Topic: Just had a Dyno run on the bike

[Grabcon]

Just had a Dyno run on the bike today. This is a 74 CB750 K4 stock motor and carbs and airfilter. Exhaust is a combination of cb750F 4 to 1 and a Mac muffler.

I had three runs on the dyno all at or near 52 hp rear wheel. Test went to 8K RPM. The tech said that the motor was still pulling at 8k.

This motor has 21k miles on it and ran really well on the dyno. Solid runs and no farting and popping. I am in Denver so there is an altitude issue here so the HP may seem low to some.

I would just like some thoughts on how this test compares to others. What kind of HP do you have.


PS; this is a barn bike that sat for 5 years and other than plugs and a good carb cleaning and sync. I have do nothing, not even timing it.

[scottly]

There is a thread on the high performance and racing page dedicated to dyno tests. If you got a printout, that is the place to post it, as well as see others test results.

[david 750f]

52 hp in Denver is a great running bike. You loose about 3% per 1000 feet of altitude.. But all dynos are different.

[HondaMan]

Actually, 52 HP on the rear wheel of a K4 at 5000 feet is quite good! They were often 50 HP at sea level, back in their day. 

[Duke McDukiedook]

You should do a full tuneup before you think about touching carbs.

[bollingball]

Grab: If you don't mind how much did that dyno time cost.

                     Ken Thanks in advance

[Grabcon]

Guys thanks for the input. Is there a formula to translate Wheel HP to Crank HP?

Bollingball:  It was at an event sponsored by a local cycle shop and one of the deals to draw people was the Dyno test. The cost was $20 for the dyno test. This was not a full blown test. Meaning I didn't get a torque curve or exhaust readings. If I want that I can go to their shop and get the full test for I think $40. Then that's where they then want to do the full monty with tune up, crabs, jetting, etc.

[bollingball]

A lot cheaper than I thought allways wanted mine done but thought it would be in the hundreds
Thanks for the reply.

                      Ken

[Jerry Rxman Griffin aka MuthaF'er]

Welcome Grabcon.

Boy, I'd sure like to know where/who this shop is?! You ain't getting off that easy  Only dyno I know of in the Springs is the Harley dealer. The service manager said he'd do my 750 when I'm done with it but said it would just be the report and no work which would help me tune the carbs. They also told me my 83hp/94 lb torque on my Fat Boy that came from their dyno IS an adjusted figure for altitude. I'd sure like to do another run and compare.

[Gearheadgreg]

Guys thanks for the input. Is there a formula to translate Wheel HP to CrankHP?                                                                                   About 10-12% loss from the drive train, on a motorcycle,, My pull's are $100 bucks up here from the Doctor,, but i get 10 to 20 pulls and some time to turn some screws, But the AFR testing is most important and for me it has solved many problems,and picked up several HP and TQ, (145 hp 127 Tq.) W/O the NOS... also by the use of Video i picked up the sound of a loose Blower belt you can hear it @ 7000 rpm on this Utube,, i should be at the 160 hp mark now,, Dr Dyno has done all my pulls and is one of the best in my state (great guy also) 3 pulls 4th gear-5th gear,,and AFR testing on the last pull @ 65 MPH 100 mph and 152 mph she was lean up top end, had to Drill my main to "260" 45HSR flatslide. http://www.drdyno.com/ dyno

[Grabcon]

Jerry; Epic Motorsports out of Longmont, CO. The only thing I know about these guys is one meeting at this Bike Night event that I attended. Thet have pricing on their website.

http://epicmotosports.com/

[brewsky]

Local honda shop had a dyno day yesterday....2 pulls for $25, so I brought my 750K8 for a try....one pull @ 1/2 throttle and one @ Full throttle.

I had replaced the previously installed UNI pods with stock air box and K&N filter, and thought the pervious up jetting would be too much...and it is!!

127.5's and 6 shims under the needles too much for this setup...stock motor, (42,000 miles), Mac 4/1 with baffels, 2,500' elev

[supersports400]

Hi Brewsky,

Seems you got the taste of it ?
What is a run costing you on a normal day ?

Jensen

[Simpson]

Local honda shop had a dyno day yesterday....2 pulls for $25, so I brought my 750K8 for a try....one pull @ 1/2 throttle and one @ Full throttle.

hehe, Hillbilly Cycles... that's funny.

[brewsky]

Hi Brewsky,

Seems you got the taste of it ?
What is a run costing you on a normal day ?
Jensen

A dyno tune is around $350.00, and the last time I asked I believe a single pull only was around $50 or so.

They wanted to charge extra for the A/F readout at the shootout, but I finally talked them in to throwing it in.

I plan on switching the Dynojet from my CA77 to the 750 for jet tweaking.

[brewsky]

Local honda shop had a dyno day yesterday....2 pulls for $25, so I brought my 750K8 for a try....one pull @ 1/2 throttle and one @ Full throttle.

hehe, Hillbilly Cycles... that's funny.

Yea, and what's better, is my record for LOWEST HP is still posted there for my 305 Dream...15.4!
They had to shut the dyno down when my friend ran his turbo Busa, I believe it was in the 350 range!