cylinder works problem

[hanzito]

well i finally got my yfz back together. I chose to run a cylinder works +3 98mm big bore kit and a +3 hot rods crank. Both made by pivot owrks. after many hassels i finally got it together and it ran for just under a hour total. 75% of the run time was at idle tuning my rekluse clutch. I got to run one 5 lap moto on th emotor.

some of the problems i ran into are as follows.

when the crank first arived for my 06 yfz it was wrong. I recieved a yz dirt bike crank. i had to send it back.
then i received my cylinder works +3 mm big bore kit. The cylinder arrived with casting flaws. you couldnt fit the timing chain down the slot that it rides in on the side of the cylinder. so i had to send it back again.

then the replacement cylinder arrives, sweet.... not so fast. the rings for the piston are broken inthe package. they had been crammed in the box and broken during packing. so again i had to wait to have new ones sent out.

Finally i had my parts. had paid for over night shipping twice to get parts to me intime to make the upcoming races. and both times parts were messed up and had to eat the overnight shipping and wait for more parts.

so i finally get my motor together. did the oil mod and new 07 high flow oil pump. put on the gytr kick start kit and got it running. Pulled hard and ran great..... for a minute...

then i was out tuning the new rekluse clutch and bang big puff of steam. and this is what i found...... pulled the wrist pin out of the bottome of the piston. sent it back to cylinder works at their request. they said that it was lack lubrication and sent it back to me and said tuff ****. so now i would like to spread the good word and share my experience.

http://i81.photobucket.com/albums/j237/hansshanks/blown%20yfz450%20motor/2.jpg

http://i81.photobucket.com/albums/j237/hansshanks/blown%20yfz450%20motor/1.jpg

http://i81.photobucket.com/albums/j237/hansshanks/blown%20yfz450%20motor/14.jpg

http://i81.photobucket.com/albums/j237/hansshanks/blown%20yfz450%20motor/12.jpg

http://i81.photobucket.com/albums/j237/hansshanks/blown%20yfz450%20motor/9.jpg

http://i81.photobucket.com/albums/j237/hansshanks/blown%20yfz450%20motor/5.jpg

[Ride1Rob]

Man that sucks! But honestly, it should have been a red flag to you after the 2nd time you had to send parts back because of their error. My opinion on the lack of oiling... "They are screwing you bigtime!" I don't see the 1st heat mark on the wristpen or the piston where it snapped. And did you advise them there was an oil squirter on that area?

My personal opinion is that it was either one of two things that could have possibly happened...
1). You put the piston/wristpen circlips in wrong and at least one of them popped out causing play in the wristpen until it finally snapped the bottom of the piston.
2). The crank wasn't ballanced properly and there was vibration that finally caused this damage. I've heard that these +3 stroker cranks give the motor quite a bit of vibration.

These are just my opinions based on what I see in the pics and the mods that you say were done to the bike. Was any damage done to your head or the cases?

[Gommer450r]

that has to hurt it sucks beening screwed over been there done that

[hanzito]

the piston rings and wrist pin were both intalled and double checked. and the circlips for the wrist pin were in great shape. one was in the bottom of the motor. and one was stuck in between the case halves at the front of the motor at the point were the case and cylinder meet. after doing more reading in the past couple days it appears the it is mandatory after bying a new hot rod crank to send it out and have it trued and balanced with the exact piston you are going to use. So for hte money you can save the 400 dollar initial purchase of the hot rod crank and just send your oem crank to crank works and they can stroke balance and true it for about the same price as the intial purchase of the hot rods crank and then still have to send it out fo rbalancing and tureing.... I AM PISSED.

The dude steve i have been dealing with at cylinder works first time i talked to him sighed when i told him what happened, like he wasnt suprised. he said to send all the parts back to him so he could confirm. actually gave me a good feeling for a second thinking they were goingot stand behind their crap part. Then i the next contact with him he some how thinks i am reusing the stock crank and connecting rod and trys to blame it on that. Then i remind him that it is his companys brand new crank in my motor. he back peddles and says he will get back in touch with me. Then he drums up this damn lubrication storry. trys to tell me that their parts dont work on motors with out the oil squirter. Then again i remind him that the oil squirter mod was done. and if the parts wouldnt work with out it. Why does hteir website and every piece of literature online not state anything about it. And FURTHER MORE WHY THE HELL DOES THEIR PRODUCT LIST IT FOR 04-08 YAMAHA YFZ450.

at this point i am very frustrated. i went out of my way to buy all new parts and bearings to avoid this. now my mx season is a complete loss. well at least i will save money on gas and oil this year.

[Ride1Rob]

Yeah, I figured that the ballancing was an issue. ALOT of peeps don't know this just as you didn't. You'd think that they would state that or have something in the box stating the crank isn't ballanced and needs to be or failure will occur. You should have noticed more vibration in the motor and that should have raised a red flag. Myself, that's why I use OEM cranks and pistons straight from Yamaha. If I can't win with suspension, portwork, cams, and a nice exhaust I need to work on riding skills. That's just me though :ermm: ...

