Sudden rough running

[JZ05220r]

I put brand new reed petals in, I must’ve tried 4 spark plugs. Everything I said I did here, I absolutely did. There’s a few extra things I checked that I didn’t list here, but nothing worth listing. Could I have a bad batch of AMSOIL dominator? That’s one of my last suspicions, but far fetched. I have been running dominator on this set up since day one. So here’s the plan now coming to me as I type this… I’m gonna start with a fresh new bottle of AMSOIL dominator, and mix it with an entirely new gas station. I’ve been exclusively using Sunoco. We have a brand new Mobil down the street. I’m talking brand new, two months ago. You think that’s worth a shot? cause at this point, it’s either gotta be something stupid or something related to my leaks. Also, the air filter is still questionable to me, but I’ve already degreased my spare filter and oiled it correctly and squeeze it out as much as I could.

[ss109]

I know you said it isn't the plug wire but did you ohm it out and do so while also flexing it? Plug wires are cheap so just a thought. I was really leaning towards an electrical issue since it could come and go but now I'm also suspecting it could possibly be water in your fuel or just bad gas period. At least that is a simple one to test.

That said, if you have air leaks, and you said it really was bad, it's hard to fix another issue when one already exists and can taint the results of everything you're doing. Maybe it was running good before because the leak(s) weren't that bad but now are. They can get worse over time. Just another thing to consider.

[JZ05220r]

The air leaks are definitely the elephant in the room. But it was pretty clear to me when going up and down on the main that the 140 was much closer than the 148-150 after back to back testing. Air leak should not cause it to run rich. There is the possibility that the higher main jet sizes are just naturally creating a spot that’s overlapping with my issue. But I swear the 140 main was cleaner than the 145 I had been running.

[ss109]

A 140 is stupid lean for your elevation and especially so with air leaks. Even though you haven't noticed it dropping it sounds like a right side crank seal leak could be a real possibility. It only takes the tiniest amount of gear oil to affect the running of the bike. As small of an amount as between a single step in a jet change makes. Out of curiosity, how is your coolant level?

Man, I'm really hoping you do find the answer as I'm dying to know what the problem is/was.

[JZ05220r]

My coolant level is right up to the filler neck with my reservoir remaining steady since I got the bike together over a year ago. I have noticed I do get some loss out of the breather hose so it might’ve gone down a little bit, but I confirmed small losses through that hose early on while I was out riding and checking on the bottom of the hose to see that there were drips coming out of it.

I understand your concern about the gear oil. Right now for the gear oil to effect high RPMs in this type of manner you think it would sometimes affect lower RPM ranges, it never ever gives me a single issue at low to mid RPMs.

Thank you for following along with me as I try to figure this out. I have to admit I am getting close to giving up, but each time I get on the bike I get to test I get more motivated

[ss109]

The issue is that as the rpm's increase your flame front has less and less time to propagate. We're only talking milliseconds so even the tiniest amount will affect it and will be noticed more as rpm's increase. Just thinking out loud. Hope that's not the case but I so want to get this problem figured out.

BTW, how do your plugs look? Got any pics of them after running them?

[JZ05220r]

Here’s one of the plugs on my shelf. It looks lean. I believe this one was the one I pulled right after a stroll around a 6 acre field with the choke on by accident. Something I don’t do often

[SpruceItUp]

What jetting were you running with that plug, is it from when you really leaned out the jetting? How long has it been in the bike as well. If it has been in the bike for a while I'd say that's dangerously lean. Especially if that is from running with the choke on.
You can't really say exactly without a plug chop, but with how white that porcelain is I'd say so unless it's a new plug with only a couple of runs on it. I like to have a chocolate brown color on my plug (if I'm just looking at it from long term use, not plug chops).

[JZ05220r]

I agree it’s reading lean. There are absolutely no lean symptoms when running. Never any big from low rpms even if I stab the throttle. When the engine was fresh I purposefully started where it sputtered and went to a 148 and it stopped sputtering. I ran the 148 for the longest time. It was only until this year I realized that I can go down one more size to the current 145 to clean up some mid range jetting as I was on the 2nd clip position on the needle and needed a small reduction at 1/4 to 1/2 throttle.

[Chuck78]

What are the compression test readings on the engine now? And how does the top of the piston look as far as carbon buildup?
The rings could be getting worn and compression it could have dropped slightly, or also, you could have a lot of carbon build up on the piston and even the head, creating abnormally high compression, giving it different jetting requirements entirely.

First though, you need to get some good fresh gasoline and mix up a gallon or two at your normal ratio, drain the fuel tank, and run the new fuel just to be certain you're not chasing your tail due to a bad batch of fuel.

Had you pressure tested the crankcase previously? I assume so since you said you had discovered a slight leak around the outside of a crank seal and on the base gasket, but that it had been running fine with those?

Perhaps test it again and see if that has gotten worse?

How much leakage are we talking? From what I read from doing a little bit of searching, 6 or 7 PSI over 5 to 10 minutes with 1 PSI loss is acceptable.
I was incredibly shocked and pleased to find mine held rock solid after 465 hours on the rebuild.
The coolant system I pressurize up to 28 PSI as my aftermarket radiator cap should relieve at 27 PSI (1.8 bar), and at that point I was dripping coolant out of all the hose clamp connections... When I used my old MityVac pump needing to rebuilt, I couldn't get it over 13 PSI (vacuum /pressure pump needing rebuilt) but it held rock solid on the cooling system at that.