The Dyno Run Stats and Questions

[E Lee]

X'ers,
After installing used 80 engine(Valves adj, manual cam chain adj) in 81 did a Dyno Run.
Dyna S Ing & Coils,
K & N indiv. filters,
DG 6:1 with baffle packing removed,
Dyna Jet Stage 3 with 122 jets, needle clips at middle and 2 1/2 turns on idle mixture.
Compression even and good; only smoked a little when shut down from 9.5K rpm.

Max HP at rear wheel 86.6
Max Torque 106.2
The mixture was so rich it did not read on the scale that starts at 10.
A quick removal of entire baffle improved it to 12.4 (even in the sealed dyno room the sound was lets say made the whole bldg vibrate - would get busted in a block!

To make sure all good removed air cleaner to check choke full open.

Tech said I could probably go down to 116 based on this data.
Same info given to rep at Dyna an he was a bit courious, saying should be up at the 128 area stating to much oil on K&N - "nope".

???? any other cause for such a rich condition ????
???? anyone else out there do a dyno run with simular equip an result????
Thanks,
Later,
Ed #5428

[Ric]

My 80 CBX has:

Dyna Coils
6:2 Kerkers
Individual K&N's
Newly reworked valves, excellent compression.
Newly reworks carbs, excellent tune
Stage 3 jet kit.

Dyna jet recommended 130 main, way to rich !!! By the numbers 122 mains are also way to rich. I worked all the way down to 117.5 mains and pilots out 2 turns. The needle clip is on the middle slot.

I haven't dyno'ed mine because at the same time I was doing this I was in communication with another fellow who was in the middle of doing much the same setup. He was using a dyno & a sniffer. I don't recall what his exact numbers were (91 rings a bell ?) but we ended up with pretty much the same setup. I don't think my bike could run any better. It's very strong and responsive. It pulls strong starting at aboug 3,800 rpm and really kicks in between 6,500 & 7,000. From there it never looks back all the way to redline.

Judging by your setup, I'd recommend jumping straight to the 117.5 mains and the middle clip position.

One last very important point (you may already know). With the individual K&N's make sure you run the engine case breather hose well away from the carbs. If you don't they'll suck in the nasty stuff and you'll never get the motor tweaked in to perfection. I ran mine all the way back past the swing arm pivot. Make sure to keep the hose running downward after it leaves the mounting point on the case so oil won't puddle up in it.

[sr71cbx]

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[E Lee]

Thanks,
I ordered 116 and 118 from dyna jet. $2 each might as well.
With the extension bolts I put on the carb bowls should not take long since don't have to tilt.
I will check/play with timing - have to find a degree wheel.
Yes, the crank case breather needs to be run way back there, I gag when at stop lights.
I think I might get into the 90's with a cleaner mixture.
Though my V65 sabre will leave the X in it's dust, I don't get the looks like the X!
Hey, Mark, you get the pictures?
Later,
Ed

[E Lee]

Thanks,
I ordered 116 and 118 from dyna jet. $2 each might as well.
With the extension bolts I put on the carb bowls should not take long since don't have to tilt.
I will check/play with timing - have to find a degree wheel.
Yes, the crank case breather needs to be run way back there, I gag when at stop lights.
I think I might get into the 90's with a cleaner mixture.
Though my V65 sabre will leave the X in it's dust, I don't get the looks like the X!
Hey, Mark, you get the pictures?
Later,
Ed

[sr71cbx]

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[E Lee]

Mark,

What about the Oregon meet. You going that way?

Later,

Ed

[Ara]

Anyone know of a good shop in Houston to do dyno tuning? I have a set of chrome 6-2 Kerkers that I want to install and have the bike rejetted at the same time.



Ara

[jt]

Hi Ara,

Honda of Houston just had a dyno day on the 3rd of this month. But give them a call they have them all the time.

[Passx]

