Excessive engine RPM during dyno test

Hi all

Was talking to a workmate the other day (he has the same ride as me) and he asked me whether I had done any upgrades to my bike yet and it came out that the biggest obstacle to him doing the upgrades that he wanted to his bike was that he had witnessed a bike on a dyno somewhere (I didn't ask him where) that was according to his description really being tortured from an RPM standpoint. He also mentioned that he was very unimpressed with the size of the cooling fan that they were using. Your thoughts?

Take care
John

I have had mine on the dyno when they set up the SERT and it does sound like they are running the crap out of it. I believe it is necessary to tune/test the performance across the entire RPM range. Running your bike on the dyno may be like making sausage......you don't want to watch it being done.

dyno

exactly why mine will never be on one again,,,watched a bike explode on one,,, was at cohns,,, and he is ,,or was real good with dyno,,,now he has sold it,,,stay with carbs ,,,pops

The operator is the key - including knowing what it is you want to accomplish. Many runs I've seen were done in 4th gear (5-speed trans) starting around 2000 rpm, whacking the throttle wide open & running the engine to the rev-limiter, then chopping the throttle. A couple runs like that will give you a baseline, but you don't have to keep on doing it & you can sure blown an engine apart that way. As to cooling, the best setup I've seen was 2 big "squirrel cage" blowers, each with a flexible hose as big in diameter as the cylinders are tall pointed right @ the cylinders & even then the engine was shut down after the 2nd run. An optical pyrometer is handy so you can see what the engine temps are & stay within the range that the engine actually runs in on the road.

The last time I went to the dyno with one of my engines, it was run for several minutes @ 10% to 35% power, keeping the rpms between 2500 & 4500, just to let it warm up, check for oil leaks (collapsible pushrod tubes), etc. before it was ever run hard. And when you're tuning a street bike, the rpm range & throttle position you actually use on the road is more important than what peak HP is @ redline. Several times the bike can be run up thru the gears as you would on the road & that'll tell you a LOT more than just a blast from 2000 rpm to the rev-limiter. "Dyno shootouts" & "bragging rights" for the most HP is one thing - getting the bike to run the way you want out on the road is another & the operator should know the difference. If not, don't go there.

Hey art,,,thnx for earls add,,, he was of some help,,,went ahead on my own and only took 4 hours,,,simple as heck,,,, i do not think i lost a thing,,, now idles fine,,,no limit on top end,,, great to have simple again,,,,pops

Excellent, Pops - I was positive Earl had done the EFI-to-carb conversion on big twins several times before & could answer any question you might have. When I talked to him on the phone, he said the folks who wanted it done had the same reasons as you - ride a lot of miles, have enough tools & mechanical experience to fix things on the roadside, but not enough to dig into the fuel injection if that goes bad. So just get rid of it & go with the trusty CV carb that you can tune with a screwdriver & $15 worth of parts. Makes perfect sense to me !!

earl

jeez been since last year we were in earls neck of the woods on way to rolling thunder,,,stay in salinas georgia with good old boy and wife,,,,i misted over when he started his conversation,,,love it,,, it is like a different,,,real world ,,,, my buddy died in salinas,,,so will have no place to stop down ther now,,,he lived with me in oregon after service and i lived with him some,,,pops if i ever get close to earls,,,i am going to stop,,,

hello Art_NJr

read your letter with great interest. If I'm reading it right you can bolt on a carby and get rid of the fuel injection pain in the arse? Would it be possible for me to contact your mate earl so as i can learn how to do it to my bike? Sounds like a great idea to me no more decel popping!

Terry

You can zip an e-mail to my friend Earl Calhoun @ ECS Engineering here:
hdrepairman@yahoo.com

He's been working on Harleys for 40+ years, has done the EFI to carb conversion & it's not all that difficult. One thing he mentioned when I talked to him about it is that the newer Delphi systems have the ignition module tied in so you have to replace that too, but with the earlier MM systems you don't.

Art_Njr and Hotroadking

thank you both for the info. been haunting cyber space for 12mths or more looking for a solution to decel popping. spent heaps of dollars on electronics and dyno tunes, this seems like the solution. its either this or the straight jacket. let youse know how I go

Terry