood.

I did change all fuel hoses with new. The only one I didn't change was the impulse line which I need to check for traces of wet fuel anyway. I have a kit for fuel pump but not change it so I will do that. Are these black specs of deteriorated fuel line big enough to see or smaller. The reason I ask is when I pulled carbs apart I saw no traces or small chunks of fuel line.
 
3) What is your idle speed set at? I'm not sure of the exact setting but if it is anything higher than about 2000 RPMs, the chokes will not function properly.

Good point I think I do have the idle at 2000 rpms or a tick higher.