manual cam chain tensioner

[400man]

I blew up my motor (busted cases, broken connecting rod) this past weekend in a race and after taking it apart I found that my cam chain tensioner was compressed in and stuck and not working like it should with the springed tension. ive decided that this must have been what caused my motor to blow. I think my tensioner was a few years old though, so I guess it finally gave out?

after doing some reading and searching on here, I seen where some people recommend using a manual cam chain tensioner because the stock spring loaded tensioner could possibly fail without warning (like mine did?). and a manual tensioner is basically a threaded stud with a lock nut, so it will never fail. but the only thing that makes me weary of it is you never really know how much tension is on it while your riding and stuff, and if its too loose or too tight?

so what would be better, a oem tensioner and replace it once a year (cheap insurance), or manual tensioner and take more time and maintaince to check it?

[mtsnieg]

I have manual one on my 400ex. It appearrs to be the oem tensioner with the spring stuff removed and replaced with a thtreaded rod. It was ike this when I bought the quad last fall. Seems thet my cam chain is stretched to almost the max on the oem rod on the tensioner. Maybe thats why to preveious owner modded it. I set the engine to tdc and tighten the rod till resistance is felt. Seems bullit proof compaared to the oem set-up. I'm gonna do the cam chain soon, still undecided if 5'm gonna relace the manual tensioner with an oem one.

[400man]

I ended up ordering a new oem tensioner for my other 400ex with the stock motor. Im guessing that it still had the original tensioner cause the motor appears to never have been messed with. but I think im gonna try one of these manual tensioners. is there any way to tell just how tight you adjust it without over-tightening it?

[DnB_racing]

why do you think a cam chain tension caused the motor to blow....I can see it causing a bearing to go, but you would see signs of this during routine oil changes...

[400man]

why do you think a cam chain tension caused the motor to blow....I can see it causing a bearing to go, but you would see signs of this during routine oil changes...

well, when I removed the tensioner it was sucked in and wouldn't come out? but, I didn't really mess with it until yesterday to test and see why it was sucked in. took the phillip head screw out and turned the screw inside and it made a pop and kicked back out. And it acts fine now? :uhoh: maybe that's not what caused it then? I guess when it all happened the force on the chain caused it to push in maybe and lock?

the thing was running great and the oil never had any debris in the oil when I changed it before the race.