Topic: cam chain time

[petercb750]

Greetings - the 400/4 camchain is really rattly and I'm no longer able to ignore it. I assume that not only is the camchain stuffed but the slider tensioner thingy too will need replacing. Is this job possible without removing the engine?
Any tips?
Cheers
Peter.

[mattcb350f]

You can replace the chain if you buy a "soft link" without pulling the engine, as well as the slippers. But you have to split the cases to get at the rest.

The 400F should look similar to this:


If the chain has been loose for a long time, it can rub the "U shaped" part under the crank and cause this:


 Matt.

[petercb750]

Thanks for that Matt - if the "u shaped" bit is worn, what would be the effect of changing the chain and sliders without splitting the cases and changing that bit? I would bet that a lot of people just replace chain and sliders given the difficulty of the other bit (which I also believe are not available anyway?).

[mattcb350f]

If the U shaped part (I forget the actual name  ) is as bad as mine was, it will be hard to set the tension properly or it will be seized altogether.

However, I'm pretty sure with a good flash light you should be able to see this part from the top of the engine after you take the cam out. Have a look when you're in there and if it looks good than carry on.

 Cheers, Matt.

[bryanj]

No point in fitting chain and slipper unless the tensioner mech is working

[petercb750]

Yes, good point.
How can I tell if that is working as it should? The cam chain rattle barely changes when I go through the adjustment procedure, and I'm assuming that is due to there being no adjustment left in the chain - ie it's at its full stretch and is knackered.
From the drawing provided by Matt it's hard to tell if the adjuster itself has a part that would wear or stick and therefore not work. Is there a bit there that might be adding to my woes? Maybe numbers 16 and 19 in the drawing? And is it replacable/available?
Many thanks for your interest.
Peter.

[ttr400]

For a quick check to determine if the lower U shaped adjusters is working correctly:

1 Remove tappet cover.
2 Remove # 5 top slipper retainer
3 loosen lock nut # 18
4 Back off the tensioner bar lock bolt # 12
When you backed off # 12 the slipper # 8 should move up, you should be able to push it down and it will come back up, then you know that the U shaped adjuster is moving freely.

If it doesn't move it is locked up and will require the motor to be stripped. it is common for the chain to chew into the pivot and lock it up ( as in the pic from matt), if this is the case it can be repaired.

Another method (not ideal) if the U shaped tensioner is locked up is to remove the bolt # 11, start the motor, loosen the lock nut #18 and back off bolt # 12, insert a long screwdriver into hole from bolt #11 and gently tap down on the push bar until it moves and the chain adjusts. only problem is if you go too far (tight) it can not be slackend off.

Kevin

[petercb750]

Ah ha - I think I'm learning something here. So the spring #6 pushes down on the U shaped thingy #3, which in turn then pivots up and causes slipper #8 to push inwards, which in turn tensions the chain? Then testing by pushing down on #8 will compress the spring on the other side and it should bounce back to its natural resting position against the chain (assuming chain has enough life in it to have any tension). Actually makes sense to me (if I've interpreted that correctly).
What do bolts #14 bolt into then? If my understanding is correct, that end of the U thingy #3 should be able to move? What holds it in place?
One other thing - is there a chance that the adjusting locking bolt mechanism #12, 18 and 16 is not locking properly into place when doing the adjustment and therefore not allowing the U shaped thingy #3 to do its job? Is it just locking by friction or does it go into a groove or something on the shaft # 7 or 9?
Sorry for so many questions, but this is a learning curve for me - we've not laid a tool on the 400 since owning it - it's been fabulous. I'm more familiar with our 750 set up, which seems a lot simpler and easier to me.
Cheers guys.

[Terry in Australia]

Come on Pete, pull that little engine out and get stuck into it, it's great fun! Cheers, Terry.

[petercb750]

Come on Pete, pull that little engine out and get stuck into it, it's great fun! Cheers, Terry.

 

[bryanj]

Bolts 14 hold the adjuster to the crankcase and need to be torqued carefully (or you will strip out the threads in the cranlcase) and with a dab of locktite,

Every one i stripped over many years where the camchain has rattled at all has had the two wear grooves that bur the metal and stop the horseshoe pivoting on the bolted piece

Take lots of time and care to make sure that this pice pivots properly and free and whilst the engine is out and split make sure the treads in the case for the lock bolt are in good order as the only sure way to helicoil these right is with the engine out.

This tensioner was the only real fault in the 400 and yes the horseshoe is obsoleted but having said that i only ever foound one that was so bad it couldnt be saved.

There is somebody on this forum that i think is fabricating replacements but cant be 100% on that

[mattcb350f]

Bolts 14 hold the adjuster to the crankcase and need to be torqued carefully (or you will strip out the threads in the cranlcase) and with a dab of locktite,

There is somebody on this forum that i think is fabricating replacements but cant be 100% on that

ttr400?

here's a link to a cool fabricated job, I think this is his website... scroll down the page to see it

http://www.ttr400.com/photo3_2.html

I got one from Western Hills Honda in Ohio, but I'm not sure if they have any left

 Matt.

[Bodi]

TTR has a picture of a really nice horseshoe unit but that's all... I haven't asked for a price but maybe these are available?
The stocker can get worn enough to lock up and be easily revived with a file and some fiddling, there seems to be enough metal remaining after unsticking mine that it isn't weakened much at all... of course another one may be worn beyond redemption.
If the horseshoe is working OK you can change the cam chain without cracking the main cases using a master link chain, just make sure you have a riveted master link as a clip type will not last long at all.
I have worked on quite a few 400s in the last 20 years and not one had a cam chain adjuster that worked when using the Honda or Clymer procedure. The springs have lost tension over the years I think, even with completely free horseshoe pivots they will not tighten the chain guide enough. Remove the top bolt #11 (this is just a hole plug and the springs can not shoot out) and press down on the actuating rod #9 with a thin screwdriver or a nail with the engine running (I can't recall if this is the Honda or Clymer method's approach). Press down until the rattling just quiets down and tighten the locknut.
The guide runners wear out, and may be available from Honda. There may be a wear spec in the service manual? The little rubber widgets that the ends of the runners slot into should be replaced if you can get them... but unless you break them they are not critical - the rubber just turns extremely hard after 20 or 30 years.

[petercb750]

All good info and tips thank you. 
All parts are still available (eg David Silvers, who are a lot cheaper than my local dealer in Oz) except of course the horseshoe. Will do the "tests" first and see where we go from there.
thanks again.
Peter

[ttr400]

Yep, I do make the horseshoe, see photo below of one installed.
They are available from myself or from www.400fourstore.com

Kevin

[bender01]

I just used ttr/ Bodis tips on my 350f last night. It wasnt how i wanted to do it but it  worked well. I might do it a little more in the near future but i dont want to overtighten it. Before the lock nut and adjuster wouldnt catch on any thing. Now it does. Had to remove the frame engine mount to get at the bolt hole with any force and it took some force to move it. Light hammer tapping. Thanks to all for the tips.
  Ben