Jeff Wolf

I guess compression is a wonderful thing...cause she runs! Gotta get the valves adjusted a bit...she kinda taps right now but she purrs and not much smoke... thanks everyone for their help. Now to change gear oil in diffs and get rear brake adjusted.

So we disassembled the head and jug and the piston. The rings were stuck...after soaking for a while we were able to get them free and cleaned them up good. Also cleaned the seats in the piston and lightly sanded with 1200grit so the rings are nice and smooth. Oiled everything up and in the process of putting back together. Fingers crossed.

After putting a little oil on top of piston compression went up to 120... is this a sign of bad rings?

Still no go. Check compression with starter. Get right at 50. I know this machine has the compression reduction while starting...does 50 sound about right for a cold engine just turning it over with the starter?

Ok...we pulled the carb and cleaned the jets again...confirmed air fuel mixture was set 3 turns out... But then we saw this orriface that was caked with dirt and totally plugged outside and on top of fuel bowl. I'm having trouble seeing on diagram what it is...maybe just a breather and a short tube should be connected? I tried to put an arrow to it on photo...its right beside choke connection.

Main jet was plugged..got that cleaned and other two checked....they weren't bad.. Reassembled...still wont fire up. Got a back fire but nothing else... scratching my head here.

Got it back together....turned over by hand fine then by starter. We are getting spark. Now we are cleaning carb in hope of firing this thing up.

Ok... after further inspection the neutral light came on when lifting shifter lever. Sensor was removed again and rotated slightly and functions properly again..whew! Now just waiting for valves to arrive and top end can go back on. Getting closer....

We will inspect and continue troubleshooting.

You are the MAN! After grounding the green the neutral light came on.. also with the starter disconnected we could hear the starter relay clicking on and off when pressing the start button.... so now to re-evaluate that switch... see how expensive to replace.

When the ignition key is on and transmission is in neutral the "neutral " light should come on whether the engine on/off switch is in either position right? Need to find a wiring diagram I guess... anyone know if the bayou 300 wiring is the same?

Thanks for the tip... will grease it up good.

Probably...I'm surprised these machines dont have low oil alert lights...(maybe they do and I dont see it yet). Would have prevented a lot of damage. Picked up some cheap 10/40 oil for when we get finished.. was thinking run it a couple of hrs then change oil and filter just in case?

I know right? Crazy damage... still not sure how it all happened. Drive shaft and transmission gears look great and parts not strapped in engine look like they are new. Who knows. Hopefully electrical stuff will work.

Worked on quad some more this weekend. I've included pics of damaged piston, jug, and connecting rod. Also a bent valve. Have the case back together with replacement crank and connection ng rod in. Put crank in freezer for 4 hours and propane torch on case (225f) and it slipped right in. Pretty cool. New valves should be here thursday and it will be back together. Plan on turning it over by hand a few times before installing plug or spark. Next will be electrical evaluation.

got it all apart. Bearings look good... in fact everything in bottom end look good except for connecting rod and bearings. There is a chunk out of rod and bearings blew up. So... we have a used crank with connecting rod, and used cylinder and piston on the way. Also a used oil pump gear. Plan on cleaning everything up real well and reassemble. Will get some new seals for valves and clean up head well and reassemble. Also some new seals for side panels. So far it has been a fun project for my son and I. Any suggestions on what I may be missing?

When we took off the right side cover, the plastic oil pump gear was deformed and not attached to the keyed shaft that drives the oil pump, so that for sure needs to be replaced. Could have been run without oil though because the roller bearings on the connecting rod at crank are totally shot, with some of them in the bottom of engine. The bottom of the piston sleeve has a chunk of metal out of it, half moon about .5 inch. Piston is all busted up. One valve looks like it might need to be redone. Trying to get the flywheel off now. We don't have the special puller. Does it take a 33mm puller? Tried the pry out with screwdriver and tap on slightly undone center bolt with no luck so far.

Bought a nonrunning 1996 bayou 400. Tore down engine and found major problems. Piston is damaged and cylinder liner needs replacing. Looks like cause was a broken oil pump gear. Question is can a piston from a prairie 400 be used? Is it the same engine? I assume the liner is replaceable?

Diesel the best? Why not a penetrating lubricanct like pb blaster or such. If the cylinder is seized bad will it not need new rings as a minimum?