The diaphragms are in excellent shape. I checked them many times yesterday and I'm very careful about making sure they seat properly when putting the caps back on.
Also thank you! And thanks to everyone helping thus far :)
Ok so . . . I took a 20-30 min test ride using the settings mention above and below:
13mm float heights
A/F screws 1.75 turns
Needle clip (Factory pro) in Center ("Stock") position
Jets -> ALL STOCK
Prior to riding I blasted all four choke plungers with carburetor/choke cleaner and observed NO change in idle speed.
The symptoms, when warm, are as follows:
- Hesitation when giving lots of gas quickly between 1000rpm and ~6000 rpm. This is more pronounced in the 5000-6000 range where almost any amount of throttle results in hesitation before the power kicks in
- 6000-12k (redline) seems OK! If I give max throttle quickly the bike will reach the rev limiter without issue and the rpm gauge doesn't even get a chance to hit 12k. If i quickly, but gradually give gas it will reach 12k and pull the entire time - once it gets over any hesitation hump from the initial throttle.
- Completely unpredictable idle. It started out around 1200 and worked its way up to ~2000. I adjusted it back to ~1200 then it worked its way . . . all over the place. Before I rode home I stopped in a parking lot and it was idling around 3000. Blipping the throttle would sometimes set it straight and sometimes would drop it under the set idle. When I got home it was idling around 1,000 rpm. Sometimes it flutters at idle and other times it seems pretty ok.
- The longer the bike sits at idle the lower the rpms drop when you blip the throttle
- Example 1: Bike is idling at 1200 rpm for 1 second. Blip the throttle any number of times. The rpm will rise then drop down to ~1200
- Example 2: Bike is idling at 1200 rpm for 15 seconds. Blip the throttle and the rpm will drop low enough to kill or almost kill the bike. Immediately after you can blip the throttle over and over and the bike seems ok
- The bike sounds like its running on 3 cylinders INTERMITTENTLY during the ride. If I let the bike sit for a while like 30 seconds or so then take off the bike sounds smooth as butter. If I ride it for a few seconds I get a constant fluttering thud and the bike loses some power. The odd thing is that the idle doesn't seem to change at all. This is most noticeable when taking off from a dead stop as the bike feels like its about to bog and you have to give it more throttle. I know its not running on 3 cylinders CONSISTENTLY because it was doing that in the past and I had to keep the revs around 5000-6000 to get home. Taking off was nearly impossible.
- When coming off of WoT I get a series of pops coming from under the tank so I assume this is the carburetors backfiring. Maybe 4-10 pops.
- Temperature gauge runs at normal ~half way point
- Fuel pump (aftermarket) is running and seems to be maintaining fuel
So it seems I have a low/mid-range lean condition. Last time I was running at 2.25 turns on the A/F screw and the 4th (1 step richer) position on the needles and it had similar symptoms, but the plugs were black as soot.
Is it possible I'm also chasing an ignition related issue considering it feels like im running on 3 cylinders intermittently? The fluttering noise sounds EXACTLY like a cylinder dropping out, just not as loud as on that's 100% dead. At second glance I'm running one OEM coil and one aftermarket cheapo coil. The cheapo is brand new and hasn't seen much use at all . . . though I have had a few of these die on me. The OEM one is SLIGHTLY out of spec, but was used to replace the aftermarket ones that went bad on me. This is an issue the bike has had since I got it . . . I want to say it did the same thing on OEM coils, aftermarket coils, and my current combo. The spark plug wires are brand new NGK wires. The boots are the OEM boots. Boot #3 is brand new and was ordered to replace a broken boot. I quadruple checked to make sure all plug wires were well seated in their boots.
Can the igniter cause issues like this? The reason I ask is because I recently fixed a 1992 EX500 that sat for 18 years. When I got the engine to start I couldn't rev it past ~5k. It sounded like a rev limiter was being hit (the ex500 doesn't have one!) so it seemed like something was breaking down under load. The issue eventually turned into intermittent spark on both cylinders. I replaced the igniter and the bike revved normally without issue.
Considering the needle clip position supposedly affects 1/8 throttle up to 3/4, while tapering off, should I try adjusting my needle clip position and leave the a/f screws at 1.75 turns?
FWIW I am in the Denver area which is why I backed them out 1.75 instead of 2.0. I know the elevation doesn't matter that much since these are CV carbs . . .
^ Around 0:50-1:00 to see the blip that almost kills it.
^ Idle in parking lot . . . I adjusted it down towards the end and give some blips
^ This was as soon as I got home