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I’d go down one size and reset your mixture screw. I’d leave the timing where it is for now.
They don’t look bad but a tad rich to me. Humor me… try indexing them. Get the strap opposite of the center of the chamber. In other words have the plug gap face the valves and the strap face you when you’re looking at the motor.
I bet once indexed the timing mark will be closer and easier to see.
I don’t know with a CV if 2.5 out from a seated mix screw is too much or not. If it is that might be another indicator of the jet size
Last edited by Rains2much; Apr 16, 2026 at 05:14 PM.
1990 EVO w/17k miles. Completely disassembled to reseal. Cylinders and rings were perfect. All new gaskets and seals. Factory CV rebuilt and has a 185 main and 48 slow jet with the mixture screw out 2.5 turns. Factory air cleaner with most of the back cut out and K&N filter. Stock head pipes and SE Slash Cut mufflers with no baffles. Bike runs excellent with no pinging whatsoever. I run 89 non-ethanol gas. The only issue is once in a while when it's idling and I crack the throttle, it will pop thru the carb. I sprayed brake cleaner around the intake to head gaskets and there is no vacuum leak. New plugs with 300 miles on them. Left=Front and Right=Rear. Thoughts?
Sorry to leave you hanging @BigMike and thanks for the second set of photos. I can't swear I see a timing mark(s) but I can tell you, that's what the plugs will always look like, black.
You do need to run a 45 but you can't with the open pipes. I tried the same thing with a SE3 (EV27) Tour pipes and SE mufflers but they did have baffles that were of no use without packing and the front diverters were cut out. Like yours it ran Ok, got decent mileage but the plugs were al\ways black until I changed baffles so I could use a small amount of packing.
Good news is, you have the best factory cam "L" and a round float carb meaning it has an N72S needle which is a good one. So if you ever decide to quieten down slightly with baffles and a small amount of packing, you can run a 45 and everything will tune out better.
Sorry to leave you hanging @BigMike and thanks for the second set of photos. I can't swear I see a timing mark(s) but I can tell you, that's what the plugs will always look like, black.
You do need to run a 45 but you can't with the open pipes. I tried the same thing with a SE3 (EV27) Tour pipes and SE mufflers but they did have baffles that were of no use without packing and the front diverters were cut out. Like yours it ran Ok, got decent mileage but the plugs were al\ways black until I changed baffles so I could use a small amount of packing.
Good news is, you have the best factory cam "L" and a round float carb meaning it has an N72S needle which is a good one. So if you ever decide to quieten down slightly with baffles and a small amount of packing, you can run a 45 and everything will tune out better.
I haven’t spent a lot of time with CV.. however, I’d be inclined to just install a 1/4” inch bolt at the end of the pipes/mufflers, install a 45 jet and leaving everything else. .40 cents and drill a little hole is all it takes to find out. Your running a richer jet to mask a different problem in my opinion.
With an E in that situation, I bet it would end up a .28 or maybe a 29.5, but you could run smooth as silk with open pipes and a ev 27 if timing is right with TTI’s or lollipops in there. And don’t know with cv, but with E your float might be set to low, leaning and you’re compensating with a larger jet.
I was fiddling with my buddies 98. EV27, CV, SE mufflers same as you… finally convinced him to go 10:1 & an E (due to my lack of tuning ability with a CV) and he went V&H baffles, no packing and I put in the thumb screw 3/4 of an inch from the end and the bike is super smooth. .28/72
Last edited by Rains2much; Apr 18, 2026 at 08:31 AM.
Sorry to leave you hanging @BigMike and thanks for the second set of photos. I can't swear I see a timing mark(s) but I can tell you, that's what the plugs will always look like, black.
You do need to run a 45 but you can't with the open pipes. I tried the same thing with a SE3 (EV27) Tour pipes and SE mufflers but they did have baffles that were of no use without packing and the front diverters were cut out. Like yours it ran Ok, got decent mileage but the plugs were al\ways black until I changed baffles so I could use a small amount of packing.
Good news is, you have the best factory cam "L" and a round float carb meaning it has an N72S needle which is a good one. So if you ever decide to quieten down slightly with baffles and a small amount of packing, you can run a 45 and everything will tune out better.
I bought the mufflers on eBay and wondered why they were so cheap and in great shape - they didn't have baffles. I'll see if I can find some but might have to look for another set of mufflers. The bike had drag pipes on it when I got it.
EDIT: I just double checked the mufflers and they do have baffles which means I got a smoking deal for $75 shipped. Let me know what jets you would run and I'll install them.
Liked mentioned reversion is the ghost of Harley tuning, 48 isn't a deal breaker except the pop off idle is most likely air being pulled backwards thru the exhaust leaning out, going have to mask the lean condition with more fuel and not the direction on a smaller engine.
From tuning with a Digital Wego a CV accelerator pump puts a large hit of fuel in and a consistent afr crossover on the needle, with todays gas the large hit off the pump isn't a bad deal. The CV air/fuel screw setting only affects afr in the idle to 1200 and low jet change doesn't touch the needle cruise area which is mpg unlike a Mikuni air screw and low jet change affecting cruise area when on the needle(mpg loss) Mikuni is a different creature.
Follow the Evo guys, 45 and some kind of exhaust restriction should put you spot on. You can try some exhaust restriction and leave the 48 in adjusting the air/fuel screw down, I'm a believer in a richer idle for peace of mind in a traffic jam because a few dollars in fuel is cheaper than sticking a piston when the ability to keep a cylinder cooler is simple plus easier start ups.
Tuning my 127" with a 3" Dragos baffle, I'm fully aware of how much air can be pulled backwards in a de-accell, digital wego seez WTF lean, start adding more fuel in the idle circuit to mask it. Restrict the exhaust like requested above the big engine is smothered up top so each situation is approached different.
Last edited by 1997bagger; Apr 18, 2026 at 10:30 AM.
Take the baffles out (hopefully you can), measure the OD to the smaller OD and order -"ceramic fiber fabric" off ebay. Either 3/4 or 1/2 should be just right and do not overlap it.
.Don't use fiberglass, it'll burn out in 50 miles. Start with that and we'll see how it goes.
I bought the mufflers on eBay and wondered why they were so cheap and in great shape - they didn't have baffles. I'll see if I can find some but might have to look for another set of mufflers. The bike had drag pipes on it when I got it.
EDIT: I just double checked the mufflers and they do have baffles which means I got a smoking deal for $75 shipped. Let me know what jets you would run and I'll install them.
Thanks for all of the help!
Sorry this wasn’t directed at me and there are a lot of chefs in the kitchen…
But just remove the bolt that holds the baffle… go to the hardware store and buy two bolts that is long enough to almost touch the other side when tightened. Put in a 45 jet, tune your mix screws and I bet your problem is 90% fixed…
if so, buy the largest size Thunder Torque insert from DK Customs and then your problem will be 99% fixed.
Thumb screws work well. These have been in these 36” long drag pipes for over 25 years. G carb 32/82, bored out with shaved throttle shaft in my 70 93” Shovel motor. Runs super smooth around town and turns up the nasty in a blink of an eye spreading hate and discontent among the r6 and vt1800 crowds.
Last edited by Rains2much; Apr 18, 2026 at 12:20 PM.
I've also been thinking about installing an Arlen Ness air cleaner. They say they are for 93 and up due to the head breathers, but I can block those holes on the backplate and use the use the stock screws to hold the backplate to the heads. The factory air box has about the entire back cut but is drawing air directly from the cylinder fins. I feel like it would breathe better with a stage 1 type air cleaner using the stock cover. Thoughts?
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