Ha Ha, I broke my piston today!

[BlasterIan]

I thought i seized my motor! After racing down the drag strip my motor sputtered and started "grinding" I stopped immediatly and got towed to my my pickup, put my quad on the trailer wipped out the toolbox and started wrenching away.

Stripped tank, plastics and pipe, got the motor open took the head off, and guess what... piston was moving but still couldnt move it up or down, I was confused, anyway I saw pieces of aluminum on top of the piston and I thought, well dam, maybe im lucky and just broke a piston skirt, and yeah, I WAS RIGHT. Due to my Quick thinking when this happened (hold the clutch in and switch the bike off when things went wrong) while I was doing about 60km/h - 70km/h on the drag strip, I saved my bore!

Not a scratch! only thing I need to do is get the pieces out of the crank case and get a new piston.

If I remember, ill take pics of the procedure, and I will create a How to change/replace your piston in a thread for the guys who dont know!


Thanks for reading about my day at the track today

 

[quadsrus1]

Glad to hear you got to it before it got bad GOOD JOB bro

 

[Prime]

You might want to split the cases to make sure that skirt didn't bust through the crankcase.

 

[BlasterIan]

all is ok, just finished, no holes in the crank case, luckily! and recomendations on pistons? I was thinking of getting Wiseco!

 

[twistedink0]

have ur cylinder check for clearance too , to be on the safe side .. usually if u brake a skirt u have to much play in the cylinder causing the piston to angle at the bottom of a stroke hitting and snapping it off just to be safe hate to see u waist money and time and the same thing happen all over again.. if not atleast get a fresh hone so the new rings seat better .. o and go with a pro x piston .. i went like 2 years on one i always use them .. wiseco over rated

 

[Braaaptor]

Wiseco, wiseco, wiseco! You wont regret running one, and they arent that much more expensive than other brands of cast pistons. If you're gonna go cheap with parts, cheap out on stuff like grips and cosmetics, not on important parts such as pistons and gaskets. Forged pistons are all I will run. My Blaster has a Wiseco piston and Im not afraid to run it hard. Like has already been mentioned, its a good idea to measure your cylinder for wear before buying a new piston. Give it a light honing if the bore is within spec before putting things back together.

 

[Blaner]

you must first figure out WHY it went. since its the skirt, chances are that you had a bit of slap. this would mean your bore is out of spec. you need a max clearance of 0.05mm on a cast. If you go forged, run it a bit looser at 0.07mm or so due to the unequal expansion natur of forged metals. get a micrometer, measure the piston, then you will need a inside micrometer or a bore gauge to check your bore them do the sums.

other reason may be jetting, give us a pic of the piston crown too while you at it.

Be careful with those bit in the crank...pistons are made of a aluminium/silica mix and those bearings WILL have bits of silica in them, and silica is basically sand and it is very hard. the aluminium wont do too much damage but make sure you get it all out.

pics pics pics!!

 

[Blaner]

although your 290 in CT should be ample since you are not ported. so i dont think you would have been lean. that only leaves your bore being too loose, have you ever had the motor rebuilt before? or is it still the original that broke now?

 

[BlasterIan]

Im gonna break my silence I had an airleak at my intake boot that I was actually aware of My stupid mistake, I cleaned my carb and never tightened the clamp enough. At least Im honest!

Clearance is perfect, Little to no piston slap, im on the second stock oversized piston you get. Will send the bore for a hone and a double check on clearance anyway.

Might sell my Blaster after putting the new piston in, I will run it in for the new owner and give it a service.

Might go for something a little bigger next, once I have a bigger quad, Ill then later buy another Blaster for smaller tracks etc.

 

[Blaaster]

Good news on the bore, but as Blaner said, there could be abrasive in the crankcase.

It would be a smart idea to split the case and service and/or replace the bearings and seals!

Pro x pistons seem to have a bad reputation.

 

[Blaner]

nothing wrong with ProX they are the suppliers for Yamaha OEM. Vertex is OEM for KTM, they all ok, but forged is the more hardy.

 

[BlasterIan]

AH MAN! My crankcase has a crack! gonna send it in tomorrow for welding/repair!

Ill do the piston myself, but I dont have the tools to split my motor, so ill have to send it in for that.

Will keep you guys posted.
Should I keep the Blaster after repairing it, or look at getting the Polaris 500 Predator Troy Lee design?

 

[Blaaster]

Should I keep the Blaster after repairing it, or look at getting the Polaris 500 Predator Troy Lee design?

You ask this on a Blaster site, keep the Blaster!

 

[Blaner]

those things are not fantastic. and whatever you do dont get a outlaw, they battle on off camber muddy banks and on the technical stuff, but then again on the open veld they are machines.

you better off getting a raptor 700 or yfz450.

Keep the basty! get it ported and upgrade the suspension and you wont want any other bike. i promise.

 

[BlasterIan]

those things are not fantastic. and whatever you do dont get a outlaw, they battle on off camber muddy banks and on the technical stuff, but then again on the open veld they are machines.

you better off getting a raptor 700 or yfz450.

Keep the basty! get it ported and upgrade the suspension and you wont want any other bike. i promise.

Thanks Blaner, so you recon porting makes a HUGE Difference? heres pics of my Blasty in the Garage and the motor kinda stripped and in pieces (Save on labour costs) I am going to drop my motor off at Dirt Rider tomorrow for repairs, while im there im gonna ask what he would charge for a port job.

Sorry dont have pics of the piston, but was black on top and before this it was always a dark brown to black colour. same for the spark plu, was tan to brown in colour and after this it was Black to Grey. (AIR LEAK!)

 

[Blaner]

biggest power gains you will find come from porting, hang il even do it for you! but id also recommend a redesigned head...big difference.

the blasters were designed to be under tuned and under perform for their capacity, their port timing is equal to that of what a performace 400cc 2stroke should run.

PM me your email addy and i send you some files i put together when doing sums for my porting...you can see what a blaster should be at in terms of port timing

 

[BlasterIan]

biggest power gains you will find come from porting, hang il even do it for you! but id also recommend a redesigned head...big difference.

the blasters were designed to be under tuned and under perform for their capacity, their port timing is equal to that of what a performace 400cc 2stroke should run.

PM me your email addy and i send you some files i put together when doing sums for my porting...you can see what a blaster should be at in terms of port timing

PM sent! Thanks man!

 

[York Racing]

I say sell and get a 450 or a TRX250R.

 

[Larry's Shee]

I say sell and get a 450 or a TRX250R.

Why would you say this ^^^ ? If we that have broke things did this, most would have no use for this site

My son melted it down on the ice @0* or less, jetted for about 20* (OOPs), recently had balance shaft brg blow case out (or did gear fugg up first?).

 

[BlasterIan]

I went and bought another blaster! gonna put that motor in my blaster