Worn cams: worth regrinding to Stage 1 for my setup?

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Worn cams: worth regrinding to Stage 1 for my setup?

11 Sep 2025 14:50
#917038
Hello, I have a spare cylinder head that I plan to rebuild, and also a set of worn camshafts. Would it be a good idea to send the cams out to be modified into a Stage 1 profile?My current setup is a stock head, Mikuni RS34 carbs and a Delkevic 4-into-1 exhaust. With this configuration the engine pulls very strong up to 8,500 rpm.If I rebuild the spare head with larger valves and use the modified Stage 1 cams, how much improvement could I expect?Does anyone have the exact Stage 1 cam dimensions that I could use to modify the cams here in my country?Any suggestions are greatly appreciated. Thanks! 
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1977 Kawasaki KZ1000 A1

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Re: Worn cams: worth regrinding to Stage 1 for my setup?

12 Sep 2025 22:44
#917077
Does the engine have stock pistons and 1015cc? 
1978 KZ650B2 w 1197cc Z1 engine
1977 KZ650B1 w 750cc Spectre engine
1979 KZ650C3 w 831cc Hot Rod engine
1978 KZ650C2 w 762cc DFI project
1977 KZ650C1 stock restoration project
1978 KZ650B2 modified project
1978 KZ650B2 Injected Drag 831cc
1980 Z1 Custom Frame Drag 1327cc
1981 Z50R Honda tow bike

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Re: Worn cams: worth regrinding to Stage 1 for my setup?

13 Sep 2025 00:10
#917078
Injected wrote:
Does the engine have stock pistons and 1015cc? 
Leonardo's BOTM feature says 72mm so I guess 1075
1982 KZ1000 Ltd
www.kzrider.com/forum/11-projects/617631...-82-begins?start=192
kzrider.com/filebase-alias?view=download...d-fault-diagnosis&ca
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Re: Worn cams: worth regrinding to Stage 1 for my setup?

13 Sep 2025 08:17
#917081
Injected wrote:
Does the engine have stock pistons and 1015cc? 
Hi, yes as Wookie said it’s a 1075, I forgot to mention that detail.
1977 Kawasaki KZ1000 A1

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Re: Worn cams: worth regrinding to Stage 1 for my setup?

13 Sep 2025 08:36 - 13 Sep 2025 08:39
#917082
Sooo, my questions is: what Stg 1 cam are you referring to?  The only camshaft company that used stages was Yoshimura that I’m aware of.  Other than them it goes with “Grind” numbers.

Andrews X1, X2, X3
Cammotion Z1, Z2….Z14
Web Cams #118, #119, #110, #109, etc
APE K410 & K435

Later, Doug
1978 z1000 Streetfighter
1976 z900 Stripfighter
1979 z650 Resto-Mod
1983 Gpz750 Resto-Mod
2018 Z900RS
Last edit: 13 Sep 2025 08:39 by StreetfighterKz.
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Re: Worn cams: worth regrinding to Stage 1 for my setup?

13 Sep 2025 08:43
#917083
StreetfighterKz wrote:
Sooo, my questions is: what Stg 1 cam are you referring to?  The only camshaft company that used stages was Yoshimura that I’m aware of.  Other than them it goes with “Grind” numbers.

Andrews X1, X2, X3
Cammotion Z1, Z2….Z14
Web Cams #118, #119, #110, #109, etc
APE K410 & K435

Later, Doug
Hi Doug, thanks for clarifying! You’re right — I used the term “Stage 1” in a general sense, but what I’m really asking about are the mild performance grinds that give more duration/lift than stock, without going into full race specs.From what I understand the common options would be something like Web #118, Andrews X1/X2 or Cam Motion Z2. My goal is to keep good mid-range torque for the street, but get a bit more pull past 8,000 rpm (the bike is 1075cc with RS34 carbs and a 4-1 Delkevic).Which grind would you recommend as the best ‘street friendly’ upgrade in my case?
1977 Kawasaki KZ1000 A1

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Re: Worn cams: worth regrinding to Stage 1 for my setup?

13 Sep 2025 08:45 - 13 Sep 2025 08:56
#917084
OK 1075cc 10:1 comp forged pistons, this was a key question on if you should proceed on not. Stock cast lower compression pistons are a weak base to build on.

