hot starting problem 96xp

[96xp800]

I have posted on this topic before. I have an sbt motor in my xp. I was having a hot start problem and discovered a broken ring so I replaced the top end. I am still having trouble starting it hot. I have 160 psi in both cylinders. I have replaced the N&S in both carbs but did not spring for the entire rebuild kit. I have adjusted the low speed both ways but nothing seems to cure the problem completely. Tech support told me to try turning the low out a 1/4 turn. This seemed to help for awhile but now it's bad again. You have to crack the throttle and grind on it for 5-10 seconds before it will go. If you stop it and start it right away it will fire right up. If you wait five or ten minutes the problem is really bad. It cold starts great though. I am thinking I should have replaced all the internals on the carbs?????? Any Ideas??

Thanks

[johnnie7]

Re: hot starting problem 96xp

have u tryed w8ing the 10 mins ...then removeing the spark plugs ...and injecting a small amount of pre-mixed fuel and then replaceing plugs and trying?
:D
if the above helps then ...its possibly carb related
if not then u may have other problems...maybe crank seals or electric probs for example
just a few sugestions before any the tecs get a chance 2 reply

regards

john

[Bill O'Neal2]

Re: hot starting problem 96xp

Could be a worn rotary valve cover.

Could be that somehow, fuel is getting past the needles and seats when it is hot. Maybe a clogged up vent check valve on the gas tank vent line, making the mixture too rich?

Opening the low speed adjusters made starting it easier? That would mean it was too lean to start.

Is it too lean to start or too rich to start when it gets hot?

[96xp800]

Re: hot starting problem 96xp

It's tough to say. When it does finally start it doesn't smoke or act flooded. I have the lows out about 1 3/8 and if you run it slow for a long way it seems to load up a little. I ran it around 1/4 to half throttle down the lake and shut it down clean. The plugs look cardboard brown. I started with the screws at 1 1/8 and when the hot start problem occured it seemed lean because it had a dead spot at about 1/4 throttle you had to work it through. I turned them out to where I am at now and it still has the problem but the dead spot is gone. It runs great otherwise. Also, the battery light comes on very easily. The battery is new last season. I also put in a new starter this year because I had the motor replaced by a dealership about four years ago and they said the starter was on it's last leg then. This is the dealership that put in the SBT motor. I have only replaced the top end.

Thanks

[Bill O'Neal2]

Re: hot starting problem 96xp

Have you removed the sparkplug wire connectors and snipped off about 1/4 inch of wire and reattached the plug caps to some fresh wire core strands? Sometimes that is all that is necessary to solve a problem such as this one.

[96xp800]

Re: hot starting problem 96xp

I have not tried that. I will do that tonight. The plug wires are in original form from 96! Thanks for the quick response!!

[Bill O'Neal2]

Re: hot starting problem 96xp

Yeah. They are good for a couple of seasons of riding before they need to be snipped again. I'm sure yours are due......

[96xp800]

Re: hot starting problem 96xp

Bill, I forgot to mention that I had a bolt on the exhaust header pipe break and the motor sucked in enough water to score the intake side of the pistons. The ski kept running after I fixed the problem and I noticed the piston damage when I was replacing the top-end. I was reading another post about the rotary cover and water ingestion. Do you think I messed up the RV cover when I was ingesting water?? The hot start problem was there before the ring broke.


Thanks

[Bill O'Neal2]

Re: hot starting problem 96xp

I'm sure if you sucked water into the carbs and the motor, it did some damage to the RV cover. How much can be detirmined by measuring the gap between the cases, rotary valve and the RV cover. You need between .010 to .014 clearance. Over .014 will create a hard starting situation. BTW, the gap increases as the motor heats up.

If you need a new cover, SBT has them for $100.00 exchanged.

[96xp800]

Re: hot starting problem 96xp

I'll check that out. Thanks alot for the help. I think it's a combination of the plug wires needing to be clipped and the rv cover being out of tolerance. The water is geting colder up here in Northern Minnesota so I may not make it out again this year. Thanks again!!

[96xp800]

Re: hot starting problem 96xp

Well, I clipped the plug wires back and it was the same so I pulled the carbs and removed the o-ring from the rv cover. I bent a feeler gauge to fit in the port and a .014 fit in with room to spare on the corner of the MAG port and all around the port on the PTO side. Just to make sure, I am supposed to measure the tolerance between the actual cover and the valve right?? Anyway, looks like I need an RV cover.


Thanks for all the help on this subject. I will post the results if I get the cover and test it this season.

[Bill O'Neal2]

Re: hot starting problem 96xp

Yep, that is how you measure it.

[96xp800]

Re: hot starting problem 96xp

I have replaced the rotary valve cover and the ski still starts hard when it's hot and let sit for a few minutes. You really have to grind on it to get it to start. Yesterday we actually had to put it on the trailer and then it fired right up. Any ideas where to go from here.


Thanks

[Bill O'Neal2]

Re: hot starting problem 96xp

Is this 1996XP completely stock?

[96xp800]

Re: hot starting problem 96xp

Yes it's completely stock. It has an SBT motor in it and it's 1.0 oversized but thats it. No other mods.


I checked the fuel tank vent valve. It's a little hard to blow through. I cleaned it but it still takes quite a bit of pressure to blow through it. Is that normal?