petcock

im having trouble with my petcock. the only way i can keep it running is with it on prime. any ideas what this problem may be? i took it apart and nuthin seems to be stuck of obviously wrong. any problem with just running it on prime all the time?

 

If all the float valves are shutting down, you can run in PRI, but if you are going to do this for any length of time, you should fit an in-line tap.

 

what are the fload valves? and by in line tap what do ya mean?
thanks

 

floats are in the carbs. They keep the bowls from overfilling ond flooding the carbs and ultimately filling the crankcase with gas. the petcock is designed to operate by vacuum. On setting is RUN which is your everyday setting. Then there is RES which stands for Reserve. This setting is for when your bike starts to "starve for fuel" when at the bottom of the RUN setting. This is your reminder that you'd better get gas soon cuz you're getting low. After you switch to reserve, you still have some gas in the tank, but you'd better get ready to get to a station to fill up. Then you switch back to RUN.

PRI is for Prime, which is what you'd use if you did run out of gas after switching to reserve. This setting allows gas to flow through the petcock without needing vacuum. The fuel flow is always on, whether the bike is running or not..

This is where an inline 'tap' is a safety precaution. It's also called a manual fuel valve, fuel cutoff, or whatever other name you may know it by. It's the same thing as a shutoff valve on a lawnmower, snowblower, or snowmobile. Using one is simple....open it and start the bike.....stop the bike and turn it off. You just have to train yourself to use it. Otherwise, you'll get a mi up the road and all of a sudden you'll 'run out of gas' til you remember you forgot to open the valve while hoping no one was watching you as reach down to open the valve. DAMHIKT

Dave

 

Hey, just had a thought......check your vacuum line to the petcock. See if it's plugged or fell off the port, or has a hole in the hose somewhere.

Dave

 

ya i got that i thought there was sumthin i didnt know of called fload valves, lol. if i didnt have enough vacuum to open the petcock wouldnt it run noticeably bad? ill have to look at the hose and al the carb boots. anyone have any idea how many inches of vacuum it takes to open it? ill check it with vacuum gauge if i can get a #. i do have a feeling its a little lean, i cut off the megaphone and added a little shorty muffler and now have a little pop on deceleration. i also noticed when i rev it up it takes a few seconds to come back to idle rpm. is this normal for cv carbs? could it all be related?

 

The petcock doesn't need much vacuum. Actually, you can rupture the petcock by sucking on it via mouth. some people will test it that way to see if they feel or hear the diaphragm move. but, ya gotta be careful doing that since it can be ruptured easily.

If it seems to run find with it on prime, but not with any other setting, it would seem to indicate that the petcock is restricting the fuel somehow.

The new pop could be a result of less backpressure due to a muffler change. You'll have to do sparkplug readings, plugchops, as somepeople call them.........and do your homework on possible re-jetting issues related to the muffler change.

dave

 

So my vaccum petcock is leaking and I hate it. I tried rebuilding it and apparently didn't do a good job.

That being said, what can I do to bypass it completely and just use a shut off valve instead. Does some one make a plate with just the nipple that the fuel line connects to?/

 

You can plug one of the fuel ways with epoxy putty & then the pet cock works like a straight on / off, a few of us guys have done this with success.

 

rebuild kits aren't that expensive. just redo.

i think it's just a diaphragm. and a spring. and maybe a seal or two.

i think they were $12 bucks out here for the kit.

 

Yeah, rebuilds aren't that much. But if you just want to make it non- vacuum, just set it to prime and leave it there. Then, for adding the manual shut-off, just cut the fuel line between the fuel filter and the petcock and put it in. Make sure it's easily accessible, and remind yourself to tun it on before starting, and turn if off when you shut the bike down. If you don't have a fuel filter (which many don't ), I HIGHLY recommend that you put one in the line while you're at it.

Dave

 

The secret to a successful petcock rebuild is the condition of the valve seat. In a lot of cases, corrosion has taken its toll on the seat and led to pitting that is too deep to polish out. On the other hand, a lot of petcocks are very "rebuildable" and it's just a matter of reversing the effects of time and wear.

Take a look: http://xjbikes.com/Forums/viewtopic/t=25058.html

 

This just happened to me on a ride today, it started to run rough, then sputtered out. Tried reserve, no go, tried prime, started back up.

Off to Len for a petcock rebuild kit I go!

 

But.... but..... don't you want to check that vacuum line first before you throw a rebuild kit at it???
Just an FYI while we are at it... for vacuum line in this application you must use vacuum line. I have read about the same problem on Motorcycles and Snowmobiles where the owner puts on new fuel lines, and uses fuel line (not vacuum line) for this short run. The difference is the vacuum line has reinforcement strings imbedded in the rubber so it retains its shape.

