My 25 year old XV250

[FinalImpact]

So if you swiftly open throttle you can see the accelerator squirt fuel? If yes. Good sign.

If yes and you snap throttle open 2 to 3 times before starting it should fire right off, no choke.

Can you try that?

 

[fazil]

So if you swiftly open throttle you can see the accelerator squirt fuel? If yes. Good sign.

If yes and you snap throttle open 2 to 3 times before starting it should fire right off, no choke.

Can you try that?

Yes it squirts fuel, i saw it.
I also tried that 2-3 times snapping throttle, before starting, but doen't work.

 

[FinalImpact]

Do it six or eight times then.
One thing about those plugs, they seem pretty loaded up. That would indicate main jetting being off. Is there a needle on the slide entering the main jet? If so, you might pull the slide and needle and lower the needle by raising the clip one or two notches.
From 1/4 throttle to WOT throttle in 2nd gear it should roll on smooth. And hopefully clean up the plugs and tail pipe.

 

[TownsendsFJR1300]

Do it six or eight times then.
One thing about those plugs, they seem pretty loaded up. That would indicate main jetting being off. Is there a needle on the slide entering the main jet? If so, you might pull the slide and needle and lower the needle by raising the clip one or two notches.
From 1/4 throttle to WOT throttle in 2nd gear it should roll on smooth. And hopefully clean up the plugs and tail pipe.

I'm thinking with the extra "squirts" and it not helping (and the nasty plugs), perhaps it's flooding from the get go...
Jerking with the throttle (his normal starting procedure) may be clearing out the excess fuel.

I don't know if that needle has adjustment slots for the height. He can richen it with very small washers under the needle CLIP if need be.

Fazil, for those stuck vacuum slide screws atop the carb, a small vise grip should be able to break them loose or use a hand held impact tool...

 

[fazil]

Thanks for the advice.

Yes there is a needle, and yes it can be adjusted, as i know from the old carburator, There are 6 pins, and it was in the middle (3th) pin when i opened the old carb.
I need to open this newer carb's diaphram cover soon. I don't know impact wrench can be useful, i can use a little saw to make new screw driver lines to hold the screws, I have done it in the old carb. I'll let you know hopefully next weekend.

 

[ozgurakman]

you can use dremel for making new screwdriver pattern on screws, too.
.
If cold starting was fine at summer, valve adjustment may be cure. Because if valves are tight, engine will start hardly when cold.

Also, spark plugs are carbon fouled. a/f ratio is way too rich. Maybe needles may not be fully sitting? Is carb bleeding when bike is not running?

 

[fazil]

After start up, everthing looks fine, performance is nice. So i don't think valves are not adjusted.

Is carb bleeding when bike is not running?

No. But when i was in holiday last summer, a strange thing happened, apartmant service man called me and told me that, fuel was dripping from my bike. I told him to turn the tap under the tank, he did, and he said ok, no more fuel coming. Later i rode it without any issues, i don't know what happened that time.

 

[ozgurakman]

After start up, everthing looks fine, performance is nice. So i don't think valves are not adjusted.



No. But when i was in holiday last summer, a strange thing happened, apartmant service man called me and told me that, fuel was dripping from my bike. I told him to turn the tap under the tank, he did, and he said ok, no more fuel coming. Later i rode it without any issues, i don't know what happened that time.

a friend of mine has same issue as yours, his xj900 was pissing some fuel to his garage floor sometimes. He tried so much things to carb and nothing was solved the issue. Fuel was dripping either in cylinder or floor, if the fuel line not cut when bike is parked.

Finally, he bought brand new idles and o-ring set. Then dripping was solved. Needles were not oem but japanese made, from ebay seller who sells from polland.

 

[FinalImpact]

In the case of the continued leaking that vacuum diaphragm between the tank and the carb is supposed to stop fuel flow when there is no engine vacuum present. That said, if left in prime mode, it is bypassed.

On to the float bowl. It has a vent to prevent (reduce potential) engine flooding. If the main needle seat leaks fuel, it will continue to enter the bowl where it has two options; drip out the overflow or follow gravity and fill the cylinder(s).

That said a bike in the sun, left in prime mode and if the tanks vent is plugged they can build enough pressure to flood the carb. In this case two or more failures have occurred but this stuff happens especially when a bit of sediment is stuck in any of the valves or needle/seat combo....

Back to your bike; it is possible that once the fuel is shut off a leaking needle seat / or improperly adjusted float allows fuel into the combustion chamber and as Scott put it, it begins life flooded and no choke is needed as it has fuel already.

Here is where the FSM comes in and you measure the float level and set it to spec. Then you take a syringe full of gas, connect it to the fuel inlet, fill the bowl and PURPOSELY OVER PRESSURE the syringe while looking at its position. You should not be able to overcome a sealed needle seat when the carb is at its normal position on the bike. Lets just say your bench test should have the carb level or however it sits when in use.

In short; fuel should never run out of a properly functioning carb. If it does, it has an internal leak at the seat or the floats have a hole in them and have taken on fuel. In the old days you used to weigh them after having them submerged to make sure they are indeed floats and have not allowed fuel to ingress.

Do you have an FSM for this?

