Topic: different sleeves?

[Terry in Australia]

Thanks Frank and Joe, back in 1981 I cooked the engine's top end (a "mechanic" used silicon on a gasket and it clogged the oilways in the head) so I needed to rebore it for 4th oversize pistons, new cam and cam towers. The cam towers cost a fortune, as did the pistons and rings (I bored it myself on my cousin's old Repco boring bar) and I'd almost run out of money and couldn't afford the OEM cam, so bought the Andrews cam, which was half the price of the OEM item.

Looking at the Satanic Mechanic site I'm pretty sure it was the A grind cam, from memory it had a little more lift and duration than the stocker, and was a good torquey cam, if you don't want yours Frank, do you want to swap it for my 125/75?

   Description and Application
--------------------------------------------------------------
A      20/40    .345    240    Good bottom end torque
       40/20    .345    240
--------------------------------------------------------------
D      19/40    .385    244
       40/19    .360    244
--------------------------------------------------------------
K      35/63    .370    278
       63/35    .370    278
--------------------------------------------------------------
4      32/68    .400    280
       68/32    .400    280
--------------------------------------------------------------

[754]

I dont want to pul, it out yet and it wax new in the box.
 The motor is bone stock except for good valve job and springs.
But I did not degree it, and my Webers are sitting here waiting.. so I would try that first.
 I wouldn't call it torquey under 6K but I bet the carbs will change that.

[Terry in Australia]

Yeah mate, well if you change your mind my Megacycle 125/75 is still in its original box, with less than 1000 miles of use, so the lobes are still grey and un-polished.

[scottly]

Since we are on the subject, DP315's absurd valve lash of 0.3 mm makes absolutely no sense to me.
What's the rationale behind changing valve lash to change performances?

The factory owner's manual that came with my 1953 BSA had two settings for valve lash; a looser setting for increased low RPM torque (less effective duration), and a tighter setting for increased high RPM HP (more duration). .001" of lash is worth about 1 degree of duration, depending on the lobe ramp shape.

[PeWe]

Terry, an Andrews A cam is for sale
https://www.ebay.co.uk/itm/honda-cb750-performance-camshaft-andrews-drag-chopper-race-CB-750-cam-rc-sohc/142695696457?hash=item2139538849:g:2vMAAOSwokJaiz0E

The 125-75 might need more cc? You need a 1000cc kit to match it getting more from bottom

I measured my DP315 with 0.3mm lash and 0.25mm since I saw that it can be a way to adjust. Maybe different lash IN in vs EX to have a little adjustment possibilities like a twin cam.
duration IN/EX  265/266   28,5/56,5     60/26   overlap 54,5  @0.3mm   (0.0118") lash
duration IN/EX  267/269   29,5/57,5     61/28   overlap 57,5  @0.25mm (0.0098") lash
                    278,5/282,5  35/63,5      67,5/35             70    @ 0 lash

I have a small timing wheel so it is not very exact, not less than 0.5 degree accuracy. I cared to not touch anything during the process. Doublechecked IN again after doing EX to ensure same numbers.

[scottly]

It would be interesting to see how different lashes perform on the dyno?

[MRieck]

Terry, an Andrews A cam is for sale
https://www.ebay.co.uk/itm/honda-cb750-performance-camshaft-andrews-drag-chopper-race-CB-750-cam-rc-sohc/142695696457?hash=item2139538849:g:2vMAAOSwokJaiz0E

The 125-75 might need more cc? You need a 1000cc kit to match it getting more from bottom

I measured my DP315 with 0.3mm lash and 0.25mm since I saw that it can be a way to adjust. Maybe different lash IN in vs EX to have a little adjustment possibilities like a twin cam.
duration IN/EX  265/266   28,5/56,5     60/26   overlap 54,5  @0.3mm   (0.0118") lash
duration IN/EX  267/269   29,5/57,5     61/28   overlap 57,5  @0.25mm (0.0098") lash
                    278,5/282,5  35/63,5      67,5/35             70    @ 0 lash

I have a small timing wheel so it is not very exact, not less than 0.5 degree accuracy. I cared to not touch anything during the process. Doublechecked IN again after doing EX to ensure same numbers.

