Topic: Ooops - broke my Cam Chain Adjuster bolt, CB400F

[dagersh]

Arrrrg!

So, I was tuning up my CB400F, valves, oil change, timing and carb sync.  Got everything done great, and decided to go after making sure my Cam Chain was adjusted.  Well, I got a little too gorilla fisted and broke off the Adjuster bolt located at the lower front of the engine.

I am searching ebay, but no luck so far.  I think its the same as the 350, 500 and 550's.  Anyone have a spare they want to sell?

If not, can I replace it with a 6mm threaded bolt and use 2 nuts as a lock?

Thanks!

Gersh

[vames]

Ain't exactly cheap but this guy's got 'em

http://cgi.ebay.com/ebaymotors/Honda-CB250-CB350-CB400F-CL350-SL350-Bolt-Tensioner-NOS-_W0QQcmdZViewItemQQhashZitem483f21dc7bQQitemZ310296829051QQptZMotorcyclesQ5fPartsQ5fAccessories

Or this guy

http://www.phildentonengineering.com/product.asp?pid=190

[Deltarider]

Well, I got a little too gorilla fisted and broke off the Adjuster bolt located at the lower front of the engine.

Don't blame yourself. Many before you share your experience. Poor design by Honda.

[vames]

I haven't had to adjust mine yet, but it looks scary down there so I ordered a new one just in case. Lots of PB Blaster and patience, I suppose, when the time comes.

[DarcyCB400F]

Funny (not really) I did much the same as you today...valve clearnace, timing, dwell... cam chain adjustment only to discover PO stripped it!!

Not sure, but I think I will change the bolt first but suspect the case is stripped!

Let me know if you find some for less than $25 on StealBay!

[bryanj]

Those bolts ahve been obsoleted for some time but you can use an straight 6mm setscrew with a 6mm nut and plain washer to the case, it may weep a small amount of oil but never seen one leak bad

[-CB-Jamie-]

The PO of my bike must have stripped the threads in the crankcase too on my bike, but he came up with a handy enough solution to it. He had a big SS nut with a 6mm thread welded onto to the crankcase and then threaded a 6mm SS bolt through this with a locking nut on it with a washer. Whoever done the welding on this thing was really tidy as well. Now there should never be a problem with stripping threads again hopefully. Also when I got this bike it had been sitting for at least five years and the bolt loosened with minimal effort. It's tidy enough looking as well.

look closely in this pic and you can see it.

[dagersh]

Thanks Guys!

I will probably just order a new one.  I did not study the diagram carefully, and thought that was where you were supposed to insert a screwdriver if the CAM chain did not react.  So when I tightened it back up, I thought I was activating the the "pusher".

Lesson learned - all the bolt and locknut do is keep the plunger set, the 10mm cap bolt, located about 4 inches above, is where you can manually push the tensioner.

[vames]

Would love to see a better scan of that article.

[HondanutRider]

If it's the bolt with the locking nut that you broke, and you can remove the remains from your engine with the threads still intact on the case, then I don't see why a 6mm bolt of the approximate length as original wouldn't work as a substitution.  All it's doing is pressing into the plunger shaft to lock it in place.

That plug above this bolt, can also be replaced with a longer bolt with a locking washer on it.  Rather than sticking a screwdriver down that hole to apply more pressure to the adjuster, a more accurate adjustment can carefully be made (with the engine running), by screwing that replacement bolt in or out more as its end presses on the end of the adjuster linkage.  As I'm sure the articles explain about using a screwdriver in the hole to augment the springs weak adjustment, you don't want to be too heavy-handed in applying too much pressure/tension to the cam chain.  Just a bit more to reduce the slap and rattle as the chain runs 'round.  Then you can lock it in place with a nut, as well as tighten (carefully) the bolt you snapped, also locking it in place with its nut.

[dagersh]

That is a great idea!  Will give it a try and post the results.

Gersh

[dagersh]

Would love to see a better scan of that article.

Vames,

Its on the SOHC4.net site under 400F Tech articles.

Gersh

[vames]

Thanks!