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Discussion Starter #1
I just can't get the damn line on the cam sprocket to perfectly align horizontally with the cam casing.....

Timing mark on stator goes I'd say goes 5 mm counterclockwise past the mark before the cam sprocket line goes truly horizontal. I've had the cam side covers off and re timed maybe 6/7 times but I just cannot get the bloody thing to align.

Am sure last time I did it it was spot on. I've replaced the big wheel on the tensioner with a non oe replacement from David silver. Would this cause this issue?

Please someone chime in, tearing my hair out with this one. Thanks
 

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Is your head torqued?
Cam chain tensioner set?
Post some pics of the sprocket and stator generator markings
 

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Discussion Starter #3
Hi doode, thanks for the quick response. Head isn't torqued down, and I've tried it with and without the cam chain tensioner set and it will just not line-up.

A few photos. Apologies on my iPhone and can't tell which is which. But, these are with cam chain tensioner set. To get the sprocket line perfectly horizontal, you can see the lt mark goes maybe 5 mm. if I set the lt mark spot on the sprocket line just doesn't sit square.

Am I being to picky here?
 

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A couple of things

1- new cam chain?
2- peek through the plug hole to make sure lt is indeed top.
3- this might be okay as long as there is no valve interference

I occasionally have challenges lining up perfectly, but double check to make sure it's a chain stretch issue and not something else
 

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Discussion Starter #5
Hi, no it’s the existing cam chain. It’s definitely at top - confirmed by mr chopstick.
Paranoid about dinging a valve, just replaced a bent one and new guide.

Think I should just get new cam chain to be sure?

How could I check for valve clearance? Tried small zip tie through plug hole and hand cranked it over to see if it caught but not convinced..... thanks
 

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So. You want to be absolutely 100% dead certain you're not going to smash another valve huh?
Here's a video for those of us who just have to see things with our own eyes. ...just to be sure. ;)


 

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Considering how Honda puts the crank together it will always be + or - half a tooth. The sprocket on the crank is not aligned, splined or keyed. If you really want it to be perfect, you should degree the cam. You can buy a degree-able sprocket at THR racing.

In the images I see that you do not have the head torqued down. This will affect the timing lines.
 

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By the way, it is easy to check for valve clearance. Adjust the valves at 0 lash and stick a 0.7mm or 1 mm feeler gauge inbetween the follower and the stem (takes some convincing). Then turn the crank gently to see if it gets stuck. 0.7mm is typically the advised clearance. I like to use 1mm, just to make sure.
 

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Discussion Starter #10
Thanks for your responses guys, really appreciate the advice.
All gaskets are correctly installed.

Erwin, not sure I completely follow the clearance check - could you elaborate for dummies?
What crank position, between the follower (rocker arm?) and top of stem? Thanks again
 

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Have to disagree with Erwin .... every 350 engine I have built has had the marks line up.... think I'm up to number 10.

I always use a new timing chain.

If you didn't have to tighten down the cam case to install the cam that tells me your chain is stretched. With a new chain you have to tighten things down before installing the cam covers. I just use a couple large nuts as spacers and do two of the center studs.
 

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Discussion Starter #12
Cheers Boomer,

Am going to order a new chain anyways. Have come too far and spent to much money at the shop to screw this up now. Cylinders were honed and fitted new rings. Last time I did this it lined up spot on and only thing I changed since was a new non oem tensioner mid wheel. Going to whip it out and check whilst replacing the chain.

Question now is - do I split the cases to replace the chain or put in a soft link ?
 

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Erwin, not sure I completely follow the clearance check - could you elaborate for dummies?
What crank position, between the follower (rocker arm?) and top of stem?
First adjust the valve clearance to 0. Then pry open a valve and put a 1 mm feeler gauge in between the stem and the follower. Exactly where you normally measure valve lash. You now have valve stems that are in effect 1mm longer. That means that the valves are always 1mm more into the combustion chamber. Now gently turn the crank 720 degrees to see if you feel any resistance. If you feel no resistance, you are okay. If you feel any resistance, that means that the valve and the piston are less than 1 mm apart.
 

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Question now is - do I split the cases to replace the chain or put in a soft link ?
the proper way to do a 350 cam chain is to slip it over the crankshaft, yes, but I'm pretty sure some have used a stake/rivet or pressed-type master link. If you did do that, you could use the same link the DOHC 450 uses. This is the staked version master link and DID chain from two different sources

https://4into1.com/genuine-honda-d-i-d-cam-chain-master-link-219t-rivet-type-ca-cb-cl72-77-cb-cl-350k-450k-sl350k-cb500k-550-750/

https://www.ebay.com/itm/NOS-Honda-CB750F-CB750-Four-CB350-TL250-CB250-DID-Cam-Chain-219-T-94L-219TX94L-/121006786580
 

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Discussion Starter #15
Thanks for doing that Erwin completely understand your description. Going to give this a go tonight. And thanks also to the others who have helped me out here?
 

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I figure that the time taken to split the cases is time well spent. Good time to clean things up and replace seals.

If you have never riveted a chain then the time and leaning curve to do it properly ... you hope ... is greater than the time to split the cases. Some engines you of course have no other option.

Personally I find splitting the cases far easier than doing the top ends.
 

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Agree with that - bottom end jobs are pretty simple and straightforward, and the chain remains intact as well, plus you get to see just how gunked up things are
 

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Discussion Starter #19
Thanks to your advice gents I split the cases and really glad i did. First what a mess in there jeesh so much old oil and sludge. Second, it was easy as you said and third I found one mushed up cam roller pin rubber and another lying in the bottom case. So thanks for the advice again saved me some arghhhhhh. Cheers
 

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Yep - Opening up the bottom end of a motor someone else has rebuilt is like opening a box of chocolates.

you never know what's really in there.
 
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