About the 127-75.... Doctor D made 84.47hp with 54 lbs torque with an 836, perfect torque curve. My 915 made about 98hp with over 60 lbs....perfect torque curve. Another client of mine with 836cc made 90hp.....I built that engine. Same deal.
 All those cams were timed correctly.....not thrown in like stock. Small cams can be installed without timing and they will work...performance cams cannot.
 Rick Stetson's friend with the lay down rare aluminum framed dragbike is making 92 hp and going 10.86 with a 110 lobe center 125-70. He is going that quick after a 35 year lapse in racing and still figuring out gearing. Stetson loves that cam but what does he know (former USA Pro-Stock champ)....for street use.  Kenny at Cycle-X likes it too.
 It's easy to blame equipment. You have to time the cam. I ....and others....have years of success with that cam on different CB configurations. One persons negative experience with no dyno data is just a wholly subjective opinion with no lucid or objective basis. It's a great cam if it is installed correctly with common performance equipment.
 Somebody should buy that 125-75....it's probably the last of the billet series and you won't see anymore...just hardwelds and they are expensive.

[Terry in Australia]

Thanks Mike, if you remember, you gave me all the timing info for that cam all those years ago and I set it up as per your instructions. It was a great WOT cam with the RC 836 kit and your stage 3 or 4 head, 29mm CR's etc, but it was pretty weak at low to mid range RPM.

I'm looking for a torquer cam now, something a little better than stock for a daily rider, without having to waste big money on one old bike when I've got much faster modern bikes to ride now. Cheers, Terry.

[MRieck]

 Megacycle gave the timing instructions. Without dyno charts I do not know what you mean by weak. Poor ring seal from used old pistons/rings size can kill compression and kill low end. Torque can live even if the equipment is mediocre as the valves close early or you increase static compression. Maybe some of the other parts (old clunky pistons) weren't that good.
 If you saying I sold you a crap cam than just say it....don't beat around the bush. I'll send you a refund including a generous amount of money of your choosing to cover the cost of you having to install it.... you can keep the cam. I've read about this to many times from you and will put it to bed once and for all. Sick of seeing it pop up again and again like herpes.
 Too many people have have great success with the 127-70/75 for a blanket statement it sucks in terms of low end torque. It is extremely subjective and erroneous.

[Terry in Australia]

Hey Mike, I've never accused you of anything, you didn't make the cam, nor did you ride my bike with the cam in it, so I'm not sure why you are so upset about my opinion not agreeing with yours? A motorcycle forum is a place where everyone is able to share their experience whether it agrees with your experience, or not. If that's a problem for you, well, you only need to press the "ignore button", and I'll disappear off your radar.

Those old RC pistons are still within spec and when I can find them I'll probably use them again, or there's some "Action 4"s in a box, if I can find some rings for them? Have a good one! Cheers, Terry.

[PeWe]

Terry, a dyno might show the torque better? The cam provide a lot from 6000-7000 that make it to feel weak before but is not. I have tested CX-7 that has a little bit more duration, otherwise same numbers.
The "torqier" has no sudden power at the top. I did some dyno runs last summer.

Less open exhaust (diffusers in) gave better torque before 4300 rpm. Diffusers out gave more torque between 4300-6500. Dyno runs  after each other, nothing else changed than diffusers out/in.

[JoeCooley]

So.... Does anyone have an idea of what the static cr would be with these 12:1 890 pistons and a F2 head?

Also, does anyone have a good used DP315 or DP327 laying around that they'd like to sell? Haha 😈🤘

[Terry in Australia]

Terry, a dyno might show the torque better? The cam provide a lot from 6000-7000 that make it to feel weak before but is not. I have tested CX-7 that has a little bit more duration, otherwise same numbers.
The "torqier" has no sudden power at the top. I did some dyno runs last summer.

Less open exhaust (diffusers in) gave better torque before 4300 rpm. Diffusers out gave more torque between 4300-6500. Dyno runs  after each other, nothing else changed than diffusers out/in.

G'Day Per, you're probably quite right mate, my memory is that the 125/75 "came on" at around 6000 RPM, and rocketed to, and way past, redline, but as most of my riding is on the street, making power after 6K is pretty much useless when 4K RPM equates to 60 MPH in top gear.

