Author Topic: Cycle x is coming out with copy of SS-1. The SX-1  (Read 499 times)

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Offline Dime

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Cycle x is coming out with copy of SS-1. The SX-1
« on: December 17, 2024, 01:17:17 PM »
Was emailing back and forth with Cycle x and apparently they are doing a copy of the SS-1 cam.

Pretty exciting news. They said price will be $399 USD.

I am definitely adding this to the list for my build.

They said it should be available soon as it is in production.

Offline PeWe

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Re: Cycle x is coming out with copy of SS-1. The SX-1
« Reply #1 on: December 18, 2024, 07:23:11 AM »
My K6 had an SS-1 cam with 836cc, ported head 34mm in valves.
Worked fine with stock carbs with pods.
Later Mikuni TMR32 carbs. +80WHP on dyno. Before a few hp less I guess,  but not much.

Really good cam. I made long tours, high speed on Autobahn Germany and south. 150-180kmh all day.
It has a mild lobe shape saving the top end.

Mine from Action Fours.
I doubt it can be used in a stock engine. Deeper valve pockets in pistons.

At last install:
Total lift IN/EX: 9,17 mm (.361")/9,17 mm (.361")

Open/close @ 1mm (0.04")lift,  0 lash:
IN:22/55   Dur:257   LC:106,5
EX:56/24   Dur:260  LC:106
Overlap. 46°

SS-1 cam description :
http://www.satanicmechanic.org/a4scam.shtml
« Last Edit: December 18, 2024, 07:37:09 AM by PeWe »
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline Dime

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Re: Cycle x is coming out with copy of SS-1. The SX-1
« Reply #2 on: December 18, 2024, 08:35:32 AM »
My K6 had an SS-1 cam with 836cc, ported head 34mm in valves.
Worked fine with stock carbs with pods.
Later Mikuni TMR32 carbs. +80WHP on dyno. Before a few hp less I guess,  but not much.

Really good cam. I made long tours, high speed on Autobahn Germany and south. 150-180kmh all day.
It has a mild lobe shape saving the top end.

Mine from Action Fours.
I doubt it can be used in a stock engine. Deeper valve pockets in pistons.

At last install:
Total lift IN/EX: 9,17 mm (.361")/9,17 mm (.361")

Open/close @ 1mm (0.04")lift,  0 lash:
IN:22/55   Dur:257   LC:106,5
EX:56/24   Dur:260  LC:106
Overlap. 46°

SS-1 cam description :
http://www.satanicmechanic.org/a4scam.shtml

It was one of your posts that got me interested in this cam. I was hoping to use the cruzinimage big bore kit though. Maybe not

Offline Dime

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Re: Cycle x is coming out with copy of SS-1. The SX-1
« Reply #3 on: December 18, 2024, 08:46:08 AM »

Offline PeWe

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Re: Cycle x is coming out with copy of SS-1. The SX-1
« Reply #4 on: December 18, 2024, 10:03:36 AM »
You can most likely make the valve pockets a little deeper

I guess that 1 mm more will help. 1.5mm with same shape as valve cover up for the lift difference, stock vs SS-1. 0.315 vs 0.360"

See this thread, post #15 where the pockets were cut rather much. Not tested yet.
http://forums.sohc4.net/index.php?topic=171550.0

The thickness of domes have a minimum. If still 4 mm thick it must be OK.
Maybe a person done this will chime in.
« Last Edit: December 18, 2024, 11:32:44 AM by PeWe »
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline johno

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Re: Cycle x is coming out with copy of SS-1. The SX-1
« Reply #5 on: December 18, 2024, 10:13:23 PM »
Nothing wrong with those cruzin image pistolies. The units I have measured have plenty of meat for notching, OK for bigger cams than your planning, ie 315 etc  The thinnest point I measured was 6.5mm and that was a spot where the valve notch didn't even reach,  it just got way thicker the closer to the edge. 👍
GRASSHOPPER SOHC HONDAS ARE THE MEANING OF LIFE.

