Bogging and carb issues on 125 bobber build

[kmahnke93]

Info about the bike:
2002 Kawasaki 125 Eliminator

Whats been done/observed (that affects function):
-Straight pipe
-New KOSO 28mm slide carb (from stock mikuni that I cant find parts for)
-Uni Foam filter (from stock box filter)
-Reed valve system plugged at end (see picture)
-Crank case breather at very top of engine is uncovered and seems to
suck air in (see picture)

Problems:
All problems worse/happen when bike is warm/hot
-Will idle high (no tach, but id say 1.5-2k rpm) then drop to low rpm
then die (When cold)
-will not idle, stalls (when hot)
-Bogs 1/8-1/2 throttle (only when hot)
-If Idling at stoplight for 10 seconds+, rolling onto throttle causes
instant stall.

I can still ride, just have to avoid certain rpm ranges, and manually hold an idle at lights.

I know I've changed the ratio's and would take excellent tuning skills to get it back on track, but I've tried tinkering with jet sizes, the idle mixtures screw, and needle jet clip adjustments. The problems still persist. Tried carb cleaner to check for air leak and new spark plug.

Any ideas or do I just fail at carb adjustment?
https://s32.postimg.org/dtexyo135/IMG_1374.jpg

https://s32.postimg.org/41c9t0q69/IMG_1375.jpg

https://s32.postimg.org/6g45dg6f5/IMG_1378.jpg

https://s32.postimg.org/xf808lsw1/IMG_1379.jpg

[stinkwheel]

Some observations and questions in no particular order:

So it's running ok on wide open throttle?

Your inlet manifold length seems short compared to standard.

It it a proper manifold or have you jammed a piece of silicone coolant hose between two big jubilee clips?

Does it backfire?

1/8 to 1/4 throttle is determined by the cutaway on the slide. You may have the wrong slide.

What is different about the fuel:air ratio the carburettor delivers when the engine is hot compared to cold? (I'll answer this for you: Nothing.). So is your poor running actually a carb problem at all?

Electrics are known for breaking down when hot. Have you changed the plug?

If I was going to guess your (main) problem, I'd say it's an inlet manifold air leak when the engine is hot, exascerbated by the wrong cutaway on the throttle slide.

Y U no use the mikuni. What couldn't you get for it?
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[kmahnke93]

[stinkwheel]

Small differences in slide cutaways make an enormous difference to midrange. As do differences in the needle profile.

Was this carb supplied as suitable for that bike or just bought on the choke diameter?

To adjust the needle on a Mikuni CV carb you'd usually put a washer under it.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.