Topic: Cylinder studs- stock vs HD

[Dime]

Trying to get my head wrapped around what I am going.to need for the top end job on my 78.

I have read posts for and against HD studs. I also read a post using stock studs with din 6331 collar nuts 10.9 grade.

I want to do this right. This engine will be hot rodded a little. Most likely a max of 1mm over, some head work and a cam if I can swing it.

What are your guys thoughts?

Thank you

[PeWe]

HD studs needed when using MLS head gasket that need higher torque, not flexing studs.
High compression big bore need too.

Stock bores with fiber gasket, stock studs are fine.

I use stock nuts + washers with HD studs tightened 22 ft lb.

In the 80's, 836cc, stock studs, fiber gasket. Head nuts tightened 28Nm (20.6 ft lb).

My almost stock K2 61.50 mm pistons (392 K7/K8 with higher domes) got HD studs since I had no other. Stray parts build.

[scottly]

My high compression 836 with a stock type head gasket has the stock studs, and has never had a problem. The only time I've ever heard of stock studs breaking was when someone tried to remove them.

[Dime]

This is great info guys thank you.

My plans are for stockish compression. Even if I ended up with a 836 it would be Cruzinimage and would result in stock compression with my 392 head.

Stock style head gasket is planned. So stock studs it is.

[seanbarney41]

My high compression 836 with a stock type head gasket has the stock studs, and has never had a problem. The only time I've ever heard of stock studs breaking was when someone tried to remove them.

+2, except my engine was only built a couple years ago and only seen about 2000 miles

[HondaMan]

The stock studs are fine with up to 9.2:1 compression (like mine!), so long as the cylinder deck is milled back the 0.010" needed from having thicker head gaskets these days. The milling will preclude oil leaks from the main oil journals in the back (which leaks out the front, having followed the empty cam tunnel inside).

It's the high-compression, high-RPM racers who really need the HD studs, if the rest of the assembly is right. For roadracing, absolutely: for daily riding/hotrodding, not so much. I usually install the HD studs on 836cc engines I build for others as more of a security blanket than for any other reason, or if the OEM studs were somehow defective/rusted/damaged. Honda used their stock studs on the K7/8 engines, which were already 9.5:1-ish compression, with little troubles.

[scottly]

The stock studs are fine with up to 9.2:1 compression

The stock studs are fine with up to at least 11.5:1 compression, in my experience.

[grcamna2]

The stock studs are fine with up to 9.2:1 compression

The stock studs are fine with up to at least 11.5:1 compression, in my experience.

Scott,is that a Wiseco ?

[Dime]

Wow this is great. Thank you so much.

[Dime]

The stock studs are fine with up to 9.2:1 compression (like mine!), so long as the cylinder deck is milled back the 0.010" needed from having thicker head gaskets these days. The milling will preclude oil leaks from the main oil journals in the back (which leaks out the front, having followed the empty cam tunnel inside).

It's the high-compression, high-RPM racers who really need the HD studs, if the rest of the assembly is right. For roadracing, absolutely: for daily riding/hotrodding, not so much. I usually install the HD studs on 836cc engines I build for others as more of a security blanket than for any other reason, or if the OEM studs were somehow defective/rusted/damaged. Honda used their stock studs on the K7/8 engines, which were already 9.5:1-ish compression, with little troubles.

When you say 9.2:1 do you mean corrected compression or static Hondaman?

The reason I ask is because from my time as an engine builder I have found that for a street engine 9.2:1 corrected is the optimum performance on pump gas.

[willbird]

The stock studs are fine with up to 9.2:1 compression (like mine!), so long as the cylinder deck is milled back the 0.010" needed from having thicker head gaskets these days. The milling will preclude oil leaks from the main oil journals in the back (which leaks out the front, having followed the empty cam tunnel inside).

It's the high-compression, high-RPM racers who really need the HD studs, if the rest of the assembly is right. For roadracing, absolutely: for daily riding/hotrodding, not so much. I usually install the HD studs on 836cc engines I build for others as more of a security blanket than for any other reason, or if the OEM studs were somehow defective/rusted/damaged. Honda used their stock studs on the K7/8 engines, which were already 9.5:1-ish compression, with little troubles.