Offline johno

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Re: Cycle x is coming out with copy of SS-1. The SX-1
« Reply #6 on: December 18, 2024, 10:53:03 PM »
In fact, now I remember that RC315  build well. I was chasing compression without using dome pistons as I have this thing about domes getting in the way and ign. advance etc. It was the first time I had used CI pistons and I used 1.5 mm longer 900 rods to pop em up and machined the corner of top edge of piston to suit, got the compression I wanted and using the 315 with about .365" thou lift notched the pistons with room to spare. The reason I remember it well was it was the first time I had used the 315 cam and when I bolted on the finished head / guides/valves etc done the checks WALLA standard guides don't do .365" lift and I was peeved off for not checking before I finished the head.  Lesson learnt
Re the raised flat top piston trick its the same way Kenny X got the comp on his road race 900 and makes a massive difference to lots of things.
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Offline PeWe

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Re: Cycle x is coming out with copy of SS-1. The SX-1
« Reply #7 on: December 19, 2024, 12:13:00 AM »
Good info about CI 65mm pistons and CB900 DOHC rods. I have a set of those longer rods ;)
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline Dime

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Re: Cycle x is coming out with copy of SS-1. The SX-1
« Reply #8 on: December 19, 2024, 04:24:44 AM »
In fact, now I remember that RC315  build well. I was chasing compression without using dome pistons as I have this thing about domes getting in the way and ign. advance, etc. It was the first time I had used CI pistons and I used 1.5 mm longer 900 rods to pop em up and machined the corner of top edge of piston to suit, got the compression I wanted and using the 315 with about .365" thou lift notched the pistons with room to spare. The reason I remember it well was it was the first time I had used the 315 cam and when I bolted on the finished head / guides/valves etc done the checks WALLA standard guides don't do .365" lift, and I was peeved off for not checking before I finished the head.  Lesson learnt
Re the raised flat top piston trick, it's the same way Kenny X got the comp on his road race 900 and makes a massive difference to lots of things.

That peaks my interest. My brother, I bought my cb750k sohc off of is the same guy that bought my cb750c dohc off me. I also.sold him.all the parts I had collected to build two more engines. In the parts was a set of cb900 con rods that were shot peened and had cb1100f con bolts. I believe I also sold him a set of rare MTC con rods in the cb750 dohc length. Might see about buying them back for a future build when I spilt the cases.

Offline newday777

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Re: Cycle x is coming out with copy of SS-1. The SX-1
« Reply #9 on: December 19, 2024, 05:20:35 AM »
In fact, now I remember that RC315  build well. I was chasing compression without using dome pistons as I have this thing about domes getting in the way and ign. advance, etc. It was the first time I had used CI pistons and I used 1.5 mm longer 900 rods to pop em up and machined the corner of top edge of piston to suit, got the compression I wanted and using the 315 with about .365" thou lift notched the pistons with room to spare. The reason I remember it well was it was the first time I had used the 315 cam and when I bolted on the finished head / guides/valves etc done the checks WALLA standard guides don't do .365" lift, and I was peeved off for not checking before I finished the head.  Lesson learnt
Re the raised flat top piston trick, it's the same way Kenny X got the comp on his road race 900 and makes a massive difference to lots of things.

That peaks my interest. My brother, I bought my cb750k sohc off of is the same guy that bought my cb750c dohc off me. I also.sold him.all the parts I had collected to build two more engines. In the parts was a set of cb900 con rods that were shot peened and had cb1100f con bolts. I believe I also sold him a set of rare MTC con rods in the cb750 dohc length. Might see about buying them back for a future build when I spilt the cases.
Remember though, the CB750DOHC have 1.5mm shorter rods than the CB750SOHC have. It is the CB900 that are 1.5mm longer than the SOHC rods.
« Last Edit: December 19, 2024, 05:24:07 AM by newday777 »
Stu
Honda Parts manager in the mid 1970s Nashua Honda
My current rides
1975 K5 Planet Blue my summer ride, it was a friend's bike I worked with at the Honda shop in 76, lots of fun to be on it again
1976 K6 Anteres Red rebuilding project, was originally my brother's that I set up from the crate, it'll breath again soon!
Project 750s, 2 K4, 2 K6, 1 K8
2008 GL1800 my daily ride and cross country runner

