Zr 580 Bogging Problem!! Plz Read And Help Me!!! - Snowmobile Forum: Your #1 Snowmobile Forum

furious D · 09-11-2006, 07:46 PM

HEY, I have a 94 ZR 580 carb, and its driving me absolutely nuts. The sled has a severe low end bogging problem when given full throttle, but when it reaches 6000 RPM it takes off like a jet. the exhaust ports are extremely wet, and the sled appears to be running very rich. The sled starts extremely well, and will idle all day long.

It all started when the sled melted a piston on the clutch side. We replaced the piston and it turned out the guy b4 us had it jetted way too lean, but just to be safe we also replaced the crank seals.
One day, about a week after the rebuild, the sled started a slight bog off of the line. It appeared to be running very rich, so we tested the fuel pump and it tested ok, we went through the carbs, and set them up perfectly to spec, tested the needle and seat and checked the choke cables and all was ok.

We also replaced the 3-1 throttle/oil injection cable, this did nothing, and the bogging appeared to just be gettin worse. We then decided that coolant must be leaking into the engine, so we took apart the crankcase, resealed it, and replaced the water pump seal. This did nothing.

The sled then melted a piston again on the clutch side during the winter, and the piston was cracked between the rings. I replaced the piston, and did a test for the clutch side crank seal, and when I sprayed the crank seal with WD-40 the motor did not idle up at all. We then thought maybe it was an ignition problem so we replaced the flywheel, stator, and CDI. ALL DID NOTHING .

I then just got fed up and clutched the sled to engage at 5000 RPM but the motor continued to bog. The last thing I did to the sled was replace the oil injection pump check valves because they all tested to be re-setting themselves at 2 low of a pressure, I just put it back together, lifted the track and gave the sled full throttle. And (surprise, surprise) the sled bogged the same as always. I continued to test the sled during that afternoon and found if it is held at 3000 rpm for a while the sled bogs a hell of a lot less.

I am completely puzzled on this sled PLEASE HELP ME!!!

**smallengineguy** · 09-11-2006, 10:07 PM

You need to check how the spark plugs look. Are they wet and oily? If so, there is either too much fuel, or not enough air to the engine. Since you replaced all the spark related parts, I'd say that's not it. See if the plugs are wet. I also noted on another thread it has PSI pipes on it. Is it jetted to those pipes, or jetted stock?

BC_Dan · 09-12-2006, 12:08 AM

I found even after cleaning my carbs on my 94 ZR 580, the pilot jets were still gunked up. Pull the jets and clean them with a strand of wire or some monofilament fishing line; also do the same to the pilot jet passages. That made almost all my bog go away. Also inspect the needle jet and jet needle for wear; if there are a lot of miles on the sled, you may need to replace those as well.

I also had a severe bog due to a worn roller on the primary; clean and inspect the primary and make sure nothing is binding or worn. When I discovered my problem, it was bogging, then finally would not even go; the clutch was the problem. One of the rollers had a groove worn into it, as well as the clutch weight. I replaced the 6-post Comet with a 9 post Arctic Cat and have way less clutch issues.

**RJ Gleason** · 09-12-2006, 12:50 AM

If the outer crank seals were OK, then you need to have the center seal replaced.

IndianRvrShiver · 09-12-2006, 07:01 AM

I agree with Dan, check out the primary clutch!!

chevette_boy · 09-12-2006, 10:58 AM

im with rj guy i got my sled of melted it down and when it did he said it bogged bad and had no power and the crank seal is ****ed i can fill one side up with gas and it leaks over to the other

not good

furious D · 09-12-2006, 02:11 PM

the clutch is a bran new comet 108 exp with a racing spring, and the plugs appear to be extremely wet and oily as well as the exhaust ports. I have been through the carbs numerous times and have tested the needle and seat, and it tested ok. The sled is jetted lean because if I jet it richer for the twin pipes I doubt I would be able to ride it at all. I will look into a centre seal, but I don't know how I'd do a leak-down test on a reedless motor, and how to make reliable port plugs for this test.

**RJ Gleason** · 09-13-2006, 12:48 AM

This is more of a repair shop thing.
Just pull the engine and ask the shop to do a pressure test.

Or, you could just make plates that fit over the ports and make gaskets for them so that they seal tight, then just make an adaptor that fits into the plug holeand pressurize the cyl. You will need a gauge on the head to tell if it holds pressure or not.

IndianRvrShiver · 09-13-2006, 07:12 AM

I used to pressure check all my kart motors prior to running them. "D" is on to the procedure......make plates that block off the exhaust & intake; then pressurized it using a hand squeeze bulb with a gauge. Would want to hold 8psi for about 30min w/o more that a 1psi drop. Use soapy water to check for leaks.

Used the same pump to set pop-off on the inlet needle on pumper carbs.

furious D · 09-13-2006, 01:47 PM

thanks for the tips guys im gonna take the sled into school and manufacture port plugs for it. I'll let you know what I find out, luckily if I have a leak I have another bottom end I can slap on it.

IndianRvrShiver · 09-13-2006, 07:36 PM

Only 1 more thing....this method will not tell you if the middle seal is bad!

furious D · 09-13-2006, 07:40 PM

sum beach, oh well maybe my crank case is porce, you never know? with this sled nething is possible. Ill run the test neways and see wut i come up with

**RJ Gleason** · 09-14-2006, 12:10 AM

Quote:

Originally Posted by IndianRvrShiver

Only 1 more thing....this method will not tell you if the middle seal is bad!

It will as you are pressurizing the side rather than just the cyl area, if it bleeds down too fast, from one side, and not the other, it means that the center seal is bad.

**smallengineguy** · 09-14-2006, 06:49 AM

That's what I was thinking, but I'm not going to argue with IRS again....

furious D · 09-14-2006, 02:03 PM

Thats what I was thinking. If the piston on the side im testing is postioned so the ports from the bottom end in the side of the cylinder are open, I would pressurize that whole side.. But if I did this and there was a leak, how would I check to see if air was leaking to the other side??

IndianRvrShiver · 09-14-2006, 03:10 PM

You could either install a pressure gauge in each side or, if possible, pressurize 1 side at a time (leaving one side unsealed) to see if it holds air! That may give you info about the center seal.
Pressurize both sides at a time to check flywheel/pto crank seals.........again use soapy water.

furious D · 09-18-2006, 07:30 PM

Today I tried a new kind of test for the centre seal. I closed the gap on the end of the spark plug on the left hand side cylinder, and left the right hand 1 set to fire. I then started the sled,(running on 1 cylinder)Then I reached my hand in the left hand side carburetor, pushed the throttle slide to wide open, and the sled idled up, meaning the centre seal is f***ed
YYEEEEEEEEEEEEEEEEEEEEHAAAAAAAAAAA

**smallengineguy** · 09-18-2006, 07:56 PM

Good way to test that! I think I'll remember that one!

**RJ Gleason** · 09-19-2006, 12:16 AM

Add the tidbit to the sled how to's.

furious D · 09-25-2006, 02:16 PM

I tried the same test for the centre seal on another sled that I know runs good just to be safe, and this sled idled up even more than mine did. I started thinking on why the sled wud do this, but then I realized that the sled idles up as a result of less pressure in the non-firing cylinder, making the motor easier to turn for the firing cylinder causing the motor to idle up. But, luckily The crank and bottom end in my other motor is in great condition, I'll put that one on anyways just to see what happens.