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This all very helpful as I restore my Brit 1969 K1/2 450 engine which is in pieces, with the casings heading of to be 'blasted' into new condition. Fortunately, all of the upper running gear is in excellent condition, but the exhaust valves a little worn, possibly now sourced, New Timing chain and top roller now sourced.

Your photos are of excellent quality and we will refer to them, along with the Honda workshop manual as we put her back together over the next 2 /3 weeks Many thanks for your time and effort and good luck with your project.

Nige.UK.
 

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Thanks very much for taking the time an trouble to complete this great write-up to share with others. Perhaps this forum could do with a few more of these ? Just a suggestion. Thanks again. Good Kharma is surely coming your way ;)

ratKat
 

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Hi,

Instead of shimming your cam with these very thin shims (which are vulnerable and sometimes end up as grinded up sheet metal), I use the thickness of the gaskets self to "shim" the cams. I have different sizes (thickness) of sheet gasket material, this way I can manipulate the clearance.

When you have a few of the standard pré-cut Honda or aftermarket gaskets you can also measure the thikness, they differ, a little puzzling and voilà, no shims needed, saves a few bucks too.

Jensen

btw, In general, give the gaskets time to get set to the torque of the bolts, no matter what method you use. Measure directly after tightening the bolts, and after one or two days again. If the gap is exactly according spec directly after tightening the next day the gap can be too small ! (I have seen that a few times, especially with cheap aftermarket pré-cut gaskets).
 

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Hi guys

Do you torque the cam "bearing" holders at a specific kN ?
My intake cam is jammed when I torque up the 6 mm. allen bolts by "hand" - maybe to thin gaskets (aftermarket) ?
 

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Hi,

Do you have the shims inside ? If you have no shims, and your intake cam is jamming, you need a thicker gasket (one side or both sides).
Yes, I torque them down, M6 standard torque. Using a torque wrench with allen bolts is simple, and much easier than the Philips screws.

Jensen
 

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Hi,

Do you have the shims inside ? If you have no shims, and your intake cam is jamming, you need a thicker gasket (one side or both sides).
Yes, I torque them down, M6 standard torque. Using a torque wrench with allen bolts is simple, and much easier than the Philips screws.

Jensen
I have no shims on the intake, but one on the exhaust cam...
Will try with the thicker gaskets - btw do you know what standard thickness for the gaskets are? ( really crazy question, I know:))
 

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Hi,

No not a strange or crazy question. The OEM gaskets are around 0,5 mm, from 0,35 to 0,65. Most after markets gaskets are slightly thinner, around 0,25 to 0,50 mm.
The problem with most after market gaskets is that the thickness isn't stable and get's thinner after a few heat cycles. I always measure the cam side play twice once after torquing down the screws, and once after a few heat cycles.

Jensen
 

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I had mine open the other day to check the valve clearance and thought I better measure the clearance as I have used aftermarket gaskets. I was very glad when i found that the clearance on both cams was within spec. Fairly close to the lower end of the specs and without any shims. At least I know that the gaskets have now settled (1000 km) - so I dodged the bullet this time.
 

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Has anyone advice on the best after market gasket manufacturers? I have found some pretty poor quality gasket sets in the past although I cannot remember the manufacturer. I should have kept the manufacturers name and made sure I did not try to buy them a second time.
 

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Excellent post, I will be doing exactly the same job in the next few days.
I have 2 cb450's I'm rebuilding, the machine shop will have one head and cylinders done this week.
Thanks
 

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Great article...have a question though:
The bolt that holds the valve seal down...is it necessary to use thread locker on it?
I've put mine back together, and since then been told to use Locktite or similar. Is this simply a good idea or a must do?
 

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Great article...have a question though:
The bolt that holds the valve seal down...is it necessary to use thread locker on it?
I've put mine back together, and since then been told to use Locktite or similar. Is this simply a good idea or a must do?
I asked the same question in another thread and never got a reply. I plan to take mine back out and use loctite..i figure it won't hurt and if nothing else it will give me peace of mind.
 

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Hey thanks Gritsak,
Yeah it seems no one wants to stick their neck out on this.:D
I think I'll pull it apart again and Locktite 'em. haven't linked the chain yet so I guess it'll be worthwhile to do....I'd hate to see that bolt jumping around in there!
 

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Hi sorrry but i am having a hard time under standing the cam shaft. as of right now i have both the exhaust and the intake cam shafts in. my question is do i have to get both of them aligned with the timing marks. before i put the chain on?
 

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I'd say that's the idea...mind you, when i did mine there was no mark on the Exhaust cam and it turned out it wasn't right!
However you can still move the chain around them, but you need to pop off the cam end housings and slip the rockers to one side of the valve. This gives enough clearance to manipulate the chain around to cam sprocket.
 

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thanx Zeek for the reply. to answer your question, I went a head and loctite the valve seal bolt. Like you said it would bad to have that bolt bounce around in there.
 
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