[MAaudioX10]

Originally posted by Ride1Rob
Yeah, I figured that the ballancing was an issue. ALOT of peeps don't know this just as you didn't. You'd think that they would state that or have something in the box stating the crank isn't ballanced and needs to be or failure will occur. You should have noticed more vibration in the motor and that should have raised a red flag. Myself, that's why I use OEM cranks and pistons straight from Yamaha. If I can't win with suspension, portwork, cams, and a nice exhaust I need to work on riding skills. That's just me though :ermm: ...

Actually, HR recommends using the +3 crank with the stock 95mm piston. So, really if they truly wanted to be dicks, they could deny everyone service who runs that crank with an aftermarket piston.

Almost everyone I know that gets a new crank, gets a new HC piston.

I ran the HR stroker for a year with no problems, unbalanced and all, however, that being said.....if I had to do it again, I'd have it balanced. The vibration is annoying.

[Ride1Rob]

Now that you say that, I did hear that about these cranks when they 1st came out. Can't exactly remember why but I think with the longer stroke the compression goes up with the stock piston??? Not quite sure about that but something along those lines. Still, if that's what they recommend they should have that somewhere in the packaging or in the kit. If they did and he missed it that's on him.

[industry48]

I've had many problems with just about everything you get from that company. I say we take a road trip to headquarters and burn it to the ground... lol!!! Who's down????

[MAaudioX10]

Originally posted by Ride1Rob
Now that you say that, I did hear that about these cranks when they 1st came out. Can't exactly remember why but I think with the longer stroke the compression goes up with the stock piston??? Not quite sure about that but something along those lines. Still, if that's what they recommend they should have that somewhere in the packaging or in the kit. If they did and he missed it that's on him.

For me, it was printed on the box the crank came in.

The compression is upped about .5 points with the +3 but, I am curious to know if it vibrate horribly with the stock piston.

I'm running an HR HD 06's crank w/ a 98mm Venom 14.25:1 piston and, this thing doesn't vibrate at all.

Now that being said, you'd assume the HR HD crank would be balanced to the stock piston so, logically, if the +3 crank is balanced to the stock piston...adding an aftermarket piston shouldn't upset the balance all that much.

I think its that fact that the +3 crank is some 2 lbs lighter than stock. The piston doesn't rotate so, effects of a lighter piston should be minimal.

This is just me thinking logically.

[rt20ps]

It shure looks like it ran without oil. Maybe the dummies at Hot Rods know what they are talking about. I would double check the updated oil pump and make shure you installed it right. I have seen the same thing happen when the oil tank strainer is plugged and not getting oil to the pump.

[Ride1Rob]

I did see those heat marks on the piston. But if you look at his wristpen there are none. I would think that if it was due to the piston and pen not being lubricated correctly the pen would have heat marks on it just the same. I think those heat marks on the piston got there once the piston failed and the crank was still rotating for just that minimal amount of time. If this is a JE high compression piston I'm willing to think it was the culprit as I personally have had 2 to crack on me. One was the exact same place as his did. There were 5 hairline cracks, one nice sized crack, and then a huge crack that was causing the pen to vibrate against the bottom of the piston. I saved it because I shut the motor down before the catastrophic damage that we see in his motor.

[rt20ps]

Heat marks???

The piston is melted on the exhaust side. It doesen't get much hotter than that. Gauling on the wrist pin and piston pin bore is also evidence of a lack of lubrication.

If balance was an issue it would not present itself in 5 minutes of runtime. Vibration takes time to destroy parts.

I am not a big fan of the Hotrods cranks or cylinders, but I have used them and never had these issues.

[Ride1Rob]

Melted???

The piston is not melted. The damage on the bottom of the piston is a direct result of it coming into contact with something else inside of the motor. If you look at it closely you can see where it has rammed itself against something. Another thing to ask yourself, "How could a piston melt on the bottom side where there's less heat but the top side where all the heat is is unaffected? His rings are not melted either. Also, since when does not having the oil squirter make the top of the piston overheat? That mod is strictly for lubricating the wristpen area. So that theory is out the window. The damage to the front of the piston where you do see heat marks occured after the piston let go. That's a direct result of it scouring itself against his cylinder walls. More than likely on the upstroke. That's what knocked the front of his cylinder wall out.

As for the 5 minute run time... He ran his for a 5 lap moto. So I'm more than sure the bike was being ridden at a nice clip. An unballanced crank at those RPM's will do the exact damage you see in those pics. You're talking about aluminum parts (piston) having to hold up to all that vibration. If your bike has the same setup and it's not ballanced properly it's probably only a matter of time before you're in the same situation my friend. It may also be due to the type of piston he used as some aren't quite as durable as others.