Dirt Rider Magazine

reverendsteady

HELP!! I just bought a Yamaha yz 125 dirt bike that had been bored out. Bought it as a project it had been siting outside for a couple years in the weather motor was froze carb and gas tank hand junk in them. I took the head off got the motor un-froze and oiled up cleaned out the gas tank and carb and bought a new plug. tried to fire it up and nothing so i took the plug out and no spark, I can hol

d the tip of the plug on my turn the motor over and no sprak what so ever. i think its the magneto not kicking out anything i took the cover off it and it was rusty so i shot it with WD-40 and whiped as much as i could get to out. Im thinking i need to get that magneto completely off and give it a good cleaning the problem is the bolts on the flywheel so when i try to take the bolt off the motor turns over. Ive even put the bike in gear put WD-40 on the bolt and a breaker bar in the back tire to hold it firm it still wont break lose.
Any thoughts?

pojp58

Sense the bike sat outside then most likely everything electrical inside is rusted. You will need to check all electrical systems and I would start with the kill switch. Disconnect it then check for spark.

markyrocks

This kindof a dumb question but are you grounding the plug when ur doin spark test? Also why was the bike parked in the first place? I would assume that something was wrong with it before that point. Did you do compression test? I would also think seized motor would mean corrosion in the cylinder an to the ring (an prolly bearings and more) most likely whole engine gona need rebuilt, fresh topend ect.

Edit: I'd just like to add that the statement you made about the spark test is kinda unclear about what ur holding to what. If your unsure as to how to do the test I suggest Google it or YouTube it. Most auto parts stores sell a tool like this http://m.advanceautoparts.com/mt/shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_adjustable-ignition-spark-tester-thexton_22983650-p?searchTerm=spark+tester

cody12319

I wouldn't say the Wholee motor needs to be rebuilt. But a compression test defiantly would tell you if the top end needs a rebuild. Or you could just look at the piston and tell if it looks worn down or not. But for the electrical systems I would look on ebay and pick a used one pretty cheap. If you put the plug against the cylinder head and kick it there should be a spark. But it not getting spark is a no bainer why it wont start.....

gearman

To loosen the magneto nut use an air impact wrench, you will also need a magneto puller tool to remove the magneto.

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