is this possible?

kbest.1990 · Jul 18, 2011

i have a 03 1m 800 efi and im having problems with the electrical. the exhaust side cylinder isnt getting gas and its the ecu but its expensive as hell for a new ecu so i was thinking about goin carb? is it cheap to swap or even possible? let me know!

diggerdown · Jul 18, 2011

kbest.1990 said:
i have a 03 1m 800 efi and im having problems with the electrical. the exhaust side cylinder isnt getting gas and its the ecu but its expensive as hell for a new ecu so i was thinking about goin carb? is it cheap to swap or even possible? let me know!

????? Both cylinders have exhaust and both are fed with the same fuel line. If one cylinder isn't getting fuel it's either a bad injector, bad injector wiring, or a weak fuel pump. I suppose it could be the ecu but check your wires and pins. You chould be able to pick up a used ecu for that sled for a couple hundred or less, switching to carbs would cost a lot more and you are back to jetting and having about an hour a day that it runs tops!

kbest.1990 · Jul 18, 2011

i meant the side the can is on. and it has a new fuel pump so im thinking wiring ?

diggerdown · Jul 18, 2011

Check for injector pulse then swap them side to side, check the voltage at the plug ins, they should be the same on each side. By the way, that is the mag side, clutch side is pto side. I take it that you have pulled the injectors out and pull a few times on the starter rope to come to the conclusion that there is no fuel being delivered? I say this because a lot of guys have one cylinder go down and assume it's fuel or spark, when it is low compression.

kbest.1990 · Jul 19, 2011

fuel is getting to the fuel rail and threw the pto side injector just not threw the mag side injector. it was blown up when i bought it and it was the mag that was the blown side but i rebuilt both sides. after i rebuilt it the mag side wouldnt get fuel so i touched the injector to a dewalt battery and put it back in and it ran so i got used injectors and i thought the problem was fixed but it did it again so i got different injectors and it was fine for about 5 miles and then the same thing happend. im having a hell of a time with this thing. anymore input would be great no one around here seems to know what the deal is?

diggerdown · Jul 19, 2011

I think you need to track your injector wire from the injector to the ecu and test each pin with an ohm meter doing a little jiggling of the wires as you do it. If continuity seems good you could have a bad fuel pressure regulator. If a regulator is bad it can let too much fuel return to the tank and you don't have enough pressure in the rail to support two injectors. The fuel is fed in on the left side (pto) fills the rail and flows back though the regulator located on the right side of the rail. Thats why the mag cylinder will burn down if the fuel pressure is low, the pto side is the first to feed off the fuel source. Although if worked for a while after you used a battery to open the injector, so I would go after the wiring and plug ins first. Injectors can be checked with an ohm meter, but that doesn't sound like it's your problem. Reeds could be bad on that side also. Just throwing out some ideas.

kbest.1990 · Jul 19, 2011

thanks for all the help. i will try some of this tomorrow and let you know if it works. thanks again

kbest.1990 · Jul 20, 2011

so today i checked both reeds and there good. took the fuel rail off with injectors connected and they both squirt gas. took the heads off and the mag side piston is not a circle..more oval..this is what the other piston looked like from that side when it blew up. why would the mag side keep blowing up? there has to be a reason.

diggerdown · Jul 20, 2011

If the fuel feed is equal there is a good chance the crank is out of sync....thats sucks! Other causes can be throttle plates out of sync, air leak in the rubber intake boot, or crank seal leaking.

kbest.1990 · Jul 20, 2011

how do i check to see if any of this is the case? it is the front of the piston by the power valve..its like rounded off if you get what i mean?

diggerdown · Jul 20, 2011

I usualy see the intake side looseing the crown edge with a lean burn, but it can take either or just stick the whole thing. Did it brake the rings and tear up the exhaust ports? Is the dot on top of the piston on the exhaust side? The dot must be on the exhaust side or the rings will catch in the ports. Also what side is up on the exhaust valve? Bid taper goes up. If it is in upside down, it can catch the piston.