The "Unknown" cam that's in that bike now made good power in the low to midrange, and as I had no need to ride my bike 10/10th's it was a much better street cam. I wish I still had it. (the cam, not the bike, the RC51 I swapped it for is a great bike too)

[bear]

About the 127-75.... Doctor D made 84.47hp with 54 lbs torque with an 836, perfect torque curve. My 915 made about 98hp with over 60 lbs....perfect torque curve. Another client of mine with 836cc made 90hp.....I built that engine. Same deal.
 All those cams were timed correctly.....not thrown in like stock. Small cams can be installed without timing and they will work...performance cams cannot.
 Rick Stetson's friend with the lay down rare aluminum framed dragbike is making 92 hp and going 10.86 with a 110 lobe center 125-70. He is going that quick after a 35 year lapse in racing and still figuring out gearing. Stetson loves that cam but what does he know (former USA Pro-Stock champ)....for street use.  Kenny at Cycle-X likes it too.
 It's easy to blame equipment. You have to time the cam. I ....and others....have years of success with that cam on different CB configurations.
[/quote]

I'm miffed! I didn't get a mention.

[Terry in Australia]

About the 127-75.... Doctor D made 84.47hp with 54 lbs torque with an 836, perfect torque curve. My 915 made about 98hp with over 60 lbs....perfect torque curve. Another client of mine with 836cc made 90hp.....I built that engine. Same deal.
 All those cams were timed correctly.....not thrown in like stock. Small cams can be installed without timing and they will work...performance cams cannot.
 Rick Stetson's friend with the lay down rare aluminum framed dragbike is making 92 hp and going 10.86 with a 110 lobe center 125-70. He is going that quick after a 35 year lapse in racing and still figuring out gearing. Stetson loves that cam but what does he know (former USA Pro-Stock champ)....for street use.  Kenny at Cycle-X likes it too.
 It's easy to blame equipment. You have to time the cam. I ....and others....have years of success with that cam on different CB configurations.

I'm miffed! I didn't get a mention.
[/quote]

Ha ha, well I still love you Brian, now where's my CB750 parts stash?

[bear]

I'm sure there will be something in the hord you might want to swap that sh-i tty cam for

[Terry in Australia]

I'm sure there will be something in the hord you might want to swap that sh-i tty cam for

Ha ha, I've got this mental picture of a tandem trailer full of CB750 parts hooked up to my shiny red Territory Brian, please don't kill my dream........

[bear]

I'm sure there will be something in the hord you might want to swap that sh-i tty cam for

Ha ha, I've got this mental picture of a tandem trailer full of CB750 parts hooked up to my shiny red Territory Brian, please don't kill my dream........

Your in a happy place Uncle Tez, I wouldn't dream of dragging you out of it.

[PeWe]

Terry, I think you have got a new project!
Build an engine with that cam. Frame kit so you can change the timing if needed without pulling the engine. I'm sure you will regret if you sell that famous cam.

I had a thread here for 2 years ago where I had bought a mysterious cam on eBay. I finally found an inscription under the washer with a shaky RC295 inscription  seen when letting the ligt shine in a specific angle. The numbers when I timed it were close to an RC295. The numbers where not that long from a 125-70/75 cam card either. High lift and relatively low duration keeping the dynamic compression and ensure power from low.

It had nice cruising responce from 80-90kph on 5:th gear where I twisted the throttle and it ran smooth without any hesitations. I found that I could increase main jet 1 step to get better low response at WOT at that speed. This with a rather open 4-1 and 836cc.

I think it is the DP315's rather big overlap that need back pressure before 4000 rpm I mentioned earlier.
(I read a thread about rings in V8 headers to create back pressure to match a cam)

It was really tricky to tune my carbs on low rpms when taking off and drive slowly on the streets with open pipes. With diffusers in, the low rpm issues disappered completely. I changed fuel screws following my nose, closed them (to 3/4 turn open) until the rich smell disappeared when idling. Before that I had tried all kind of settings riding around with a screwdriver for at least 200km with several stops. Starting from 1/4 turn open until 1 1/2 in 1/8 increments all done with warm engine to ensure same condition. 1 turn out was the closest I could find, still bad low behaviour.

Wide open exhaust might be good on a race/dragbike, different on a street bike that need good and even low rpm.

DP315 was the cam I got different torque and power curves with diffusers in or not.
Lotus Root 4-4 that gave less top hp than the more restrictive HM300 replica (No numbers) but more torque. Both exhausts restrict top power to around 8000-8500 rpm. The cam should scream well at least 1500 more.

