All my SL engines came with bolts marked 11 on the head. 1 used engine I dissassembled did have bolts marked 9, I do have some of the NOS Honda bolts marked 9 on the head.
If anyone want some NOS Cam bolts marked 9 on the head I have some at low cost. Somewhere in time Honda may have replaced the supplies with Bolts marked 9, they were in stock at 2 Honda shops that's how I bought them, they carried the same part numbers.

 

Is it safe to use the No. 11 bolts on the older fat cam sprockets (the stock ones were marked 9 on mine)? I purchased a NOS set from eBay for about $20, and they are the newer ones marked 11. I would think that using a stronger fastener should be fine, if not better..

 

Yes bolts marked 11 are original NOS bolts for all 250 and 350 Twins from what I've seen.

 

Tip I learned from midge: safety wire and blue loctite the cam sprocket bolts. The originals bolts did just fine for 40 years but I doubt the bike was ridden the way I plan to ride it on the race track. Hopefully this helps avoid any future calamity. Loctite is best applied to clean, dry bolt threads and I'm not about to tear down my motor once again to remove the cam so I can spray brake cleaning solvent inside the threaded holes. So the Loctite I used is probably more a placebo than anything. But it can't hurt.

 

Tip I learned from midge: safety wire and blue loctite the cam sprocket bolts. The originals bolts did just fine for 40 years but I doubt the bike was ridden the way I plan to ride it on the race track. Hopefully this helps avoid any future calamity. Loctite is best applied to clean, dry bolt threads and I'm not about to tear down my motor once again to remove the cam so I can spray brake cleaning solvent inside the threaded holes. So the Loctite I used is probably more a placebo than anything. But it can't hurt.

Hi freedomgli,
I want to ask you how your camshaft/camchain upper sprocket has been working out ? I see in your pictures that you have a Camella Tsubaki HD cam chain like I have and you're using the standard stock #312 sprocket also.I wanted to know if you get a little tiny rubber 'squeal' noise coming from your upper cam sprocket area once you turn off your engine ?? I have my Tsubaki HD cam chain looking exactly as yours does as far as engagemnet depth of the links down into the the chain;I'm worried that my chain isn't making full depth engagement w/ my sprocket teeth.I think that I'll remove the sprocket and machine off just enough of that rubber damper material to let the sprocket teeth have Full engagement. How has your experience been with this ?

Bill

 

The safety wire is probably in the same category -- a placebo. Safety wire does not hold torque or prevent loosening. It will prevent a fastener from working its way completely out and falling off. The failure mode here seems to be partial loosening and then shearing of the bolt shank. At least if yours break off, it may make it easier to find all the pieces. :wink:

I used Red Loctite, which I only do in rare circumstances and only if I think I could heat the fastener with a torch without collateral damage. This weekend, we are supposed to have balmy weather in the 60°F range and dry. I'll be trying out my CL350, while trying not to think about these bolts.

 

The safety wire is a good idea, on my next engine I'll drill some bolts and test them to see if it weakens them.

Remember keep your cam chain tight, it will run smoother with less snapping back and forth.

 

I have a stash of these NOS bolts for sale. They are $25 for the pair, shipped. If anyone is interested, PM me for details. (overseas shipping charges will be more)

 

Do you still have a pair of these bolts? If so, I'd like a pair.
Hank

 

How about using a lock washer like the one on the rear sprockets?

It should be relatively easy to make one from thin sheet metal with a pair of tin snips. I'd imagine this would be more secure than the safety wire and would not require any drilling of the bolts. The connecting arm will probably need to be more arched. What do you guys think?

 

You would need longer bolts. They need to use all the thread.

I don't think the problem is the bolts coming loose, I rode with at least 7 friends with 350 Twins back in the day and we ran them as hard as you could on/off road and never had a cam bolt issue. I never heard of a cam bolt failure untill people started rebuilding them, I think it's just a issue if they're not tight enough to start with.

It's like motor mount bolts, if not tight enough they will break engine cases and frame mounting ears.

 

I guess I am just overthinking this

 

ninadm,

The lock tab made of soft sheet metal would only make things worse. You could stick the bolts through it and bring them to initial torque. (Remember that torque is only important as an indicator of the inches/inch of bolt stretch within the elastic limit of the bolt.) Within its elastic limit,the bolt is trying to return to its original size and shape. Bolt stretch within the elastic limit is what provides clamping load and also works with friction to prevent the bolt from working loose. That soft metal locking tab would deform over time and compress. As it does so, there goes the bolt stretch. Now the bolt can work loose, fret and break.

Split ring lockwashers (I think the Brits called them shake-proof washers) are also worthless junk. They already have one break in them. They tend to spread as the bolt is tightened. Typically in order to get enough bolt stretch, the lock washer is already starting to fail. A much better way to hold torque (maintain bolt stretch) is to use a hardened flat washer with no split in it. Given a good, hard surface as a seat for the bolt head, or nut in some cases, and the proper amount of torque (as an indicator of bolt stretch) the fastener will stay in place.

Note that Honda did not call for lock washers or lock tabs under these cam bolts. The sprocket is case hardened to provide a good seat for the bolt head.