Prior bikes....
1972 Suzuki GT380 I had charge of it for a year in 1973 while my friend was deployed and learned to love street riding....
New CB450 K7 after my friend returned...
New CB750 K5 Planet Blue, demise by ex cousin in law at 9,000 miles...
New CB750 K6 Anteres Red, to replace the totaled K5, I sold this K6 at 45k in 1983, I had heavily modified it, many great memories on it and have missed it greatly.....
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Offline Dime

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Re: Cycle x is coming out with copy of SS-1. The SX-1
« Reply #10 on: December 19, 2024, 05:38:51 AM »
In fact, now I remember that RC315  build well. I was chasing compression without using dome pistons as I have this thing about domes getting in the way and ign. advance, etc. It was the first time I had used CI pistons and I used 1.5 mm longer 900 rods to pop em up and machined the corner of top edge of piston to suit, got the compression I wanted and using the 315 with about .365" thou lift notched the pistons with room to spare. The reason I remember it well was it was the first time I had used the 315 cam and when I bolted on the finished head / guides/valves etc done the checks WALLA standard guides don't do .365" lift, and I was peeved off for not checking before I finished the head.  Lesson learnt
Re the raised flat top piston trick, it's the same way Kenny X got the comp on his road race 900 and makes a massive difference to lots of things.

That peaks my interest. My brother, I bought my cb750k sohc off of is the same guy that bought my cb750c dohc off me. I also.sold him.all the parts I had collected to build two more engines. In the parts was a set of cb900 con rods that were shot peened and had cb1100f con bolts. I believe I also sold him a set of rare MTC con rods in the cb750 dohc length. Might see about buying them back for a future build when I spilt the cases.
Remember though, the CB750DOHC have 1.5mm shorter rods than the CB750SOHC have. It is the CB900 that are 1.5mm longer than the SOHC rods.

Yes right on. I am rusty on all this stuff. Been a min since I messed with the bottom end stuff.

Technically speaking couldn't you have a spacer of 1.5mm machined for the bottom of the cylinders using the cb900 dohc rods to give proper deck hight?

Offline MRieck

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Re: Cycle x is coming out with copy of SS-1. The SX-1
« Reply #11 on: December 19, 2024, 05:44:17 AM »
In fact, now I remember that RC315  build well. I was chasing compression without using dome pistons as I have this thing about domes getting in the way and ign. advance etc. It was the first time I had used CI pistons and I used 1.5 mm longer 900 rods to pop em up and machined the corner of top edge of piston to suit, got the compression I wanted and using the 315 with about .365" thou lift notched the pistons with room to spare. The reason I remember it well was it was the first time I had used the 315 cam and when I bolted on the finished head / guides/valves etc done the checks WALLA standard guides don't do .365" lift and I was peeved off for not checking before I finished the head.  Lesson learnt
Re the raised flat top piston trick its the same way Kenny X got the comp on his road race 900 and makes a massive difference to lots of things.
Johno....I have used .375 lift with the OEM guide. The caveat is you have to use them the brown, OEM valve guide seals. They are at least 1mm shorter than aftermarket seals like the Kibblewhite red Viton. As a side note.....the brown OEM seals are Viton and excellent quality but they are expensive.
 Also....100% with you on the use flat top based pistons.
« Last Edit: December 19, 2024, 05:46:20 AM by MRieck »
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Offline Dime

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Re: Cycle x is coming out with copy of SS-1. The SX-1
« Reply #12 on: December 19, 2024, 09:05:27 AM »
I guess the next question I have is how much beadwork is needed for the SS-1 say vs the CX-1?

The cruzinimage pistons are cost efficient but if I need to spend big money on the head to utilize the SS-1 vs the CX-1 that may be the deciding factor.

I would already have to find someone to deepen the valve pockets with the SS-1 cause I don't know of anyone locally that can do it.

Offline HondaMan

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Re: Cycle x is coming out with copy of SS-1. The SX-1
« Reply #13 on: December 19, 2024, 11:26:15 AM »
I guess the next question I have is how much beadwork is needed for the SS-1 say vs the CX-1?

The cruzinimage pistons are cost efficient but if I need to spend big money on the head to utilize the SS-1 vs the CX-1 that may be the deciding factor.

