So I'm still working on this.

What is the width of a brand new belt for the 90? I measure 17mm on the old belt and if you are 15.9mm or less then you are at threshold, per manual. Is a new belt 30mm wide?

Going slow because I keep going further than I anticipated. Had a problem with the new rings as one came damaged (bent) the other one wasn't as bad. So I had to get that taken care of. The pipe has soaked a good long time, I'm going to repaint and install. I have the new cylinder, piston and rings in. I can tell you by pushing down on the kick starter it is a lot stiffer. Not back in the bike yet so I didn't do a compression test yet. Changed the oil which was horrible, cleaned out the stator, cleaned the oil injector. Had to wait for a new gasket for the trans case, and now it looks like I'll need a belt too. If I knew I was going to do all of this I would have ordered everything together.

Anyway, still chugging along.

 

Didn't measure belts,just checked if they were worn/burnt or had a lot of slack then they were changed out.You always find extra things to replace once you tear into any used machine..

 

This one feels very tight but when you pinch it (top to bottom) it kind of has this crackling noise, like it feels dry so maybe dried out. I'm going to replace, might as well since I'm in there and would hate to have to get another gasket in like a month or two.

Oh yeah I ended up ordering a new filter for the trans case when I did the gasket, should have just did the belt too. Well what is another week to get parts.

 

Ok so it has been awhile. I tore a lot of stuff down and the further I went in the more stuff I decided to tear down, refresh or just clean up.

I've only been working this part time off an on. I have it almost all buttoned up and it looks like I'll be ready to fire it up maybe tomorrow.

I think I may have discovered the issue with needing to open the choke to run over half throttle. I was getting ready to put the carb back on tonight and decided to dump the fuel so I could get fresh fuel and then pre mix it. (I pulled the oil injection pump to clean it and I need to run it with pre mix to test the pump, plus I need to break in the new top end.)

Anyway, when I pulled the lines to drain the tank the fuel just trickled out of the lines. I took a wire and ran it up the reserve line and out came crud and it flowed better. Went down and got new fuel line, and pulled the petcock apart and cleaned it.

I still needed to do all the rest of the maintenance but I'm betting the dirty lines had a lot to do with it not pulling enough fuel.

Anyway, when I fire this up I'm expecting to see a world of difference.

 

Thought you were going to check fuel flow mentioned in your second post.Yes fuel valves could get stopped up with the crappy ethanol fuel we have. That's why they have the bowl that can be removed and cleaned out and check for flow.Polaris Manual Fuel Cup Assembly 2006 Predator 90 0450366 | eBay Sounds like you had multiple problems on this old machine. Hope it finally fires up and runs ok for you.

 

Yeah I did but then it seemed like it was flowing ok.

So I got this thing put back together and I'm at a loss as it is somewhat worse than before.

1. Engine fires over and idles.
2. When I put the throttle down I can only get half power out of it like something is governing it back. No I don't have that circuit plugged in to govern it back nor is the throttle screw turned in.
3. Everything is set like it was when I swapped over carbs. 3/4 on air and 1.5 on slide and number 3 clip. Carb bowl is filling and not overflowing. Float set level.
4. Running a mix of 50:1 in the fuel for the break in and I confirmed the oil pump is running and I also have it plugged in.
5. I soaked the exhaust in kerosene for several days prior to assembly plus sat empty for like a week or two, and it appears to be flowing normal to me. Smokes pretty well too but figuring because of the pre-mix and the oil pump working.
6. The plug looks to be burning fine, not white and not black. Gap is set at 0.036 in.
7. When I get it going it doesn't seem to want to go. When it moves it is very slow and sometimes it doesn't want to move at all almost like you are holding the rear brake.
8. The rear brake, when the lever is off, the rear light will occasionally flicker. If I were to grab the wire right outside the perch and either lightly tug it or pinch it the light will go back off and occasionally I can get it to flicker.
9. If I lift the rear wheels off the ground and peg the gas, the wheels turn but I would say maybe half of full speed. If I let off on the gas occasionally the bike keeps running like it is held open. I checked the slide and the throttle cable and nothing is sticking. When I let off the slide operates normal. Double checked the slide with the air box off and it is working. If I hit the rear brake it cuts the idle and it stops. One thing I did notice was the first time I started it up, if I hit the rear brake, it seemed like it was giving it a little gas....yeah weird.
10. Now the best for last, which is very disheartening, before writing this I went out and screwed in the compression gauge and I'm only getting 50 psi out of it. I have new piston, cylinder, gaskets, rings and every thing is torqued down per spec.

