Gas leaking through air box

Hello all! I am new to this forum and am hoping to gain some info.

Early this riding season, i purchased an 82 maxim 550. The bike ran great all summer, however when it got cold here in PA i started to have some starting problems. I would try to start the bike and it would turn over, but would not take off. I had spark to all the cylinders. Starting fluid was no help. So when i pulled the plugs i noticed that the left most plug was wet ( gas ) and black. So i figured i must have really flooded the engine. I waited a few days put a fresh charge on the battery, and finally got the bike to start. It was idling ok, but after about 5 mins of running i noticed a puddle under my bike. It was gas. So inspecting the bike while running i noticed that there was some fuel dripping from the gas line connecting the tank to the pet-cock above the carbs. i shut the bike down got some new tubing and clamps andthought i had the problem fixed. The next time that i started it up there was no gas dripping from the tube, so i let it run for a while. And noticed that after about 5 min there was another puddle!!!! i inspected everything and finally noticed that the drip was coming from the air box.

What i am assuming is that one (or several) of the floats or neddle valves in the carbs are sticking, thus pushing gas through the carbs into the air box. I am pretty new to motorcycle engines, and i have never rebuilt carbs before, so i wanted to see if anyone else had any other ideas of the root of this problem, before i rip the carbs out and attempt to rebuild them.

any suggestions would be appreciated.

Thanks,

eiredoc514

 

You are pretty much right on in terms of your diagnosis. However, you may have overlooked another important component, your vacuum-operated petcock. If your bike has the original stock petcock, it is vacuum operated and should NOT allow fuel to flow while in the "ON" or "RES" positions with the bike off. These fail with great regularity (but can be rebuilt) and combined with a stuck float can also fill your crankcase up with gas. You need to be sure to check the oil EVERY TIME you ride the bike until you get this issue fixed. Foolproof oil checking procedure: With bike on sidestand you should see little or nothing in the sight glass. Stand bike up toward vertical and you should see the oil level start to rise in the sight glass. Put it back up on the centerstand and look; there should be just a slight "bubble" at the top (just ABOVE the upper mark) when the level is correct. If your bike suddenly has too much oil in it (which also smells strongly of gasoline) then you will need to change the oil before riding it very far. Carbs ARE the "Achilles heel" of the XJ series, you will also need carburetor work as well from the sound of things.

 

Needle valves would be the problem. I am assuming you have no leak with the engine off so your petcock is working properly?


Here are some links to help you clean the carbs. One warning the instructions are for the HSC32 carbs. Yours are a different manufacturer but the guts are pretty similar.

Clean enrichment circuit
http://www.xjbikes.com/Forums/viewtopic/t=8918.html

Clean carbs
http://www.xjbikes.com/Forums/viewtopic/t=2908.html

Carb Sync
http://www.xjbikes.com/Forums/viewtopic/t=2132.html

Bench sync
http://www.xjbikes.com/Forums/viewtopic/t=6366.html

 

Thanks for the responses!

In response to the petcock, i did notice that when i pulled the gas line off that i did not have any leaking gas, but when the engine cycled, it would spit gas out. I have no idea how much is an appropraite ammount, but at least the engine was getting some gas.

And my fears are confirmed, i have to take the PITA carbs out and see what i can do. Thank you for the links to previous threads!

I will keep everyone posted of what happens in the next few days with the carbs. Thanks again!

--eriedoc514

 

When the engine is running the vacuum opens the petcock so looks like yours is working....

Good luck.

 

well just an update...

ripped the carbs out last night, and got everything tore down (after about 4 hours, and the invention of several new swear woeds) and in all of the carbs when i took the "needle seat" (the thing with the mesh filter on the end of it) had a ton of crud both on the mesh and in the tunnel that the main gas line runs into to distribute fuel to all the carbs. Varnish was minimal. I think that the crud is the likely culpret. So after much carb cleaner, i got everything nice and sparkling clean. All the parts appeared to be in good shape, but i think since i have them torn down i am just going to rebuild them while i have the chance.

I do wnder though, the rebuild kits come with new "needle seats" do i/ should i put the mesh filters on the new ones, as the do not come with them on? Or will it be ok with out? Also i appologize in advance for not knowing the technical name, but there are what appears to be brass circular valves, that open and close as the throttle is engaged/disengaged on the inside of the carb assembly. The "valve" in the #1 carb was slightly open, when the remaining 3 closed. Should they all be closed or is it nomal to have the one on the #1 carb slightly open?

Thanks

--eriedoc514

 

You need the screens. Also you need an inline fuel filter to stop that stuff from getting in (at east minimize it).

Are you talking about the butterfly valves? Look at bench sync link- you need to do that .

 

bill,

Thank you. some how i missed the bench-synch link in the above post.

Yes the name i was looking for was the butterfly valve, and by reading that tutorial i guess that all of the valves should have a small gap in them which in my case only the number 1 carb does. also thanks for the advice on the screens.

This is a stupid question i am sure, but is there an easy way to check and see if i have an in-line fuel filter?

--eriedoc514

 

There are no stupid question, only way you learn is to ask. You will see it - they were not stock. should be right near your petcock. Get a small (3/4 to 1 inch) inline fuel filter. Clear is best so you can see when to change it.

Search out the fuel filter posting there are excellent pics on placement.

Bench sync is pretty easy just take your time and do it right.

 

An inline filter is usually plastic, usually clear, and was installed by cutting the fuel line between the tank and the carbs. So if you have a clear plastic thing with fuel lines sticking out each end of it, one going to the tank and the other going to the carbs, you have an inline fuel filter. If you have straight/normal line from the tank to the carbs then $3 and a knife will allow you to add one. I was lucky when I installed mine, it just happens to site in the 'cradle' made by carbs 1 and 2.

 

thanks guys,

I looked and my bike does not have an in-line filter, but i will deff. go pick one up before i but all of the pieces back together. Still waiting on the rebuild kits to come, hopefully soon, we have few nice day coming up here in the forcast and it would be a shame not to get out. (it will probably be the last nice days too, gotta love Erie, PA winters)