Typically what happens, the line gets hot from engine heat, and the vacuum sucks the line and it collapses on itself, then your fuel flow stops. No vacuum= no fuel delivery.

 

mtnbike.......'fore you go and do that......check to make sure that the vent on the gas tank cap isn't getting plugged.

I've never seen the vacuum line get sucked in on itself on these bikes. The vacuum isn't that strong that I know of. Also, I've never seen any vacuum line for these bikes that have reinforcements in it. Plus, I'd think that if an engine is getting so hot as to soften the hose like that, then there's something more drastic wrong. It shouldn't be running that hot......the line only goes from the manifold to the petcock, it's not in contact with the engine. If a bike is getting that hot, I'd be more concerned about the 5 gallon potential bomb sitting between the vacuum tube and the rider.

It's going to be difficult to use fuel line for the vacuum line as they are different sizes.

Most

Not saying that anyone is wrong, just that I've never seen anything like that on dozens of xj's and xv's that I've either rebuilt, repaired, sold, or kept....

Snowmobile fuel line is pretty strong and retains it's shape quite well. I actually have a section of snowmobile fuel line on my 700n, running from the petcock to the carb port, it's plenty long........runs the length of the carb rack and back, as I have a manual fuel shut-off in the line and is operated by the right hand. the line lays right on top of the carbs both directions and has been on there for three years with no problems.

just my experiences, others will probably chime in..........

Dave F

 

Pet cock. Lol. My pet rooster. Sorry just had to.

 

Sure you have, every time you see on original XJ vacuum line. Except it's not reinforced with strings; it's in the construction of the line. Len carries real vacuum line for replacement (automotive vac line is often a tad "chunky.")

Usually what happens if someone uses the wrong type of automotive (or non-automotive) tubing, it will cave in and kink in the apex of its bend once it gets too hot, aided by the vacuum that's being applied.

SOME tubing is fine; but you have to be aware that some isn't and a lot of folks aren't. Hence my recommendation to use the real stuff.

 

Question. What will happen if the vacuum line isn't attached to anything? The reason I ask is because I just noticed the vacuum line on my petcock is only about 3 inches long. I'm guessing this isn't the way it's supposed to be. :roll:

 

The petcock won't be vacuum operated if it's not connected; and if the vacuum spigot on the intake manifold isn't capped, that cylinder will be experiencing a vacuum leak.

Read this; it explains how they work and how to fix them: http://xjbikes.com/Forums/viewtopic/t=25058.html

 

Ignore my last post. My tank's not on my bike right now and I've been up all night working so I had a bit of a brainfart. I was thinking the vacuum line wasn't connected to anything when it was on my bike but surely it was. I doubt it wouldve ran very well if not

 

I'll have to look at my lines again.............

Hmmmm.....sounds like a TV show in there---- "What's My Line?" Maybe someone will use that someday.

Dave

 

http://www.xjbikes.com/Forums/viewtopic ... mower.html

It appears that is what has happened to my 1982 XJ550. I really know very little about engines. I was a bad, bad owner, and left it to sit (with no winterization) for five years. The battery needed replacing. After that, I added a can of Seafoam (to the OLD gas). I turned the petcock to PRI ...and after a few minutes, a puddle of fuel started dribbling down by the kickstand. Switched it back to "ON", and this seemed to stop the flow.

The bike started right up. I was shocked! I drove it for a couple days and didn't see any issues (other than some throttle-hesitation), but I parked it, & left the petcock set to "ON". Within a couple days, I noticed a fuel smell in the garage, and again, a small puddle of gas down under the kickstand. I couldn't see exactly where the leak was coming from, but the petcock exterior was totally dry (so I think the leak must be internal - i.e. diaphragm, maybe?). However, the little "pan" right underneath the #1 carb had a meniscus of fuel ...dripping about twice per minute.

Now there is the smell of fuel in the oil. I guess I also have a stuck float / needle, which is causing fuel to leak from the carbs, right?

I removed the tank, and checked the petcock. "PRI" allows the gas to flow freely from the main port, while both "ON" & "RES" ...still allow it to dribble - a few drops per second. (The vacuum port didn't "leak" any gas.)

...

So, here is my plan to at least get the bike running soon-ish:


1. Open the tops of the carbs to find which float needle / valve is stuck, and try to free it up - without doing a complete rebuild of the carbs (for now).

2. Temporarily install a simple inline shutoff switch (ON / OFF) in the main fuel line hose just beyond the existing (vacuum-operated --I think factory) petcock, and leave my petcock set to "ON". (Later, I'll fill this space with a fuel filter.)

