Wont start. Coil?

[jcm2792]

Just got a 2001 blaster, engine is fairly stock. nothing serious done to it. The person i bought it from said he was just riding and it shut off then he started it againran for a second and shut off. Lead me to belive it was the ignition coil. I run a voltage test before the coil and pull up about 3v. when i hook the coil up i get nothing to the plug, no spark. It is a brand new coil though.

Any knowledge would be appreciated. Thanks

 

[sicivicdude]

Be suspicious of new parts. If someone changed something you don't really know what's going on and also, just because it's new doesn't mean it's automatically good...

You need to check out the voltage coming out of the source coil. There are a bunch of wires coming out of the front of the left side cover that loop back around and connect to a bunch of bullet connectors on the frame right beside the carburetor. That's where the coil gets it voltage from.

If you have the yamaha blaster factory service manual there is a very good diagnostic section (section 7-7) for ignition trouble. It steps you through the process to check everything right down to the last possible step, replacing the cdi unit.

One thing to check before going off the deepend, disconnect the two wires from the back of the box mounted on the top of the carburetor. This is the TORS sensor box. If the switch inside starts acting up, it acts like a kill switch. Simply unplugging it is an easy way to test to see if that (or the related handlebar switch) is acting up.

 

[jcm2792]

The t.o.r.s isnt there. i believe it was removed.

Im trying the tests now.

 

[jcm2792]

Alright. im getting voltage from the stator, before the switch, after the switch, all the way up to the coil once it gets through the coil i loose the voltage. What is the average voltage comming out of the stator?

 

[Braaaptor]

I don't know about the stator, but you need at least 9 volts coming from the CDI box to the ignition coil under the seat for that ignition coil to fire the spark plug. Ideally, you should get 12 volts at the orange coil wire if the CDI ignition system is working properly. The voltage output will depend a little on how hard you kick the engine over, but anything under 9V means you've got a bad CDI box, source coil, or possible bad ground.

Do you have a Clymer manual for your Blaster? This book is great for helping you through stuff like this, and it tells you how to check the ignition coils mounted behind the flywheel on the stator plate. If those coils test good and you still don't get enough voltage to the main ignition coil, the CDI box is likely bad. I'd make sure all the TORS system is, indeed, gone (including the 3-wire 'black box' under the hood) before going and replacing expensive electrical parts. (The CDI box has a 5 individual wires coming from it with individual bullet connectors.) Also, how is that black ground wire beside the ignition coil? It had better be connected to the frame, tight and clean, if the ignition is to fire.

Good luck! I enjoy electrical problems, so keep me informed how things turn out. I'll try to stick around and help...

 

[jcm2792]

checked it all. got good voltage going into the cdi but none comming out of the orange wire. I just ordered a CDI box. Hopefully this fixes it. I used a test light to test everything again today. so ive come to the conclusion that it has to be the CDI box. Thanks for the fast responses. I will keep you updated on when i get the CDI box and stuff. im sure ill have more questions.

On a stock 200cc blaster can you push the kickstart with your hand?

 

[sicivicdude]

With some resistance as it comes back around to the compression stroke. You should not be able to simply push it all the way down by hand.

 

[jcm2792]

maybe its not good that i can then. awesome. and yes i have one of the clymer manuals. I should prolly do a compression check.

 

[Braaaptor]

Yeah, I would check the compression when you can. Scew in the gauge, hold the throttle wide open, and kick it good 4-5 times. Any compression reading below 125 psi usually indicates that your top end is going, or gone. I've seen Blasters run on 80-90psi compression, but an engine like this is worn-out and usually needs at least a top end done.

 

[sicivicdude]

Well, as long as you can get it to fire and fuel into the cylinder you can bump start it to prove that it does run. Once you know it runs you can justify a top end rebuild. New piston and a bore and hone and you should be good to go!

 

[jcm2792]

outta curiosity what is a good bore size for when it comes time and how much does a shop normally charge to bore out a block?

Thanks again

 

[sicivicdude]

The best bore size EVER: the next available. Pistons are made in .25mm graduations up to 2.5 mm oversize. Boring 2.5mm does not make more power, it only leaves your cylinder unable to bored again once it's time for a top end rebuild.

$50 is reasonable for a bore, hone and chamfer the ports. It could be more where you're at but somewhere in the $50-$60 range is about right.

Obviously you'll need to buy a piston to match. Woodward specialties (a member of this site) sells parts to BF members at a discount. I bought a wiseco piston and gasket set from him cheaper than I could get a wiseco piston elsewhere.

 

[jcm2792]

So your saying just bore it out like .50 the first time then go from there this way in the event that the top end needs to be re built I can bore it again.

 

[sicivicdude]

Exactly! They make pistons in .25mm graduations. Once you get it to pop start and make sure that it CAN run, take the top end off and take it to a machine shop to get it sized for the next up piston. Once the machine shop sizes it, you can order a new piston in that next size up and have them bore it to match once the piston comes in.

 

[jcm2792]

Oh gotcha! makes sense. Thanks for the help. I appreciate it.

 

[bob3345]

I just got a 2001 blaster and im totally stumped because i replaced the spark plug because it wouldnt start so i figured it would start if i replaced the plug i couldnt get it to start though so i had my buddies push me down the road and it started i drove it about 35 feet and it died so they pushed my again and this time it started i drove it around for 3 minutes then let it idle for another 2 and it died so i kicked it and it started first kick drove 35 feet and died and now it wont start at all why did it do this coil maybe????