'94 Jag 440 dlx has no power

[T_Snowbike]

Just got this sled, 2,000 miles. Would like to use it tomorrow.

It starts easily, but has no power and won't idle, drops right to zero if throttle is not cracked. Seems lean, have to keep tickling the choke. According to the jetting chart on the airbox it seems to be jetted spot on for this altitude & temp. Has fresh gas.

I took the carb apart and it's clean as a whistle, really perfect condition. All jets all passageways clear and clean, there was no funk at all. I suspect someone else cleaned it trying to solve "the problem". I took the heads off to have a look, was very nice in there.

It backfires HARD thru the carb sometimes, once even blew the carb off the manifold. I see a lot of bubbles going by in the clear fuel line. I expected that the bubbles would almost stop once the float chamber is full.

Any ideas?

What kind of engine is this, Reed valve? Case reed? Crank valve?

 

[AZ800]

When the engine is cold I'd expect to have to feather the choke on off for a cpl min til it warms up. That's normal.
Backfiring tells me it's probably loading up with fuel if there's no timing problem with the spark. Rarely is.
Air bubbles in the fuel line could be an air leak somewhere in the fuel line, at the tank or fuel pump. If it's filling the float bowl though that's not the primary problem as it will run fine until the float bowl empties.
There's something wrong with the carb. Not sure what carb is on it but the pilot jet controls idle fuel and there's sometimes an air screw to control idle air on older carbs.
I'd say there's still something blocking fuel in the carb. I've had carbs that I've "disassembled and cleaned" 2-3 times before they worked right.
Also could be a vacuum leak somewhere. Would keep it from running. Case seals on the crank or just the vacuum lines to the fuel pump and carb.
Sorry this isn't more of a help......

 

[MT Backcountry]

TPS

had a 94 ext 580 in which the Throttle positioning sensor went out and had similar symptoms. Replaced and ran great, did need to adjust to postion correctly also.

 

[T_Snowbike]

Does this (Suzuki 440) engine have a reed valve? Or is it piston port? Do main bearing seals ever go bad if crankshaft mainbearings are still good?

This sled has only 2000 miles and original brake pads which have never even been adjusted. Its had an easy life.

It acts like a vacuum leak, not enough vacuum to idle, period, and can't suck enough gas to run without feathering the choke-enrichment. I checked all passageways in the carb, all clean and clear, sprayed thru with carb cleaner & reamed the jets with wood toothpicks, they are both clean and polished.

OR a reed valve problem. Would really like to know if there is a reed in there. Is there anything in the exhaust that can get plugged?

It's hard for me to work on this sled because it's at a remote location. I have to gather info - then go there and work on it in the cold. Any help is appreciated!

 

[T_Snowbike]

had a 94 ext 580 in which the Throttle positioning sensor went out and had similar symptoms. Replaced and ran great, did need to adjust to postion correctly also.

Thanks but that sounds like an injected engine, this has a carburetor.

 

[NEWDUCK]

If you give it about 1/4 throttle does it stay running?

 

[T_Snowbike]

Yep as soon as you lift the slide off the idle stop - it runs, and sounds "OK". I have not adjusted the idle screw other than just setting air at 1-1/4 turns out and have not touched the slide position screw which could be the idle problem for sure. Agreed - might as well try to solve idle problem if it will cooperate.

Main problem I've focused on is that I have to tickle the choke to get the sled to make enough power to start moving. Then it will gradually bog down and quit UNLESS I open the choke enrichener a little, again, then close it before it loads up. To "keep moving" I have to open the enrichment periodically. As if it has a big vacuum leak such that it can't get enough fuel.

Engine has great compression on the rope. As said before I took the heads off and the cylinders look perfect, can still see original hone marks all the way around the bore(s).

Can anybody point me to a site that tells me what kind of engine this is, or more specifically, IS THERE A REED VALVE or any component other than the carburetor? -----that I should look over? The sled is 100 miles from here and out in a barn.

 

[NEWDUCK]

I would start with bypassing the throttle safety switch. There is a youtube video on it. Pretty simple to do. Those engines do not have reeds. Possible carb boot leak?

 

[T_Snowbike]

I may have found the problem. Siphoned the gas out for off-season storage using a clear tube and the gas looked funny. So I poured it into a clear jug and there was about a pint of water onthe bottom. I never noticed water in the carburetor but I think water in the gas tank could cause some trouble.

Fingers crossed that it runs good next winter. And fingers crossed for more snow.

 

[Idcatman3]

For what it's worth, that engine is piston port, no reed valves. If you suspect crank seals, you can spray starting fluid in short bursts around where you think leaks might be. (seals, carb boots, etc.) If it revs up, you've got a leak.

I use this site for parts diagrams: http://brownsleisureworld.com/