I agree with captb that most of the failures are because the bolts were not tightened properly.

Anyway, I'll find out soon enough. I just put a new license plate and sticker on my CL350. All I need now is a little decent weather.

Ray

 

Good info Ray! Makes sense..
I think your bike should do just fine. Good luck!

 

bilbikek411, I wasn't disagreeing with you. I think you can read whatever you want about this, pick your method, and hope it works. I have yet to fire up my engine for the first time, so I really am not in a position to advise. I'll tell you what I did though. I used a 1/4" drive extension with a universal joint (total length from the torque wrench to the end of the socket is 5 1/4" in my case), and I set my wrench to 11 lb.ft., hoping that the fastener "felt" 10 lb.ft. of twisting effort (some had to be lost in "winding up" the extension and U-joint). I used Red Loctite. I first tightened one bolt to 70 lb.in, then the other one the same. Then I went back to the first bolt and took it up to 132 lb.in. (or 11 lb.ft.). Finally I did the second one to 132 lb.in. as well. My wrench has a digital readout, so I could watch the numbers go up as I tightened the bolts. That let me know where I was at in the process. Selecting lb.in. units let me see it more gradually -- very reassuring! My bolts could break at startup -- I haven't tried the engine yet.

The members with much more experience have said:

captb: I did mine at 12.5 Ft/lbs with red loctite on threads and I swapped cams after 2K hard run city miles, it was still torqued tight but came apart fine. The bolts were used twice.

outobie: . . . for what it's worth on an already long thread. I torque them to 7 ft/lbs with red locktite. been doing this for 2 decades with never a failure on any race bike or street bike and I reuse these bolts every time I rebuild an engine and have never had one stretch or deform.

 

OK,I understand now.I appreciate you explaining that for me.I want to be sure that when I apply that Loctite that I don't over-torque those little bolts.I remember reading on that link you gave me(and looking at this one )that someone said that applying Loctite or having oily threads would allow the bolts to be over-torqued(not an exact quote)and I really didn't want to do that at all.

thanks Ray

 

Great thread, very helpful. Thanks everyone and thanks captb for doing this test.

 

Here's one easy way to stop the cam from rotating while tightening the cam bolts, but you would probably need another pair of hands to help you:

To keep the camshaft from turning while torquing the bolts, I stuck a smooth drift into one of the holes in the rotor, then had my wife hold a screwdriver pry-bar fashion between the drift and the rotor center bolt. I had the camshaft bearing blocks slipped into position, so the cam chain did not try to jump a tooth on the crankshaft sprocket. You could just hold the camshaft with a pair of vice-grips on the rough part of the shaft, but I feel that any nick, anywhere on the shaft, could be a potential stress riser (not a good thing),

 

Locking pliers on the rough casting area of the cam seems less dangerous. Plus it's less stressful for the chain.

 

Seriously? So, when the engine is running, the chain never, ever, sees that much tensile load? What is the dangerous part?

Either way is O.K. I just offered an alternative.

 

Well, it's just my opinion... but here's why:

Sure, it works fine... Just hope nothing loses grip and you end up destroying the wiring on the coils.

 

Heh, yeah. That guy is probably O.K. as long as he took the time to peel off that pesky label that says "Do not stand on or above this step".

To each their own, but I'd have to say that if somebody could let that screwdriver get away from them and ruin a coil on the stator, they are way to clumsy to be thinking about riding a motorcycle in the first place. When you think about it, there is very little torque trying to rotate the camshaft when tightening those two bolts to 11 lb. ft. The bolts are close to the center of rotation, while the cam chain is clear out on the periphery of the sprocket. The ratio of those two radii, each of which is a moment arm, is in your favor. Then there is a 2:1 ratio from the cam sprocket to the crankshaft sprocket, again cutting the torque in half. The 12" long screwdriver easily puts the advantage into the hands of the person holding back.

Regardless, since the day I took that picture, I've run up another 4,400 miles on that engine without anything letting go. I'm calling it good on those cam bolts.

Ray

 

Well done! May this small sacrifice save many more bolts/valves/chains/pistons/heads in the future

 

1971 Honda CB350 Twin. When assembling my cam sprocket to to camshaft, it seemed to fit very tight. I have it in the correct orientarion to the camshaft, the correct timing, and I have the special bolts in the correct holes. Still, the bolts seemed to turn pretty hard. Is there a torque setting to which these bolts should be tightened to? What do I do if the sprocket wobbles? Should it wobble at all- is there a tolerance?

 

Without seeing the camshaft, there's no explanation for why the bolts threaded in hard. However, the sprocket has to be tight to the camshaft, it cannot wobble as you described or disaster will be the result.

 

You can get correct ones from Honda, they are still used in various motors.
You will need a parts person who gives a damn though as the original part number will have been superseded multiple times and may not have been updated for an 'obsolete' bike'
I can't remember if they are same as late model CB/CM400/450 three valve motor as I haven't had one in pieces since about 1979 when I worked at Honda dealers.
Pretty sure someone here will have new part number but, like you said, may not get a reply?