Where do I start now? The stator I believe is working fine too because it charged up the flat battery with all the messing around I did with it.

What can be leaking compression? Do I need to tear this back down again? Do I have a faulty rear brake lever and wire?

 

I think I solved one problem, maybe with the cut in power. It would appear that the cable going down to the oil pump is not smooth and there for not pulling the cable back far enough up in the throttle and tripping the ETC switch. I tried lubing the cable, making cable adjustments and none of that work. It seems to be getting hung up in the black coupler that splits the cable into the oil pump and the carb cable lines. I see there is a crack in the barrel so maybe something inside is hanging there. Doesn't look like it can be repaired. Looks like something else to buy.

 

I'd say you have a faulty brake light/starter interlock switch if you can pinch the wire and the brake light will go out.Plus have you ever checked/repaired the clutches,replace the belt? Could be the reason on lack of power. Compression should be at least double what you show unless gauge is faulty. If you're able to have the cylinder pressurized to 7 psi you can tell with soapy water where you possibly may be loosing compression. If this doesn't help you may have to tear the top end back down and inspect the cylinder and head mating surfaces along with piston to cylinder clearance even though this is a new kit.

 

Thanks OPT for all the help on this. I think the family is doubting this will ever get going.

I ordered a throttle cable and brake switch/cable late last night. Sigh.....looks like another two weeks down before I get all the parts.

Not sure about the brake lever, I can roll the machine around the garage floor pretty easy, but I'll fool with it and see.

I replaced the belt and the clutch spins freely and the spring is like really tight. When you hit the gas it feels like when you have the rear brake on and the machine doesn't move and you can fell it loading up. Doesn't feel like the clutch is slipping or revs high. I can open that back up and look again.

 

I got the whole thing put together. Tried to take it for a ride and it just didn't seem to want to go. Pulled the crankcase open again. Everything looked normal. Pulled the belt off again. Pulled the front sheave off. When I did I noticed the cam plate that holds roller in was stuck to the sliding sheave. I previously replaced the sliding sheave and the fixed sheave with direct parts from Polaris, but I didn't replace the cam plate. After digging out the old slide sheave I noticed that the new slide sheave is built slightly different. To fix the problem, I had to take the dremel out and file down parts of the casting ribs on the slide sheave that was sticking to the cam plate. Once done, the two pieces no longer stuck together. The new sheave has thicker ribs than the old style not to mention some other subtle differences.

Got that all put back together and the bike would finally run and get up to speed.

New problems:

The bike sounds like it has a miss in it. Like it will sound like chug chug chug. When I started the bike with no front sheave and belt on it sounded normal, and I could rev it up (I had the air box back on to ensure it would run right.), there is a second of hesitation and then it reved up. Put it all back together and took it for a ride and it rode good enough to take around the block twice.

When I returned and stopped the bike was making the chug chug chug sound again. I turned the idle screw up 1/4 to 1 3/4 turns out and it seemed to make the bike fall flat when I took it out for a test ride so I put it back.

The other thing, I have a new throttle cable in there and it is moving smooth and I verified the action. However I have noticed on occasion during my test ride, something seems to either hang it up or maybe electric where the bike will keep accelerating when off the throttle. I can't reproduce it and it doesn't happen all the time. I'm guessing that maybe the oil pump hangs because I saw it do that when I had the old cable, but so far have not seen it happen with the new cable.

Is it running a little crappy because I have 50:1 mix and the oil pump connected to it? I see the inside of the carb throat looks a little oily inside.

The exhaust pipe, I can drop a rod down it until I hit a screen about 6-7" back from the pipe end. Smoke comes out and the exhaust doesn't seem to be flowing weak.

What next?