I would already have to find someone to deepen the valve pockets with the SS-1 cause I don't know of anyone locally that can do it.

Most racing-type machine shops can divot the pistons, but will charge too much $$ for it (IMHO).
I miss Action Fours. We used a lot of their stuff back in the day. They had an 811cc kit that knocked my socks off, with cams to boot. They wisely started the whole 825cc thing, too. They didn't even make the pistons, but found them from some other Japanese bike.
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Offline Dime

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Re: Cycle x is coming out with copy of SS-1. The SX-1
« Reply #14 on: December 19, 2024, 11:54:40 AM »
I guess the next question I have is how much beadwork is needed for the SS-1 say vs the CX-1?

The cruzinimage pistons are cost efficient but if I need to spend big money on the head to utilize the SS-1 vs the CX-1 that may be the deciding factor.

I would already have to find someone to deepen the valve pockets with the SS-1 cause I don't know of anyone locally that can do it.

Most racing-type machine shops can divot the pistons, but will charge too much $$ for it (IMHO).
I miss Action Fours. We used a lot of their stuff back in the day. They had an 811cc kit that knocked my socks off, with cams to boot. They wisely started the whole 825cc thing, too. They didn't even make the pistons, but found them from some other Japanese bike.

I am talking myself out of the SS-1 cam. As we have already talked about the cruzinimage pistons, the head rebuilt and spring for the CX-1 cam should be a solid combination. I have new motivation to get this back together for the spring. I am cutting out some of the powder coat I had planned and putting the money into the engine instead.

Offline PeWe

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Re: Cycle x is coming out with copy of SS-1. The SX-1
« Reply #15 on: December 19, 2024, 12:01:39 PM »
It must be possible to make a fixture that holds the piston.
Drilling machine in correct angle also with support that can be moved down to grind piston 1 mm  for valve to start with.
34 mm for In, 30mm for ex.
This will make wiggle room for stock valves 32 vs 28mm.

It is not much needed.

I add an old photo of my old Action Fours SS-1 cam I downloaded from this forum. Added it years ago.
Lobes look friendly, not that steep angkes when open nor close.

This is a good cam. Made my bike to run well.
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline Dime

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Re: Cycle x is coming out with copy of SS-1. The SX-1
« Reply #16 on: December 19, 2024, 12:20:40 PM »
It must be possible to make a fixture that holds the piston.
Drilling machine in correct angle also with support that can be moved down to grind piston 1 mm  for valve to start with.
34 mm for In, 30mm for ex.
This will make wiggle room for stock valves 32 vs 28mm.

It is not much needed.

I add an old photo of my old Action Fours SS-1 cam I downloaded from this forum. Added it years ago.
Lobes look friendly, not that steep angkes when open nor close.

This is a good cam. Made my bike to run well.

Reached out to a machinist buddy of mine and he put me onto a local guy. He can do it but it would cost $400 Cad just to relieve the valve pockets in the pistons.

Offline PeWe

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Re: Cycle x is coming out with copy of SS-1. The SX-1
« Reply #17 on: December 19, 2024, 12:23:22 PM »
Valve locations 1-4
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline Dime

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Re: Cycle x is coming out with copy of SS-1. The SX-1
« Reply #18 on: December 19, 2024, 12:51:24 PM »
Valve locations 1-4

PeWe the engine you had the SS-1 cam in, what compression 836cc was that? I am just wondering what compression the SS-1 likes? The cruzinimage 836cc kit is not going to have much compression. Just wondering if the SS-1 will be a waste in low compression engine?

Offline Tracksnblades1

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Re: Cycle x is coming out with copy of SS-1. The SX-1
« Reply #19 on: December 19, 2024, 04:01:15 PM »
It must be possible to make a fixture that holds the piston.
Drilling machine in correct angle also with support that can be moved down to grind piston 1 mm  for valve to start with.
34 mm for In, 30mm for ex.
This will make wiggle room for stock valves 32 vs 28mm.

It is not much needed.

I add an old photo of my old Action Fours SS-1 cam I downloaded from this forum. Added it years ago.
Lobes look friendly, not that steep angkes when open nor close.

This is a good cam. Made my bike to run well.

I used to make homemade fly cutters to make sure the piston reliefs were exactly where they needed to be..