 

[fazil]

Update to carb problems:

Today i took the carb out again and give it a good clean, Soaked in the white vinegar for a couple of hours then, i disambled every part of it, also i used some wd40 and a guitar wire to open all the holes. Then i put it al together, every part seems ok, but there is a tiny o ring that is sitting behind the main jet.



That little o ring was in a very bad shape, hardened and lost it's circular shape. But i put it inside though with its bad shape, because i can't find a new one. And put the carb on the bike. The bike started fine, chooke was working this time, problem seems to be gone, but now i have an other problem, bike can't rev in mid range. Then i opened the carb's jet side and took that little oring out, thought it would stuck main jet hole, but nothing changed.




Here is a picture that i found on the internet:





Do you think that little oring can cause this?

 

[TownsendsFJR1300]

When you re-assemble the jet to the nozzle (your last pic) WITH the o-ring, can you see if it's closing up the orifice at all?

I don't remember EVER seeing an o-ring there, the main usually just screws into the nozzle, but it seems with your parts fisch Yamaha did.

Do you have any local shops you can match the old o-ring up with?

Does the old carb have a good o-ring?

*I have to doubt that o-ring is the issue (but you still need to rule it out).

Can you post an audio / video of the engine bogging?

 

[fazil]

I think i found the mistake while looking at the photos that i took while putting everything back together.
Needle jet hasn't sit on it's place completely.
I'll check it tomorrow.

 

[fazil]

Yes the engine is bogging after 2000rpm if i use chooke after 2000rpm, it takes gas normally, so it can't get fuel.
And yes there was an oring inside when i opened it, but it's very hardened and old. So no need to put it back again, it looks like it's not the issue.

Later, i discovered a little rail system on the main needle noozle, that's why it didn't fit in its place. Now i have a 30 minutes additional work to make it done.

Thanks for the help Scott.

 

[fazil]

lat update,

Now everything works perfect. Carb issues are all gone, chooke responds perfect. It's like a brand new bike.
Dealing with a carburator needs attention and concentration, i had to do the same work many times because of carelessness. It's good to write the parts and the order of installation before starting carb rebuilt. But now, i feel like a carb expert

By the way, that little main jet oring seems useless, now it works without it. But i'll buy a rebuilt kit anyway and put it back later. Who knows, may be it is really needed...

 

[TownsendsFJR1300]

Congrates!!!

BTW, anything, with multiple parts and specific order, I'll have a piece of paper, lay out the parts in the correct order, (with notes if necessary).

Say you have a side case cover with different length bolts. I'll roughly drawn a pic of the cover, then punch holes in the cardboard and put the different length bolts in the appropriate holes. Especially if doing a major engine overhaul with multiple cases, simply label the cardboard and keep them in order...

Laying parts in the order they come off is also a big help..

Saves the guess work later and usually no "do overs"..

 

[fazil]

Do overs...

While installing the carb this morning, i put all the parts back together and started the bike, everything seems ok but the engine respond was a bit slow to the gas.

then i saw that, i've forgotten to put on the diaphram spring it was looking at me.

It works without the spring though, then i had to take the tank off again to get access to the carb's diaphram side and put the spring back. Now it responds much faster with the spring.

 

[TownsendsFJR1300]

Gravity can ONLY do so much....

It also helps to have a nice clean area for ALL your parts so as you go along, if there's anything left, you can stop, go back and install..

 

[gnyce]

Congrates!!!

BTW, anything, with multiple parts and specific order, I'll have a piece of paper, lay out the parts in the correct order, (with notes if necessary).

Say you have a side case cover with different length bolts. I'll roughly drawn a pic of the cover, then punch holes in the cardboard and put the different length bolts in the appropriate holes. Especially if doing a major engine overhaul with multiple cases, simply label the cardboard and keep them in order...

Laying parts in the order they come off is also a big help..

Saves the guess work later and usually no "do overs"..

I just did my first carb rebuild (really, first _anything_ with a carb) the other wknd. There ARE lots of parts and pieces... two things that I found that helped me: 1) take the occasional picture with your cellphone-camera, to refer to later, and 2) when I lay out all the parts, I'll use the backside of an past desk-calendar - you know, the really big ones (2ft x 3ft) - and put parts into quadrants and circle them with a pen and make notations about where they came from, what stage they were, etc. NOTE: this works really well for disassembling cell phones and other tiny electronic gear. Mine worked pretty well too, though I do think I have a spring (or something) partially pinched, throttle cable back-off not strong (tho' could be helped by cable lube as well). Congrats, it is a nice looking bike!

 

[fazil]

Most difficult part of the work is putting back the two throttle cables and chooke plunger into the carb. Also you can adjust the throttle cable freeplay while you are there. So may be that's the issue in your bike.


Virago is still on sale in US. In Europe and here i guess ast virago was sold in 2001. If i need OEM parts, i have to go to Ebay US. But shipping is not affordable for small parrts. I on't know why Yamaha doesn't sell this bike in Europe anymore. May be because of the Chinese replicas.

 

[TownsendsFJR1300]

Also you can adjust the throttle cable free-play while you are there. So may be that's the issue in your bike.

+1 ^^^..

If your newly cleaned carb has a RETURN CABLE, if the "closing cable is too taught", that can cause binding. The return cable should have just a knats hair amount of up and down play...