Hi Ed,



The guy Ric was talking about was me and our bikes are setup very similar, 6-2-1 header (1 3/4 or 2" baffle, no difference but noise), 79 cams (degreed in, int +4), Ind. K+N's, Dyna coils, Dynajet stage 2 kit w/ clip in the 4th position and 113 main jets. I just redyno'd mine last weekend and can tell you that it's still reading rich at about 10.5-1 a/f. I had the replacement k+n in it and 98 mains and it was perfect starting of at 15-1 at idle & just off (just like factory) and then went to 13.3-13.8-1, never fouled plugs got great mpg's and then I had to screw with it, oh well. It looks like about a 110 main jet and I'll move the 1 washer that I have on the bottom of the clip back to the top because it's rich from the git. The idle mix screws always end up at 1 3/4 - 2 turns out. The dyno shop that I deal with just recal'd their dyno and installed a new Lambda sensor which needs replacing at about 300hr intervals. Don't get to hung up on the numbers that come out as much as the trends, the dyno's usually have a +/- 1 percent accuracy so you can see why it's easy to be off a little. Mine picked up 2 hp at peak which really disappointed me for the effort made but will do a lot more once the jetting is right, the really great thing is that from 2- 6500 there's 5-6hp and torque more than before. Also Mark is right about the timing and more dyno time, seat-of-the-pants will lie to you everytime. I've been tuning hipo stuff for a lot of years now and I never am surprised when things aren't as they appear. Cheap dyno access was a great gift. Good luck and if you have any ?'s feel free. Also while your in the carbs pay some attention to getting the floats the same. Also once you get the jetting right your bike should get a little cold blooded and if it's a little on the lean side weather sensitive, anyway good luck



Steve P. #5220

[Ric]

YES !!! It was Passx !



How ya doin' Steve ? What's the matter dude, can't you leave well enough alone ? Do you live in Denver Co. ?



Last I remember you were on 115's (I thought). I've stayed with the 117.5's. I never dyno'ed or sniffed but the plugs are always a nice light color and she's running great. No rough spots, easy to start, pulls hard from the git. Maybe it's the 80 cams ?



Anyway, good to hear your still out there in the electron stream.

[EMS]

When you do a Dynamometer run, don't get hung up on peak HP. It does not mean much for actual street performance. Rather look for improvements in the useable rpm range between 2000 and 6500 rpm. Here you want a flat torque curve, high over a wide range of rpms.

I accept "only 2hp" at peak for 5-6hp at mid-range anytime. And remember: TORQUE is what you feel as the response of your bike when you twist the grip, not HP!

[E Lee]

Hey guys,

Some great advice.

I just put in the 118s and will do a test ride.

Going further down in jet size will only be after all the other checks, adjusts etc... Then back to the dyno. I have to keep in mind it's going to get hot soon, rather have that reserve rich than climate induced; Hot 100 degree (density altitude), over lean.

No ultimate HP is not the goal, a good running engine first, it's an 80 so midrange is OK by me; cost to much to spend a lot of time up Big HP rev range.

Question, any tips on fine tuning the idle mixture screws? I'm at 2 1/2 now.

Clear tube float check all even and right on the seam at middle carb.

Later,

Ed

[Passx]

Ed,



A well tuned engine will always make best power and efficiency and have maximum life, that means timing, jetting and cam timing is matched to your combo. I set in on a Dynojet seminar a year or so ago and I must say that I've been doing this stuff a long time but was amazed at some of the things that I learned such as the only true power gains to be made in a engine come from compression or camshafts the rest is just reclaiming lost parasitic power. I have always approached engine building and tuning from a perspective of making each piece compliment the rest of the combo and usually been rewarded with more HP's AND MPG's. Jetting is one area that people tend to go too rich, 14.7-1 air/fuel ratio is ideal but in a carbureted application hard to maintain and not get to lean which will "hole" a piston, to much fuel and you'll wash the cylinder walls and cause excessive wear between the walls and rings. The stock CBX runs about 15-1 a/f ratio at idle and just off for emissions and then goes "pig" rich to around 10-11 to 1 a/f which was great for Mr. Honda's warranty reduction by keeping the cylinders cool and the performance constant in varying weather but bad for mpg and longevity. If you can get your bike to around 13.5 - 14-1 a/f you'll have the best overall performance, make the most HP and mpg's. My 80 before I screwed with it had just a 6-1 header and replacement K+N air filter and a D-Jet stage 1 kit, it required a # 98 main jet at a 13.4-1 a/f ratio and picked up 5 hp over the recommended 104 mains and picked up from 23 to 30 mpg to 52 on a steady cruise. Adding 79 cams picked up another 5 across the board and leaned the same 98 main jets to 13.7-1 a/f. Anyway I've rambled enough and all I'll say is that you need to dyno it to get the carbs right, seat of the pants will always lie to you and as EMS said don't get hung up on the total numbers just look at the trends. Good luck



Steve P. #5220

[E Lee]

Wow, there is some great knowledge out there. The 118 seemed to help. I'm getting some mid range "goooowwww" rolling on from 3500 and goes away at 6500. Part of it was timing to advanced and think; after some riding needles need to go down some also. Dyno time is costly but don't want to guess, to much and pay more the hard way. Plugs are looking a bit dark still.

I'm just wondering what Dyna Jet had in mind with the original stage 3 jet supplied?

I might just look through the supply and try 112+-.

Later,

Ed