Use a used intake and exhaust valve and silver solder an old parting tool or 3/16” or smaller hss turning tool bar stock on the valve faces. Once soldered grind sharpen your preferred cutting edge on the high speed tool bit..

Have your engine mocked up with bearings, pistons no rings, head gasket, and since you already degreed your cam and you know where the measured clearances are needed. Roll the crank up to the degree on the degree wheel where the piston needs additional clearance. Set the head on and snug up. Set the collar lock on your homemade cutter a little shy so it limits how much you cut into the piston by limiting how far the valve stem can move into the valve guide..

You can modify the o. d. of your cutter if you want more insurance at the cost of a little compression. But if it contacts during a valve float you’ll end up with neither..

My cutters only had the long piece of hss silver soldered on not all the extra ones  like the one in the picture.
I only used a manual drill to turn it. Never a electric or air drill, turned to fast and chattered to much especially if the cutter was only contacting in one spot..
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Offline Tracksnblades1

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Re: Cycle x is coming out with copy of SS-1. The SX-1
« Reply #20 on: December 19, 2024, 04:32:42 PM »
There are probably some good you tube videos that can show you how to set the cutter up for cutting and measuring..
Way better than me trying to write a book trying to explain it…It’s not real complicated. The degree wheel is not required but will really show you where the valve(s) and pistons are at their closest…

PEWE may know if you need to check the valves’  face to face clearance for that cam since he remembers using it before…🤔
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Offline Don R

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Re: Cycle x is coming out with copy of SS-1. The SX-1
« Reply #21 on: December 19, 2024, 10:59:33 PM »
   I probably have the poster child for wrong cam/piston pairing. I'm running a Kenny Harmon F cam over Cruisin Image pistons. I did nick an intake valve, probably due to close clearance and old springs, when I replaced the valve, I added new springs and some base gasket for a tad more breathing room.
   The same motor seemed pretty torquey with a Honda F2 cam, I'll likely put that back in and use the K/H F in something else with either 65mm MTC alcoa pistons or Wiseco 10.25's.
« Last Edit: December 19, 2024, 11:02:51 PM by Don R »
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Offline PeWe

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Re: Cycle x is coming out with copy of SS-1. The SX-1
« Reply #22 on: December 19, 2024, 11:50:18 PM »
The K6 engine had relatively low compression most of the time.
It had RC 836 pistons that had wider crowns, chambers had to be widened making them +24cc.

Those pistons replaced by Action Fours pistons for stock chambers ca:  22.5cc. They were 1.5mm lower plus not as wide domes.

So compression were much lower. Maybe close to CB750 stock. No surprise wheelies when twisting the throttle on 1st  2nd gear, then with VM 29 carbs.
 Later stock carbs due to cracking carb boots, AF pistons. Higher speeds still OK. Good acceleration.

Compression test I made with the NOS RC836 pistons with RC295 cam were 175-190PSI. (Same head as before)

Same cheap comp tester on my K2 with CI stock 736 pistons and stock K6 head 150-160 PSI. Same engine with CI +0.50mm K7 pistons +170 PSI.

CI 65 mm pistons will increase the compression.
Thinner base gasket as RCS 0.001" will lower cylinder 0.25 mm.

It ran fine anyway. Probably a better tourer.
I wrote a post about it when I restored the bike after +20 years sleep 2012-2013.

Here with Mikuni TMR 32 carbs. Wrong needles there, found the correct years later.
http://forums.sohc4.net/index.php/topic,104925.msg1173151.html#msg1173151

I found NOS RC pistons older than mine with crowns matching the ported head.
Dyno with SS1 cam and the better matching RC836. It reached 10k rpm at that dyno.

From that dyno run




The SS1 cam have not much duration and overlap.

 I used 34mm in valves. So valve to valve is no problem.

RC 315 (DP 315) was very close years later.
(RC295 much better cam, more valve to valve clearance and better power from low to high rpm.).

So the SS1 cam will be fine.

About compression.
My K6 a few years later with 1005cc did not reach +100Whp until compression reached a little over 200 PSI with same tester. Then Megacycle 125-75 cam.

