Heres my deal, I have a 01 Raptor that I have been racing motorcross with it. Recently started smoking and bored it one over. Shortly after repair cyclinder cracked on left side. Dealership replaced cyclinder shortly thereafter my left crankcase has a crack where the cylinder bolts on the left rear. Whats up!

The dealer said this is caused by my rear engine mount at the swingarm bolt is loose and causing the cases to flex causing it to crack in this area. Has anyone else had this problem? I know I can't be the only one who races motorcross tracks with this awsome machine. Need info quickly this is getting expensive. Thanks

 

Thats a new one by me, never heard of that before ever.

 

Justasking,
Did you throw a chain while riding hard, and do you have a casesaver. A thrown chain will smach the case really hard, enough to crach it. Also have you considered maybe the dealership dropped the case. I do race MX and i have to admit, i have never heard of a raptor case cracking. Can you post some pictures of the crack. In my opinion your dealer is reaching hard for a possible reason why your cases cracked. I have to see a picture to really think about possible reasons why it cracked. A loose pivot bolt will not cause the cases to flex. There is not enough space for the cases to flex, in addition, all the bolts holding the motor in would have to be loose for the cases to "flex". I personnally do not trust any dealership mechanic, but i have a mech. eng. degree so i know when they are bullsh!tten me. Post a pic and you will get more input from me and others.
herbdon out......

 

Holy schnikeees....sounds like a load of bs from Yamaha....as usual



BRAAAP

 

OK here's an update.

Did a show-n-tell at the shop and this is what I was shown

All motormounts are torqued, there are three. All solid, non shock mounted. If you put any leverage bar between the motor and the frame at the back by the swing arm the motor moves up and down slightly. You can then see the case crack get bigger and smaller.

The three mounts are like a right angle with the head and fwd lower eng bracket firm and the aft able to float. So what you are saying is that even if this aft mount was able to float it would not try to seporate the cylinder from the engine case at the weakest point??

I'm not the smartest guy when it comes to this type of things but it does sorta make sense???. Am I being suckered or could there be truth behind this.

I know the case was not dropped 'cause it was never removed fron the frame, just the cylinder.

Will try to get a pic if I can.

What do you think could cause this?

On the first cylinder the cylinder cracked at the lt fwd base mount bolt in the timing chain cutout area
On this one the cylinder is fine (brand new) but now the case is cracked at the lt rear base mount bolt where it enters the lt case half.

Was told that these are not made for motorcross

Any info or opinions would be helpful

thanks

 

When i purchased my 87 warrior it was missing the chain gaured and has a number of holes into the case. After all the JBweld was picked away i could see the damage. Drew up a few CAD drawings of the a affected area, and took it to a professional welder. 2 weeks later and 100 bux later my warrior was set and ready to roll. You can get some one to weld your case, if they know how to deal with delicate Alumminum.

 

I'm no expert on the raptor motor, but isn't there a mount at the cam/valve cover? I thought it had a cross bar that bolted to the frame and mounted the top end of the motor. If this mount is in place and tight, how could the motor flex in the way they are saying and cause the breakage? I would pull the gas tank and check this mount befor I let them do anything else to the bike. If they left that mount loose, or forgot it all together, the last time they worked on your bike, then this repair should be on them. Just an idea!

 

there is a mount on the top of the valve cover, I have found through many years of owning yamaha, if something is left loose for a few rides you can expect to never get it to hold tight ever again

I agree though, something was left loose

 

The plot thickens;

OK went to the shop when they were taking it apart. All three motor mounts are torqued to spec but the aft mount (back of engine @ swing arm) still allows the motor to move up and down.

Can see the gasket on the right side kinda flex when the motor is moved. So I figured the cylinder must be loose. They disassembled and checked each major bolt with a torque wrench prior to removal. All did the click thing.

Got to the cylinder bolts and the two on the right are torqued to spec, but the two on the left (where the case is broke) --the aft one is totally stripped out (where the case is broke) and the fwd one is all but stripped--mechanic afraid to put it to torque cause it didn't seem to get tight.

OK, pulled the bolts and they are two diferent lengths. The parts fish identifies them as different but the repair manual doesn't show that they are different and just gives a torque value for all four.

What is the deal?? Where do they go?? Is this the problem?? If so who caused it?? I agree with the mechanic who said that there is no way he torqued only two of four bolts of the same bolts when he re-assembnled---considering the shop made him buy me a new cylinder--blaming him for the last (first cracked cylinder) mistake.

Where do I stand?

 

So you are saying that the bolts caused the problem? I want to believe that so how can I make that arguement??

The manual they showed me shows the bolts, does not specify the length difference (which is about 2 1/2 threads). Which side do the long bolts go on and how do I prove this??

And when all is said and done do I worry about the movement of the back of the engine or not?

Also, why did I see movement on the rt side of the cylinder too when the back of the engine was moved up and down--those bolts were tight.

thanks