When you say 9.2:1 do you mean corrected compression or static Hondaman?

The reason I ask is because from my time as an engine builder I have found that for a street engine 9.2:1 corrected is the optimum performance on pump gas.

For air cooled old school engines like ours that typically do not have any knock sensors or engine management ?? Or for engines in general ??

[Dime]

The stock studs are fine with up to 9.2:1 compression (like mine!), so long as the cylinder deck is milled back the 0.010" needed from having thicker head gaskets these days. The milling will preclude oil leaks from the main oil journals in the back (which leaks out the front, having followed the empty cam tunnel inside).

It's the high-compression, high-RPM racers who really need the HD studs, if the rest of the assembly is right. For roadracing, absolutely: for daily riding/hotrodding, not so much. I usually install the HD studs on 836cc engines I build for others as more of a security blanket than for any other reason, or if the OEM studs were somehow defective/rusted/damaged. Honda used their stock studs on the K7/8 engines, which were already 9.5:1-ish compression, with little troubles.

When you say 9.2:1 do you mean corrected compression or static Hondaman?

The reason I ask is because from my time as an engine builder I have found that for a street engine 9.2:1 corrected is the optimum performance on pump gas.

For air cooled old school engines like ours that typically do not have any knock sensors or engine management ?? Or for engines in general ??

In general, air or liquid colled. Typically 9.2:1 corrected is the rule of thumb for a good street engine unless know limiting factors are present.

I am not familiar enough with these sohc cb750's to know if that is not the case.

[willbird]

The stock studs are fine with up to 9.2:1 compression (like mine!), so long as the cylinder deck is milled back the 0.010" needed from having thicker head gaskets these days. The milling will preclude oil leaks from the main oil journals in the back (which leaks out the front, having followed the empty cam tunnel inside).

It's the high-compression, high-RPM racers who really need the HD studs, if the rest of the assembly is right. For roadracing, absolutely: for daily riding/hotrodding, not so much. I usually install the HD studs on 836cc engines I build for others as more of a security blanket than for any other reason, or if the OEM studs were somehow defective/rusted/damaged. Honda used their stock studs on the K7/8 engines, which were already 9.5:1-ish compression, with little troubles.

When you say 9.2:1 do you mean corrected compression or static Hondaman?

The reason I ask is because from my time as an engine builder I have found that for a street engine 9.2:1 corrected is the optimum performance on pump gas.

For air cooled old school engines like ours that typically do not have any knock sensors or engine management ?? Or for engines in general ??

In general, air or liquid colled. Typically 9.2:1 corrected is the rule of thumb for a good street engine unless know limiting factors are present.

I am not familiar enough with these sohc cb750's to know if that is not the case.

I entertain myself quite a bit with YouTube. Lots of it is Honda K series based where they put a lot of boost on that engine family. Some of it is V8 drag and drive based stuff too. Most of those engines are not designed for peak power on pump gas but often a tune is included FOR pump gas. So higher compression is an asset with the peak performance fuel (might be E85 or Methanol)  and the engines will tolerate some lower power level on pump gas.

In the SOHC world we typically end up kind of locked into one fuel air ratio and one timing curve, there are some exceptions but they are not the norm. We have the benefit of an aluminum cylinder head, even in the car engine stuff that helps prevent the hot spots in the combustion chamber that are common with cast iron heads. I have been daydreaming and scheming about a simple fuel injection setup for the SOHC engines. I am not alone there for sure but so far there is not anything that just drops right on. There is a huge potential market for a drop on kit where the user provides their own ECU. The end of good points and condensers may be the trigger point that finally makes the market "work".

With OEM carb parts and ignition parts the SOHC bikes can run as good as the day they were made...which honestly was pretty decent really...but as that stuff dries up a comprehensive engine management system that does fuel and spark both has a lot going for it compared to some of the after market ignition only solutions avail.

