Huge Problem...Engine died. Take a look at these pics
#61
06-29-2011, 04:19 AM
However, I don't see it as a cause for piston-valve contact, at least if the setup can sustain cutoff rpm without problem. Hard shifting like you do induces very rapid crank deceleration, a condition where the cam shaft inertia tends to advance the cam timing (chain stretching and guides deformation can surely induce a few degrees of transient timing change). This transient advanced cam timing increases the piston to exhaust valve clearance. For example, if the engine reaches 10krpm between your 5 to 6th gear shift and settles to 5K when you dump the clutch, that 10k to 5k sudden rpm change will produce temporarily increased exhaust valve clearance.
#62
06-29-2011, 04:30 AM
Join Date: Jun 2011
Posts: 592
This seems overabuse to me. Are you doing wheelies at every gear shift or what? I expect you will toast the clutch disks, groove the clutch basket, break the drive chain, stretch the cam chain, and all sort of other nasty effects by doing this. But this is your choice...
However, I don't see it as a cause for piston-valve contact, at least if the setup can sustain cutoff rpm without problem. Hard shifting like you do induces very rapid crank deceleration, a condition where the cam shaft inertia tends to advance the cam timing (chain stretching and guides deformation can surely induce a few degrees of transient timing change). This transient advanced cam timing increases the piston to exhaust valve clearance. For example, if the engine reaches 10krpm between your 5 to 6th gear shift and settles to 5K when you dump the clutch, that 10k to 5k sudden rpm change will produce temporarily increased exhaust valve clearance.
However, I don't see it as a cause for piston-valve contact, at least if the setup can sustain cutoff rpm without problem. Hard shifting like you do induces very rapid crank deceleration, a condition where the cam shaft inertia tends to advance the cam timing (chain stretching and guides deformation can surely induce a few degrees of transient timing change). This transient advanced cam timing increases the piston to exhaust valve clearance. For example, if the engine reaches 10krpm between your 5 to 6th gear shift and settles to 5K when you dump the clutch, that 10k to 5k sudden rpm change will produce temporarily increased exhaust valve clearance.
#63
06-29-2011, 06:25 AM
Looking at this picture you posted, I'd say the head gasket was toast before the valve let go (you can see a lack of carbon build up and 'staining' on the left hand side of the head.) The extra heat certainly could have caused the valve to drop. The mention of "..The oil was dark and crappy looking..." supports the overheating of the head/cylinder. Just an observation.
Just for future reference for those embarking on a big bore kit.
Torque the head bolts (M10) in sequence, and in 2 stage with a liberal coating of molybedenum desulfied grease. Stage one 15 N.m. Final stage 46 N.m.
Just for future reference for those embarking on a big bore kit.
Torque the head bolts (M10) in sequence, and in 2 stage with a liberal coating of molybedenum desulfied grease. Stage one 15 N.m. Final stage 46 N.m.
Last edited by WestOzKLX; 06-29-2011 at 06:37 AM.
#64
06-29-2011, 09:27 AM
Jhoffy , Iīm sorry to learn about your engineīs early demise .
In a older , slightly abused engine you can have lots more plays developing here and there , the valves may not seat right on their seats allowing them to heat up more than they should , the valve guides may be worn enough so the valve never seats in the same position etc.
What is certain is that you will need to visit a machine shop before anything .
Maybe ( a big maybe ) they can rescue your head . I would take also the cylinder so they can have a look at it . Iīve seen them welding cracked heads and doing all kind of neat tricks with supposedly dead heads . The most problematic would be the exhaust valve seats , there is a risk they may go in too much if they try to reshape for original valves . If you are willing to go with 1 mm bigger valves itīs a different story . You NEED to visit a good machine shop even if you buy a different head ( new or used ) have a profesional inspect all the plays sizes and shapes on it and install stems or reshape seats if necessary .
Also most of us know that less than 40% of the energy of an explosion gets transformed in actual horsepower , most of it is disipated trough heat ( exhaust gases , cooling system , friction etc ). A increase in power is a increase in the heat generated by the engine , and if for some reason ( leaner mixture , feathering the clutch at top revs , cam mods ) you agravate an allready tired head that cannot properly cool itīs valves , itīs just a matter of time before the valve sticks open a fraction of a second waiting for the piston to slapp it out of existence .
