[Dieselboy93]

So I just bought a 2014 zforce 800ex guy I got it from said it had a wiring issue and would lose spark on the front cylinder. So I traced wiring found nothing but both plugs were fuel fouled so I replaced them and this thing started and ran good but had noise in front cylinder. I removed the wave cover and found the head was cracked around the intake side rocker shaft. The previous owner had just replaced this head for the same issue I have the old head that's cracked in the same place. Is this a common issue or what? I have I didn't waste a bunch of money on this thing

[davidpaul]

Never heard of cracked heads before, has she been overheated ?

[NMKawierider]

Nope, me either. Never heard of this. Not a common problem for CFM but have heard of some Can Am's with cracked heads after being over torqued...and these 800s are a rough copy of the Rotax 800.

[Cosmosdan]

Check the mating surface. I think something is up with it, like a low spot by the tapped hole or maybe it's not as flat as it should be, high between the mount points.

[Z8rider]

a stiff or kinked cam chain could have been the initial cause that contributed to the cam chain jumping and having a piston to valve collision. Machine have around 900-1200 miles on it? was it cracked on the boss where the rocker arm shaft slides in, opposite side of the cam gear?

[Dieselboy93]

The the ear on the inboard side of the intake rocker shaft is cracked/broken off I'll try and upload some pics later thanks for the input so far

[Dieselboy93]

a stiff or kinked cam chain could have been the initial cause that contributed to the cam chain jumping and having a piston to valve collision. Machine have around 900-1200 miles on it? was it cracked on the boss where the rocker arm shaft slides in, opposite side of the cam gear?

This is exactly what happened timing chain tension seems loose to me but haven't looked in the manual guy I got it from is a second generation Mechanic him and his dad put it together you think there may be a faulty tensioner?

[NMKawierider]

a stiff or kinked cam chain could have been the initial cause that contributed to the cam chain jumping and having a piston to valve collision. Machine have around 900-1200 miles on it? was it cracked on the boss where the rocker arm shaft slides in, opposite side of the cam gear?

This is exactly what happened timing chain tension seems loose to me but haven't looked in the manual guy I got it from is a second generation Mechanic him and his dad put it together you think there may be a faulty tensioner?

Well...there has been some known tensioner issues....

[davidpaul]

a stiff or kinked cam chain could have been the initial cause that contributed to the cam chain jumping and having a piston to valve collision. Machine have around 900-1200 miles on it? was it cracked on the boss where the rocker arm shaft slides in, opposite side of the cam gear?

This is exactly what happened timing chain tension seems loose to me but haven't looked in the manual guy I got it from is a second generation Mechanic him and his dad put it together you think there may be a faulty tensioner?

What's the issue with the chain tensioners ?

Well...there has been some known tensioner issues....

[NMKawierider]

a stiff or kinked cam chain could have been the initial cause that contributed to the cam chain jumping and having a piston to valve collision. Machine have around 900-1200 miles on it? was it cracked on the boss where the rocker arm shaft slides in, opposite side of the cam gear?

This is exactly what happened timing chain tension seems loose to me but haven't looked in the manual guy I got it from is a second generation Mechanic him and his dad put it together you think there may be a faulty tensioner?

Well...there has been some known tensioner issues....

What's the issue with the chain tensioners ?

Not exactly sure but they either are wearing fast in some cases or coming apart.

[davidpaul]

a stiff or kinked cam chain could have been the initial cause that contributed to the cam chain jumping and having a piston to valve collision. Machine have around 900-1200 miles on it? was it cracked on the boss where the rocker arm shaft slides in, opposite side of the cam gear?

Ok thanks
This is exactly what happened timing chain tension seems loose to me but haven't looked in the manual guy I got it from is a second generation Mechanic him and his dad put it together you think there may be a faulty tensioner?

Well...there has been some known tensioner issues....

What's the issue with the chain tensioners ?

Not exactly sure but they either are wearing fast in some cases or coming apart.