Yamaha Blaster keeps burning piston!!!

[Blaster30]

Ok guys i have an 02' Yamaha Blaster Bored 1 size over and i have installed the piston an after 3 rides it started bogging and finally cut off and wouldn't start any more so i just took off the cylinder jug again and the piston was cracked and ate up on the side of opposite the arrow in which the rings were burnt as well... please help how can i tell if the jug has been bored or just honed as well as knowing how to stop the piston from burning its my second one im goingn on my third and want it running the right way just let me know what u think is the problem thanks alot........ I:I

 

[acezeesawtooth]

is the jetting ok? if you are burning up rings and pistons you either have a bad air leak (do a leak down test after reassembly) or your jetting is off and you are running way hot. now if its chewing the piston up. i would say your bore is either not round the hone isnt smooth or you have a crank bearing or wrist pin issue throwing the piston out of plane

 

[DirtDiggler]

Yup , something isn't right . What's your current jetting? What's your current modifications? Let's start there

 

[nboldman]

I CANT STRESS IT ENOUGH! IF YOU DONT KNOW YOUR JETTING CHECK IT! After that do a leakdown test. I believe my blaster blew its top end due to those. Those is what i would check first. If you dont have a leakdown tester slickerthanyou sells them.

 

[Larry's Shee]

Did you get both pistons from the same shop? Do you still have both reciepts? Does it show the piston sizes? Does it have charge for bore on both? Do you have your original and piston number one to compare sizes with a micrometer/caliper? If everything else checks out consider taking your business elsewhere.

No offense to O P, but anytime you blow up, do a leakdown BEFORE you tear it apart to eliminate possible causes of the failure.

 

[blasterdemon7]

Did you have it done by someone that knew what they are doing when it comes to 2 stroke motors? I just wonder if they chaffed the ports.

 

[Blaster30]

is the jetting ok? if you are burning up rings and pistons you either have a bad air leak (do a leak down test after reassembly) or your jetting is off and you are running way hot. now if its chewing the piston up. i would say your bore is either not round the hone isnt smooth or you have a crank bearing or wrist pin issue throwing the piston out of plane

I can't really tell if he did a bore because the stock piston and new one are the same size and i think he cheated me and just honed it and sent a piston back with it

 

[Blaster30]

and as well as that im running a stock carb im getting ready to do:

-Block Oil Injection
-New Air Filter
-New Oil
-New Reeds
-New Crank Seal
-New Carb Rebuild Kit
-New Piston & Rings
-Remove TORS System
-New Spark Plug

If you think i need to do more please do tell or share what you think because i really dont wanna replace anything more because i bought the blaster for $450 , spent $160 on a scamming boring service, now im getting ready to spend another $200 and my limit is $1000 in all.....

 

[Blaaster]

What is the size of the main jet? Did you do a plug chop to see if it was correct?

Did you do a leak down test after assembly, prior to starting?

Did you do heat cycles, re torquing and easy riding for 2 tanks of gas?

These tests are important things to do to a fresh rebuild.

 

[bummer981]

Just wondering why you feel the need to replace the crank seals? If you know they are bad this could be your air leak. AIR LEAK = NEW TOP END

 

[Blaster30]

Thanks a lot i will rebuild the top end & then check for air leak once reassembled...because of course theirs going to be an air leak if my piston keeps burning the f*ck up no affence... but i dnt want to start it until im fully sure its gaining full compression and if any one knows whats the size of jetting on a stock carb then theirs thea answer because i promise im new to working on a blaster even though i work on atvs, and motorcycles be watching my page today i will be posting a vid and pics of the blaster because i just went ahead and took the motor off the atv

 

[acezeesawtooth]

well the stock main jet for a blaster is 230 u said that you had an fmf pipe though that should bump that jet up to 280-290

 

[Blaster30]

@Blaaster Do mind guiding me through the step because when i had rebuilt it all i did were let it ru n for 3 hrs. then ride it smoothly less than full throttle but for some reason i have to check for air leak and split the case im pretty sure i'll find it out as well a that it may just be the gasket maker started to disolve from it just sitting for 3 or 4 yrs. with oil in it

@bummer981 I figure once i get to split the case it will be the crank seal becuase they do go bad and if their r any more seal or bearing that are bad i will replace them because it may just be over overheating so it will work out

 

[Blaster30]

i have a 230 main jet then i have a stock exuast

 

[Blaaster]

Take off the carb.

Place the leak down tester into the inlet boot.

Block off the exhaust by fitting a crutch tip or rubber plug.

Pressurise the tester to 7psi, it should hold 7psi for 10 mins.

Spray soapy water over the complete motor, and plugs.

Watch for bubbles on everything, including tester, paying attention to gaskets and case joins.

Immerse gearbox breather tube in fluid and watch for bubbles.

Do all this before pulling motor down, to know what parts need attention, and repeat after re build.

 

[Blaster30]

thanks bro i will check it out 8-|