1981 xj650H carb problem

Need some help guys if you follow my thread you know i got a project xj650.. it was sitting 21 years not started, pulled the carbs, float bowl gaskets were ok, so cleaning jets, all plugged up spraying carb cleaner through jet hole all clear....needle valve /piston slides ok /diaphragms were ok. pulled brass fitting for mixture screws left them at 2.5 turn out.... fuel tank clean no rust.
Last owner said it ran ok when parked 2001
Set float level 17.5 mm and did the fuel hose to carb base to recheck height ... refitting carbs it started up, on the road it had no power, bogging down had to give it a bit choke to get home .
Using carb cleaner i found vacuum leaks at the carb shafts. none at the carb boots, i know these shaft seals are special... pulling apart i decided to go double up using two O ring seals each side of carbs, gave the return spring extra turn to bring throttle back to off... tank fuel valve ok no restrictions..... out on road again bogging down past 1/4 throttle.... bringing it home in garage , revving up it will not go past 5k stumbles out, i can rev it up to 5 k no problem and smooth idle.... using carb cleaner again it did not do anything so no vac leaks.
This bike has no baffles in the exhaust rotted away so no back pressure ... clean stock air filter, spark plugs grey after run out so not rich.... how about the carb float bowl vents dont see any on this model
feels like its running out of gas on highway winding the throttle open feels like the gas was shut off..... something like when you feel its time to turn the petcock to reserve when tanks low....what did i miss.... using vacuum tool the petcock opens the valve, fuel flowing good

 

Be sure the vacuum hose to the petcock is rated for vacuum,thick wall. A non vacuum hose will collapse when the heat from the engine soften the rubber hose.

 

vac hose ok thick wall...

 

I will start in the morning on choke and see if it will be the same at 5k after a minute.... got to be something simple.... what am i missing here

 

Thinking back to yesterday after running in garage for a few minutes getting warm engine, i went down drive way in first gear pulling away no problem, after twenty yards shifted into second and gave throttle started to bog again.....so its ok below half inch throttle past there it bogs down like its getting no gas... pulling in clutch and revving it seems to have a flat spot at 5k.... so i can sit there stopped off road at 2k 3k 4k rpm no problem.....engine under a load problem?.. if it was ignition related i would get backfire and flames out the exhaust lol

 

Update ..i did something that i did years ago when i had a datsun 510..... on the 650 i pulled the boots to the air box started up and gave it some revs holding my hand over each carb restricting air at 5k.... did each carb this way sucking up the fuel.... coming down to idle nice and smooth revving past 5k ..pleased with that some blockage in carbs..... out on road it will pull to 5k beyond that and full throttle it surges now ..... would the mixture screws have anything to do with that, they are set to 2.5 turns out...i am thinking about the carb to head boots.... i went on a five mile run came home and pulled the spark plugs..

One thing i forgot when the surge was going on i gave it a little choke and it came back to life for a moment.... got to be a lean cond would 3 turns out on mixture do anything.... leaning towards carb boots

 

rechecking carb boots with carb cleaner no vacuum leaks... revving up it stumbles at 7k like a rev limiter... but it does have spark checked with timing light.... fuel flow is ok it does have the brass in line filter.... so what i did blocking the intake with my hand did improve a bit ..left mixture 2.5 out

 

Did you do anything to the vacuum diaphram side of the carbs?
Were the slides removed and the slide bores cleaned?
Were the diaphrams inspected for pinholes?
Were the needle jets removed and cleaned?
Were the air jets emoved, and if so did they go back exactly where they came from?

 

K-moe... thanks...diaphrams were in good cond no holes...slides smooth as silk ...cleaned needle jets .... air jets on the top ...decided to take another look at them #1 was plugged up 2 was partial plugged... 3 4 ok... jets in right place...dam how did i miss that... back together engine running still bogged down at 7k... i decided to play with the mixture screws #4 turning out about 3 1/4 noticed rpm go up a bit, same with 3.. 3 turns out.... on 1 and 2 carbs were at its best 2 turns out
So restarting and giving it throttle straight to redline no bogging down.... to dam hot to ride here in Cali 92F... what happened???

 

Are you saying that she's all good now?

Since when is 92 too hot to ride in? Get a hydration bladder and go.

 

Too hot for me .lol..... prefer mornings before noon this time of year ....i will not know how it runs until i test ride Wednesday

 

Yeah, heat is a killer. I still ride in it but one of the best investments was a mesh jacket. The back, shoulder and elbow armor is there but most of the rest lest the air flow right through. Now, if only I could do something about the excessive engine heat on my legs!

 

When i ride on weekends i wear leather jacket/pants/boots .. seen what happens when you go down wearing jeans or mesh jacket... dont want to take a chance out there....

Getting back to the 650 i got good response with mixture adjustment on 3 and four.. but not 1 and 2 ... when i pulled the carbs down for rebuild i didnt pull the brass insert.... only after i replaced the shaft seals, i did that second time carbs were removed... could there be a blockage in the carb pilot jet.... guess i wont know until test run and pull the spark plugs

 

This is my hot weather mesh jacket. Still plenty of protection:
https://www.revzilla.com/motorcycle/bilt-blaze-2-jacket?sku_id=1596519

 

Plenty of protection here too...my hot weather jacket.
https://www.chapmoto.com/joe-rocket-phoenix-5.0-hi-viz-vented-textile-jacket.html

 

Never been out for test run came down with the covid five days ago, so laying low not going out.. over the worst now, yeah let my guard down not wearing mask... i will put Gumout in the gas and take it out at the weekend, at a guess i think the passages from the mixture screws have partial blockage.... will update...

 

Twenty mile run today country roads warming up noticed serge around 5k ...60mph in 5th are my gages right.... adding a slight bit of choke fixed that ... so onward choke off /still serge ... giving it full throttle , winding it back and forth slow ... come on gumout..... what the hell is causing this.... air comes in piston/needle pulled up, fuel entering engine...what could go wrong... came home checked for vacuum leaks nothing all spark plugs light to tan color... lifted rear of tank did the mixture adjustment again all ok nice idle....... I will take it out again Sunday

 

Once the air temperature exceeds your skin temperature (around 93 degrees F) that mesh is doing more harm than good.
https://www.ironbutt.com/ibmagazine/IronButt_1002_62-66_Hot.pdf

 

The pilot jets are very likely to be clogged if the needles weren't removed for cleaning.

65 MPH in 5th should show you around 5K on the tach.

 

MPH gage must be off a bit ... i was able to pull mixture screw/spring/washer/seal on #1 carb and spray carb cleaner through it...... re doing the mixture again getting some action from 1 and 2 carb..... i decided to look again at the stock air filter that i replaced, it was not pushed against the filter box, i used tapered wood to wedge it in.... rubber piece i used did not work like running engine with no air filter could that be the problem, long guess