help with my XJ650 carbs?

I'm no expert just a tinkerer, I finally got my XJ650 carbs back together and on the bike so I could test, still haven't started the motor so it will idle.

I was sure the fuel O-rings I used wouldn't work and the carbs would leak.
Sure enough with fuel in the tank they leak, but not from where I had guessed.

They leak fuel from the 2 spots I circled just on that one carb.


This leads me to believe that my fuel petcock doesn't work as intended because it will flow some fuel all the time when valve is turned on NOT just when the engine is providing some vacuum to the other hose.

So, what part is probably leaking on the carb(s)?

I'm at an end with these carbs and ready to find someone with a good set I can pay/trade them.

 

The carb is flooding; the float needle valve assembly is not shutting off the fuel flow into the bowl (or the float is set incorrectly). The bowl over-fills with fuel and those air vent ports are one of the escape routes for the fuel.

The petcock should not allow fuel flow when the engine is off while set in the ON or RES position. If the petcock is set to PRI, it will flow all the time.

 

thanks that helps

 

WARNING:

If the Fuel Level is rising so high as to exit those Atmosphere's ... you need to check and see if Gas has contaminated the Crankcase.

 

The vacuum petcock is the worst idea, because no matter how well you maintain your ride, it can fail without warning causing major problems.

 

yes I know it contaminated the crankcase before

I've been through the whole bike, getting a bike going that hasn't been on the road in 2 years.

I've had the carbs off and back on the bike 3 different times now tonight.
Clean one float valve, carbs back on, another one is leaking. Clean new float valves, this time the OTHER one is leaking again. etc etc

They look clean and seem to operate normal, been cleaning further with chemtoolB12.

I've had the float valve problem on dirt bike carbs before, not sure where to turn, other than trying to get a new rack of carbs.

 

If nothing is bent or broken, you don't need new carbs, get 4 new needle valves & seats, set the float heights, no more flooding, now either replace the petcock, turn it into a manual, or fit a lawnmower on / off fuel valve after the petcock. Be cool, dude.

 

STOP Petcock Leakby
END Carb Overflows

Briggs & Stratton -- Fuel Shut-Off

$10.95 at most well stocked Hardware Stores

BRIGGS VALVE <>------------<> INSTALLED

 

also located in the lawn mower section of your local shucks/checkers/O'reily conveniently next to cheap-o inline fuel filters, another must have.

 

yes yes

thanks guys, I'll see about getting new needle valves & seats etc

I think my petcock is ok..

 

I just can't get my carbs right yet, but I think my engine is ok!
Kinda depressing, dang Hitachi maybe you have tried to manufacture too many types of things.
Ahh it is what it is just old carbs, I only wish I had more options.


My carbs have 3 new Hitachi needle valves for the floats, including in the 1 carb that keeps leaking when fuel turned on.
I'll take them apart a bit and check one more time today, I'm trying not to but doubt that I will be able to get anywhere..

 

I'd tell you to give that bowl a nice little knock with a plastic hammer to make a stuck float/tip move, but they already think I'm a witch doctor here, so I wont.


:lol:

 

+1 on what Jeff said. Unless you have adjusted the float down stop they can and will hang up on the side of the bowl and leak. I had 3 doing it until I located very small washers and shimmed the floats so that the float stayed in the center of between the posts. Have you been adjusting the level using the clear tube method? If not try it. Secondly the vacuum valve is a POS and it will fail. That's why the float level and the float valves are so critical. If they are right it dose not matter if the petcock seals or not. I mean really how can you trust some thing call a petcock anyway

 

Hey whatever works, I install a lot of these when carb/cylinder flooding becomes an issue on lawn tractors, since the fuel does a job on the viton float needles.

 

Sorry to resurrect the thread......

But I am experiencing this exact same situation with my carbs. One floods, I fix it, place carbs back on, then another one floods......etc, etc.

I'm beginning to think that it has to do with the stock open-ended float valves. The open end allows for the float to slide it's direction, possibly causing hang-ups. As a troubleshooting test, I grabbed an old rebuild needle from a Suzuki BS34 carb set I had laying around (fit perfectly, has a 'closed' tang holder). It was about 1mm taller than the stock needle valve, so I adjusted accordingly, and that carb never flooded again.

I'm about to go down and do the same to the other 3 carbs, and report back with my findings. Wish me luck!

 

Welp.

The bike runs amazing! I just tuned for my UNI pod filters w/ #118 Dynojet mains and stock #40 pilots and A/F screws are @ 3 3/8 turns out and she's running awesome!

I just bought myself some brand new replacement float valves/valve seats/washers off Ebay, so they will 'eventually' be replaced.

 

hello everyone.
I am working on restoring (cosmetically) a 1982 XJ65o Seca (runs great). I have CUT the air box out and purchased the CHEAP POD filters. After reading all the advise to do exactly the OPPOSITE of what I have done, it is now to late, and the air box is long gone . I read a great post by Xj4ever about the way the cheap pod filters have a smaller (inside diameter) rubber boot preventing the correct airflow and vacuum entering the cylinders.
So I have already accepted that I will be getting real familiar with jetting, jetting, and re jetting my carb's to accommodate the loss of the stock filter, but I am curious if I can limit the damage by ordering a better set of POD filters.
I have found the UNI FOAM POD's and they seem like they would be a little closer to stock and actually better for filtering out dirt.... I am hoping someone who has used the UNI filters can give me a starting point with the MAIN and PILOT jet size. I am running the stock headers, with 2 new "shorty" slash cut tips from dime city cycles (4 into 2). I am at sea level. I have read the thread about the formula on adding +2 for 4-1 and PODs etc, but am hoping to get it close on the first few jet sizes.
THANK YOU AND SORRY FOR THE DESTRUCTION OF MY STOCK AIR BOX!!!!

 

you had tubes that went from the airbox (R.I.P) to the carbs. Put those back on and the put the pods on those. People have reported good results with that setup.

 

That's the first time I ever heard of using the 'joints' with pods. Interested in hearing the results (although my airbox is happily installed mind you).

 

That has been something that has been recommended here for a few years for those who simply must use pod filters. Those little boots just happen to be shaped velocity stacks (it's almost as if the engineers at Yamaha knew something )

 

tpayne, another thing to consider is that the airbox supports the back half of the carbs. You may want to fab a bracket to hold up the carbs. They weigh a lot, and in your current setup are only supported by the remaining carb boots (head side).

 

Personally, I used a 12" worm clamp/band and went around the carb support bracket and the frame under the gas tank. Worked perfect. I also sleeved some fuel tubing around the worm clamp so it didn't scrape/rub anything (especially the alum carb bodies!)