2nd time grenade

[bustamove]

i bought this blown up from a guy, and this would be the 2nd time this engine has grenaded on me in the last 10miles. i thought i would post some pics caution some of these might make your wallet hurt, i know mine does.
i have replaced both reeds, cases, crank with the larger taper, new pistons spi, cylinders, heads slp, and this happens... im pretty sure it happen since i put it into reverse trying to get it off the truck.

next i will trying oem 06 pistons, new injectors, new reeds again, new cylinders, new heads again,

anything eles you guys suggest while im at it... im getting really depressed about this motor, i just wanna ride it.

 

[sks rider]

yeah. Im pretty sure that pics like this make me want to sell my sled.

Sorry man.

 

[Z-Man]

Ouch, that thing had some major piston failure. Might be wise to only run engine a couple minutes and check the plugs to make sure it is getting fuel to both cylinders.

 

[Z-Man]

I wonder what caused it. The broken skirt like you see in your pics is what the stock 05 pistons did when they failed, that is the reason they changed them and the SPI are supposed to be a copy of that bad design.

Makes me wonder if you had used the 06 pistons they might have stayed in one piece and just scarred up your cylinder instead of blowing a big hole in your engine case.

 

[TRS]

I am not sure. But the pistons look as if they were installed backwards.

 

[TRS]

I am wrong it is a 900 motor.

 

[Z-Man]

Just out of curiosity, What oil are you using? and did you premix 1 pint per 5 gallon in the first tank like Polaris recommends?

 

[guidoxpress]

HOLY %&^T%&*, i just threw up!!

 

[Z-Man]

HOLY %&^T%&*, i just threw up!!

Ditto

 

[bustamove]

I wonder what caused it. The broken skirt like you see in your pics is what the stock 05 pistons did when they failed, that is the reason they changed them and the SPI are supposed to be a copy of that bad design.

Makes me wonder if you had used the 06 pistons they might have stayed in one piece and just scarred up your cylinder instead of blowing a big hole in your engine case.

sadly this is what i heard. i did do hours of research before i bought them on the forums and so on and never found anything bad about them.

yes i premixed oil in the tank with the most expensive stuff the dealer could sell me. lol i got a bore scoope and a heat gun. i will be the worst riding partner every 5 min i will checking this motor.. im REALLY hoping the problem was with the spi pistons, cuz if this happens to me with the 06 pistons.

when i had it first running it ran great pulled first time, let it warm up cool down over night. started again in the morning loaded into the back of the truck np, then when we got to the place i put it into reverse, and ever since then this thing has been giving me trouble. i think it broke off then, cuz i did hear a rattle in the engine but it wasn't harmonic with rev's and i though maybe it was just this paint shaker vibrating someone in the chassis.

so all your motor heads out there any tips maybe im doing something wrong with my rebuild?
rings locators are pointed the right way
checked ring gaps
wrist pin clip at 12 or 6
used 3 bond sealant
always followed torque sequence
everything is coated in 2 stroke oil when installed

 

[mountainhorse]

You say SPi pistons....not good... they are copies of the inferior 2005 pistons.

I'd go with a full long block assyembly from Indy Specialties.... With a TM-1 crank kit that gives you all new parts and you know it is built with more care than a production environment at the factory can do.

With all that shrapnel...you will need to take apart the crank anyway... spendy... Your cases are shot as well... Time for a new motor... done right...

IMO... dont buy a "good used" motor as you might just be buying someones problems.

 

[bustamove]

You say SPi pistons....not good... they are copies of the inferior 2005 pistons.

I'd go with a full long block assyembly from Indy Specialties.... With a TM-1 crank kit that gives you all new parts and you know it is built with more care than a production environment at the factory can do.

With all that shrapnel...you will need to take apart the crank anyway... spendy... Your cases are shot as well... Time for a new motor... done right...

IMO... dont buy a "good used" motor as you might just be buying someones problems.

how much is that? im into this motor 3500 already, his stuff is super nice!! but expensive but you get what you pay for thats for sure. but i just can't afford it anymore. the crank in there is the upgraded poolaris one. has anyone you seen or know had problems with the spi pistons cuz when i bought mine i could find anything wrong with them?

 

[shakenbake]

TRS is right the pistons were installed backwards your ring gap should be on the intake side of the motor

 

[mountainhorse]

I just re-read your post... sounds like you have the upgraded new crank with the new clutch etc.

Send it to Indy for complete inspection and replacement of the PTO side bearings with the tripple setup with snap ring.... and ANY other bearings that will need replacement.

He will assemble the entire bottom end with your crank and the new case you are going to need to buy (I wouldn't try to repair your old one).

Send in the Primary and flywheel at the same time (heck... send the whole motor...even pretty bad cylinders can be repaired at a reasonable cost.)

Send in your injectors to Witchhunter perf for clean and flow check.

Check your reeds, clean them... check the TB boots carefully for cracks and replace them if needed.

 

[bustamove]

TRS is right the pistons were installed backwards your ring gap should be on the intake side of the motor

its a 900 the intake and exhaust are on the same side. they were installed correctly.

 

[mountainhorse]

Regarding piston installation... I believe that they were installed Correctly.

Here is a Post from Super Dave3, a Polaris Master Tech... owner of a 900 and fixed more than I've seen.

The pistons are installed correctly when the transfer port is installed to the rear of the motor (water pump side).

Also the 05 manual had a misprint in how to install the pistons. The transfer port in the piston should be installed to the rear of the cyl. As a rule of thumb, on a two stroke engine the piston ring locating pin will always be located away from the exhaust port.

I hear ya on the expense...
With all that Debris in the motor... IMO, it would be foolish not to pop the crank open and check/replace the bearings.
Plus the crank could have been knocked out of phase or out of true when that chunk was blown thru the case.

Photo from Polaris Display of a cutaway of the 900 motor.

 

[shakenbake]

sorry guys did not know that about a 900 engine

 

[bustamove]

Regarding piston installation... I believe that they were installed Correctly.

Here is a Post from Super Dave3, a Polaris Master Tech... owner of a 900 and fixed more than I've seen.

The pistons are installed correctly when the transfer port is installed to the rear of the motor (water pump side).



I hear ya on the expense...
With all that Debris in the motor... IMO, it would be foolish not to pop the crank open and check/replace the bearings.
Plus the crank could have been knocked out of phase or out of true when that chunk was blown thru the case.

Photo from Polaris Display of a cutaway of the 900 motor.

yeah im taking the crank right now to a shop to get it checked out, bearings feel smooth so im hopefully

 

[bustamove]

sorry guys did not know that about a 900 engine

basically any 2 stroke engine has ports inside the cylinder wall, every ring locator pin is located between 2 intake ports my guess is cuz there smaller. so the gap in the ring never passes over a port.

 

[Z-Man]

I'm going to have to second what MountainHorse has recommended here. Because of the way that piston came apart there is no way to know how much of that went down into your crank. If you try to throw this crank in a new case with new pistons it will probably fail in 10 more miles. At this point you need to have someone completely check out that crank to make sure it is OK. You will be far better off to have Dan check it and put your bottom end back together. He has cheaper options than the TM3. I highly recommend giving him a call and talking to him about this, you don't want to spend more money and have it fail again.