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Discussion Starter #1
Hello,

So I just got new tires put on my nighthawk and put it back together finally, took it for a short ride last night and she feels and runs great. But ever since I did the manual cam chain adjustment, I'm scared if I rev it too hard that the cam chain is either going to snap or jump teeth. I'm confident I adjusted it properly, there was no looseness on the front of the chain, and I could only lift it like 1 mm off the back side, which from what I gather is normal since the tension is on the front side.

I dunno, its a weird psych thing that I'm scared if I get on the throttle too much I'll hear the horrifying sound of the cam chain going and my pistons slamming my valves into the head. I guess I could just use some thoughts/reassurance on the matter.
 

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Sensei
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If you adjusted the cam-chain correctly, the engine should have no complaints with higher revs......
80% of redline is about where the top of the power peak is......6500 to 8500 RPM is the engines "happy place".....

Now, IF you have fresh cylinder hone and new rings, most recommend a max of about 65% of redline until its broken in......
 

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Discussion Starter #4
Just going to have to grit my teeth and go for it I guess.:twisted:

I'm just happy its all put back together, I haven't got to ride for 3 weeks on account of my tires splitting along the sidewall and tuition draining my bank account. Hoping it doesn't snow until late December so I can ride for another month or two.

I did notice the engine makes a "tappy" sound now, but I think thats normal when the valves are properly adjusted. When I adjusted the valves the intake ones were so tight I could barely fit a .001 feeler through the gap, and they're supposed to be .004.
 

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I would be more concerned with old, tired valve springs than the cam chain when revving a 35 year old bike up in the higher ranges.
 

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As my grandfather used to say..If it ain't broke, you just ain't trying hard enough son.. :p

Better perhaps go and try it flat out somewhere close to home first, see what. happens. If it survives that and doesn't make funny noises afterwards, you'll be grand.
 

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The cam chain would have to be extremely loose for any possibility of it jumping timing. As for breaking? given the design of the chain I'll say close to impossible.
 

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Discussion Starter #9
Thats reassuring then. Really I wouldn't expect it to be close to breaking, the chains on cars usually last longer than the rest of the car.
 

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As my grandfather used to say..If it ain't broke, you just ain't trying hard enough son.. :p

Better perhaps go and try it flat out somewhere close to home first, see what. happens. If it survives that and doesn't make funny noises afterwards, you'll be grand.
Or Mario Andretti: "if everything is under control you are not going fast enough."
 

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The 400 series engine uses something similar to a car-style cam chain (what used to be referred to as a Fairbanks-Morse Hyvo chain) and has many more plates in contact with the "teeth" on the cam sprocket as well as the extra durability that comes with the larger number of plates secured by the link pins that go through all of them, spreading the load. They rarely break, as mentioned, with respect to their long-standing durability in car engines (which, in the case of the older V-8s, had no tensioner). Our older vintage twins are still using roller chains and they are pretty durable as well, given the proper regular maintenance including correct tensioning. These engines love to rev as mentioned earlier, so if the chain is correctly adjusted - as boldly pointed out by Steve - you have nothing to be concerned about and everything to gain in terms of getting the max performance out of the engine.

More about Hyvo chains: https://www.cycleworld.com/driving-camshafts-roller-chain-silent-chain-morse-hy-vo-chain/
 

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Discussion Starter #12
Just went out for a ride around town and took the Nighthawk on some less populated roads and let er rip, and it seems my fears were indeed unfounded, as she happily reved to 8K and hauled some serious ass without any complaint. :D Still blows me away how much pull a "little" 450 has, but I think that might be because so much of what you see on YT and forums is people with 600+ CC supersports, and a lot of people seem to have this notion that anything under 600 CC is "slow". Once the engine warms up its idling nice and smooth, and no dead spots in the rev range, power comes on quickly. Only difference in the sound of the engines is I can hear the "ticking" noise of the valves a little more, but as I mentioned before thats probably because they're in spec now where as before I adjusted them they were quite tight.

I took my GoPro out for my ride but there was a big smudge on my lens so the footage isn't very good. Might post a few clips though of revving it up as it sounds so delightful. A lot of people love the sound of V-Twins but for me the sound of a revving parallel twin is glorious.
 

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Still blows me away how much pull a "little" 450 has, but I think that might be because so much of what you see on YT and forums is people with 600+ CC supersports, and a lot of people seem to have this notion that anything under 600 CC is "slow".... ...Might post a few clips though of revving it up as it sounds so delightful. A lot of people love the sound of V-Twins but for me the sound of a revving parallel twin is glorious.
Not too bad for a vintage ride, huh? And to think you were going to pollute a waterway with it.

Here's another twin that sounds just as glorious - and look at what beat it in the eighth mile with a better holeshot (the other rider is an expert at power-slipping off the line) and 650cc of modern technology

20190313_174245.jpg

 

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Sensei
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AND....You are NOT even using all the "pull" of your bike........You let the revs drop below 6K several times.....
Unless slowing for a stop, keep the transmission in whatever gear keeps the revs between 6K and 8.5/9K regardless of actual speed......
(Yes, this means you will still be in second gear at any speed between 23 and 42 MPH...., Third up to 55/57.....)
Otherwise, you will only be producing and using about 1/3 to 1/2 of your engine's possible output.....(In essence, riding without using 1/2 your motor's power)....
 

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Discussion Starter #19
Looked like the tach needs a bit of lubing so it can get up to redline without all that weird jumping. Unless that had something to do with the speedo that suddenly went black :eek:
Yeah I noticed that with the tach. I'll lube up the cable see if that helps. And I don't know what you mean about the speedo going black, all I saw was a motorcycle definitely obeying the speed limit ;):twisted:
 

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I agree I think the sun must have just been reflecting at a weird angle.

There's a youtube video by an old guy from florida called "saving old motorcycle speedometers", it worked for my speedo which gets a bit bouncy/whiny at 100km/h
 
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