Hard to say how much power a big valved ported head with high lift cams would add but I would guess about 15-20 HP depending on how good the porting is and what cam you pick.

If you big valve the head and port it to Stage 1 (this is where the "stage" is) you could run any cam in it, usually up to .435" lift (APE spring limit) Yosh lists several classic profiles as being "stage 1" but you want to pick your cam lift to where the CFM drops off (flow bench test)

Why are you running out of pull at 8500? Stock springs??

BTW: Those "stage 1" Yoshi cams don't really start to pull till about 7K (Bonniville) and will run you right out past 10K with aftermarket springs. Stock springs will float right about 8500. To get max RPM out of the engine the springs need to be pressure tested at the installed height.

Cam grinders don't list profile dimensions, pretty hard to replicate those grind patterns and is a highly guarded trade secret. All they list is lift, duration, base circle, and grind number (profile dimensions)

www.webcamshafts.com/pages_vehicles/moto...e/kawasaki/1730.html

If you want to keep your stock shim over bucket setup you need to stay under .410" lift, if you want some midrange maybe something like a .370" lift with 240 duration with a milder port job. You would not even have to big valve it (your choice) To get that combo past 9K you need aftermarket valve springs.
 
1978 KZ650B2 w 1197cc Z1 engine
1977 KZ650B1 w 750cc Spectre engine
1979 KZ650C3 w 831cc Hot Rod engine
1978 KZ650C2 w 762cc DFI project
1977 KZ650C1 stock restoration project
1978 KZ650B2 modified project
1978 KZ650B2 Injected Drag 831cc
1980 Z1 Custom Frame Drag 1327cc
1981 Z50R Honda tow bike
Last edit: 13 Sep 2025 08:56 by Injected. Reason: sp
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Re: Worn cams: worth regrinding to Stage 1 for my setup?

13 Sep 2025 09:15
#917086
Injected wrote:
OK 1075cc 10:1 comp forged pistons, this was a key question on if you should proceed on not. Stock cast lower compression pistons are a weak base to build on.

Hard to say how much power a big valved ported head with high lift cams would add but I would guess about 15-20 HP depending on how good the porting is and what cam you pick.

If you big valve the head and port it to Stage 1 (this is where the "stage" is) you could run any cam in it, usually up to .435" lift (APE spring limit) Yosh lists several classic profiles as being "stage 1" but you want to pick your cam lift to where the CFM drops off (flow bench test)

Why are you running out of pull at 8500? Stock springs??

BTW: Those "stage 1" Yoshi cams don't really start to pull till about 7K (Bonniville) and will run you right out past 10K with aftermarket springs. Stock springs will float right about 8500. To get max RPM out of the engine the springs need to be pressure tested at the installed height.

Cam grinders don't list profile dimensions, pretty hard to replicate those grind patterns and is a highly guarded trade secret. All they list is lift, duration, base circle, and grind number (profile dimensions)

www.webcamshafts.com/pages_vehicles/moto...e/kawasaki/1730.html

If you want to keep your stock shim over bucket setup you need to stay under .410" lift, if you want some midrange maybe something like a .370" lift with 240 duration with a milder port job. You would not even have to big valve it (your choice) To get that combo past 9K you need aftermarket valve springs.

 
Thanks a lot for the detailed explanation! That makes perfect sense now — the reason my engine signs off around 8,500 rpm is valve float with the stock springs, not the carbs or exhaust.

So the real bottleneck right now are the stock valve springs.

I want to upgrade them so I can safely rev higher (9,500–10,000 rpm) and take advantage of a mild performance cam. Do you recommend APE or Kibblewhite springs for this setup (1075cc, 10:1 forged pistons, RS34s, 4-into-1 exhaust)?
1977 Kawasaki KZ1000 A1

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Re: Worn cams: worth regrinding to Stage 1 for my setup?

13 Sep 2025 11:59 - 13 Sep 2025 12:02
#917091
APE seem to be easier to get and always on Ebay so I usually buy them. Just make sure you get VS900K as the VSP500's are for drag racing and will only last for 100 miles.

You would be surprised on how much a good cam will wake up a engine even without big valves or extensive porting. 

