Dyno Results

jensen · Post by **jensen** » Sun Oct 25, 2009 8:57 am

Hi,

That's not to say, depends on the scales on both sides.
But like a said, I expect the curve end around 9000 rpm, instead of 6000 rpm, it still make no sense.

It's good to know that all other things are right, so the info in the curve reflects the power curve of the engine not colored with problems due to the points mentioned in my previous mails.

Tonight I will scan a resent curve of my C77 and dump it in this thread, so you can compare.
Now, the weather is too nice this time of year, to sit down behind the computer, so I will take my CB72 for a ride,

Jensen

jensen · Post by **jensen** » Sun Oct 25, 2009 1:54 pm

Hi,

As promised, a run from 20/09/2008 of my C78 '64.

Engine rebuild 30.000 km back, new crank, pistons (0.5mm over), new head and perfect gearbox.
Carb rebuild complete, everything important replaced by original Honda parts, including needle.
Paper oil filter conversion, no spinner filter (read my other threads about it if interested).
The head is flowed a bit (intake channels) to make them exactly the same, internals are new.
It has early cams and has the early two piece stainless steel mufflers.
Full synthetic oil (10W50) super-bike oil does the job inside.

Engine revs to 10.000 rpm, and feels strong all the way. When you open it up quick, you will get the massive mountain between 2500 and 4500 rpm. In the midrange I have it a little rich (needle) for better acceleration. It stops pulling at 7500, after that it will take a long time to hit 10.000 rpm, it sure doesn't feel as rev happy than the CB72 in this area.

In it's days a c77 was a sport bike, now it's not anymore compared to modern machines.

This typical engine runs good and I can drive it on the highway (120 km/hr). It's not that I wanted a high performance bike, but to get as close to perfection as possible.

I never saw other dyno runs from a C77, other then mine, so it's a bit of experimenting

Before you start comparing, please notice that the torque is koppel in dutch and we use newton meter.

have fun,

Jensen

brewsky · Post by **brewsky** » Sun Oct 25, 2009 5:57 pm

Thanks for posting your graph, and it appears you have a very strong engine compared to stock advertised numbers.
I cannot seem to find any other dyno results posted for the single carb 305 engines either.
Now I am convinced the tech did not max out the RPM on my run and I need to find a supplier of jets for Keihn carbs.
I agree today was better for riding than sitting in front of the computer trying to do formula conversions!...so I spent it on my FZ1, and almost came home with a ticket!!
I should stick to the CA77!!
Regards,
Brewsky

jensen · Post by **jensen** » Mon Oct 26, 2009 3:22 am

Hi,

yes it's in great shape, it does 98 miles / hour, see this thread :

Honda305.com Forum -> Honda Dream - CA72 | CA77 | CA78 - dream 305 top speed ?

Enough to get a ticket too, I guess.

My CB72 '67 does 103 miles / hour, but the engine of my CB72 is a little tweaked.
It revs above 10.500 rpm, and it doesn't stop there. A few specialists on this forum say I could do 11.000 to 11.500 without destroying it, but I rather stick to 10.500, because of the "accuracy" of the rev counter and the money involved.

My standard CB72 '62 isn't that fast, I like to drive it the way it is, it's not my daily driver, my CB72 '67 is.

It's a pity that the C77 lacks a rev counter, but that's the way it is. I stop pulling around 85 miles / hour, it's enough to ride the highway here in the Netherlands.

I think it's best to do another run, this time after the tech found out why the rpm scale isn't giving the actual rpm of the engine, it shouldn't be that difficult to find out for him.

If it's only the factor 2, he didn't rev it up, but looking at the curve, I doubt that.

Again, it's very good to put the CA77 on the dyno, maybe others are inspired too.

It's a relative cheap and and quick way of "looking" into the engine and see how it's doing.

Like I stated in my previous mail, first get the air fuel mixture on 13 or so before hitting revs above 6000 a 7000 rpm, never let these engines run too lean, you will destroy the engine, no matter what kind of oil you use.

Jensen

brewsky · Post by **brewsky** » Mon Oct 26, 2009 4:32 am

I will have it done again once I find some jets to work with, and fix the clutch.
The reason I don't think he reached peak is the graph doesn't show a gradual decline after the peak?
I purchased some different size mains from a local supplier (different brand) but it appears the thread pitch is different.
I agree the dyno is the way to go for tuning and for $20 for two runs is cheap enough.
(business is down now!)
I have even considered purchasing one of these to "see" into the engine while running.
Do you have any experience with them?
http://baconsdozen.ecrater.com/product.php?pid=4057790

jensen · Post by **jensen** » Mon Oct 26, 2009 5:55 am

Hi,

I knew these existed, but I never used it.

Well, 20 USD for a run is a bargain, but only if it's useful.

No, that's why I asked if he pulled it into the high regions, the torque curve should go down around 6000 a 7000 rpm, like mine does, that's normal.

I think he has a mechanical rev counter as well, ask him to use that one to calibrate the dyno results .

Maybe the tech wasn't sure (scarred) how far he could pull it.

jensen

sdaigle240 · Post by **sdaigle240** » Mon Oct 26, 2009 10:29 am

very nice to see your efforts. cant wait to see some legit curves. never worry about power numbers, its all about those curves!

interesting little bit about the carbs, now i understand the lean peaks down low.

perhaps this is taboo with these 305's but has anyone expirimented with advancing the base timing for power gains? apples and oranges here, but i was able to add almost 9* to my car with out detonation before it was turbo. yeilded almost a 20% gain on others dynos with similar setups.