00 Z370ES Hesitation - Snowmobile Forum: Your #1 Snowmobile Forum

motoboy · 12-06-2006, 11:24 AM

Last year I had to replace a crankshaft bearing on my wife's sled. After getting it all back together, it starts right up, idles fine once warm and you can rev with no problem. But once out riding and this happens more often then not the engine will start to bog down usually around mid throttle ranges and up. release the throttle and will continue to idle fine up to about 1/4 throttle. I thought plugs might be fouled but after new ones installed the smae thing happens. Nothing was adjusted everything went back together great and made sure the Stator was set right ( made alignment marks prior to disassembly). Can't figure this out. On a stand it revs up great with no hesitation.
Almost feels electrical, it will backfire once and a while too. Is it possible the throtttle safety switch is causing this.
Any help would be appreciated

Thanks
Motoboy

kccats · 12-06-2006, 12:08 PM

what about clutching? could the drive clutch be worn?

motoboy · 12-06-2006, 12:43 PM

I didn't even think of something like that. Is it even possible for that to cause engine misfiring and bogging down? It does not appear to be a drive problem. The engine seems to actually quit running when this is happening.

Thanks
Motoboy

**RJ Gleason** · 12-06-2006, 03:50 PM

Check the throttle safety switch.

A worn or dirty/binding clutch will cause the mid-range performance that you are describing.

**smallengineguy** · 12-06-2006, 06:38 PM

Backfiring is a sign of a lean condition. How do the plugs look? Are they dark dry brown? If they are light tan to white, it's too lean.

JL Club · 12-06-2006, 08:06 PM

you never said what kind of sled it was. if its carburated, then i would say that your probably
have a fuel to air mixture problem, like smallengineguy
said. and a backfire is caused from unburned fuel entering
the exhaust pipe. you said that if you have it on a stand
that it revs up with no problem. thats probably cause you
have no load on the motor and it can get up the revs. i would try adjusting the carb(s) if there is one(or some),
thats probably the simplest thing to cross off the list of
**** that didnt work if it doesnt! good luck.

kccats · 12-07-2006, 08:57 AM

does this thing smoke like a frieght train? Did you oil up the lower end when you put it back together? You did go through the carbs. Also check all the ground wires.

motoboy · 12-07-2006, 11:44 AM

Hey you guys, thanks for all your input. Yesterday I found that when the throttle lever is pushed in and tilted down a little the switch must be shorting out and killing the engine. I disconnected the harness and she runs great with no problem. From what I found you can only repleace the entire throttle assy. and not just the safety/kill switch assy? Is this true? They want $75 for a new assy which isn't that bad considering you get everything.

Thanks Again
Motoboy

SawBlade · 12-07-2006, 12:35 PM

good find. throttle safety switch has found its way into numerous threads. what a pain. arctic cat should have made a recall on that piece of crap switch. had to replace mine too. what's its purpose anyway?

**RJ Gleason** · 12-07-2006, 01:29 PM

The real purpose of the throttle safety switch is to get more money for the manufacturer and the dealers when you need to replace it because it had failed and is making the sled run like crap.