bike is a 2001 Suzuki ls650 15,000 miles.

2 cans of carb cleaner through passage ways.
used carburetor rebuilt kit
Ebay item #312770968210
main jet listed is 130
pilot jet listed is 70

results after install
1}current bike runs
2}start right up without choke. (pulling out choke increases rpm from 1300 to 1800)
3}air mixture screw turned all the way in does not effect the idle.
4}air mixture screw 3 turns out increases rpm

my main concern
5}motorcycle does not acceleration "well" after 4,000 rpm
details: bike revs fine from idle to 5000 in neutral, first, and second, however in third, fourth, and fifth the acceleration at 4,000 breaks up and the motorcycle has trouble passing through 4000 to 5000.
Example: fourth gear>3,000>WOT>rev fine to 4,000>rev breaks up falling and climb between 4,400 and 4,000 (for 2 seconds or 1/8 mile)> rev past trouble rpm range> 4,500 to 5,000 normal.

background:
I've tried all needle clip positions middle, bottom, and top with no changes to bad acceleration at 4,000 rpm.
I've adjusted float level to spec 27mm to 29mm from carburetor body (without pushing in float needle trigger)


I tried research what are signs of rich or lean condition. but haven't learned much.
This is my first post. Help.

Sure thing,
Quick background: Got motorcycle few months ago (not running). Owner said it sat for 6+ years. Its stock. First time owning motorcycle and working on carburetors. I've been using the forums for techanical references the past few months and was able to get the ls650 back on the road, thanks for keeping the forums online. I wouldn't have been able to learn about the suzuki ls650 s40 so quickly without this website. mainly through the technical references, thank you for organization and the content.

I did some minor work, new battery, lube maintenance recommended joints, new spark plugs, new head gasket and head plug (without removing the engine), retighten all bolts that I could stick a socket on.

First carburetor disassembly: Removing the bowl I found black gum-tar-like residue, continued to complete the disassembly and blast 2 cans of 16oz carb cleaner through all the ports. Reassembled using an aftermarket carb rebuild kit. It came with an adjustable needle which I set to stock height. The motorcycle fired right up. Super about bring life to a motorcycle that sat for over half a decade.

Since my ownership I have been running the bike under 4,000 rpm for 200 miles and no issues.

currently:
the float level was set to 27mm still had 4,000-4,300 no-acceleration,
adjusted to 28.5mm today will test again when the sun comes out
the aftermarket main jet looks-like it has the same bore as stock main jet,

This past week I've been slowing pushing the bike to higher rev range and found acceleration trouble at 4,000~4,500 rpm.
I have videos and picture of all my work. let me know what you want to see.

verslagen1 wrote on 11/12/20 at 20:27:34:


......

He also said when turning the pilot screw out to 3 turns the rpm increased which suggests going larger on the pilot.
His carb definitely has some “emotional issues” that need to be worked out.

A carb sitting for 6 years with gas in it will have a lot of hard and gooey rubbery deposits, and often more than carb spray/air is needed; sometimes you have to revert to the carb tool wires and then redo spraying/air.

North America less than 1,000 feet elevation.

I believe the aftermarket jets are the same sizes as stock just different brands marked different numbers.
I'll rip the carburetor off and do another cleaning of all ports with some cans of carb cleaner.

update:
ran 120 miles round trip. marked throttle grip at closed, 1/8, 1/4, 1/2, and WOT.
cruised at 50-53mph normal, burned through some oil (was filled at max, end trip showed minimum level), mpg measured normal, float level adjustment didn't make any affects, couldn't accelerate past 4,000 rpm again.


symptoms, cruising 50 mph at 3,900 just below 1/2 throttle. wanted to cruise at 60 mph, As soon as I got at or above 1/2 throttle (4,000 rpm) the bike would sputter and backfire. adjustable needle positing is at top clip aka leanest position. rpm would fluctuated, down and up, causing me to be pushed forward and backwards on the bike and also sputters from the exhaust.

i'll try to add some photos and videos next update.

last question:
is it possible to adjust foot pedals? I want to ride with boots and can't  reach the shifter or rear brake because of the limited ankle flexibility from stiff boots.

raptor petcock (i did notice the outlet barb brass fitting is smaller then stock petcock, also adding a inline fuel filter cramped/semi-kinked the fuel line)
new to carbs, how do I check if slide is working properly?
just adjusted clip to lowest position, richest, resemble the needle plate so that the two holes are clear and set air fuel screw to two turns. testing tomorrow.

niceast wrote on 11/14/20 at 21:06:46:
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That is probably a Chinese knockoff and what varslagen1 said could be true.



niceast wrote on 11/14/20 at 21:06:46:
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Make sure the slide clean and the black coating isn't worn off.  Make sure the diaphragm is properly seated in the top of the carb. If you remove the airbox and run the bike, you should see the slide moving with the throttle changes.  Plenty of what people think are "jetting issues" could be caused by sticky slides. I replaced mine...best $120 I've ever spent on my bike.




niceast wrote on 11/14/20 at 21:06:46:
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This is where you have this  ALL WRONG.  You fix performance issues by finding the cause of the problem, not jetting. Jetting is for tuning only.  The bike will run properly with the stock jets, start there.

1.) You are using eBay after market jets...WRONG.  You'll never know if the problem is the jetts you're using or something else. Clean and/or replace the stock jets and put them back in.  This will eliminate that as a potential problem.  (And make sure you don't mix up the fuel jets in the bottom of the carb with the air jets on the top of the carb.)

2.)  You might have issues fuel delivery to the carb.  Use a genuine Raptor petcock from Yamaha.  Ditch the inline fuel filter.  The petcock already servers that purpose.

3)  Make sure the slide functions properly.

4) The people on here are very helpful. DragBikeMike and LANCER both pointed out the jets you are using are not the correct jets for this bike.  These are two are carb experts.  If you choose to not follow good advise, we won't waste our time guessing what's wrong with your bike.

Is your 3-clip position needle a stock unit from an 80’s model CV carb or did it come with the kit you bought on eBay ?
If it came with your kit I would remove it and use what was in the carb when you got it.
If it’s from an 80’s CV carb then put the clip in the center groove.
If it originally had a single groove needle then put it back in.
You need genuine Mikuni jets to know for sure what we are working with.
If you have them or can easily get them then use a #50 pilot and #152.5 main and set your pilot screw at 1.5 turns OUT.
If not, I have them.

That is as nasty a carburetor as I have ever seen, and I have seen a few.  It’s got to be in the top 3-4.
If you have not run carb tool wires through every little/tiny passageway in your carb body then stop and do so before doing anything else.
I had a carb sit for 1 year and I needed to use the carb tool during cleaning. It’s essentially the same as a welders tool used to clean the jets on gas welding torches.

How did you determine that the no-name jets were the exact size of the  Mikuni’s ?
Is the jet needle stock or not ?