Gas in AIr box? Part of rebuild or tear it down again.

My 83 XJ 750 was working fine but I have been trying to slowly upgrade and catch up on maintenance. It has 20k miles on it. I put it back together after taking the carbs apart. I used the rebuild write ups found here. I cleaned it. Replaced the lower seals, float valves, I cleaned out the idle lines, set them replaced all screws and hardware with stainless allen screws (all parts came from XJ4ever so reputable source). I also replaced the springs and the fuel V seals, basically tried to rebuid everything but the body and the upper spring/diapghram). I then put the bike together (in the process I added clear fuel line and a new inline fuel filter). When the bike started it idles real rough (I sorta expected that) when I rev it it shoots water gas oil etc into the air box. I am wondering if this is a problem with my rebuild (ie should I tear the carbs back out..) or it it normal and I just need to continue to set and synch the carbs ( ie once the carbs are adjusted it will fix this abnormal situation)

I took a video of what it is doing. In the first run of the bike the water spits when I hit the throttle. In the second run of the bike the throttle was not touched.


http://www.flickr.com/photos/metmop/6019596361/

Ron

 

Oh my, don't run that bike anymore until you fix your petc0ck.

That's gotta be gas dumped from your tank to the crankcase, so it's oil/gas mix, that's why it's so water like (or more gas like)

once the extra fluid in your crank gets thrown into the airbox, it won't do it again till you let it sit and dump more gas down into your crankcase.

#1 Fix Petcock NOW, either by replacing it, or rebuilding it.

I'm sure Rick and Fitz will tell you to just replace it with a modern petc0ck.

 

OK I am looking into a petcock rebuild kit from chacal as we speak. I agree that it is a fuel oil mixture. I figured it was more likely to be something associated with the carbs since I had just worked on them.... float heights not set or set wrong... or maybe a vacuum leak up to the petcock or.... you get the idea... its why i asked

 

Holy crap.
You must have a tank of gas in your crankcase.

Drain the Crankcase ... PRONTO. Before the Gas starts to attack Seals and the Primary Guide.

Until such time as you get ALL the kinks worked-out of you Petcock and Carb Floats, ... Install a FUEL SHUT-OFF VALVE ... Immediately after the Petcock.
Hardware Store.
Briggs & Stratton Fuel Valve -- 10-Bucks.

Drain the Sump.
Remove the Oil Filter Dome.
DO NOT remove Middle Gear Drain Plug.

Let the Crankcase evacuate.
Blow low-pressure air through the Oil Filler Cap.
Vacuum Cleaner Hose in the Exhaust of the vacuum.
Blow-out all the Gas and let the Sump air-out.

Rebuild or REPLACE Petcock.
Install Briggs Shut-off
Replace Carb Float Valves, Seats and Pins with aftermarket ... Spring-loaded, Viton-tipped Float Needles.

Clean carbs, Airbox.
Adjust Float Heights to Specs.

<> Briggs & Stratton Shut-off <> Installed; Painted Black +

 

Good call. I drained the sump and did what you said as far as vacuum and air to clean out the sump after the smell of gas went away I drained the sump and immediately refilled with fresh oil. I will repeat that tommorrow. In the mean time the good news is the pet cock off position seems to be holding. When I got the message about the petcock last night I immediately turned it to off and crimped the fuel line with a vice grip. after monitoring the clear inline fuel filter it appears the off position of petcock is working atleast the tank is no longer draining. I am still in the position of finding out the problems with the carbs and/or the petcock. This was the first run since the carb were redone I must have missed something somewhere. Here is a list of various parts I installed in the carbs, if there is anything I missed (especially if it can cause this) please let me know.



Hcp8878set4 Bowl drain screw
HCP56Set16 Carb Bowl Screws HCP57Set16 Carb Hat Lock washer HCp2296 Carb Cleaning Drill Bit HCPHCP92Set6 Fuel O-Ring hCP329Set10 Carb hat Short Screw
hcp330Set6 Carb hat Long Screw HCP336Set16 Carb Hat Lock Washer
HCP38BSET8 Throttle valve V seals (8)
HCP2561SET8 Butterfly Valve retaining screws
HCP8393KIT4 Idle mixture screw kit (4)
HCP2776SSET4 Lower End Deluxe Rebuild kit
HCP953 Man sized cleaning wire tools set
HCP9798 Float Height Ruler
HCP4926x2 Fuel Level tube guage

As you can see from this list I tried to be fairly extensive. I guess I just restart till i find out what I did wroing my guess is something with to floats.

Ron

EDIT : I will get the on.off valve on my way home from work tommorrow and drain the oil again.... sigh

 

You had an enormous amount of Fuel in the Crankcase.

Protect yourself.
Add the Shut-off Valve.

Polish the "Cylinders" of the New Float Seats with 2500, ... then, Polish them.
Observe the Travel of the Float Pins as you manually manipulate the Float.
Correct any problem with the geometry.

Take the time to adjust your Float Heights so that they are all right on the money.

 

I decided to buy it tonight. I will add it tommorrow.... right now I am using the 2 foot of 1/4 inch fuel line i also bought to drain the gas tank into a gas can... wether I take the carbs out or the petcock... that tank needs to come off... I also am debating adding that 1/2 fuel test tank to my chacal order.... but that is another story I been fighting with the real tank... the shutoff will help with that also

I been using 2000 wet/dry... is that fine enough or should I special order some 2500.

 

2000 will do the trick.

You can even twist a few Q-Tips together and use Rouge or Buffing Compound.

I use 2500 rolled-up; followed by Buffing with ZAM (A jewelry cleaner).
The Float Valve Seat Cylinder gets mirror finished.

I still close the Shut-off Valve when the Bike is going to sit overnight.