1996 AC ext 580 bogging

[afroman]

I resently bought a 96 ext 580. test drove great looked good. I got it home and the next day it wasnt running great. I have fresh premium gas, new plugs, fuel filter.She starts good (considering the -35 temp). let it warm up for 5-10min. then when i hit the throtle she bogs. I can play with the throtle to get the revs good or else it stalls will start again on first pull (with chock).It will run good then start spiting and bogging and backfireing then take off again and it seems to contiue this back and forth. I havent been out for more than 5-10 mins at a time because i dont want to blow it up. when i stop the idol is at about 2500 for 30-60 sec. then back down to a normal idol(1500).

I have been reading the other forums and i am thinking i should clean my carbs(not fun in -30 weather).any other suggestions

[hanson]

afroman-

Welcome to FishingMinnesota, sorry to hear about your sick Cat.

Couple things-

1- How cold was it when you did your test drive?

2- Sure wouldn't hurt to go through the carbs.

3- While your carbs are apart, double check your jetting. With air temps that cold, that might be part of the problem.

[afroman]

it was cold -25 to -30 on the test drive. as for the jetting do i realy have to change it every time the temp changes? around here it's changing every day yesterday was -2 deg. cel. the day before was -40 deg. cel.

[lawdog]

I don't think that sounds like a jetting problem unless they are EXTREMELY rich and are choking it off and not allowing it to run. You should have a pretty broad temp range on a set of jets. There should be a chart with altitude and temps giving you the proper jetting in the manual and on the sled somewhere.

Clean those carbs and make sure your fuel pump and filter are good and then see where you are at. Also, check the chokes too to make sure they aren't stuck and make sure the needles are set the same and the same jets are in each carb.

[hanson]

lawdog-

I tend to agree with you that it isn't a jetting problem but with -35 temps, you never know, and its easy to check.

afroman-

Lawdogs advise is pretty sound. It sounds like the sled is possibly choked on you. Really dirty carbs tend to show symptoms like this which can result in a burndown.

Otherwise I'm thinking a compression check is in order.

[afroman]

thanks for the advise guys. i plan on thaking the carbs apart this weekend.

does the thumb over the spark plug hole compression check realy work? i tried this once before on my dirt bike that died and there was enough compression to blow my thumb off the hole but in the end it did turn out to be a cooked piston.

second i dont have a manual for my sled and i was looking at my carbs and the ckoke seems to be electric(there are 2 wires going to the carb where the choke would be)how is this different from a mechanical choke? i have taken carbs apart before(motorcycle/dirtbike)but not on a sled.anything i should note?

[ChuckN]

There is always a mechanical choke on the dash of a Cat in '96, UNLESS you have the EFI model. Do you have EFI on that sled? The EXT's had EFI and carb models back to '95 I believe.

Personally I would run the sled in warmer temps and see how it operates. I can't tell you how many sleds I have ran that backfire, bog, etc.. when it's -35 degrees. It takes a long time to warm them up and get the engines used to the cold. Just do not overrun those engines in cold and you should be ok, jet wise.

The thumb test only works as a indicator for a blown piston/rings in the field. There will be little/no compression if that's the case. You need a full metered compression tool to give the actual test, mechanics have these.

[Macgyver55]

One more thing to check before you pull the carbs....

I seem to remember (what little I do remember) working on that same model sled and had a similar problem years ago. It had an adjustment on the throttle lever that wouldn't allow it to rev up or run right if one of the carb cables was binding or sticking. Not being a Cat owner I dont remember how to adjust it, but I bet one of the other forum Cat owners or a dealer could tell you how to do it or at least check it. (And refresh my memory)

[afroman]

chuckN

on the dash is the normal choke lever but on the left side of the carbs is 2 wires going into a little black piece of plastic mounted on the side of the carb. what is this thing?

[lawdog]

I don't know, and this is a complete guess, but I wonder if that isn't an electronic idle control. I know some sleds had those...

[Leader]

it's a throttle position sensor safety switch,

and if it were out of adjustment it would only cause a problem at an idle. it would run erratic at idle and clean out as you throttle up.

have the carbs been cleaned this winter? a new fuel filter?

do you have a compression tester? if not you can,

try this, pull both spark plugs out.

make sure kill switch is in OFF position and put your thumb over the spark plug hole on 1 cylinder at a time applying pressure and have someone pull it over, checking compression on both cylinders and see if you can FEEL a noticable difference between the two cylinders.

post your findings, Good luck.

[hanson]

Thanks for the input everybody!!!

I learned something today. My first guess would have been a Dial-A-Jet carb setup but I realized they are not actuated with wires at all. My experience with mid-90s cats isn't the greatest.

I hate to say it but I'm leaning towards a compression problem at this point. I'd start with everything that has been previously mentioned because that will cost you the least amount of money.

You aren't out much with a carb cleaning other than some time. Make sure your carbs are in sync and the choke plungers aren't hung up.

I'd look at compression after that. That sled will run on 1 cylinder but it will be VERY rough. If the other is lagging a little in compression, that might be it.

[rmh2o]

I would bet the carbs need cleaning,one of my cats was doing the same thing and I cleaned the carb and now she just purrs.

[Valv]

Afroman, I have 2 '95 ZR 580 and I had some bad bogging with 1. I thought same thing you did, compression, but then after I checked it, 1 was just slightly lower than other cyl.

I then replaced the very good looking spark plugs....that was the ticket, now sled runs very well.

I assume you already did this, but if you didn't you might want to try, it's a $ 5.00 well spent.

Now I have to post a question about cooling...

[afroman]

hey guys thanks for all the advice. i cleaned the carbs, redrained he gas and replaced with new, and the temp is now a nice -15 deg. cel. the cat runs great. unfortunatly i dont know witch one of the three fixed it.

one other question is i did a compression check and both cylinders climed to about 110 psi but neither held. both fell to zero. is this a problem with the gage or the motor? the sled runs and idols good now.

[Macgyver55]

I'd say the gauge is the problem. The gauge should hold whatever PSI that is pumped into it. Most have a schrader valve (like a tire valve style) or a small button to release the pressure after reading it, but it should hold for several minutes without a problem.

Any used cylinder on a motor will leak down some percentage. If that percentage becomes too high, thats when there is a problem. You can do a "leak down" test if necessary but if you have 110 lbs compression I doubt you have anything wrong.

Glad you got it running good.