My DP315 cam need a 4-2-1 and maybe a new timing to tweak the hidden horses closer to 100 rwhp as should be reached with the parts used.
I'll see if I can get a timing where IN has same numbers as EX but inverted. Dynoman and RC have specfied 23/53, 53/23. Exact numbers might not be possible but the internal relations IN vs EX. Play in the valve train gives different readings. Last time with low mile cam hoilders with less play that change the numbers.

I understand why Mike recommends timing with running lash that will compensate for various play in the valve train.

[Terry in Australia]

No worries Per, I don't have any plans to build a hot CB750 though, it's just too expensive to do it nowadays, and as you know, one thing leads to another, a stock CB750 with a red hot engine makes for a poor handling death trap that doesn't stop, so on top of the thousands of bucks that you've poured into the engine, you need to modify the frame, forks, rear suspension, wheels, tyres, etc etc to make the rolling chassis handle the extra power.

Or, you can enjoy a stock or mildly modded CB750 and use just a fraction of that money to buy an awesome modern(ish) bike that will do everything you want when you want to go fast. My 1996 VFR750 that I bought a couple of years ago for $2200 (around $1600 USD) from a 71 year old man is in mint condition, has awesome brakes and handling, can be ridden all day and has about 100 BHP to play with. The wail of a CB750 at 8500 RPM doesn't even come close in the "sexy noise department" to the howl of that V4 with it's gear driven cams @11000 RPM, thru the stainless Remus pipe that came with the VFR.

Don't get me wrong, I love to watch the CB750 based Post Classic Racers (and sidecar racers like Brian) going faster than they ever did "back in the day" and I was seriously thinking about buying a really well set up Post Classic Racer recently with the idea of putting it on the road, but common sense took over again when I remembered that I've got other bikes that I like to ride just as much as my 750, that will go a lot faster, not that going really fast is a good idea anyway.............

[MRieck]

Hey Mike, I've never accused you of anything, you didn't make the cam, nor did you ride my bike with the cam in it, so I'm not sure why you are so upset about my opinion not agreeing with yours? A motorcycle forum is a place where everyone is able to share their experience whether it agrees with your experience, or not. If that's a problem for you, well, you only need to press the "ignore button", and I'll disappear off your radar.

Those old RC pistons are still within spec and when I can find them I'll probably use them again, or there's some "Action 4"s in a box, if I can find some rings for them? Have a good one! Cheers, Terry.

I'm not upset at all....just looking to clarify. Calling it a "sh!t street cam" is a bit extreme and can give people the wrong idea. With no dyno chart showing A/F,HP and a torque curve it all becomes a bit specious. For example.....it may very well have been a carburetor tuning issue (s) such as high needle height, excessive fuel level in the bowls, fuel enrichment circuits not fully closed (very, very common with CR's) or a combination of things. CR carbs are very finicky for sure. The same symptoms (poor low speed running) will occur but without an accurate A/f reading (from some type of O2 sensor or sniffer) you never know. Plug reading isn't that precise.
 I guess my problem is I'm a concrete fella and I depend on numbers whether they come from the flow bench, precision tools or O2 sensors/dyno analysis using A/F ratios to figure what works and what does not work.
 Also....I pretty sure the ignore feature just blocks PM's from other members but I could wrong about that.

[cbr954]

I'm running a 125/75 in my street 970 motor.  For me it has a very steady pull from idle up till I decide to stop, it seems to keep pulling.  I am running a F2 head on a K bottom end using K pistons.  I milled the head to get right at 10:1 compression.  For me it works very well at all RPM's.

[PeWe]

Terry, most important is to follow your ideas and dreams. This forum is a good place to find  ideas.

Scheisse, this discussion make me interested to try another cam
It's very easy to become a cam horder, right?

It would be interesting to see how different lashes perform on the dyno?

I might do that later on. But the lashes I have left is smaller that will increase the duration and overlap. Maybe different lash IN vs EX. More duration on EX is used by other cams.

[Jerry Rxman Griffin aka MuthaF'er]

Terry, send the 125/75 to me......

[Terry in Australia]

Ha ha, thanks everyone, but Brian (Bear) threatened to unleash the beautiful Ev (his wife and bodyguard) on to me if I don't give it to him, so he's the winner. Cheers, Terry.