Topic: Post your Dyno Graphs here.

[flatlander]

well you know, i was thinking i may try a different cam and see what i get. but that will be a winter project 

[MRieck]

well you know, i was thinking i may try a different cam and see what i get. but that will be a winter project 

As long as you enjoy your bike Attila....that is all that matters brother.

[flatlander]

i enjoy it a lot, it's great! but i can't stop tinkering further with it. i mean, i can stop for a while... while it's summer i ride it instead of installing new stuff

[Tews19]

mrfish2, good idea to do a before/after!

here's my CB550F with the below works.
graph is from about 400km after assembly.



pistons: wiseco 59mm 10:1 CR
cylinder top decked -0.004in

MLS head gasket 0.030in

head:
mike rieck porting stage 2+
-0.004in decked
serdi cut valve seats
+1mm intake valves
tapered guides
kibblewhite valves/springs/ti retainers

camshaft: megacycle hardweld 126-00

intake manifolds matched to ports

carbs: stock 069A

original airbox, with stock airfilter

exhaust: original 4-into-1

ignition: boyer-bransden micro power

Is 54 BHP at the crank or wheel? Is there a difference? Now I'm highly interested in swapping out to thone pistons is that the case. 10 more hp then my 605.

[scottly]

Tews, do you have a ported head? I doubt you will get 10 HP from pistons alone. Yes, there is a big difference between rear wheel and crankshaft HP, but most dynos measure at the rear wheel. It does seem that the European dynos are somewhat optimistic, though.

[scottly]

I never did post my "after" results on this thread.
836 TRW pistons, mystery cam with about .320" lift, Weber carbs with 30mm chokes, unknown, possibly Winning 4-1 exhaust, and stock K1 head. The top end was last touched in 1979.
 

[Tews19]

Yes Scott my head is the exact same set up. MReick also did all the head work as well. That's why I was like damn! The only difference is the cam. I have the 650 cam.

[scottly]

Can you post you graph here? Apologies if you already have.

[Tews19]

Let me see if I can find it. I know I posted somewhere around here.

[flatlander]

Is 54 BHP at the crank or wheel? Is there a difference?

it's at the rear wheel. there is a difference, as scottly says. i think the rule of thumb is that there's about 10% loss in the drive train.
would be good to see what you get with the 650 cam. apparently (i haven't confirmed this through testing) even a mild performance cam like the 126 should be somewhat better than the 650 which was made to control emission, instead of maximising power.

[Tews19]

Here is my graph. As you can see my carbs weren't syncd

Sent from my SM-N920V using Tapatalk

[flatlander]

that's really tiny. what does it say? and what was your setup there, next to the 650 cam?

[scottly]

Flatlander, did you do a baseline run before all your mods?

[flatlander]

yes, here: http://forums.sohc4.net/index.php/topic,134863.msg1522043.html#msg1522043

[scottly]

Attila, sorry to burst your bubble, but I don't believe in the accuracy of your dyno tests. Your baseline of 44.6 HP and 30.7 N/m (22.64 ft/lbs) is in stark contrast with mrfish's 37.69 HP and 25.86 ft/lbs, and he had a 650 cam and exhaust mods. Even if you were still producing 22.64 ft/lbs at 9500 RPM, the HP would only be 40.95. Your "after" results show an increase in torque of more than twice the baseline, more than my 836, and the HP peak is supposedly well below 8000 RPM. Something isn't quite right here...

[flatlander]

hmmmm.... the only thing i can do then is find another dyno to cross-check.

[BAmann]

Hello, I found this thread and thought I would add a dyno results from last weekend. The engine is a fresh 915 with Keihin 31mm CR Special carbs, with a Kerker exhaust.  It put out 80HP @ about 8400rpm and about 52 lbs of torque @ 7500 rpm.

[scottly]

Hello BA! What cam, and was any head work done? Where in AZ are you?
Scott

[Jerry Rxman Griffin aka MuthaF'er]

Hello, I found this thread and thought I would add a dyno results from last weekend. The engine is a fresh 915 with Keihin 31mm CR Special carbs, with a Kerker exhaust.  It put out 80HP @ about 8400rpm and about 52 lbs of torque @ 7500 rpm.

Good numbers. I have a similar build I hope to dyno eventually. RC315 cam with JMR Stage 4 head work. May I ask what cam you are running and what if any head work?

[MRieck]

 A longitudinal look at my engine development. The second 915 chart is with the installation of a 5mm valve conversion kit, CR-31's and more extensive porting. First and second chart have a 125-75 Megacycle cam. Third chart is a Megacycle 125-30 with RS-34's and 71.25mm pistons

[gschuld]

Mike,

Have you gotten a chance to change the cam(125-35) out for the 125-75 on your 1005cc engine like you were wanting to do?

George.

[MRieck]

Mike,

Have you gotten a chance to change the cam(125-35) out for the 125-75 on your 1005cc engine like you were wanting to do?

George.

George....I am struggling to get stuff done like your flow work which I have been remiss....(which isn't even appropriate because of my lateness). European customers with loads of headword etc etc....nuts.

[MRieck]

Mike,

Have you gotten a chance to change the cam(125-35) out for the 125-75 on your 1005cc engine like you were wanting to do?

George.

Plus.....I would not recommend that 125-30 (35) cam. It is responsible for the weird spike early on and poor idle. I'd stick with the125-70(75) cam.....if ANYBODY says it isn't good it is because they DID NOT time the cam. Some people (shade tree) pretend they know about the intricates of engines BUT in reality do not not. Like a farmer that throws manure.......if you throw enough stuff will grow.  Best cam built for the CB750 with good mods.......I have talked a long time with Jim Dour about it's heritage. He also said anybody anybody having problems with the cam doesn't know how a cam has to be set up.

[gschuld]

To be fair, the 125-35 was meant for road racing.  At least that is what Mark McGrew used it for based on Jim Dour’s recommendation(high compression 762cc race engine).  Mark won quite a few races with that cam.  But for his purposes, lack of smooth idle and pretty significant dead spot around 5000 or so wasn’t a big deal considering he was running a Nova close ratio trans and generally staying between 6000-10,000 rpm.  That cam sure seems to pull clean and strong from 6000-10,000.

But for a streetable cam, oh sure, not very pleasant😉

I am though curious to see the dyno comparison between that cam and the 125-75.  I’d guess a hp peak a little lower and a reduced dead spot.


George

[MRieck]

To be fair, the 125-35 was meant for road racing.  At least that is what Mark McGrew used it for based on Jim Dour’s recommendation(high compression 762cc race engine).  Mark won quite a few races with that cam.  But for his purposes, lack of smooth idle and pretty significant dead spot around 5000 or so wasn’t a big deal considering he was running a Nova close ratio trans and generally staying between 6000-10,000 rpm.  That cam sure seems to pull clean and strong from 6000-10,000.

But for a streetable cam, oh sure, not very pleasant😉

I am though curious to see the dyno comparison between that cam and the 125-75.  I’d guess a hp peak a little lower and a reduced dead spot. Also....after measuring the cam the advertised full lift numbers were not achieved.


George

i Do not anticipate any less peak HP George and I expect more torque as well.....it is a good cam.