I changed the piston and piston rings out and the bike had good spark but after i had put it back together it had none. in the process of taking off the head my brother got into the magneto i was wondering if this could be the problem
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Tim, I would look at three main things first. Compression, spark and fuel. Once in awhile us mechanics can get a "hunch" of what's wrong but overlook some common problems. I would invest in a compression tester and a spark tester. Both are fairly cheap and available at any parts store. Simply unscrew spark plug and srew in compression tester and turn starter over. Observe the reading, do this for all cylinders. Then put plugs back in and install spark tester. Turn starter over and observe spark. If you can get your bike started again, check compresiion and spark when your unit fails. This should put you in the right direction. Hope this helps!
1. check for spark, check spark plug for fuel too. alot or none.
2.make sure your getting fuel to the carb
3. check your compression since you put the new top end on.
must be 114 psi or better.
3.make sure your reed valves are good. 4. make sure, your exhaust pipe is not clogged.
If you have good spark, fuel flowing, and compression, it will start.
if you took the rotor off make sure the keyway was installed or it wont fire correctly, the rotor will spin on the shaft if there is not a keyway installed.
make sure you have good gasoline, and good oil mix i run 50:1 fuel oil mix. You bike will start up if you have, spark, fuel, compression Best Regards Big Al
Just cause the piston looks fine dosent mean the rings are still good did you do a compression test if you don't have one buy one they are great to have with 2 stroke bikes put the cylinder head back on and cover spark plug hole with finger it should first **** a bit then should blow finger off the hole the compression should be greater than 120 psi of a 125 not sure on the 250 rule of thumb if you have less than 120 your piston or rings is pooched..
No, their would be no reason to change the piston and rings first up, unless you know that they are worn from the previous owner, Get the bike up and running first and go from their, will be a good chance the piston and rings will be fine.
Change the oil first up as their is a good chance condensation has occurred and put water in to the oil. Drain the fuel from both the tank and carburettor, as this would have gone stale. Change battery or jump start if required.
suspect. With the spark plugs out, crank the engine over a few times. (ensure oil level correct) If it winds over all good, put a few drops off oil in the cylinders. This will help build compression. Re-fit spark plugs, Full choke and give it a shot. Away it should go! Aerostart or ether may come in handy.
check compression, does the motor spin ez? you should talk with the previous owner and find out what he did. if he did change the piston and ring he should have rebuilt the whole motor. if he did change them why did he!?! find out and get back to me Mark Woodring
Here is the deal; Assuming the rings that were sent to you are the correct thickness for the piston ring grooves but were actually made for a 1st, 2nd or 3rd oversize piston, they may still be able to be used. Put a single ring into the cylinder. There should be an end gap of about .025 in the ring. If not, you can carefully grind the end of the ring by using a bench grinder or a rotary grinder. File off any rough edges. Re-fit in the cylinder and check the end gap. If you do not have a thickness guage, .025 is about the thickness of a paper matchstick. Once all rings have been fitted for cylinder size, mount them on the piston and put the bike back together. Please rate my answer. Thanks.
cud be a combo of both-running rich from carb or weak spark--chec plug and cable for wear and resistence or test ign unit--may need jet ajust--breakin procedure is the same as new bike--get a maintenance manual-sayonara
take off the 4 bolts on the head after you unplug the spark plug. then take out the c clips that are on the side of the piston where it connects to the crank oh ya if the cylinder wall is scarred then you will need to repair or replace it, but if not then keep following after you take out the clips the piston should come off im assuming you bought a rebuild kit now take the new piston and place the ring(s) on it then put the piston on the rod then slide the shaft inside the piston then put the new c clips on each side then place the cylinder on top of the piston (you will have to clamp the rings together with a special tool but if you dont have it your fingers will work fine then after you get the cylinder on you can put the bolts back in place then the spark plug wire and remember to break in the new top end by driving in first gear for a few hours.