Topic: Upside down valve guides?

[bomorr]

So I picked up this 72' motor a few years ago and since we all have so much time on our hands lately I decided to dig into it to see what I needed to replace. When I got to taking the valve springs off I got a surprise that looks like someone at some point has done a top end rebuild on this and flipped all the exhaust valve guides upside down and no there were no seals over the guides ok the exhaust side. First time I have seen this and I wanted to make sure that this wasn't something that was normal. Guides aren't too worn so I don't want to pull them if it's not going to change the overall performance since I am just doing a quicker resto-mod with mostly original parts.

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[754]

The first few years did not have seals.

[bomorr]

The first few years did not have seals.

Interesting, so on this head the intake side has them but not the exhaust.

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[bryanj]

Correct, what do the oil restrictor jets look like?

[bomorr]

Correct, what do the oil restrictor jets look like?

Haven't attempted to get them out since they won't come out with a magnet tool. I may just use a wire to clean them out and leave them as is

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[MRieck]

 I would replace those exhaust guides with guides that take oil seals. I'd also recommend using iron guides. You'll need a valve job after replacement. The oil control jet is pressed in though the occasionally can be removed......just leave them in.

[bomorr]

Yea I'm probably going to send the head over to cyclex for the whole head job.

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[scottly]

Guides aren't too worn so I don't want to pull them if it's not going to change the overall performance since I am just doing a quicker resto-mod with mostly original parts.

Just run them as is. The knife edge on the end of the guides acts as a scraper to remove some of the oil from the valve stem, in lieu of a seal. My K1 motor doesn't have seals on the exhaust side either, and sometimes it puffs some oil smoke out of the exhaust, but it's been that way for 40 years now.    

[bryanj]

Those look like the "pepper pot" restrictors so definately early head. Yamiya list the expensive restrictors

[PeWe]

No problem to take out those oil restrictors (orifices).
I had to do that, a friend told me how to which I did. Easy!
Find my post with photos.

 I sanded my restrictors when out just a little with 400 grit paper to let them go in easier next time.

http://forums.sohc4.net/index.php?topic=175940.msg2051709.msg#2051709

I also had an early head with ex guides without seals. Smoked.
Replaced them.
Maybe the valves are bad too. Mike (MRieck) has the parts, tools and skills to do it right.

[Kevnz]

Hi Team,
I'm not sure about SOHC4 motors specifically, but in general, engines don't need oil seals on the exhaust side as there is no suction on that side of the motor, only the inlet side as the fuel \air mixture is drawn in by the induction stroke.  I've never seen oil seals on the few sohc 4 motors I've had apart.
Cheers,
Kevin

[PeWe]

Oil will splash, follow the stem and smoke. No one liked to ride behind my bike in 120-160kmh.
I thought it should smoke just a little when starting it.

I did not realize how much until I tested. The recommendation on this forum was to replace the guides.
I replaced the entire head to a later K6 with new ex guides and valves. All In were good. My K2-75 needed a later head anyway.

No more smoke when riding.

That old K1 head will get new guides and all valves.

[bryanj]

Try explaining why the F2 can drop to 150 miles per pint with clouds of blue smoke when the guides wear and seals go

[HondaMan]

So I picked up this 72' motor a few years ago and since we all have so much time on our hands lately I decided to dig into it to see what I needed to replace. When I got to taking the valve springs off I got a surprise that looks like someone at some point has done a top end rebuild on this and flipped all the exhaust valve guides upside down and no there were no seals over the guides ok the exhaust side. First time I have seen this and I wanted to make sure that this wasn't something that was normal. Guides aren't too worn so I don't want to pull them if it's not going to change the overall performance since I am just doing a quicker resto-mod with mostly original parts.

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Those are the BEST valve guides Honda ever used in these engines. They are made from Stellite, hard as diamonds, and are found in K0/K1 "old factory" heads only. They do not have seals (nor do they need them) and if they still have good clearance (less than 0.0032" valve 'wiggle' when the valve is lifted 3mm off the valve seat, measured at the edge of the valve) I recommend using those guides. They went 138,000 miles on my K2 and were barely worn out at that point.

