95 XLT 600 exhaust leak?

[timms.mc]

So I recently bought a snowmobile (in title). And it came with a few problems, but also a nice price tag. From what I can tell. The main issue is an exhaust leak. This is all fine and dandy, as I am getting the crack in the exhaust welded in a few days. Now there may be more problems, but the lack of back pressure in the exhaust prevented the engine from running for anytime (not to mention it was nearly -30 celcius when we attempted to start it) but I did breifly notice that there was liquid (presumably fuel) leaking out of said exhaust leak along with exhaust. I'm just wondering if this is normal when there is an exhaust leak (low back pressure may allow unburned fuel to escape into the exhaust as the exhaust valve and intake valves open?) Or if this will be a separate problem with the carbs, maybe a stuck float or simply a few adjustments?

I'm not claiming to be a 2 stroke, or carbs expert, I have zero experience with actually working on either, but I do understand the basic functions and processes of them. I'm looking forward to learning with my new purchase, and learning from others with much experience.

Some may advise me to take it somewhere to be serviced, but... Come on, there's no fun in that.

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[medler]

Leaking raw fuel outta the exhaust isn't good ..
those triples aren't easy to work on. I had a 95 XLT. I would advise taking it somewhere and get the carbs set properly and check what size jets are in them as well. Those sleds are very quick when they run good. But can be temperamental to say the least Good luck with your purchase

 

[freeflorider]

First off there are no valves in a two stroke. A cracked exhaust or y pipe will not prevent the motor from running. If you are seeing fuel leaking from one cylinder this can happen, it's flooded big time. Take the plug out and pull the cord to clear the fuel issues, not that I recommend but having a lighter and placing it over the plug hole you can clear the fuel but it will flash and take the hair off your fingers so be careful.
these triples can be problematic, be sure to shut the fuel off when parking it( right side by the air box, should be a red leaver if I Remember right) over time the carbs can bypass (stuck float) and fuel will fill the cyl and sometimes the pipe.

 

[timms.mc]

Alright thanks freeflo. I do know that 2 strokes don't have valves, I just didn't know the proper terminology (is it simply I take and outtake?) Either way, when I remove the spark plugs to drain the flooding issue, do I also need to shut off the fuel before I pull the cord? I have unflooded a chainsaw before by simply turning the motor upside down with the plugs out, but I cannot turn a 600 upside down to do the same.

Also, I should note that we did have it briefly running. If we kept on the throttle ever so slightly, we could have it run for about a minute or two. It sounded great while it was running.

Also, should it be a stuck float, do you have any experience or tips on these carbs specifically? I found a lot of info on carbs in general, but not on the XLT 600 specifically. I know all carbs are generally the same, but I'll take any advice.

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[retiredpop]

There are crankcase drain plugs on those engines. There are 3 - 10mm bolts on the front of the engine at the bottom of the case. You can remove those to drain the excess gas out if that is the problem but you will need to replace the inlet needle valve if indeed it is full of fuel. Turn off the fuel lever in the meantime.
The liquid you saw could simply be unburned fuel and oil because of spark issues. When it was running were all 3 cylinders firing? Have you done a compression test on it yet?

 

[timms.mc]

There are crankcase drain plugs on those engines. There are 3 - 10mm bolts on the front of the engine at the bottom of the case. You can remove those to drain the excess gas out if that is the problem but you will need to replace the inlet needle valve if indeed it is full of fuel. Turn off the fuel lever in the meantime.
The liquid you saw could simply be unburned fuel and oil because of spark issues. When it was running were all 3 cylinders firing? Have you done a compression test on it yet?

Yes. That could very well be the case. It was extremely cold when I tried to start it. And I have a sneaking suspicion that the seller of the snowmobile may have had it flooded when I got there. He had tried to sell it to someone before me. He also did not know a whole lot about 2 strokes at all (which was a bonus for me as I managed to knock the price down quite a bit).

I have the sled in a heated shop right now. I'm going to Jimmy rig the exhaust leak for testing purposes (I'll likely buy a new or used exhaust instead of fixing what i have, it's pretty bad). Once I get the exhaust back on, I'll make sure it is unflooded and see if it will run.

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[timms.mc]

Ok. So it looks like it may be the needle and seats in the carbs. (Same as inlet needle valve?) I have three questions.

1. What needle and seat assembly do I need to purchase? From the research I did, all I found was that I needed a mikuni VM 28/511 1.5. is this correct?

2. When I replace the needle and seat, and it comes time to re-install the carbs, can i simply reassemble everything the way it was, or do I have to sync it? I won't be completely cleaning it, that'll be saved for later when I can take it in to be cleaned. All I'll be doing is replacing the needle/seat.

3. Am i safe to be running the machine with leaky needles until I get new ones ordered in? I want to ride on the weekend, and there is absolutely no way I can have new parts by then. Obviously, my cylinders may flood whole the engine is off (I'll be shutting the fuel valve off every time I shut the engine off) but will there be any excess damage? I can't think of any problems, aside from maybe some irritation from flooding the cylinders.

P.s. I know the logical thing is to take it in and get it completely fixed and cleaned professionally in one shot. But life sucks sometimes and not everything can happen perfectly all the time. I simply don't have the time or money to get it worked on right now. Plus I really want to learn about 2 strokes and carbs and there is no better way than doing the work yourself. So if your only advice is to take it in to get fixed, please refrain from posting, otherwise, thank you for the advice!

