Topic: DP295 cam

[Ilja]

Hi, I'm getting close to ordering the DP295 cam for my turbo CB.

Looks like it offers a lot more duration while still having quite minimal overlap and an early closing intake valve so my "guess" is it could be a perfect turbo cam to open up the powerband a bit more, with minimal loss of dynamic compression and minimal backpressure reversion.

Im using the cruzinimage 836cc pistons with an F2 head...
So I'm not sure if this cam just drops in or need additional P-V clearance... I just finished building an xr650r where I had to take 2mm! out of the exhaust valve pockets for the cam. 

Did anyone clay a cruzinimage 836 engine with this cam? Or a stocker and was it critical?
Second to that, did anyone by chance actually verify the timing?

Thanks in advance! 

[PeWe]

Not the exact answer you are looking for. Hopefully close

Not DP295 cam, but a similar cam. It must be an aftermarket, regrind or...?
The cam has RC295 scratched on the side, under the bolt and washer. Numbers not that far from RC295/DP295

IN  lift: 9,980 mm (0.0393") @ 0 lash    25/55    duration 260  @ 1mm lift (0.04")    LC 105,00
EX: lift: 9,220mm (0.0363")             55,5/22          257,5            LC 106,75   
Overlap 47

I timed cam with adjuster screw tightened until the dial indicator just started to move @ 0.
*******************************************************************************
I have a DP315 cam, now in engine. Values for verification of Dynamans cam card and RC315 numbers vs my my timing.
(This is the later RC315 version)

DP315   Lift: 9,33/9,33 mm @ 0 lash            35/62  68/33   Dur 277/281  @ 0.040"lift   LC 103,5/107,5   overlap 68

DP315  Lift: 8,95/9 mm    @ 0,3mm running lash  28,5/56,5   60/26  Dur 265/266  @0.040"lift   LC 104/107   overlap 54,5

DP315 cam numbers are more understandable for me at recommended lash of 0.3mm

[Ilja]

Not the exact answer you are looking for. Hopefully close

Not DP295 cam, but a similar cam. It must be an aftermarket, regrind or...?
The cam has RC295 scratched on the side, under the bolt and washer. Numbers not that far from RC295/DP295

IN  lift: 9,980 mm (0.0393") @ 0 lash    25/55    duration 260  @ 1mm lift (0.04")    LC 105,00
EX: lift: 9,220mm (0.0363")             55,5/22          257,5            LC 106,75   
Overlap 47

I timed cam with adjuster screw tightened until the dial indicator just started to move @ 0.
*******************************************************************************
I have a DP315 cam, now in engine. Values for verification of Dynamans cam card and RC315 numbers vs my my timing.
(This is the later RC315 version)

DP315   Lift: 9,33/9,33 mm @ 0 lash            35/62  68/33   Dur 277/281  @ 0.040"lift   LC 103,5/107,5   overlap 68

DP315  Lift: 8,95/9 mm    @ 0,3mm running lash  28,5/56,5   60/26  Dur 265/266  @0.040"lift   LC 104/107   overlap 54,5

DP315 cam numbers are more understandable for me at recommended lash of 0.3mm

Hey Pewe, thanks!
They are indeed about the same..

What kind of pistons are you running and did you modify the valve pockets for extra clearance?

I've ordered the camshaft. ;-) Looking forward to see what happens with the bike...

[PeWe]

I have used both cams with old RC 836 pistons with deeper valve pockets.  Larger In valves 34mm

DP315 today with JE pistons 71.25mm, 1000cc. Dynoman pistons, something between the CR 10.5 and 12.5:1 to fit the head that has opened chambers, (24.4cc, about +2cc)
They have also pockets for hot cams.

[Ilja]

Hey Pewe, did you measure valve lift at the cam lobes or at the valve tappets? (adjusting bolt / stem end)

I can now simulate dyno runs on my laptop so I can change from one cam to another and generate the results.. but since this engine has a certain rocker arm ratio, im not sure about the lift.

Thanks! 

[Ilja]

According to my computer the difference between stock cam and dp295 is minimal...
This is for non turbo 836cc with 9.5cr f2 head and cvk32 carbs.
I have to do a bit more research to find out if somethings holding back the cam.. 

[gschuld]

The valve pockets in the Cruzin image pistons are very shallow, just like the stock pistons.  I had a set, and milled the valve pockets deeper for a higher lift cam.  The 295 cam has a pretty tall intake lift, and if I were a betting man I'd say you will have contact...

I'd check in with Mark Paris(Hondaman), he has installed a few sets of those pistons and would know what the max lift would be without resorting to big head or base gaskets.

George

[PeWe]

Hey Pewe, did you measure valve lift at the cam lobes or at the valve tappets? (adjusting bolt / stem end)

I can now simulate dyno runs on my laptop so I can change from one cam to another and generate the results.. but since this engine has a certain rocker arm ratio, im not sure about the lift.

Thanks! 

Measured on valve retainer.
DP295 has probably too high lift for those pistons. Few cams have higher lift on the Inlet side

[Ilja]

Just installed the cam, doesnt seem to bind anywhere.. (remember i have the f2 head and the oem f2 pistons have a high dome... im using flat tops..)

The stock webcam timing marks seem off though...
Ive timed it at around 30/48 for intake valve now with 0 lash..
The card says it should be 19/46 @ 0.05".

