Im looking at a ltz400 it has the 452 big and a ton of upgrades but theres something wrong with it, he thinks its the crank, sayed he took off the side and twisted a gear and it free spun. you think its the crank? i dont mind replacing it. Would this damage anything else in the process. thank

 

The Z400 is a very reliable machine till someone puts a big bore in it. GNC racing has proved the 450cc z400 to be very unreliable. The cases in the bottom are paper thin to accomodate the extra stroke and literally blow the bottom of the motor right out. The head bolts are too far apart and they blow gaskets.
I'd pass on this particular machine.

 

<div class="FTQUOTE"><begin quote>Originally posted by: LT80

The Z400 is a very reliable machine <span class="FTHighlightFont">till someone puts a big bore in it</span ft>. GNC racing has proved the 450cc z400 to be very unreliable. The cases in the bottom are paper thin to accomodate the extra stroke and <span class="FTHighlightFont">literally blow the bottom of the motor right out. The head bolts are too far apart and they blow gaskets</span ft>.

I'd pass on this particular machine.</end quote></div>

theres z400s running around that have bb's over 500cc and cranks 5mills they run super strong nothing wrong with them never blown bottom of cases out nor do they go thew headgaskets everything fits and tightnes just fine



Snoochy the only thing u can do is tear into and check things out may be a bearing, theres a posibility there may be more internal damage, or it may not even be the crank

 

Sorry, I beg to differ. The 2003 and 2004 GNC national circiut team Suzuki results show otherwise. Many-many motors were gone thru by many riders. I was there.
I'm sure there are plenty of bb's out there. The question is, does snoochy want to buy a machine that::
1) allready has a problem
2) has questional reliability
3) is mostly stock and will be reliable
I'm thinking 3 but ya never know. [img]i/expressions/face-icon-small-happy.gif[/img]
I'm just saying that this may not be the machine he wants.

 

Any time you add in a big-bore kit to any engine you kill reliability....... most sport ATV engines are just about as reliable as they are going to ever be, so adding things outside of the original design is a risk..... exterior engine mods like intake and exhaust do not hurt reliability, but when you start bore jobs, on already thin aluminum blocks you are asking for problems..... increasing compression is also risky as most of these engines are built from the factory at the high end of their performance scale.

 

Thanks for the info guys didn't mean to start a war zone lol but everyone has brought up good points. Im going to pass on it.