Bill

[grcamna2]

The stock studs are fine with up to 9.2:1 compression (like mine!), so long as the cylinder deck is milled back the 0.010" needed from having thicker head gaskets these days. The milling will preclude oil leaks from the main oil journals in the back (which leaks out the front, having followed the empty cam tunnel inside).

It's the high-compression, high-RPM racers who really need the HD studs, if the rest of the assembly is right. For roadracing, absolutely: for daily riding/hotrodding, not so much. I usually install the HD studs on 836cc engines I build for others as more of a security blanket than for any other reason, or if the OEM studs were somehow defective/rusted/damaged. Honda used their stock studs on the K7/8 engines, which were already 9.5:1-ish compression, with little troubles.

When you say 9.2:1 do you mean corrected compression or static Hondaman?

The reason I ask is because from my time as an engine builder I have found that for a street engine 9.2:1 corrected is the optimum performance on pump gas.

For air cooled old school engines like ours that typically do not have any knock sensors or engine management ?? Or for engines in general ??

In general, air or liquid colled. Typically 9.2:1 corrected is the rule of thumb for a good street engine unless know limiting factors are present.

I am not familiar enough with these sohc cb750's to know if that is not the case.

I entertain myself quite a bit with YouTube. Lots of it is Honda K series based where they put a lot of boost on that engine family. Some of it is V8 drag and drive based stuff too. Most of those engines are not designed for peak power on pump gas but often a tune is included FOR pump gas. So higher compression is an asset with the peak performance fuel (might be E85 or Methanol)  and the engines will tolerate some lower power level on pump gas.

In the SOHC world we typically end up kind of locked into one fuel air ratio and one timing curve, there are some exceptions but they are not the norm. We have the benefit of an aluminum cylinder head, even in the car engine stuff that helps prevent the hot spots in the combustion chamber that are common with cast iron heads. I have been daydreaming and scheming about a simple fuel injection setup for the SOHC engines. I am not alone there for sure but so far there is not anything that just drops right on. There is a huge potential market for a drop on kit where the user provides their own ECU. The end of good points and condensers may be the trigger point that finally makes the market "work".

With OEM carb parts and ignition parts the SOHC bikes can run as good as the day they were made...which honestly was pretty decent really...but as that stuff dries up a comprehensive engine management system that does fuel and spark both has a lot going for it compared to some of the after market ignition only solutions avail.

Bill

I can see that as a big improvement;possibly adapt a system which is already in use from another bike?  I'm just thinking.. simple is good.

[willbird]

The stock studs are fine with up to 9.2:1 compression (like mine!), so long as the cylinder deck is milled back the 0.010" needed from having thicker head gaskets these days. The milling will preclude oil leaks from the main oil journals in the back (which leaks out the front, having followed the empty cam tunnel inside).

It's the high-compression, high-RPM racers who really need the HD studs, if the rest of the assembly is right. For roadracing, absolutely: for daily riding/hotrodding, not so much. I usually install the HD studs on 836cc engines I build for others as more of a security blanket than for any other reason, or if the OEM studs were somehow defective/rusted/damaged. Honda used their stock studs on the K7/8 engines, which were already 9.5:1-ish compression, with little troubles.

When you say 9.2:1 do you mean corrected compression or static Hondaman?

The reason I ask is because from my time as an engine builder I have found that for a street engine 9.2:1 corrected is the optimum performance on pump gas.

For air cooled old school engines like ours that typically do not have any knock sensors or engine management ?? Or for engines in general ??

In general, air or liquid colled. Typically 9.2:1 corrected is the rule of thumb for a good street engine unless know limiting factors are present.

I am not familiar enough with these sohc cb750's to know if that is not the case.

I entertain myself quite a bit with YouTube. Lots of it is Honda K series based where they put a lot of boost on that engine family. Some of it is V8 drag and drive based stuff too. Most of those engines are not designed for peak power on pump gas but often a tune is included FOR pump gas. So higher compression is an asset with the peak performance fuel (might be E85 or Methanol)  and the engines will tolerate some lower power level on pump gas.