But the alignment marks look slightly advanced at TDC.. something like 5°.
One tooth seems to advance it 10° so I'll settle for 48° IVC.

[MRieck]

What's your valve to valve clearance at overlap?

[Ilja]

I have no idea, didnt take the head off..
Should I be worried about that?

[Jerry Rxman Griffin aka MuthaF'er]

Michael, how do you measure that?

[Medyo Bastos]

Michael, how do you measure that?

uh, huh 

[Ilja]

Revving high and then check if it will still idle.... 😋😂

[Ilja]

Al-ways...

[MRieck]

Michael, how do you measure that?

I install the valves (with light springs) and the cam and spin it by hand. I use a feeler gauge at overlap when both the exhaust and intake are open and right next to each other. .040 is considered minimum though I have run it down to .032 with good, fresh springs and lighter valves. I know Stetson ran his race CB down to almost .020 with Ti valves. That's to close for me but it worked.
 Larger valves, valve job, cam duration and cam timing can effect the clearance. It is really only a problem in 2 valve heads...4 or 5 valve heads have a shallow valve angle and smaller valves.

[MRieck]

Ilja....I don't want to sound like a jerk but the#1, #2 exhaust valve springs and #1 intake valve spring appear to be upside down. The tighter coils should be on the bottom.

[PeWe]

Good to know, Mike.
What can happen when springs are upside down?  Or is the worst thing if all springs are not mounted in the same way and different tension of the springs?

[frodef2]

Larger moving mass. It would defeat the purpose of lighter valves and retainers. just a guess.


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[Ilja]

Someone interested in a dp295 cam?
Rode it for 10mins, didnt like it at all...
Doesnt work with the turbo setup, all bottom end is gone and gained nothing on top. 😂

Should have left the bike as it was... but then we would have never known I guess.

[Ilja]

Ilja....I don't want to sound like a jerk but the#1, #2 exhaust valve springs and #1 intake valve spring appear to be upside down. The tighter coils should be on the bottom.

What! Are you pulling my leg here?
Seriously, that never ocurred to me.. thought they were symmetric hahaha!

[PeWe]

DP295 is a good cam for a tuned CB750 without turbo. Pistons with deep pockets CR10.5:1, ported head.
You need a cam with almost no overlap at all, right?

Like this Megacycle. (less duration than stock?
http://satanicmechanic.org/megacyclecam.shtml
125-N-T3
.342    215   109.5   Turbo profile Norris design        2/37     .004
.312    222   110     Turbo charged engines. Use race    41/1     .006
******************************************************
Stock  K/F     K7, F2 stock cams are different
 .315    220         
 .313    235
*******************************************************
Regrind a std cam and get more lift?

[Ilja]

DP295 is a good cam for a tuned CB750 without turbo. Pistons with deep pockets CR10.5:1, ported head.
You need a cam with almost no overlap at all, right?

Like this Megacycle. (less duration than stock?
http://satanicmechanic.org/megacyclecam.shtml
125-N-T3
.342    215   109.5   Turbo profile Norris design        2/37     .004
.312    222   110     Turbo charged engines. Use race    41/1     .006
******************************************************
Stock  K/F     K7, F2 stock cams are different
 .315    220         
 .313    235
*******************************************************
Regrind a std cam and get more lift?

Well to be honest I tried this cam because the specs are close to my gpz750 turbo. Bottom end sure felt like that bike  lol, but topend not really . It took away the pleasure of riding this bike.

So actually the stock cam is fine as it has only 10 degrees of overlap.. and I think im already close to or at 150hp at 15psi. I just thought maybe the dp295 will give me the same performance with a bit less dynamic compression..

I'll do a simulation on that norris cam tonight..might be interesting though I think im going to leave the engine as it is now.

[NitroHunter]

Saw an article of that RC 295 cam used in an F-2 with the RC 836 kit. It was a strait bolt in (degreed).
Just a reminder the lumpier 315 will not give safe valve to valve clearance in the F-2 head without sinking the valves. Using downsized 33.5 intakes almost helped. Well it looked OK on the bench...   

[PeWe]

Cam experiencies and how to do! I like that
I'm just back from an afternoon ride on curvy country roads. The DP315 runs really smooth in a K-head, 34mm in, 28mm ex valves. It's very strange that it's idle is much smoother than a RC295 copy, Action Fours SS-1 cams I have used before. DP315 overlap is much more, even when valve lash is 0.3mm.

Not strange that CX-7 and Megacycle 125-20 has rougher idle and behaviour up over 6500-7000 rpm where they waked up in my 836 engine.

[Ilja]

Nice! Jeah over here in the Netherlands the weather was perfect today! I installed the stock F cam back in and my bike was back to normal.. 😎 hammered it at 15psi for a few hours although my a/f suddenly seemed unstable.. richer down low and leaner at WOT.. I might have a leak in one of the vacuum hoses after all that wrenching. Or the fuel pressure regulator is dying.

And after I put the cb750 away I did another hour on my xr650r sm.. boy thats also fun bike. 😎

[PeWe]

Maybe you need one more CB750? For the DP295 ....

[Ilja]

Maybe you need one more CB750? For the DP295 ....

Haha please no more bikes!
Already at 5.5 bikes at the moment. 😰
The cb is done, just fix the speedo and some blinkers... and a set of spoke wheels..and some new paint on the side panels and tank...