Topic: Dyno tune questions

[Shtonecb500]

I found a place close to me and they said they would be happy to do my bikes when I'm ready. It's going to be like 90/ hour.

I don't even really understand what is going on with the machine, or what they are doing, I imagine it's going to take more time with a carburetor bike rather than fuel injected, right? So that's going to cost more...How do I make this experience as cheap as possible before I take the bikes to them?

Is a dyno run just testing, tuning, or both? Can I just get the bikes tested as they sit and not have them try and tune anything?

I saw packages offering three runs for "x" amount of dollars, almost 1k for unlimited runs for the day.

I wanted to see what the k1 puts out because I think its got a bore job, would it be cheaper to buy a gasket and just open the motor to determine this?

Also want to put my black 750 on the dyno after i do the 836 kit...those are the two bikes i wanted to run.

What instruments are they hooking up the bike and measuring?

[seanbarney41]

These are mostly questions you need to ask them.  It is unlikely they will even be able to set up a fueling chart, especially if you do not pay for the extra time to set up the sensors required for a non-computerized carbureted model...that they likely do not even have.  Hopefully, they are willing to work with you, given the possibility of further business.

[BenelliSEI]

I’ve used an engine dyno on fresh built race motors (mostly small capacity 4 cyl.), many times. Generally we monitor temperature, oil pressure, exhaust gas temp. in each cyl., and RPM. Great place to do initial “run in”, check for leaks, and then a few pulls to measure torque and HP against previous builds. Often a small adjustment on main jets (up or down), total ignition advance make small improvements. The real advantage is testing different carbs, intake or exhaust manifolds etc. Usually time consuming, even if your well prepared. Also, it’s stressful. Any minor problems will be magnified and a few hard “pulls” can end in disaster......

My suggestion (and I’m sure others will have more/different opinions) is; save your money and buy a new set of tires or something else you need. The tuning specs for our bikes are pretty well defined and if your bike sounds and feels right when your riding it, that’s the best measurement.

[seanbarney41]

Also, hp numbers alone will likely only reveal more questions as to what is inside an unknown motor.  Low numbers?=a worn out poorly tuned hotrod or a healthy stocker, high numbers?=perfect tuning stocker or a mediocre big bore.  Within reason, much over 70hp means there is likely "something" going on in there

[Stev-o]

My suggestion (and I’m sure others will have more/different opinions) is; save your money and buy a new set of tires or something else you need. The tuning specs for our bikes are pretty well defined and if your bike sounds and feels right when your riding it, that’s the best measurement.

I agree with John, your money is prolly best spent elsewhere.  You could burn through $90 x 8 hours pretty quick if you want to make changes they are not prepared for [multiple size main jets].

A lot of us just use our "Butt Dyno" more fun and free!

Ask f they have a sensor they can insert at the end of your exhaust.

I believe Scottly has one in his shop. Dennis brought his salt racer there recently. I've invited him to join in this conversation for his expert opinion.

Scott?

[Tim2005]

I'd go for it. A run here is testing & a bit of advice & guidance, maybe help you to change any jets too. Ask them what they will do.

They will measure air fuel ratio at least so it'll tell you how your jetting is and should identify any other problem areas. Give it a good service beforehand. 

[seanbarney41]

Tim, I think you are in the UK?   Here in the states most dyno operators do not expect to touch anything carbureted and expect to be able to not need any a/f ratio info not provided by the bike.  They might have a wideband o2 for certain proprietary systems, not likely to have a tailpipe probe.  These shops really only exist to sell Harley aftermarket "performance" parts, i.e., loud exhausts.  This is the stuff Shtone needs to find out from them before booking time.  These guys might not even realize that points ignition CB has no rev limiter for them to gleefully bounce off of.  Of course, wxceptions do exist, especially as Shtone's geographic area is a U.S. center of gearhead resources and knowledge...

[Tim2005]

Sean, great info, I wouldn't of thought that they'd be without tailpipe a/f measurement kit. Yes he definitely needs to check what they offer

[Shtonecb500]

here is email from the shop.

Hi Ashton,
 
Yes that is certainly something we can do. I had a cb650 once upon a time.. tuning those can take some time as they have 4 carbs to fiddle with, but we can for sure get you running right!
Dyno/shop time runs 90/hr $. Would definitely get an assortment of jets in and make sure the boots are good to go for taking the carbs on and off before we got on the dyno. We are a Sudco dealer so we could source quality carb parts for you as well if you wanted. Feel free to reach out anytime to talk about it and we can get you on the schedule when you’re ready.
 
Thanks
 
 
Will Wildner
 
Great Lakes Supermoto

[Shtonecb500]

I know he says to call him but I just wanted to kick it around with you guys first - Thats a lot of money to throw at a couple leisure bikes so wanted to talk it out before wasting the shops time.

[seanbarney41]

well, that sounds surprisingly promising...but yeah, just keep talking to them to find out all that they offer.

