bear w/me on this. picked this up cheap (maybe) had no spark,charged battery,pulled plug cap off,weak spark from plug wire,ohm tested coil (new by previous owner wrong cap) good numbers,stator good,pulse coil ? .499k ohms ordered new pulse coil & plug cap, new pulse coil ohmed .363k, installed new one, now have good spark. cleaned carb at least 8 times,cleaned petcock,new gas,pilot screw 2turns out,new battery. cam timing right on. when turning over it kicksback hard enough to stall or reverse motor & spits black smoke thru carb unless choke is disengaged or throttle is opened, also valve lash is good. did get it started one time popping thru carb exhaust with throttle.went to idle stayed running sprayed wd40 around intake carb & boots no changes. it died when throttled have not got it started since. same kickback plug is black sooty tried 3 different plugs. tried holding finger on plug hole while cranking blows finger away but after 3-5 seconds cranking feel heat build up in compression. thinking carb is shot but wondering if pulse coil is triggering early or late or cdi whacked hope this enough info to get some insight which way to go on this. dont need to throw money around in the wrong direction. have read several posts making me think its lean mixture but cant be sure thanks for any & all help dammar

 

The first thing I would do if I were you, is verify the cam timing. Shouldnt be too hard to check.

Backfiring through the carb can be a lean mixture for sure. When i bought my big bear it would backfire through the carb at idle a lot. Once I cleaned the carb and got it adjusted it quit doing that.

How did you clean the carb? I cleaned my carb and thought it was good, but once I blew all the passages out with compressed air it richened up a lot on the bottom end, indicating that I hadnt cleaned it well enough the first go around. It does sound like it could be lean. Does it start right up if you put a little gas directly into the intake?

 

thanks cummins, used 2 cans carb cleaner, poked tip cleaner thru all passages i could including all jets blew thru with compressed air 100psi. changed throttle needle height up & down but no changes. putting gas straight in intake did not seem to help but Saturday tried holding my hand over throat at airbox, stopped the kickback & got a rumbling hint that it tried to start but battery got low gotta wait few hours for recharge. also noticed good amount of guessing blowby from tube going from cam cover to airbox oh yeah cam timing is right where should be all marks line up. will rent something from parts store (i hope) to do leak down test. now wonder if not creating enough vacuum to draw fuel, guess i should have tried that old automotive trick sooner, cant afford to lose much more hair scratching my head

 

Sounds like your carb should definately be clean. If it has bad blowby then that could for sure mean the rings are worn. I would definately do a compression check. If spark, fuel, and timing is there and when its supposed to be, then sounds like it could be a compression issue. Kinda weird that it kicks back so hard if its low on compression though?

I just bought a 600 grizzly that the guy said was low on compression. I could spin the engine by hand even past the compression stroke. I could hear air gushing up through the timing chain housing whenever i spun it over slow. Turned out to be the rings and piston scored badly. I guess it had injested a lot of dirt in its life...

Let us know what you find out if you do a compression/leak down test.

 

will do an update as soon as i can, no luck sunday finding 12mm adapter except $50.00 compression tester kit. monday held up with pickup breakdown & wife in e.r. both survived, only somewhat minor problems, but tied me down, no rush maybe tuesday will be better thanks

 

havent made it off work in time to find anything for leakdown test, but had brainstorm to try checking timing with automotive inductive timing light, could barely see double lines at bottom of hole. put nail polish about 1/2 inch counterclock wise from those lines and it shows up dead center of timing hole.. is a woodruff key on flywheel possibly sheared?,new pulse coil overacting? or checking timing at cranking speed only (still hasnt started) giving false spark results? even as battery gets low still have very good spark. thanks for any opinions danny

 

You said air box was oily. Maybe its never been clean out in 8-9 years. When you put your hand over the intake I think yiou said it just about fired but the battery went dead so maybe its a choke thats not closing??

 

update, 150 compression, ordered new carb, trying to start,nearly started lost battery, next day pulled carb joint found small split underneath out of sight cleaned and sealed temp to see difference, later tried again, no spark. darn it. ordered new cdi just came in, now back to where i started. chased timing around rotor it fires as magnet comes to pulse coil not near end of magnet where timing marks are. any ideas out there i cant lose any more hair.is pulse coil weak 363k ohms or rotor shifted at woodruff key wife is tired of hearing me crank on this thing and order parts that almost make a difference
thanks everybody danny

 

what an adventure. new carb new cdi same results...read another forum similar problem, someone said try switching pulse coil wires, well what did i have to lose. nearly scared me outta my boots when this thing fired right up,now i have a beat up spare cdi and carb. just wanted to pass this along in case someone else has this occur on theirs thanks