Looking at my Cam Chain tensioner 400EX

[rd2005]

I have looked at previous threads & could not find any that answer my question so here is what I need help with
1st? - My Clymer book DID NOT state about keeping the cam chain taught to the lower sprocket while removing the cylinder/top end, the only thing it mentioned was to tie a wire to the chain to keep it from falling into the engine.
After we did everything we needed to do in the engine I began reading the installation instructions in a different chapter. There it stated to be sure to keep the chain taught to the sprocket. WTF??? That was stupid to not put that part of the directions with the removal.:mad:
So here is my question: I have done everything including aligning TDC marks on the flywheel & everything the book said to do for removal, now my cam chain is off the sprocket down in the engine...Will my timing be off? I looked for marks on my chain & nothing stands out as to indicate to set the chain in a certain spot. The chain really did not move much it just was lowered to get parts around it & that is how it came off the lower sprocket.
2nd ?- My cam chain guide is eat up a bit on the edges & the inside of the engine has a slight groove on the walls from the chain. Does this mean the chain tensioner is not working? The adjustment bolt in the center of the tensioner was pretty loose leaving me to think along with half the bolts on my engine have not been torque properly???
The chain looks really good & the other chain guide closest to the tensioner looks in awesome shape should I change the tensioner & guide towards the front of the engine?
3rd ?- I read about another bike model part's working in this area...Can anyone tell me what parts would work from the other bike model on my 400EX (only the cam area)? Thanks

[fauxamish]

1st: It doesn't matter if the chain came off the lower sprocket. Make sure your timing mark on the flywheel is at TDC, the cam lobes are DOWN and the alignment marks on the cam gear are parallel with the head. It doesn't matter if the chain moved while you had it apart.

2nd: Not 100% sure about this one, maybe someone else can clear it up, since I have a similar problem with my guides.

3rd: Putting the timing chain from a CRF450R is what most people are doing because it is a heavy duty chain. It has an extra plate on the chain, making it a lot stronger and less prone to stretching/breaking. The part number is 14401-MEB-671 and it is the same chain that is in the '02-'08 CRF450R, '06-'09 TRX450R/ER.

Hope this helps.

[rd2005]

Originally posted by fauxamish
1st: It doesn't matter if the chain came off the lower sprocket. Make sure your timing mark on the flywheel is at TDC, the cam lobes are DOWN and the alignment marks on the cam gear are parallel with the head. It doesn't matter if the chain moved while you had it apart.

2nd: Not 100% sure about this one, maybe someone else can clear it up, since I have a similar problem with my guides.

3rd: Putting the timing chain from a CRF450R is what most people are doing because it is a heavy duty chain. It has an extra plate on the chain, making it a lot stronger and less prone to stretching/breaking. The part number is 14401-MEB-671 and it is the same chain that is in the '02-'08 CRF450R, '06-'09 TRX450R/ER.
Hope this helps.

Hey Thanks fauxamish for clearifying some of this. Good to know the cam chain can just go back on with no issue. I just got a crf450r chain at the local Honda shop today. Just hoping someone out there knows about the cam guides & tensioner issue. :)

[400exrider707]

1)Doesn't matter where the chain is, the important thing is to have the piston at TDC, the lobes on the cam pointing down and the alignment marks on the cam gear lined up with the head. That is what sets your timing. You can take the chain off, rotate it either way and put it back on, the motor doesn't know or care where the chain lies as it's the same in every position. Look at a pedal bike. If you take the chain off and rotate it around 20 links, does the bike care?

2)The screw in the center of the tensioner is not a "bolt" in the way you're thinking, it's spring loaded. You "loosen" it to back it off and you have to hold it there with a screwdriver. You take the screwdriver out and it should pop back in on it's own, setting the tension. With it off the motor, push on the tensioner part, if you can collapse it by hand power, it's junk, get a new one. Sounds like both your tensioner and your cam chain are junk. Replace both and the guides, the guides are cheap. 400ex cam chains are notorious for stretching and it sounds like it is if it's wearing into your cases. Shouldn't have that much side to side play. You can buy manual tensioners on ebay and from some companies, but I'd stick with a new Honda one personally. The tensioner could be good I guess, but sounds like the chain is definitely shot, but you ordered a new one so sounds good.

3) CRF450 cam chain, it's cheaper by a long shot and better!

[CJM]

In order to replace the one guide you can just yank it out, but the other one is bolted inside the lower case cover. You need to take this cover off as well as the clutch and basket to change the timing chain as well.

Your going to need a clutch holding tool, a torque wrench, new side case cover gasket and soem basic hand tools.

From the sounds of it you need the chain, guides and possibly a auto tensioner (as it should spring back into place as someone else described if its good)

[rd2005]

Awesome information you all are giving me!:D
Regards to the tensioner I cannot collapse it by hand power. I tried to make it budge but it would not move unless I put a very small screw driver in the end of it & turn it. So I can assume it is good, but the one guide (that pulls right out) will need to be changed. Should I replace both guides or just the one that pulls out? The only reason I ask this is cause the guide that is bolted looks really good & does not appear to be damaged in any way.

[fauxamish]

If the guide isn't worn or damaged, I don't see the point in replacing it.

If you do decide to replace it, just use an impact wrench to take the clutch nut on and off. Either wear a heavy leather glove, or wad a towel in between the clutch basket and inner hub to hold it. I've done this too many times to count and its always worked fine. Just make sure that once the nut is back on really tight, you tap the metal back down into the groove (you'll see what I'm talking about when you have it apart)

[400exrider707]

Just leave that one if it looks ok, replace the one being chewed up then. You shouldn't have to pull the cover to get the timing chain back on the lower sprocket, though it's hard to even get it off as there is a guide down there that's supposed to hold it against the sprocket. You may just want to take the side cover off anyway, this will at least let you get a visual in there to see everything is OK and you'll know just how it works too!

[CJM]

If the other guide looks good then Id leave it alone then.

Yes an impact gun makes it much easier, the clutch holding tool for 20 bucks is worth it. Ive done the rag and the glove method and find the tools easier and has other uses.

[fauxamish]

The correct tool always makes it easier CJM lol. I really ought to pick up the holder as often as i tear my motors apart.

[CJM]

Originally posted by fauxamish
The correct tool always makes it easier CJM lol. I really ought to pick up the holder as often as i tear my motors apart.

Thats why I bought it, rocky mtn has one for like 15 bucks :)

Having an impact makes it even easier, Im soo happy I have oneof those too