[Henning]

This has been up a few times so let me add my two cents. The early bikes without exhaust valve seals "can" smoke but not necessary "will" smoke. My K1 with 55K miles doesn't smoke at all, and neither did the K1 I owned back in the day. That said, if you're replacing the guides, seals are the way to go.

[seanbarney41]

Try explaining why the F2 can drop to 150 miles per pint with clouds of blue smoke when the guides wear and seals go

because the intake guides are just as worn out as the exhaust, seals and all.  The guides wear out due to bad valve train geometry inherent with the f2's bigger intakes.

[bomorr]

So I picked up this 72' motor a few years ago and since we all have so much time on our hands lately I decided to dig into it to see what I needed to replace. When I got to taking the valve springs off I got a surprise that looks like someone at some point has done a top end rebuild on this and flipped all the exhaust valve guides upside down and no there were no seals over the guides ok the exhaust side. First time I have seen this and I wanted to make sure that this wasn't something that was normal. Guides aren't too worn so I don't want to pull them if it's not going to change the overall performance since I am just doing a quicker resto-mod with mostly original parts.

Sent from my Pixel 4 XL using Tapatalk

Those are the BEST valve guides Honda ever used in these engines. They are made from Stellite, hard as diamonds, and are found in K0/K1 "old factory" heads only. They do not have seals (nor do they need them) and if they still have good clearance (less than 0.0032" valve 'wiggle' when the valve is lifted 3mm off the valve seat, measured at the edge of the valve) I recommend using those guides. They went 138,000 miles on my K2 and were barely worn out at that point.

Yea, I'll be checking the tolerances this weekend. I figure if they check out I'll just replace the seals on the intake side and call it a day. All the springs, pistons and cylinders check out I just have to measure the cam and valves next.

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[bryanj]

Nope, i stripped and rebuilt that motor, inlets were perfect only think worn was exhaust guides. New guides and seals with all gaskets and back to being like new

[HondaMan]

So I picked up this 72' motor a few years ago and since we all have so much time on our hands lately I decided to dig into it to see what I needed to replace. When I got to taking the valve springs off I got a surprise that looks like someone at some point has done a top end rebuild on this and flipped all the exhaust valve guides upside down and no there were no seals over the guides ok the exhaust side. First time I have seen this and I wanted to make sure that this wasn't something that was normal. Guides aren't too worn so I don't want to pull them if it's not going to change the overall performance since I am just doing a quicker resto-mod with mostly original parts.

Sent from my Pixel 4 XL using Tapatalk

Those are the BEST valve guides Honda ever used in these engines. They are made from Stellite, hard as diamonds, and are found in K0/K1 "old factory" heads only. They do not have seals (nor do they need them) and if they still have good clearance (less than 0.0032" valve 'wiggle' when the valve is lifted 3mm off the valve seat, measured at the edge of the valve) I recommend using those guides. They went 138,000 miles on my K2 and were barely worn out at that point.

Yea, I'll be checking the tolerances this weekend. I figure if they check out I'll just replace the seals on the intake side and call it a day. All the springs, pistons and cylinders check out I just have to measure the cam and valves next.

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If the intake guides have not been changed, then they will also be Stellite.

It took me 4 years to locate a new set of those prior to my 2013 rebuild, and when I took it to the machine shop my 'regular' guy was on vacation. The 'stand in' machinist there did not know me, and he reamed the guides to [his] specs after I told them  0.2600" hole size, no more than 0.0012" intake clearance. He ruined them, making them like a car's head (0.0025" clearance, 0.2625" hole size). I can't say on the Internet the words that come to mind, even now....so I had to go to bronze guides instead (and re-replace them all). While bronze guides are a close second in performance, the Stellite guides of the early engines were unsurpassed for friction reduction and longevity. Honda changed them to cast iron after the mid-year (3/1972 production) K2.

