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Author Topic: Saturday 23rd April -CB810cc dyno run  (Read 1060 times)
andy750
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« on: April 21, 2011, 05:37:02 PM »

This Saturday rain or shine (with 70% chance of rain Wink) Ill be riding to Harrys Machine shop - 50 mini from Roslindale (leaving at 8.45am). Dyno scheduled for 10am or just after. If you have the time and want to see a CB750 on the dyno then come along.

Map:

http://maps.google.com/maps?f=d&source=s_d&saddr=27+Conway+St,+Boston,+MA+02131&daddr=Harry%27s+Machined+Parts,+Belmont+Street,+Northborough,+MA&geocode=FRBHhQIdyqjC-ymRhwI6M3njiTHkCPf31Ve3uQ%3BFcsyhQIdloa6-yHSO7zo1i-ISilj3tU2HwrkiTHhkUUFOBGSQA&hl=en&mra=ls&sll=42.280802,-71.682873&sspn=0.057787,0.104628&ie=UTF8&ll=42.281516,-71.656995&spn=0.014447,0.026157&z=16
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CB750K4 (long distance bike)
CB810K2 road racer
DL1000 2003 - ice breaker
Alan F.
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« Reply #1 on: April 21, 2011, 06:42:59 PM »

Although i cannot be present for the occasion I'd like to urge as many gearheads to be present as possible. If you've never seen....or most importantly HEARD a bike on a dyno, you just have to experience it first hand. Will anyone be recording the sounds this mighty beast will put forth? Anyone with decent video gear? 
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Connito
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« Reply #2 on: April 22, 2011, 01:20:50 PM »

Andy, I am going to skip it. The rain doesn't bother me. However, rain with 20+ mph freezing wind and temperatures in the thirties is more that I would like to indulge myself in.

Yes, I know, I am a chicken, I am a pu__y... 

Stop by on your way back for a beer, I mean tea. I found some blinkers, worse than I thought. You are welcome to them. The better ones I have are from later models.

Have fun and take a video if you can. I have a small video camera (Flip) that you can borrow if you wish.

Cheers,
Peter
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« Reply #3 on: April 23, 2011, 04:20:37 AM »

Good luck today Andy! I will be at the Gardner museum for Martha's b'day with my family looking for the painting of  the Dyno at Galilee.
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Alan F.
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« Reply #4 on: April 23, 2011, 08:42:54 AM »

Happy b-day Martha! Everyone have a great day.
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andy750
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« Reply #5 on: April 23, 2011, 02:54:03 PM »

CB750K2
55,000 original miles on the bike

Mike Rieck (JMR) engine:
Bored out to 810cc
Dynoman 295 cam
Ported

Stock carbs
120/40 jets
Stock airbox/OEM air filter
Stock clutch
Oil - regular 10W40 Penzoil - not changed since rebuild.

Added 2 gallons of Ultra 93 on the way to the dyno.

And the result is....





Before the second run (blue line) the bike was strapped down at front and back as the rear wheel was slipping - turns out the rear wheel is either not balanced or out of true - its way out apparently! Anyway on the second run the clutch slipped - you can see where....so possibly a few more HP when the wheel is sorted out.

So powerband is between 5000 -7000 rpm which is exactly where i have been feeling it on the highway. The dyno was done in 4th gear.

Rick did mention the initial lag on the throttle due to the stock carbs so CV carbs or something else would eliminate this. So Bens hot rod should be smoother...not to mention more HP!!

Very happy with the numbers! Thank you Mike!!

cheers
Andy
 

 
« Last Edit: April 23, 2011, 06:58:45 PM by andy750 » Logged

CB750K4 (long distance bike)
CB810K2 road racer
DL1000 2003 - ice breaker
andy750
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« Reply #6 on: April 23, 2011, 06:08:36 PM »

Comments from Mike from the Main Forum

"I witnessed "the event". Wink Several things would have added 3 to 4 more HP. 1...better clutch springs, 2, an oil change prior to the run. 3, A rear wheel in spec and a better rear tire. The bike sounded good on the dyno.....I was 6 feet away but doing some other business. I'd like to say the pistons in the engine are very old Wiseco's that I couldn't get the top ring for anywhere. I went through a big process of installing a ring "spacer" etc, etc, etc. I don't want to talk about that as it was a PITA. Anyway....it was a top end build that turned out nice. I'm very happy Andy went to the dyno...in the pouring rain I'd add (hard Scott he is) Wink
  Remember that on a good day these engines had 50hp or so. When you start getting 80hp with only a 30% increase on displacement keep it in mind. Wink"
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CB750K4 (long distance bike)
CB810K2 road racer
DL1000 2003 - ice breaker
phactory
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« Reply #7 on: April 25, 2011, 07:18:56 AM »

Looks great! I agree with Mike! Though I will say that these motors have always been capable of big HP!

Phil
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"There are only two true sports: bullfighting and auto racing. The rest are simply games," Ernest Hemingway

1971 CB750K1
1973 CB750K3
1976 CB550F1

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