kbest.1990 · Jul 21, 2011

the exhaust port is not damaged..the rings are fine.the dot is forward and the power valves are both the same way but it had to be the valve because it is the same size as the beveled edge thats missing on the piston. i wouldnt think the crank would be bent because both cylinders would be messed up if that was the case right? maybe not enough exhaust getting out or power valve would be my opinion from the way it looks. is that possible

diggerdown · Jul 21, 2011

Cranks can be knocked out of phase and have one side running fine and the other can lead or lag on timing. The cranks are just pressed together and if you blow a belt at high revs or some other sudden change in load, one side will twist a few degrees. Is the piston burnt? If you hit the power valve it should have knock a section off, if you ran lean it would burn the edge of the piston off down to the first ring groove. Holding too much exhasut in, like you suggested, would not burn the edge off. The power valve should have a bit of clearance between the rings and the valve. Valve edges and seats can get worn and the valve gets too close. To check the crank phase you would need a dial indicator with a probe long enough to reach the piston crown so you can read exact TDC. One last thought, if it was a lean burn the base gasket could be leaking too. Lots of stuff that can go wrong with these things and most of the time finding the problem takes a lot longer than fixing it! If you can figure out how to get a couple pics of the piston on here you may get a few more guys putting some light on the possible cause.

KMMAC · Jul 21, 2011

Check the crank seal on the mag side, also check the intake gaskets if it hasn't been mentioned.
Check the cases and the bottom of the cylinders for proper mating, as long as you have constant fuel and spark then most likely it is an air leak. You can put air pressure to both cyls. and watch for a drop in said pressure to verify if there is an air leak.

kbest.1990 · Jul 21, 2011

its not burnt its like a piece got nocked off the piston. ill try to get picks on soon. how do i put air pressure in the cylinder? and how do i check mating?

KMMAC · Jul 21, 2011

I guess I missed the part about the chunk... You need a cylinder pressure tester to check for leak down,, some have a tire air valve on them to add air and you add air slow. as to the mating you will need to pull the engine and put it on a bench without the base gasket, and some ink like paint. put a thin layer on the engine case where the cylinders mate and then set the cyls. on torque them to spec. then release the torque, check for even squish marks of the ink. You can also pull all of the cyl. studs and check with a straight edge. The chunk you mention did it come from the front edge? If so, then look at the power valves or the groove they slide in there may be damage there. It could be that the valve was in backwards too. At the very least if the engine is still in the chassis get it on a bench and do a thorough check on everything it sucks but beats being towed out...

kbest.1990 · Jul 22, 2011

it looks like a chunk to me..its not burnt down to the first ring at all..but there is no damage to the power valve..im hoping to tear completly into it this weekend. im hoping its minor. how bad is it to do a crank seal or anything involving an air leak?

DCAMPBELL · Jul 22, 2011

BROKEN PISTON

CHECK THE SQUISH, TAKE A LARDE PIECE OF SOLDER AND BEND IT SO YOU CAN INSERT IT THROUGH THE SPARK PLUG HOLE TO WERE IT WILL TOUCH THE CYLINDER WALL, THEN TURN THE ENGINE OVER A FEW TIMES WHILE HOLDING THE SOLDER IN PLACE THEN MEASURE THE SOLDER. IT SOUNDS TO ME LIKE THE PISTON MIGHT BE HITTING THE HEAD

kbest.1990 · Jul 22, 2011

never gave it a thought but it does have shaved heads

KMMAC · Jul 22, 2011

Hmmm,, makes me think that possibly then that some time in it's past a ring may have broken and a piece of it was at the bottom of the crank case.. As far as an air leak or checking cyl. and case warp you may have pull the pistons and put it back together and add air.. As far as the crank seals go the only solution is to pull the crank. From the sounds of it this would be a good thing to do anyway. The 800's have a smaller pto end where the clutch mounts but I think the rest of the journal is the same as the 900 but still they had a tendency to twist or move enough to the point of losing seal. have the crank bearings checked by some one familiar with this crank and if the price is right have new bearings and seals installed also have it trued and welded I think as long as the engine is apart you might as well do all of this to make the bottom end stronger. What kills the crank along with other things (lack of oil,over heating) is jumping and landing with the throttle on, with all of the force and traction something has to give and the crank is the weak link being press fit together it will only stand so much of this. While the engine is apart look at the oil pump gear also. Not trying to scare with this stuff but might as well do a thorough bottom end inspection while it's apart.. because you don't know how it was treated by the previous owner. Hope some of this helps You might do an exchange on the crank to speed up the process of the rebuild but the rebuilt crank will not come trued and welded which I would do just to strengthen the bottom end. Some would say that it is over kill but then it will be a lot tougher.

is this possible?

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