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Discussion Starter #1 (Edited)
Hi guys! I am new here but have read a lot on this forum, mainly to try an figure out what to do with my sled. So here is the situation, starting with a little background...

I bought this sled for cheap with a seized crank, and broken shock on the xtra-12. The sled came with a spare parts motor (with crank snapped on clutch side). I rebuilt the entire sled basically. All new bearings on the crank, checked the cylinders of both motors as the motor that was in the sled had one stock sized piston and cylinder and the other cylinder had been bored out 20 thou and they were also out of round (I am an apprentice machinist, so brought the parts to work). The cylinders on the parts motor were in great shape and so was the head. Used all new gaskets, built the motor with new crank bearings and I have 120 psi in each cylinder. Wile I was at it, I replaced all bearings on the jack shaft, drive shaft, chain case, and slider cage. All new fuel pump and lines and all new vent lines and new throttle cable (yes I synced the carbs). Cleaned the carbs really well and put all brand new jets, all stock sizes from the dealer.

When my father and I set it up we had the needles set to the center notch but my dad found it boggey so we moved the clip down one notch to try to richen it up a bit. seemed to work but every time I hit a hill, unless I get a run at it, it would bog down. I moved the clip back to the center position on the needles and seemed more responsive. The sled idles great (around the 1600rpm mark) and once I get the rpm up over around 3500rpm the sled goes like snot! The minute I let it drop to idle again it idles great, but when I give it some gas to get going again it bogs down again. If I try to stay on the throttle when its bogging it dies but if I let off the throttle it returns to its great idle. The only way I have found around the bogging is to touch the choke (lightly, just lifting the lever a bit) as I give it throttle and it goes up to 4000rpm no problem when doing this. It seems its not getting enough fuel to launch out of the low rpm range. Once its over 3500-4000 rpm it climbs and screams no problem (with the choke off), will even climb hills no problem.

I am currently running mixed gas in it as my father and I wanted to make sure the bearings and everything broke in properly and we wanted to make sure the oil pump worked before running straight gas. I have burnt through half the tank already and love the machine (grew up with my dad having a 91 indy 500 black ice edition, dad rebuilt that motor twice). I have also changed the spark plugs and am running the br9es with the solid tips.

We are all stumped here, my dad has a 94 xlt now (91 500 got stollen), brother has an 89 indy 500 and none of us can figure it out. Not sure if I should move the needle clip again and go to the extreme lower position (which would bring the needle up more)?

Any help would be greatly appreciated and if anyone needs to know more information just ask! It is "my" first sled and love it, just want it to run properly and not pop the top end. Thanks!
 

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Discussion Starter #2
I am doing a lot of research on this too. What I can't decide on is whether its my pilot air screw that needs to be adjusted or if its the needle clips. From what I understand the pilot air screw would affect idle, and it seems to idle just fine. The second I hit the throttle though it wants to bog. Because of the whole "works when I give it some choke" its got me really scared to start it and pop my engine. Any ideas as to what I should be playing with here? Should I move the clip on the needle all the way down to richen it there or does this sound like a pilot air issue? How do I know when its good (other than it not bogging) when I am running mixed gas still?
 

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Have you inspected or rebuilt the clutches? When you mentioned that the sled bogged trying to climb a hill, I think of improper clutch operation due to not being able to handle the increased load.
 

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Discussion Starter #4
I haven't looked at the clutches too much as the previous owner bought a new Power Block 50 clutch just before he seized the crank. It bogs not just when climbing a hill, it bogs on flat ground too. I was pulling it into my garage last night and it bogged down too...
 

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Bogging can come from a number of sources.

- Pull the belt and check it thoroughly. Lay it on its side on a flat surface and look for gaps between the belt and the surface it's on. Flip it over and check the other side. Subtly worn spots will show as small gaps, and they can wreak havoc on performance unexpectedly.

- Pull the clutches and clean them. Check the springs and be sure that everything moves smoothly and nothing is broken.

- Pull the carbs, clean them, clean them again, and then clean them a third time for good measure. Be sure to floss the passages of the body to open them up. Set the air screws at 1 turn out, set the idle, sync the slides. Adjust the idle, and run 4-6 oz of SeaFoam per tank of fresh fuel for the first three or four full tanks. After that, an ounce per tank will keep them clean.

- Fish the pickup line out of the tank and inspect it. Bogging can be a lack of fuel based on the fuel moving to the back of the tank from position or movement of the sled. If the line is broken off, dropping down below a half tank of gas will cause fuel starvation issues.
 

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Discussion Starter #6
I'm going to pull the carbs out and do a very good cleaning and reset them both.
I just bought a brand new polaris belt.
I will take a look at the clutches. I cleaned up the outside of them to check for spider cracks but never took them apart. Not sure how to take the powerblock clutch apart either. I'll see what I can do.

Meburdick, I actually was reading your thread about the 1997 classic touring earlier. Some really good info.
 

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Discussion Starter #7
Seem to have found the problem. The pilot air screw was turned out over 2 turns. Reset it to 1 turn out (and adjusted) and had to raise the idle as it wanted to idle at 500rpm. Took it out for a test ride and it runs great now. No more bogging.
 
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