In the SOHC world we typically end up kind of locked into one fuel air ratio and one timing curve, there are some exceptions but they are not the norm. We have the benefit of an aluminum cylinder head, even in the car engine stuff that helps prevent the hot spots in the combustion chamber that are common with cast iron heads. I have been daydreaming and scheming about a simple fuel injection setup for the SOHC engines. I am not alone there for sure but so far there is not anything that just drops right on. There is a huge potential market for a drop on kit where the user provides their own ECU. The end of good points and condensers may be the trigger point that finally makes the market "work".

With OEM carb parts and ignition parts the SOHC bikes can run as good as the day they were made...which honestly was pretty decent really...but as that stuff dries up a comprehensive engine management system that does fuel and spark both has a lot going for it compared to some of the after market ignition only solutions avail.

Bill

I can see that as a big improvement;possibly adapt a system which is already in use from another bike?  I'm just thinking.. simple is good.

Kinda veering off topic here but, a few have but one thing about all the newer bike stuff is that the throttle body bore are about 50% bigger diameter than the SOHC, and the existing rubber intake system that mounts the carbs to the head is ANOTHER thing reliant upon NOS parts that are at best 20 years or more old and getting expensive. The newer bikes make twice the HP and need twice the air to do that ;-). A CBR600 throttle body for example is readily avail but HUGE dimeter wise.

Bill

[grcamna2]

The stock studs are fine with up to 9.2:1 compression (like mine!), so long as the cylinder deck is milled back the 0.010" needed from having thicker head gaskets these days. The milling will preclude oil leaks from the main oil journals in the back (which leaks out the front, having followed the empty cam tunnel inside).

It's the high-compression, high-RPM racers who really need the HD studs, if the rest of the assembly is right. For roadracing, absolutely: for daily riding/hotrodding, not so much. I usually install the HD studs on 836cc engines I build for others as more of a security blanket than for any other reason, or if the OEM studs were somehow defective/rusted/damaged. Honda used their stock studs on the K7/8 engines, which were already 9.5:1-ish compression, with little troubles.

When you say 9.2:1 do you mean corrected compression or static Hondaman?

The reason I ask is because from my time as an engine builder I have found that for a street engine 9.2:1 corrected is the optimum performance on pump gas.

For air cooled old school engines like ours that typically do not have any knock sensors or engine management ?? Or for engines in general ??

In general, air or liquid colled. Typically 9.2:1 corrected is the rule of thumb for a good street engine unless know limiting factors are present.

I am not familiar enough with these sohc cb750's to know if that is not the case.

I entertain myself quite a bit with YouTube. Lots of it is Honda K series based where they put a lot of boost on that engine family. Some of it is V8 drag and drive based stuff too. Most of those engines are not designed for peak power on pump gas but often a tune is included FOR pump gas. So higher compression is an asset with the peak performance fuel (might be E85 or Methanol)  and the engines will tolerate some lower power level on pump gas.

In the SOHC world we typically end up kind of locked into one fuel air ratio and one timing curve, there are some exceptions but they are not the norm. We have the benefit of an aluminum cylinder head, even in the car engine stuff that helps prevent the hot spots in the combustion chamber that are common with cast iron heads. I have been daydreaming and scheming about a simple fuel injection setup for the SOHC engines. I am not alone there for sure but so far there is not anything that just drops right on. There is a huge potential market for a drop on kit where the user provides their own ECU. The end of good points and condensers may be the trigger point that finally makes the market "work".

With OEM carb parts and ignition parts the SOHC bikes can run as good as the day they were made...which honestly was pretty decent really...but as that stuff dries up a comprehensive engine management system that does fuel and spark both has a lot going for it compared to some of the after market ignition only solutions avail.

Bill

I can see that as a big improvement;possibly adapt a system which is already in use from another bike?  I'm just thinking.. simple is good.

Kinda veering off topic here but, a few have but one thing about all the newer bike stuff is that the throttle body bore are about 50% bigger diameter than the SOHC, and the existing rubber intake system that mounts the carbs to the head is ANOTHER thing reliant upon NOS parts that are at best 20 years or more old and getting expensive. The newer bikes make twice the HP and need twice the air to do that ;-). A CBR600 throttle body for example is readily avail but HUGE dimeter wise.

Bill

I see