I’ve seen a few post about this issue but I have yet to see a resolution.
I have a 2000 SH with 30,000 miles on the clock, a set of Yoshamira pipes and manual CCT’s. (Stock otherwise)
Years ago it started stuttering after 6,500 rpm’s. Rejetted the bike using 6sigma jet kit. Still stuttering. Check the valves and the are all with in spec. Even Replaced both coils and plugs no change. Just finished replacing the diaphragm and all the rubber hoses to make sure there isn’t a vac leek.
What am I missing? What should I try next? I’m not stopping until I figure this same thing out.
Here is a quick vid of the bike stuttering.
this all only happens under load and in ever gear.

Thanks for your time.

 

Did the stuttering start after the MCCT install?

 

Sadly no. The stuttering has been going on for years.

 

Have you removed the valve covers and checked the cam timing?

 

I have checked timing with a light. However all the timing marks are in alignment.

I assumed if the timing was off I would have issues with or without a load on the engine. Currently I can rev the bike to the moon as long as it’s not in gear.

But it would not be the first time I was wrong. I’ll check it this weekend.

 

Ignition timing and cam timing are, as you probably know, not the same.

 

That should have read. “I have not checked with a light. However the mark on the cams are aligned.”

sorry for the fat fingers.

 

Have you checked the voltage going to the igniter?

 

I have not. I’ll try to get to it tonight. Sunday at the latest. Thx

 

Back to the cam timing. The marks on the cam sprockets can line up and be 180* off. With the cam sprockets marks aligned, where were marks in the timing port?
Prior to your ownership, did one of the auto cct fail?

 

The cams are set to the shop manual specs. I’m sorry but I can’t remember where the marks where. But when I check valve lash I checked the cam alignment. Both where what the book called out.
That is also when I changed the CCT. The stock ones I pulled out seemed to still be functioning as they should.
I purchased the bike in 2005 from the second owner. It seemed to have an easy life. Og plastics and no scuffs anywhere. The guy I got it from said it could use rejetting. Stutter was closer to 8k. Took it to a shop to jet it. No real change. Just lived with it. The stutter slowly happens at lower rpms. Life happened and the SH sat for years.
Two years ago I rebuilt the petcock assembly and cleaned the carbs.
Then I started chasing the stutter.
Jets, coils, hoses, plugs, valve lashing and MCCT.
I’m going to check the igniter this weekend.
I’ll also pull the covers and double check cam timing. But I wouldn’t think it would pull to redline while in neutral if it was 180 deg out.
Thank you for your time. I appreciate the help.

 

they will rev out if 180 out but only without load.... i had a problem very much like yours, bike was near unridable at times and turns out it was running filthy rich as it came on to the main jets, yet would still rev fine on the stand.... if it were mine id ditch the non standard carb parts and go back to what honda put in it..has to be worth a try

 

I also have a 2000 SH, also with just around 30k miles, also with this exact same issue. Stripped and cleaned the carbs, no difference. Bike seems perfectly ridable below 6,500-7,000 rpms. From what I could tell, bike still has stock jetting. When I test rode the bike I noticed the issue but assumed it was a dirty jet. Unfortunately not able to see the video you posted but sounds like the same situation I am in...

 

So am I understanding correctly that you would have changed main jet for a smaller one and that fixed the issue for you?

 

If you confirmed cam timing and didn't reference it with the timing marks in the port, then you really don't know where it's actually at.

The stock CCT's will "function" fine right up to when the spring breaks. Did you install manual CCT's? Or new stock ones?

What fabio is recommending, is to start with a known base line, as is stock jetting, air filter, etc. That way you're not chasing someone's mistakes.

What do the plugs look like after a run under load?

Is the vacuum line to the petcock on the right port?

Were the carb diaphragms inspected for holes?

There are mechanics that are good at what they do, ones that are just so so, and ones that are bad. Also not many mechanics know anything about the SH engine and how to re-jet one. The SH is one of the more difficult engines to jet properly.

Could be wrong about this, but with one of the cams 180* off, no load, the cylinder that's right has enough power to run to red line.

 

I can confirm one will run highway speeds on one cylinder. It's what they call a thumper.

 

After everything. It ended up being the TPS. Mine was riveted to the carb. I had to drill it out and adjust it to specs. Just sent it to 10500 rpms with out an issue. I so happy and annoyed. I’ve been fiddling with this issue for 20’ish years. Even took it to two techs.