Thinner gaskets, 210-215 PSI and around 105 whp. Another ported head with 33.5/28.5mm valves delivered same power and even a few more with 970cc bore
« Last Edit: December 20, 2024, 12:47:15 AM by PeWe »
CB750 K6-76  970cc (Earlier 1005cc JMR Billet block on the shelf waiting for a comeback)
CB750 K2-75 Parts assembled to a stock K2

Updates of the CB750 K6 -1976
http://forums.sohc4.net/index.php/topic,180468.msg2092136.html#msg2092136
The billet block build thread
http://forums.sohc4.net/index.php/topic,49438.msg1863571.html#msg1863571
CB750 K2 -1975  build thread
http://forums.sohc4.net/index.php/topic,168243.msg1948381.html#msg1948381
K2 engine build thread. For a complete CB750 -75
http://forums.sohc4.net/index.php/topic,180088.msg2088008.html#msg2088008
Carb jetting, a long story Mikuni TMR32
http://forums.sohc4.net/index.php/topic,179479.msg2104967.html#msg2104967

Offline Dime

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Re: Cycle x is coming out with copy of SS-1. The SX-1
« Reply #23 on: December 20, 2024, 05:16:51 AM »
   I probably have the poster child for wrong cam/piston pairing. I'm running a Kenny Harmon F cam over Cruisin Image pistons. I did nick an intake valve, probably due to close clearance and old springs, when I replaced the valve, I added new springs and some base gasket for a tad more breathing room.
   The same motor seemed pretty torquey with a Honda F2 cam, I'll likely put that back in and use the K/H F in something else with either 65mm MTC alcoa pistons or Wiseco 10.25's.

I would be happy with an F2 or F3 cam but finding one in good shape is the issue.

Offline Dime

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  • Posts: 355
Re: Cycle x is coming out with copy of SS-1. The SX-1
« Reply #24 on: December 20, 2024, 05:32:13 AM »
The K6 engine had relatively low compression most of the time.
It had RC 836 pistons that had wider crowns, chambers had to be widened making them +24cc.

Those pistons replaced by Action Fours pistons for stock chambers ca:  22.5cc. They were 1.5mm lower plus not as wide domes.

So compression were much lower. Maybe close to CB750 stock. No surprise wheelies when twisting the throttle on 1st  2nd gear, then with VM 29 carbs.
 Later stock carbs due to cracking carb boots, AF pistons. Higher speeds still OK. Good acceleration.

Compression test I made with the NOS RC836 pistons with RC295 cam were 175-190PSI. (Same head as before)

Same cheap comp tester on my K2 with CI stock 736 pistons and stock K6 head 150-160 PSI. Same engine with CI +0.50mm K7 pistons +170 PSI.

CI 65 mm pistons will increase the compression.
Thinner base gasket as RCS 0.001" will lower cylinder 0.25 mm.

It ran fine anyway. Probably a better tourer.
I wrote a post about it when I restored the bike after +20 years sleep 2012-2013.

Here with Mikuni TMR 32 carbs. Wrong needles there, found the correct years later.
http://forums.sohc4.net/index.php/topic,104925.msg1173151.html#msg1173151

I found NOS RC pistons older than mine with crowns matching the ported head.
Dyno with SS1 cam and the better matching RC836. It reached 10k rpm at that dyno.

From that dyno run




The SS1 cam have not much duration and overlap.

 I used 34mm in valves. So valve to valve is no problem.

RC 315 (DP 315) was very close years later.
(RC295 much better cam, more valve to valve clearance and better power from low to high rpm.).

So the SS1 cam will be fine.

About compression.
My K6 a few years later with 1005cc did not reach +100Whp until compression reached a little over 200 PSI with same tester. Then Megacycle 125-75 cam.

Thinner gaskets, 210-215 PSI and around 105 whp. Another ported head with 33.5/28.5mm valves delivered same power and even a few more with 970cc bore

From what I am gathering I would be much better off with a set of pistons with the valve reliefs already built in if I am going to run the SS-1 cam.

At this point I think I would be more than satisfied with the cruzinimage pistons and a F2/F3 cam if I could find one.

I plan on going to the strip maybe once or twice other than that I just want a good responsive engine for fun factor without breaking the bank.