HarleyTechTalk

While doing a hard run through the gears, I was going past 5000 rpm's, when the motor seemed to sit down and not pull as hard to redline. It actually struggled to get there. Normally, it pulls hard right to the limiter. I figured the motor had finally let go, burned a valve, something.
But, the motor runs great, still makes good power right to about 5000+ rpm, then sits down like the timing has retarded or something. This was last year, so it has quite few miles on it since. Runs great pulls hard like normal, just loses power the last 500 to 1000 rpm's. (No tach)

'01 RK
95", SE flattops and cylinders
44 CV carb
DTT ignition, set 1,2, 6100. (Maybe 2,1, can't remember)
Heads by Eagle Jim
Andrews N55G, gear drive cams
"B" lifters
SE adjustable push rods
100,000 miles on motor, 75,000 on top end

Could this be caused by a bad MAP sensor?
Bad DTT?
I will check that the carb throttle body is opening all the way, but the way it was noticed, while WOT and then losing power, I don't think the carb is it. I have not done a compression test yet, but the way it runs, I don't know if it is down.
Thanks for any suggestions.

I run a CCP test, easy and quick, might tell you something. That's a bunch of miles.

Yeah, they are all gentle, easy going miles...     

I will do a test maybe today. Put it off for quite a few months, maybe don't want to know.

If the MAp sensor fails it, typically sets the output to 4.5 volts (100 kpa) and doesn't do anything with pressure.. This means the motor will appear sluggish but wide open throttle will behave fine.    I doubt it can cause the issue you see unless it was thinking the pressure was lower and advancing the timing.. Then you get pinging..

I think that you probably have a hole in the carb diaphragm from the symptoms.   Could also be sumping or weak valve spring.. Exhaust sound should change if valve spring..

  

Could you have Gained Weight over the Winter months... 

just ask'n so don't  me...

signed....BUBBIE

Quote from: BUBBIE on February 21, 2016, 10:01:40 AM
 

Could you have Gained Weight over the Winter months... 

just ask'n so don't  me...

signed....BUBBIE

Um, yes. But this started last fall when I was WAY thinner!

No, exhaust note hasn't changed. It would be great if it is the carb. Sumping would suck. I originally figured something with the heads. Which would also suck. But, it runs great, same low and midrange power, no strange noises.
Troubleshooting to follow. Still damn cold here though, but got out for about 70 miles yesterday.

Getting out on the DD7 for the first time Hoss... 70* here before noon (SE Az.)...... I might have to have My Leathers on tho... and a tow truck follow... 

Coyote gave me VERBAL instruction... Think I followed it...

Within the Subject of you  Post:

Check you ccc, Like said above?
IT Will tell you a bunch...

I usually do a rebuild of Bore n Rings/valves by them miles you have. But what do I Know?  

signed....BUBBIE

Checked compression. Motor wasn't real warm, ran about 3 or 4 minutes, 35 degrees out.
168 rear
167 front

Did not do a wet test.
I will be pulling the carb apart soon.

Your just getting used to it Hoss. There's still time for a 177 or 124 kit before spring in Minnesota.  Tell the wife with that many miles it's due for maintenance.

I've kind of been looking at the 124, a lot. But, this one may have to wait a bit. She just told me to set the Ultra up the way I want it.
She's a good girl!

That compression is kinda low.

It is, but at least it's equal. The motor wasn't real warm, my gauge was pretty cold, and not real expensive, a Mityvac brand. Maybe the cams don't build a lot either, not really sure. The motor may be a bit tired though.
I just know I could feel the power go away on a run, instantly. I was kind of hoping the MAP sensor could cause it. I may swap in the stock ignition for the DTT, to eliminate that as a problem. And, pull the carb apart and check it.

 

Quote from: Hossamania on February 21, 2016, 04:33:31 PM
Checked compression. Motor wasn't real warm, ran about 3 or 4 minutes, 35 degrees out.
168 rear
167 front

Did not do a wet test.
I will be pulling the carb apart soon.

Did you check the math on Bigboyz calculator?   It says 168 for that cam using .030 head gasket and 85cc heads.  Bob

A long with the diaphragm like Max suggested, check the vacuum line to the petcock if your still using the stock one. Might be a good idea to check the float level, set too low can cause a lean condition at higher throttle settings. fwiw Buffalo

Quote from: FXDBI on February 21, 2016, 05:25:31 PM

Quote from: Hossamania on February 21, 2016, 04:33:31 PM
Checked compression. Motor wasn't real warm, ran about 3 or 4 minutes, 35 degrees out.
168 rear
167 front

Did not do a wet test.
I will be pulling the carb apart soon.

Did you check the math on Bigboyz calculator?   It says 168 for that cam using .030 head gasket and 85cc heads.  Bob

I looked there too, the compression is right in line with Big Boyz so I would be looking elsewhere.

Quote from: PoorUB on February 21, 2016, 05:34:37 PM

Quote from: FXDBI on February 21, 2016, 05:25:31 PM

Quote from: Hossamania on February 21, 2016, 04:33:31 PM
Checked compression. Motor wasn't real warm, ran about 3 or 4 minutes, 35 degrees out.
168 rear
167 front

Did not do a wet test.
I will be pulling the carb apart soon.

Did you check the math on Bigboyz calculator?   It says 168 for that cam using .030 head gasket and 85cc heads.  Bob

I looked there too, the compression is right in line with Big Boyz so I would be looking elsewhere.

Sweet! Who would have guessed that this motor might still be kind of healthy? That lets me look elsewhere.
I'm running a Pingel petcock, so no vacuum line. I will check for other vacuum leaks. Thanks everyone for the help. I will let you know what I find as I work through this.

Well, I was going by the assumption that the heads would have been machined for more compression with those cams.   

 "And, pull the carb apart and check it."

Pull the carb apart and CLEAN it.
Don't forget about winter fuels=sucky performance

Quote from: Trouble on February 21, 2016, 05:52:31 PM
"And, pull the carb apart and check it."

Pull the carb apart and CLEAN it.
Don't forget about winter fuels=sucky performance

Yup, but this has been running non-oxy all winter. And this started last summer. The carb will get a good going over, I want to change the needle anyway, I've been testing different ones, I think I've got those figured out now.

Do you have a fuel filter on it? First symptom of a filter starting to clog is loss of high rpm power. As it clogs up, the power loss starts to come on at lower and lower rpm. I have lots of experience with this as old Chevy's with Quadrajet did this all the time because the fuel filter  was so small. You have a classic symptom. It idles fine and runs great until the last 500 or 1000 rpm.

The only filter is the petcock screen. I will pull it and check it. Good call.

Quote from: Hossamania on February 22, 2016, 09:30:23 AM
The only filter is the petcock screen. I will pull it and check it. Good call.

Hoss...check the tank for the sealer peeling off.


86

Quote from: 86fxwg on February 22, 2016, 09:47:29 AM

Quote from: Hossamania on February 22, 2016, 09:30:23 AM
The only filter is the petcock screen. I will pull it and check it. Good call.

Hoss...check the tank for the sealer peeling off.


86

Will do, that would suck.