Rear Cylinder Oil Burning - Page 3 - Star Motorcycle Forums: Star Raider, V-Max, V-Star, Road-Star Forum
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post #21 of 30 (permalink) Old 02-04-2019, 05:23 AM Thread Starter
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Yeah, I have the 20's in a box. I've been trying different pilot jet sizes to get rid of popping during low throttle positions. Bike has the Cobra Slash Cut exhaust installed, with stock air box. I've currently got the 22.5's in with the PMS at 3.5 turns out.

Since I got a bike, I feel much better.
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post #22 of 30 (permalink) Old 02-04-2019, 05:50 AM
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if the only changes from stock are slipons. the only carb change should be to turn the pms screws out a quarter turn.turning the screws out is to reduce popping on decell..leaving the intake stock your not giving the engine any extra air so you would not give it extra gas. you have to maintain a proper air fuel mixture.to much fuel will foul the plugs and the bike will run sluggish.
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post #23 of 30 (permalink) Old 02-04-2019, 06:13 AM Thread Starter
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My thoughts on the jetting with the cobras: less resistance on the exhaust = greater air flow thru the bike. I had a hard time getting the bike to idle or low throttle without backfire with the 20's installed (even with pms turned out more)

Since I got a bike, I feel much better.
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post #24 of 30 (permalink) Old 02-04-2019, 06:32 AM
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Mikuni American Corporation opening the exhaust improves performance at high rpms. thats why you increase the mains one size.
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post #25 of 30 (permalink) Old 02-04-2019, 05:54 PM Thread Starter
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Thanks, If I get the oil leak figured out I'll give the 20's a second chance

Since I got a bike, I feel much better.
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post #26 of 30 (permalink) Old 02-04-2019, 05:57 PM
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probably thr valve cover oring......do not overtighten the valve cover screws lots of folks have stripped them out.. little threadlock and snug.
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Last edited by nick57; 02-04-2019 at 06:01 PM.
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post #27 of 30 (permalink) Old 02-23-2019, 08:15 PM Thread Starter
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Thought I'd give you guys an update. I had to order the o rings and exhaust gasket. Changed them out last weekend, went ahead and adjusted the valves on the rear cylinder. I didn't mess with the front, thought i would do one at a time. The exhaust valve was too tight, I couldn't get the feeler gauge in. I set it to the middle of the specs. The intake was good, I didn't need to adjust it. Changed both o rings on the covers. Changed the rear exhaust gasket where it was smoking before. I also put the pilots back to 20's and set the pins on #2. PMS screw is at 3 now and re-synced. I also found that my carb sync gauge needle was not at zero on one of the gauges without vacuum. Kind of saw that by accident, so I set them both the same before I started.

Anyway, It's been raining so much I haven't had a chance to get it out until this afternoon. I got in about 45 minutes before it looked like more rain. No smoking so that's good. Seems just a little more hesitant when I first give it throttle than it did with the larger pilot jets, but running pretty good. With the 20's the choke actually is useful. I still get a little pop or two when coming off the throttle somewhere between 3/4 to 1/2 throttle.

But overall I'm pretty pleased. I'll keep tinkering with it.
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post #28 of 30 (permalink) Old 02-23-2019, 08:26 PM
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thats a lot of productive work and good news

did you check the tight valve to see what the clearance actually was?, or just determine it was tighter than the low end. If would be good to know if the valve was actually tight and not closing all the way.

The bike will feel different with the right jets, running a bit rich always feels smoother.

Also the PMscrew settings are meant to be the starting point - you normally have to tweak them just a bit more after you ride for a while.

One other thing: when I take my bike out after its been sitting for months it never feels right to me. Sometimes I think its running on one cylinder - its not, its just me - when you ride everyday for months you get very intune with the bike, then when you have been off the bike for a while it seems loud, balky, unresponsive... Same for a bike you havent rode before - it takes a while before you are hitting the shifts just right and matching the throttle on the uptake, working around the slight backlash in the transmission and drive shaft...

a part of that is gas degrades after sitting for a month or more, even if its stabilized before the bike is stored, dont judge the performance of the engine with "old" gas.

Give it a couple hundred miles before you tweak it anymore.

Last edited by KCW; 02-23-2019 at 08:29 PM.
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post #29 of 30 (permalink) Old 02-23-2019, 08:34 PM
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if the needle has 5 notches the middle is stock. i think your to rich on the screws but. put a couple hundred miles on it and check the plugs.
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post #30 of 30 (permalink) Old 02-23-2019, 08:35 PM Thread Starter
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I couldn't get the low in, I didn't consider finding out what it actually was. I did crank it around a two or three times and checked it each time wasn't able to slide in the .12mm gauge.

If we ever get a break from the rain, I'll get out and put a few miles on it.

Since I got a bike, I feel much better.
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