I think , as a predentive measure , all the bikes with increased power due to whatever reason ( compression , cylinder , cam mods etc. ) should use a minimum valve lash of 0.15 mm on the intake and 0.20 on the exhaust instead of the minimum 0,10 and 0, 15 of the stock KLX . It will help keep the valves cool and us out of troubble . 3 weeks ago when I did the mod my measured lash was : 0,14 and 0,15 mm on the intake and 0,21 and 0,19 on the exhaust . I got to 2000 Km on the bike , more than 1000 with the mod .
In a older , slightly abused engine you can have lots more plays developing here and there , the valves may not seat right on their seats allowing them to heat up more than they should , the valve guides may be worn enough so the valve never seats in the same position etc.
What is certain is that you will need to visit a machine shop before anything .
Maybe ( a big maybe ) they can rescue your head . I would take also the cylinder so they can have a look at it . Iīve seen them welding cracked heads and doing all kind of neat tricks with supposedly dead heads . The most problematic would be the exhaust valve seats , there is a risk they may go in too much if they try to reshape for original valves . If you are willing to go with 1 mm bigger valves itīs a different story . You NEED to visit a good machine shop even if you buy a different head ( new or used ) have a profesional inspect all the plays sizes and shapes on it and install stems or reshape seats if necessary .
Also most of us know that less than 40% of the energy of an explosion gets transformed in actual horsepower , most of it is disipated trough heat ( exhaust gases , cooling system , friction etc ). A increase in power is a increase in the heat generated by the engine , and if for some reason ( leaner mixture , feathering the clutch at top revs , cam mods ) you agravate an allready tired head that cannot properly cool itīs valves , itīs just a matter of time before the valve sticks open a fraction of a second waiting for the piston to slapp it out of existence .
I think , as a predentive measure , all the bikes with increased power due to whatever reason ( compression , cylinder , cam mods etc. ) should use a minimum valve lash of 0.15 mm on the intake and 0.20 on the exhaust instead of the minimum 0,10 and 0, 15 of the stock KLX . It will help keep the valves cool and us out of troubble . 3 weeks ago when I did the mod my measured lash was : 0,14 and 0,15 mm on the intake and 0,21 and 0,19 on the exhaust . I got to 2000 Km on the bike , more than 1000 with the mod .
#66
06-29-2011, 11:01 AM
Join Date: Jun 2011
Posts: 592
Looking at this picture you posted, I'd say the head gasket was toast before the valve let go (you can see a lack of carbon build up and 'staining' on the left hand side of the head.) The extra heat certainly could have caused the valve to drop. The mention of "..The oil was dark and crappy looking..." supports the overheating of the head/cylinder. Just an observation.
Just for future reference for those embarking on a big bore kit.
Torque the head bolts (M10) in sequence, and in 2 stage with a liberal coating of molybedenum desulfied grease. Stage one 15 N.m. Final stage 46 N.m.
Just for future reference for those embarking on a big bore kit.
Torque the head bolts (M10) in sequence, and in 2 stage with a liberal coating of molybedenum desulfied grease. Stage one 15 N.m. Final stage 46 N.m.
Jhoffy , Iīm sorry to learn about your engineīs early demise .
In a older , slightly abused engine you can have lots more plays developing here and there , the valves may not seat right on their seats allowing them to heat up more than they should , the valve guides may be worn enough so the valve never seats in the same position etc.
What is certain is that you will need to visit a machine shop before anything .
Maybe ( a big maybe ) they can rescue your head . I would take also the cylinder so they can have a look at it . Iīve seen them welding cracked heads and doing all kind of neat tricks with supposedly dead heads . The most problematic would be the exhaust valve seats , there is a risk they may go in too much if they try to reshape for original valves . If you are willing to go with 1 mm bigger valves itīs a different story . You NEED to visit a good machine shop even if you buy a different head ( new or used ) have a profesional inspect all the plays sizes and shapes on it and install stems or reshape seats if necessary .
Also most of us know that less than 40% of the energy of an explosion gets transformed in actual horsepower , most of it is disipated trough heat ( exhaust gases , cooling system , friction etc ). A increase in power is a increase in the heat generated by the engine , and if for some reason ( leaner mixture , feathering the clutch at top revs , cam mods ) you agravate an allready tired head that cannot properly cool itīs valves , itīs just a matter of time before the valve sticks open a fraction of a second waiting for the piston to slapp it out of existence .
