Project gold

Monstar

Member
This is my 1970 ct70 and I’m in the process of rebuilding the engine. This tool I bought to scrap the gaskets is the best tool I’ve ever used.
 

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wanrep

Active Member
Does it work better than a single edge razor blade?

The true test for any gasket scraper is a oem (green) Honda cylinder base gasket.
Takes me longer to scrape the gasket than it does to replace the top end. (almost)
 

69ST

Well-Known Member
I imagine that's a top-quality gasket scraper and will last damn near forever. That said, keep in mind that carbide is way harder than steel, let alone aluminum, so it should be used with care.
 

Monstar

Member
I'm rebuilding the head right now and when i go through and use the drill and hose routine with the valve it still doesn't seem to be seating. Do i need new valves or do i need to do something with the head?
 

kirrbby

Well-Known Member
You're lapping the valves? Are you using valve lapping compound?
Most likely your head needs to have the seats cut...proper rebuild. Money well spent too.
 

Monstar

Member
You're lapping the valves? Are you using valve lapping compound?
Most likely your head needs to have the seats cut...proper rebuild. Money well spent too.
Yes I was lapping and using lapping compound. So if I get the seats cut I take it I need new valves? I'm also not sure about the rocker arms, not sure what a new one looks like compared to mine?
 

69ST

Well-Known Member
Yes I was lapping and using lapping compound. So if I get the seats cut I take it I need new valves? I'm also not sure about the rocker arms, not sure what a new one looks like compared to mine?
It's a blessing, not a curse. Consider the age, mileage and unknown history of the machine. How hard was it run? Did it sit, one valve open, for 35 years? "Tuliped" intake valves are pretty common with these. I suspect that the intakes were made from a softer alloy, back in the day. Exhaust valve wear is surprisingly uncommon, as is heavy valve seat wear...on either side. The only way to get proper sealing, that will last for any length of time, is to cut the valve seats...to the valves. That's not possible with a worn, or pitted, valve.

Lapping is just the final step of a valve job. There's some disagreement as to whether lapping is needed, or even desirable. FWIW, I'm old-school enough to believe that lapping should be done...as per the factory shop manual(!).;)

As for rocker arms, post some good detail pix. They can wear. Usually, the worst result is more valve train clatter than there has to be.
 

Monstar

Member
It's a blessing, not a curse. Consider the age, mileage and unknown history of the machine. How hard was it run? Did it sit, one valve open, for 35 years? "Tuliped" intake valves are pretty common with these. I suspect that the intakes were made from a softer alloy, back in the day. Exhaust valve wear is surprisingly uncommon, as is heavy valve seat wear...on either side. The only way to get proper sealing, that will last for any length of time, is to cut the valve seats...to the valves. That's not possible with a worn, or pitted, valve.

Lapping is just the final step of a valve job. There's some disagreement as to whether lapping is needed, or even desirable. FWIW, I'm old-school enough to believe that lapping should be done...as per the factory shop manual(!).;)

As for rocker arms, post some good detail pix. They can wear. Usually, the worst result is more valve train clatter than there has to be.
Here’s the rockers.
 

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69ST

Well-Known Member
Doesn't look bad. Those oiling grooves were machined. If the cam looks good, you should be fine. I would want to reinstall them on the same sides where they were. And, I'd suggest replacing the adjusting studs; they've likely developed wear patterns that "match" the old valves. New valves + new rocker studs and you're more likely to get a quieter valvetrain, from the get-go; the mating surfaces can break-in to each other.(y)
 

Monstar

Member
Doesn't look bad. Those oiling grooves were machined. If the came looks good, you should be fine. I would want to reinstall them on the same sides where they were. And, I'd suggest replacing the adjusting studs; they've likely developed wear patterns that "match" the old valves. New valves + new rocker studs and you're more likely to get a quieter valvetrain, from the get-go; the mating surfaces can break-in to each other.(y)
So if I get the seats cut then all I should have to replace are the valves or can I use the old valves?
 

Gary

Well-Known Member
If you get them cut I'd replace the valves. If you don't cut the seats I'd replace the valves ;) Used to be on automotive you'd cut/grind the seats then face the valves and check their margin,you didn't want sharp edges,if they were ok you could also face the stem end. The valve adjusters on the Hondas seem to pound out that end making adjustment difficult to measure resulting in a greater clearance than wanted which leads to noise. These valves are so small that there is not much to work with and they are so readily available and affordable that it is not worth having someone recover them unless you had the means to do them yourself. Spend the money on the seats. I took a head to my Honda dealer to have cut once was not happy with their results. Bet racerx would know someone who would do a quality job :)
 
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