400ex cam chain tensioner question

[RezoD]

Hey guys, got a quick question that hopefully someone can shed some light on. My cam chain tensioner (the original one) broke about a month and a half ago, my bike jumped timing and bent the exhaust valves. I replaced those 3 items, and it ran better than before. :) Fast forward to yesterday... My bike jumped timing, and because of last time, I knew to shut it down immediately. I'm tearing into it currently, and just found something.. The cam chain tensioner allows the cam chain to slacken, but does not automatically re-tighten itself. Is there a way to lock it where it's at so that the chain stays as taught as it is? I know that wouldn't be ideal, but I don't want to have to pull my exhaust off before every ride to make sure that my chain tensioner is still tight.

I didn't have directions/instructions as far as installing the new one when I bought it, and I didn't have a manual, so I wasn't sure if that T was supposed to stay in there (I didn't think it would fit with the screw in it.. does it?).

Thanks in advance boys,
Travis

[400eXr1d3rZ]

Undo the phillips screw on the tension and get a skinny flat head screw driver, look into the hole where the phillips screw was and theres something where a flat head would fit, put it in there and turn it, it will retract the tensioner, have a buddy put the bolt it to the head while you keep it retracted.

[GPracer2500]

When it's functioning properly it will extend but not retract. If you can push the plunger back into the tensioner's body, something is wrong with it. Like 400eXr1d3rZ said, it should only retract when you manually retract it from the outside.

Not sure what "T" you're talking about.

For engines that have issues with their automatic tensioners, there are manual cam chain tensioners avaliable. I'm not sure if anyone makes one for the EX engine though. I have seen a manual tnesioner made out of a stock auto tensioner--but again, it wasn't on an EX. I bet it could be done pretty easily though.

Manual tensioners:
http://www.streetandcomp.com/mcart/images/IT7405_GWEBcam_tensioner_jp.jpg
http://shop.thumpertalk.com/photos/ENG_TT_MCCT1-3.jpg

[RezoD]

400ex rider: I wasn't asking how to retract it, sorry if that's what it seemed like. I was asking if the T (It's a small T looking piece of metal that holds the tensioner retracted) was supposed to stay in there...

I can pull on the cam chain, and it will loosen the tensioner; It shouldn't be able to, right? It should keep the tension at a minimum, and actually only tighten the chain, not let it slacken, correct?

Thanks for the quick responses!
Travis

[cals400ex]

i have no idea what "T" looking piece you are talking about.....you need to make sure that you take the small circular screw out with a screwdriver. then you need to insert a very small flat blade screwdriver in and turn the tensioner so it retracts. then put the tensioner on the bike. if you put the tensioner on the bike without retracting it then i am sure you ruined the cam chain and/or the tensioner. so make sure it is retracted before bolting up the tensioner on the bike. after it is bolted on the bike with the two bolts remove the flat blade screwdriver and you should hear a click. this is the tensioner releasing and putting tension on the chain. if your tensioner retracts by pushing on it then it is bad.

[Crazy Bob]

The "T" shaped piece holds the retracting screw in the retracted postion so that you can install the tensioner more easily. YES... you must remove the "T" from the tensioner after it is installed.
This allows the screw (inside the normally covered hole) to turn. The cam tensioner will then extend, pushing against the chain guide until the chain is tight. If the chain guide is pushed toward the tensioner, it should not cause the tensioner to retract.
The tensioner WILL extend automatically, but WILL NOT retarct without turning the reteacting scerew. Bob

[quadracer500]

cyclesrus a motorcycle salvage dealer in medina ohio has the manual tensioner for the 400ex about 50 dollars the do have a web site, just search for the site and call
and ask for brandon.

[GPracer2500]

Also, here's a how-to for making your own. It's specific to a CRF450R but I'm guessing the procedure would be identical for a 400EX (and most other applications).

http://www.thumpertalk.com/forum/showthread.php?t=377469

[RezoD]

Actually, I tore into it on Monday and took it all apart. Guess what I found? That stupid skinny arse spring that they use was broken... AGAIN! Kinda sad that in 5~ hours of riding, I break the same part that broke before that.

Anyways, I removed most of the internals of the tensioner, except the part that pushes against the tensioner, then found a bolt I had that threaded into the tensioner, installed a nut near the head of the bolt, and made my own manual tensioner. :) I'll check it every couple of rides... But this one shouldn't move! :devious:

Travis