I have a friend who has a KZ900 with a 1015cc (JE 10:1) engine with RS34's and V&H pipe which made OK power (mild/home ported stock valve head/stock cams)

We put some Yosh "POP Y" Bonneville .360"/.385" cams in it and it was like somebody flipped a light switch at 7K RPM!
Felt like a extra 100cc's were added with no other changes. Only thing was there seemed to be a lack of mid range (4-6K) which may not be a issue with your slightly larger engine.

I think back in the day this was there big daddy all out speed cam set, maybe not the best choice for a street bike.
1978 KZ650B2 w 1197cc Z1 engine
1977 KZ650B1 w 750cc Spectre engine
1979 KZ650C3 w 831cc Hot Rod engine
1978 KZ650C2 w 762cc DFI project
1977 KZ650C1 stock restoration project
1978 KZ650B2 modified project
1978 KZ650B2 Injected Drag 831cc
1980 Z1 Custom Frame Drag 1327cc
1981 Z50R Honda tow bike
Last edit: 13 Sep 2025 12:02 by Injected. Reason: sp
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Re: Worn cams: worth regrinding to Stage 1 for my setup?

13 Sep 2025 13:06
#917094
Injected wrote:
APE seem to be easier to get and always on Ebay so I usually buy them. Just make sure you get VS900K as the VSP500's are for drag racing and will only last for 100 miles.

You would be surprised on how much a good cam will wake up a engine even without big valves or extensive porting. 

I have a friend who has a KZ900 with a 1015cc (JE 10:1) engine with RS34's and V&H pipe which made OK power (mild/home ported stock valve head/stock cams)

We put some Yosh "POP Y" Bonneville .360"/.385" cams in it and it was like somebody flipped a light switch at 7K RPM!
Felt like a extra 100cc's were added with no other changes. Only thing was there seemed to be a lack of mid range (4-6K) which may not be a issue with your slightly larger engine.

I think back in the day this was there big daddy all out speed cam set, maybe not the best choice for a street bike.
Thanks a lot for the detailed info! That really helps me understand the options much better. I’ll look into the APE VS900K springs, and it’s good to know how much difference a good cam can make even with a stock valve head. Really appreciate you sharing your experience!
1977 Kawasaki KZ1000 A1

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Re: Worn cams: worth regrinding to Stage 1 for my setup?

13 Sep 2025 13:46 - 13 Sep 2025 13:51
#917095
No problem, glad I helped.

Stock Z1 cams are .296"/.327" with 229-237 duration, so pretty mild.

The ports can obviously support more lift with the stock valve sizes as long as the cam you pick works within the RPM range where you do most of your riding. Those Yosh cams we tried are for wide open throttle usage, they were a set I got with a entry level drag head so I had no use for them at that time.

Most cam makers will have a recommended use description and optional equipment required for each different grind they list.

In your initial post it sounded like you wanted to spray weld those stock cams and get them ground. WebCam has done that for me in the past, I sent them stock cams to weld and grind. It ends up being more expensive than a off the shelf set.
1978 KZ650B2 w 1197cc Z1 engine
1977 KZ650B1 w 750cc Spectre engine
1979 KZ650C3 w 831cc Hot Rod engine
1978 KZ650C2 w 762cc DFI project
1977 KZ650C1 stock restoration project
1978 KZ650B2 modified project
1978 KZ650B2 Injected Drag 831cc
1980 Z1 Custom Frame Drag 1327cc
1981 Z50R Honda tow bike
Last edit: 13 Sep 2025 13:51 by Injected. Reason: info

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Re: Worn cams: worth regrinding to Stage 1 for my setup?

13 Sep 2025 14:43 - 14 Sep 2025 05:56
#917103
When Rick at Harry's machined parts first built my engine around 1982 (yoshimura 987cc 10.25:1 pistons, welded Z1 crank, yoshimura stage 1 cam, stock size valves), it was a rocketship over 4k rpm, but not very streetable under that. We swapped in Andrews 1X cams and it woke right up from 2k on up. Lost some top end, but much better on the street. Been very happy with it since. Last winter I replaced the piston rings, fresh hone in cylinders, replaced cam sprockets, idlers, and tensioner with Liska billet parts, and new valve seals. Now runs just like it did 35 years ago!
Scotty

1974 Z1A
Yoshimura 987
welded Z1 crank
Andrews 1X Cams
Delkevic 4 into 1
Superbike bars
530 conversion
Last edit: 14 Sep 2025 05:56 by sf4t7.
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