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Valve compatibility 450sc

Starmarst

New Member
Joined
Sep 16, 2021
Total Posts
6
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0
Location
Idaho
Hello everyone

85 cb450sc

Bought this bike awhile ago and it runs and operates really well. After going through it, I’ve noticed a top end tick. Opening it up to work on valves and inspect, I found my exhaust valve has mushroomed.

Trying to source a replacement is coming up a bit short, is there any valves I should be looking for aftermarket? I’d like to do a full top end if possible, but if there are no parts then I can’t really do that.

Would machining the valve to be flat and round be an option? Or is it hardened.

any tips or Info appreciated, thank you,

77E2F50A-CDC4-4963-A2BC-524699F3E9F7.jpg
 
Yeah, that's a top 10 of all I've seen. Makes you wonder just how bad it sounded while it was still being ridden.
 
Oh man, I had a bunch of spares for this engine but recently got rid of them all. Let me check, I still might have the head and valvetrain
 
I have a cb400 head with valves and springs installed. I think the valves and springs will fit your 450.
1 rocker tower assembled.
Camshaft sprocket and bolts
 
Longdistancerider,

I’ll give them a call, is that the Honda part number for the exhaust valve? What would be the intake if needed? Also I removed the tappet and nut to get the best photo. I’ll share a photo of the tappet later, it’s identically grooved.

Ancientdad,

Honestly, for what it looked like, not terrible. The sound was noticeable, but I’ve messed with bucket lifters in Toyota’s with more concerning ticking while under good clearance.

Mr. Pepper,

Id possibly be into something like that if you had the parts laying around. I’d be curious if I could relap a valve without the hardness being affected.

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Im thinking about tearing down the top end tomorrow or possibly in about 2 weeks. From inspecting my cams/ rockers, they seem in really nice condition visually. The clearance on the problem one was a bit insane, about 1mm in wiggle room while all the others were in spec. Curious if I should be looking for a clogged oil port or something for this lifter.
 
Not sure about lapping, but I can send you one or more valves. You can always use one for lapping and run the other one. Send me a pm with your email address
 
These valves cannot be ground so replacement only and only if absolutely necessary a very light lapping. The seats should be cut following the specs in the FSM, if it's done right then lapping isn't needed.
The valve number I mentioned is the TKRJ, aftermarket, part number for the exhaust. Intakes are YH0700A.
If you're replacing one valve then replace all 6, get the seats ground properly and call it a day.
While you're at it replace all of the adjuster screws since they fail also https://www.partzilla.com/product/honda/90012-414-000?ref=15b6881ce1a254fb71495e347ef385b1f285d613
If the rocker is damaged it should be replaced with good used or new.
 
These valves cannot be ground so replacement only and only if absolutely necessary a very light lapping. The seats should be cut following the specs in the FSM, if it's done right then lapping isn't needed.
The valve number I mentioned is the TKRJ, aftermarket, part number for the exhaust. Intakes are YH0700A.
If you're replacing one valve then replace all 6, get the seats ground properly and call it a day.
While you're at it replace all of the adjuster screws since they fail also https://www.partzilla.com/product/honda/90012-414-000?ref=15b6881ce1a254fb71495e347ef385b1f285d613
If the rocker is damaged it should be replaced with good used or new.

Would you happen to know the part number for the Valve Seats?

I found a set of valves, thinking about getting some seats and valves to a head shop to cut them in the needed angles. Any recommended procedures to do while the head is off?

Gonna try and clean up my rockers and passage ways incase there was a blockage that caused this.
 
Would you happen to know the part number for the Valve Seats?

Pretty sure the valve seats are not replaceable, Jim will know best.

Did you look at the Welcome Package in my reply to your introduction? There are many tips in it for lots of helpful things for our vintage Honda twins including how to look up part numbers.
 
Would you happen to know the part number for the Valve Seats?

Valve seats were never offered as a separate part. A good quality machine shop can make them using a close version or they may cut the head to make them fit, it will be expensive. There really should be no reason to replace them unless someone absolutely butchered them previously.
 
Sorry, misguided question.

I have been using some it to find part numbers, although the aftermarket numbers helped me more than the stock ones.

FSM has it labelled as 'seat' for in and 'spring seat' so I was more confused if there is a seat I can grind on the bench. Or if I had to shave that material off the head instead. Just been getting mixed results

Thank you,
 
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