[bomorr]

So I picked up this 72' motor a few years ago and since we all have so much time on our hands lately I decided to dig into it to see what I needed to replace. When I got to taking the valve springs off I got a surprise that looks like someone at some point has done a top end rebuild on this and flipped all the exhaust valve guides upside down and no there were no seals over the guides ok the exhaust side. First time I have seen this and I wanted to make sure that this wasn't something that was normal. Guides aren't too worn so I don't want to pull them if it's not going to change the overall performance since I am just doing a quicker resto-mod with mostly original parts.

Sent from my Pixel 4 XL using Tapatalk

Those are the BEST valve guides Honda ever used in these engines. They are made from Stellite, hard as diamonds, and are found in K0/K1 "old factory" heads only. They do not have seals (nor do they need them) and if they still have good clearance (less than 0.0032" valve 'wiggle' when the valve is lifted 3mm off the valve seat, measured at the edge of the valve) I recommend using those guides. They went 138,000 miles on my K2 and were barely worn out at that point.

Yea, I'll be checking the tolerances this weekend. I figure if they check out I'll just replace the seals on the intake side and call it a day. All the springs, pistons and cylinders check out I just have to measure the cam and valves next.

Sent from my Pixel 4 XL using Tapatalk

If the intake guides have not been changed, then they will also be Stellite.

It took me 4 years to locate a new set of those prior to my 2013 rebuild, and when I took it to the machine shop my 'regular' guy was on vacation. The 'stand in' machinist there did not know me, and he reamed the guides to [his] specs after I told them  0.2600" hole size, no more than 0.0012" intake clearance. He ruined them, making them like a car's head (0.0025" clearance, 0.2625" hole size). I can't say on the Internet the words that come to mind, even now....so I had to go to bronze guides instead (and re-replace them all). While bronze guides are a close second in performance, the Stellite guides of the early engines were unsurpassed for friction reduction and longevity. Honda changed them to cast iron after the mid-year (3/1972 production) K2.

Ouch, that hurts to read

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[PeWe]

I have new Honda stock steel guides for seals to be used in my smoking  K1 head with no oil seals on ex
That type has holded up well in my K6 head.

[HondaMan]

I ordered a new set of Honda's current version of these guides a few years back, and they are a low-density, somewhat porous iron material. It isn't as durable as the older cast irons, from what I can tell, but maybe the porous nature will help it lube better? Dunno, haven't installed them to find out. I've switched to bronze instead.

[PeWe]

I ordered a new set of Honda's current version of these guides a few years back, and they are a low-density, somewhat porous iron material. It isn't as durable as the older cast irons, from what I can tell, but maybe the porous nature will help it lube better? Dunno, haven't installed them to find out. I've switched to bronze instead.

Have Honda changed the material for the K2- K6 guides since the mid 80's?

[bomorr]

@HondaMan can I get the same outcome of measuring wiggle if I measure the bore of the guides and the stem size and subtracting the two? Currently waiting on shipping for a proper dial gauge to get into the head to measure wiggle.

Here is what I measured:

Bore size on EX: 0.2600
Bore size on INT: 0.2602
Stem size on EX valve: 0.2580
Stem size on INT valve: 0.2590

Taking those along with the 0.0032 wiggle spec. I should be OK right?

I obviously will be doing the wiggle test when I get in the dial gauge but I couldn't wait another few days to keep digging into the head.

Couldn't find an official spec on the stem size of the valves

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[HondaMan]

I ordered a new set of Honda's current version of these guides a few years back, and they are a low-density, somewhat porous iron material. It isn't as durable as the older cast irons, from what I can tell, but maybe the porous nature will help it lube better? Dunno, haven't installed them to find out. I've switched to bronze instead.

Have Honda changed the material for the K2- K6 guides since the mid 80's?

Yep. Somewhere around 1998-2002, from what I can tell.