You know how to change roundtop jets without pulling the carbs out of the bike?   Many don't/won't.  Even I have not managed needle clip changes without pulling carbs.  Make sure those tiny screws are not stuck.  I would certainly bring special tools you know work good like JIS drivers etc.

[Jerry Rxman Griffin aka MuthaF'er]

Yeah, that sounds like a decent shop. I have used the dyno mainly to set the carbs then to see the HP and torque readings on my highly modified engine. Stockish engines are easier. I don't like to do plug chops. The dyno is MUCH easier and accurate. My guy won't do carbs. I take it home and adjust my carbs based on the air/fuel ratio on the printout. May take it back, may not. Depends on how it runs with the changes. They insert the sniffer into my 4 into 1. I don't know how they could read 4 pipes unless they do 4 separate runs. Getting your carbs off and back on at $90 an hour can be expensive. If it's close, you may just take it home and make minor changes yourself

[scottly]

 Can I just get the bikes tested as they sit and not have them try and tune anything?

I wanted to see what the k1 puts out because I think its got a bore job,
Also want to put my black 750 on the dyno after i do the 836 kit...those are the two bikes i wanted to run.

What instruments are they hooking up the bike and measuring?

Yes, you can just have the bike tested, then do any adjustments later, if needed.
I normally do at least 3 runs to get an average, unless there is obviously something wrong, so doing a 4th run to check the AFR with the probe up each pipe would only take another minute or so. This will only show the AFR for WFO throttle, which is controlled by the Main jet.
Expect to see about 55 RWP from a stock 750, and about 62-63 from a 836 with no other changes.
Once the bike is on the dyno, inductive pick-ups are clamped on the spark plug wires on the two wires that share a coil, like 1&4 or 2&3. This provides the RPM signal to the dyno, which is required to calculate torque. The only other connection is the O2 sensor probe, which on my dyno is a 30" long piece of copper tubing that gets shoved up each tailpipe.

[PeWe]

Dyno visit will show the AFR wich is more important than WHP.
Make sure that the dyno guy will run to see AFR at idle and slowly increase throttle, stop during increase, release a little and continue up. This procedure for each 500 rpm.

This will show the jetting and where it need to be corrected.

A too rich needle will be revealed by slowly decrease throttle in needle area.

Needle area depends on carbs. My Mikuni TMR32 has a needle area from idle to 3/4 throttle lift.
I have had wrong needle model during several years impossible to get right with other jets.
Finally right model found in stock in UK which need a new Dyno visit

Stock CB750 much easier to get right.

Maybe your carbs are more adapted for your engine and more forgiving.

Only  WOT runs will not help carb jetting.

I have jetted my TMR's, dyno shop had not all jets and no really support of 4 cyl jap bikes.
Specialized on Harleys, street as well as dragbikes.

My runs of 1 hour each time. He notify how engine behave during the WOT runs and the difference when letting it cool down a little after a few hard runs, 1-2whp more after a little cool down and WOT again.
Cylinder swell when hot.

I get my homework where to change. I usually look at the AFR numbers on dyno screen during idle to full in slow steps.
I have been horrified how rich it has been running despite it ran nice an even. 11.5-12.5 not good at idle or when cruising. Fuel wash oil away with excessive wear. Not only carbonized chambers, piston domes and ex valves/ports.
Needed to open engine and clean it. Frame kit a huge help.

 12.8 at WOT another thing. 

He is almost fully booked for tuning fuel injection bikes wich take around 5-6 hours each so getting an hour squeezed in for my bike can be tricky. Engine jobs are also booked.

My K6 had 836 during several years.
80-83 whp.
Cam Action fours SS-1 or Megacycle 125-20. No dyno with RC295 but my butt told me better torque and less needs to gear down from 5th when cruising around.

This with ported head 34/28mm valves and 32 mm flatslide carbs.
But bike ran like that in the 80's with stock carbs.
Compression make a huge difference. Not too low.

My K6 has used 1005 and 970 setups the last years. Beside carb jetting increased compression
Result has increased from 90 to 107.5whp.
Last dynos +3whp after cleaning the pod filters.
I have also found the cam's best timing.
Tested more advanced and retarded and lost too many hp.
One time so bad so we stopped  after first run.

[Jerry Rxman Griffin aka MuthaF'er]

Scottly, do you have 4 sniffers? I've only done my 4 into 1 with a single sniffer.

[Shtonecb500]

Thank you for all of the insight. What I wanted to avoid was tuning and getting it right in the shop at 90/hr - this thing isn't going on the track and my bikes have nice responsiveness.  I'll have Phil tune the bikes and take them there to test, will be running 4-1 so will only need one sniffer. I have changed main jets while the carbs were still on and hot motor but never attempted needles and clips as well.

I rather build and tune at the shop and go up there for a few pulls and see what the computer kicks back.

I have a better understand of the entire process now and will be more confident chatting with their  technician, thanks all.