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[retiredpop]

Those are the right ones for your carbs as they have the viton tips which seal much better than the all brass type. Reassemble like they were and you should be fine. To adjust the floats on those you turn the carb upside down so the float tang rests against the bottom of the needle and the float arm is parallel to the body of the carb. Don't put any pressure on the float itself - just the weight of the float itself. Bend the tang to adjust. You can run it the way it is without harming anything. Cleaning carbs is pretty simple and there is no need to take it in. Remove the float bowl to access the main jet and pilot jet. Remove them and physically clean them to remove any buildup of varnish from old dried gas deposits. I'll find a write up I saved for syncing the carbs and post it later.

 

[timms.mc]

Alright. Thanks for the info, it's very helpful. I look forward to the write up for syncing.

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[retiredpop]

I couldn't post it as an attachment so here it is in original form.

Carb synchronization.

You have three mikuni slide valves with individual cables going to a cable box under the hood. DO NOT do a uni-synch (flow-type) synchronization!
You must do a mechanical synchronization.


1. get the air box off, carbs in proper place and have throttle cables
secured approximately where they would be when the air box is is in place.
(different bends of the cables will change synchronization)


2. make sure the carb caps are all hand tight on the top of the carbs, (as
they would be in normal operation)


3. Back off all the idle stop screws and let the throttle slides hang from
the cables (inside the body of course)


4. Back off each lock nut on the cable adjusters on the carb caps. make
sure the cable adjusters turn freely


5. use approximately a 1/4" piece of smooth rod or smooth drill shank
(even the stamped numbering can goof you up) and slide this in the bottom
of the throttle opening and then by turning the cable adjusters, adjust
the bottom edge, air box side, of the throttle valve, until it just
squeezes the 1/4" rod. try sliding the rod in and out slightly and you
will find it easy to tell when it first gets squeezed by the throttle
valve.


6. Do this to all three carbs and you now have the throttle valves
synchronized to each other. snug down the cable adjuster locknuts
temporarily.


7. Now go up one size in rod (17/64) and do the same concept except adjust
the idle stop screws to raise the throttle valves, to squeeze the rod. You
now have the idle stop screws synchronized.


8. From this point on adjust the cable adjusters together (count the
number of flats or turns when adjusting) also the idle stop screws
together (count the turns) and they WILL STAY SYNCHRONIZED.


9. You have to reinstall the airbox, refasten the throttle cables in
position, adjust idle speed (after starting and warming the engine),
adjust throttle cable slack using cable adjusters (should be about .030 play at the trigger
throttle) final tighten the cable adjuster locknuts.

 

[timms.mc]

I couldn't post it as an attachment so here it is in original form.

Carb synchronization.

You have three mikuni slide valves with individual cables going to a cable box under the hood. DO NOT do a uni-synch (flow-type) synchronization!
You must do a mechanical synchronization.


1. get the air box off, carbs in proper place and have throttle cables
secured approximately where they would be when the air box is is in place.
(different bends of the cables will change synchronization)


2. make sure the carb caps are all hand tight on the top of the carbs, (as
they would be in normal operation)


3. Back off all the idle stop screws and let the throttle slides hang from
the cables (inside the body of course)


4. Back off each lock nut on the cable adjusters on the carb caps. make
sure the cable adjusters turn freely


5. use approximately a 1/4" piece of smooth rod or smooth drill shank
(even the stamped numbering can goof you up) and slide this in the bottom
of the throttle opening and then by turning the cable adjusters, adjust
the bottom edge, air box side, of the throttle valve, until it just
squeezes the 1/4" rod. try sliding the rod in and out slightly and you
will find it easy to tell when it first gets squeezed by the throttle
valve.


6. Do this to all three carbs and you now have the throttle valves
synchronized to each other. snug down the cable adjuster locknuts
temporarily.


7. Now go up one size in rod (17/64) and do the same concept except adjust
the idle stop screws to raise the throttle valves, to squeeze the rod. You
now have the idle stop screws synchronized.


8. From this point on adjust the cable adjusters together (count the
number of flats or turns when adjusting) also the idle stop screws
together (count the turns) and they WILL STAY SYNCHRONIZED.


9. You have to reinstall the airbox, refasten the throttle cables in
position, adjust idle speed (after starting and warming the engine),
adjust throttle cable slack using cable adjusters (should be about .030 play at the trigger
throttle) final tighten the cable adjuster locknuts.

Thank you so much. This reassures me to my ability to do the job. I just went to see my sled today, and I wanted to see how much the crank case had flooded. Before I explain anything, I should note that the fuel was shut off over night, and in the morning I had someone turn the fuel on, it sat with the fuel on for about 6 hours. I unscrewed the drain plugs and only 1-2 drops of fuel spilled out, very minimal to what came out the first time.

What i want to know, is whether 1-2 drops is normal for every engine (remember fuel was only on for 6 hours) or if that would be a sign of faulty needles. I don't know how leaky these needles can get, or whether that is bad.

Needless to say I will be changing out the needles for viton tips, but if it can wait until spring when I do a major overhaul on the entire sled, then I would rather wait. Thanks again, you've been tons of help to this rookie 2 stroke mechanic

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[retiredpop]

I really don't know if 1 or 2 drops is normal but suspect it might be as there will be some residual fuel/oil mix that is in the crankcase due to the fact that the fuel goes through the crankcase before getting up to the cylinders through the transfer ports. It would be in the form of a fine vapor when running but when the sled cools down it might condense. That's my theory anyhow. If you turn the fuel off when you are transporting it or when it will sit for a while I can't see it being a real problem for the rest of the season.