Bert Jan
Holy Modification Batman
So.. been a while
Shop is going very well, mighty busy to keep everybody happy. ran into a problem i cant get my head around though and i hope you guys can shine a light on it.
I went for a ride on an nx650 when it suddenly stalled due to oil starvation to the head.
Piston, cilinder, cam, rockers... all went bad. As its really hard to find NX parts here i also searched for XR600r parts as they seems interchangable. Now..
Lower engine is still stock. Cilinder, piston, valve-unit is XR600r, valves/rockers XR600 - upper cover is NX650. problem is bike wont start. Not even a poofh. Nothing.
Triple checked timing of cam. "T" mark on flyhweel corresponds with the two lines on cam sprocket, altough theyre a liiiitle off. (assume from chain wear, as its waaaay less then a tooth)
Valves are .10/.12mm as per manual.
cam is XR600r, with no decomp unit. (also tried the old worn NX650 cam just to see if ot would run. Nothing)
10.5bar compression.
Great suction on intake, almost sucks your hand in.
Carb has not been altered or changed, and bike ran good before oil problem.
Timing is cdi and was not altered or changed. sparks like hell. Has wasted spark btw..
Checked the little metal thingy that holds the flywheel on the crankshaft (i figured it might have snapped, giving me a false "T" mark.) Still good.
Sprayed brake cleaner into intake, nothing. let some gas into the head via the sparkplug hole. Nothing.
Took the engine apart today. Valves are still good (i lapped them before mounting) and straight, leakdown with acetone in upside down head reveals no leaks, so valves have not touched piston. tells me timing is 'kinda' ok. Last thing i thought about is the cam chain guide. The XR600r and NX650 have other reference numbers and the pics dont look the same.
Is it possible that the NX650 guide (now sitting in the XR600 cilinder) is so much different than the XR600 guide, causing timing issues being so bad that valves are not closed at TDC?
I do not have an XR600 guide to check and they're 55,- bucks. Would like to know if its the problem before ordering a useless part.
Strangest thing i've had in my shop thus far. Can't figure it out and it pissed me off haha, so please shoot the most stupid shit you come up with as it might lead to the problem!
As we have compression, spark and fuel, i'm at loss here. Prolly something utterly stupid haha
Shop is going very well, mighty busy to keep everybody happy. ran into a problem i cant get my head around though and i hope you guys can shine a light on it.
I went for a ride on an nx650 when it suddenly stalled due to oil starvation to the head.
Piston, cilinder, cam, rockers... all went bad. As its really hard to find NX parts here i also searched for XR600r parts as they seems interchangable. Now..
Lower engine is still stock. Cilinder, piston, valve-unit is XR600r, valves/rockers XR600 - upper cover is NX650. problem is bike wont start. Not even a poofh. Nothing.
Triple checked timing of cam. "T" mark on flyhweel corresponds with the two lines on cam sprocket, altough theyre a liiiitle off. (assume from chain wear, as its waaaay less then a tooth)
Valves are .10/.12mm as per manual.
cam is XR600r, with no decomp unit. (also tried the old worn NX650 cam just to see if ot would run. Nothing)
10.5bar compression.
Great suction on intake, almost sucks your hand in.
Carb has not been altered or changed, and bike ran good before oil problem.
Timing is cdi and was not altered or changed. sparks like hell. Has wasted spark btw..
Checked the little metal thingy that holds the flywheel on the crankshaft (i figured it might have snapped, giving me a false "T" mark.) Still good.
Sprayed brake cleaner into intake, nothing. let some gas into the head via the sparkplug hole. Nothing.
Took the engine apart today. Valves are still good (i lapped them before mounting) and straight, leakdown with acetone in upside down head reveals no leaks, so valves have not touched piston. tells me timing is 'kinda' ok. Last thing i thought about is the cam chain guide. The XR600r and NX650 have other reference numbers and the pics dont look the same.
Is it possible that the NX650 guide (now sitting in the XR600 cilinder) is so much different than the XR600 guide, causing timing issues being so bad that valves are not closed at TDC?
I do not have an XR600 guide to check and they're 55,- bucks. Would like to know if its the problem before ordering a useless part.
Strangest thing i've had in my shop thus far. Can't figure it out and it pissed me off haha, so please shoot the most stupid shit you come up with as it might lead to the problem!
As we have compression, spark and fuel, i'm at loss here. Prolly something utterly stupid haha