I think , as a predentive measure , all the bikes with increased power due to whatever reason ( compression , cylinder , cam mods etc. ) should use a minimum valve lash of 0.15 mm on the intake and 0.20 on the exhaust instead of the minimum 0,10 and 0, 15 of the stock KLX . It will help keep the valves cool and us out of troubble . 3 weeks ago when I did the mod my measured lash was : 0,14 and 0,15 mm on the intake and 0,21 and 0,19 on the exhaust . I got to 2000 Km on the bike , more than 1000 with the mod .
In a older , slightly abused engine you can have lots more plays developing here and there , the valves may not seat right on their seats allowing them to heat up more than they should , the valve guides may be worn enough so the valve never seats in the same position etc.
What is certain is that you will need to visit a machine shop before anything .
Maybe ( a big maybe ) they can rescue your head . I would take also the cylinder so they can have a look at it . Iīve seen them welding cracked heads and doing all kind of neat tricks with supposedly dead heads . The most problematic would be the exhaust valve seats , there is a risk they may go in too much if they try to reshape for original valves . If you are willing to go with 1 mm bigger valves itīs a different story . You NEED to visit a good machine shop even if you buy a different head ( new or used ) have a profesional inspect all the plays sizes and shapes on it and install stems or reshape seats if necessary .
Also most of us know that less than 40% of the energy of an explosion gets transformed in actual horsepower , most of it is disipated trough heat ( exhaust gases , cooling system , friction etc ). A increase in power is a increase in the heat generated by the engine , and if for some reason ( leaner mixture , feathering the clutch at top revs , cam mods ) you agravate an allready tired head that cannot properly cool itīs valves , itīs just a matter of time before the valve sticks open a fraction of a second waiting for the piston to slapp it out of existence .
I think , as a predentive measure , all the bikes with increased power due to whatever reason ( compression , cylinder , cam mods etc. ) should use a minimum valve lash of 0.15 mm on the intake and 0.20 on the exhaust instead of the minimum 0,10 and 0, 15 of the stock KLX . It will help keep the valves cool and us out of troubble . 3 weeks ago when I did the mod my measured lash was : 0,14 and 0,15 mm on the intake and 0,21 and 0,19 on the exhaust . I got to 2000 Km on the bike , more than 1000 with the mod .
Lol, lose a valve? What happened?
#67
06-29-2011, 11:44 AM
Join Date: May 2006
Location: Pittsburgh, PA
Posts: 12,584
Long story.... my bike was making a noise it was still under warranty so i had to deal with idiot "mechanics" at a couple bike shops. I use the term mechanic loosely. My exhaust cam was replaced, then the motor was completely torn down cases split to fix a gear that i dont think was really bad, didnt fix it, so a new head was put on with all my old valves and springs put in the new head. Still didnt fix the noise, then he finally listened to me when i told him it was the timing chain in the first place, new chain noise went away. Had the bike and put 1000 miles on it then it sucked the valve, when my old valves were put in the new head he didnt check the valve piston clearance, at TDC the piston was hitting th valves, well it only could take 1000 miles of that. Then back to a different shop and everything from the connecting rod up got replaced except cams and timing chain. head, cylinder, piston, valves.... and then they checked the piston to valve clearance and it was still hitting, so they had to machine the head so the valves set in the head more. If you are fixing your bike i would highly suggest to have someone who knows what they are doing to do it and make sure they check the clearance. My motor is a perfect example of that.
#68
06-29-2011, 11:46 AM
Join Date: May 2006
Location: Pittsburgh, PA
Posts: 12,584
Oh yea, i bought my bike new, when it was 18 months old it had already spent 5 months in the shop. After all i have been through with it i love my bike to god damn death. I will never sell it. I ride the **** out of it and ride it like i stole it. I beat the hell out of it and lay it down at least every ride and it keeps ticking and it takes me everywhere i ask it to. LOVE IT.
Last edited by EMS_0525; 06-29-2011 at 11:49 AM.
#69
06-29-2011, 11:50 AM
Was the reason for piston/valve contact in a NEW motor ever determined? Actually, wouldn't that have been 2 new motors, with it also doing it after the rebuild? That is way wierd...
#70
06-29-2011, 11:57 AM
Join Date: May 2006
Location: Pittsburgh, PA
Posts: 12,584
Obviously the new heads need a little bit more machining so the valves set deeper in the head. Both heads were new from kawi. So my bike is on its 3rd head.