3. Leave the vacuum hose connected to the petcock, for now. (Or should I cap it, and just leave it the petcock on PRIME?) My thought is, I still want to be able to know when the tank is getting empty.

4. Change the oil (Castrol 4T?) & oil filter.

5. Change the air filter (it was dirty, but looked pretty new. Is there a way to soak / clean & reuse these?)

6. Add new gas (and maybe another can of Seafoam?)

7. Ride.


...Am I missing something to get this bike safely running, at least?


After that, here's what I plan to do:

8. Order a petcock rebuild kit (along with all the other parts / tools I'll need) from Chacal, and rebuild it as per: http://xjbikes.com/Forums/viewtopic/t=25058.html Then remove the temporary inline fuel switch, and instead, install an inline fuel filter.

If I find a mess when I open up the carbs, I have learned the best thing to do is to...

9. Rebuild the carbs, (including the enrichment circuit well) as per:
http://www.xjbikes.com/Forums/viewtopic/t=14692.html
http://xjbikes.com/Forums/viewtopic/p=3 ... tml#329308
http://xjbikes.com/Forums/viewtopic/t=8918/

10. Check the valve shim clearances, as per:
http://www.xjbikes.com/Forums/viewtopic ... ances.html

11. Sync the engine (I don't really understand what this is yet), and

12. Colortune, as per:
http://xjbikes.com/Forums/viewtopic/t=8 ... +plug.html

13. (I would also like to replace the factory oil filter system with Chacal's screw-in adapter.)


I work as a custom-goldsmith. Our workshop makes high-end jewellery, and we regularly use several types of jeweller's rouge, and Micro-Mesh up to 20,000 grit (no, that's not a typo), so being anal about getting tiny bits absolutely clean & polished under magnification ...is what I do.

When I bought the bike, I tought it would be a cheap ride. I didn't know it "might" need lots of maintenance. I'm not looking forward to the possibility of screwing something up with my motor in the attempts to improve it, BUT I'm willing to read lots, and wade in carefully.

I don't have a printed manual. I bought the XJCD five years ago from this site, but have moved several times. I "know" it's around, but am having trouble finding it.

**I've gotta say, there is absolutely NO WAY I could have diagnosed any of these issues, or contemplated these fixes ...without spending hours on XJBIKES.COM ...and it's beautiful search engine! Thanks so much to all you vets who have taken the time (and left a legacy) for those of us who are just starting out.

Truly, I was about to sell this bike four weeks ago, but now I've changed my mind. Thanks! This IS the best forum around.


-Allan

(Geez, this post turned into a novel...)

 

Alan, there is NO need to sell the bike. What you need to do, is literally go back to the proverbial step 1.

Before you do that, here is some info that you need to know so that you can understand why you will be told certain things.

1. Do NOT leave the petcock on prime if you are not running the bike. PRI is a setting that allows the fuel to flow without the vacuum activating the petcock. In this setting, fuel WILL run. If the carbs are in good condition and the floats are working the way they should, then the fuel flow will be stopped by the float needle. BUT if ANY of the floats are sticking even the tiniest bit, the fuel WILL keep flowing. The fuel WILL get to the cylinders, and WILL leak down past the rings, and WILL fill up the crank case. Now, you WILL have to change your oil and I'd recommend the filter, too.

2. You left gas in the bike for many years. It is now garbage, or even dried right up. Your bike ran because the new gas was able to work its way through, was probably running on only the enriching circuit, and was not getting the proper air/fuel mix from the main jets anyway.

3. The puddle forming was probably coming from the bottom of the airbox at the crankcase breather tube. The crank case fills up, the overflow pushes up into the airbox, and then leaks out. If the tube is not tight at the port from the shift shaft cover, then it can leak right out there, too.

4. The fact that your petcock was leaking is an indication that it must be rebuilt. The ON and RES positions are where it should be at all times unless you are literally PRIming the carbs. ON, and RES, only allow fuel to run when the engine is running . The engine supplies the vacuum which pulls a diaphragm to allow the fuel to run. Don' worry about capping the vac port....that will accomplish absolutely nothing.

That all being said, modify your plan of action.

a. tear the carbs completely.... COMPLETELY down. Do a THOROUGH cleaning, including installing new throttle shaft seals fuel rail o-rings.

b. Don't forget to take apart the enricher circuit, too. You MUST have EVERYTHING off and clean EVERY individual part. BE anal about that. Write down where everything was, or at least take pictures. There's not that many parts, but you don't want to get the few that can be mixed up, mixed up.

5. Now change the oil and filter.

6. Rebuild the petcock. You can put an inline shut off if you wish, it's a safety net. I'd also recommend putting a small inline fuel filter in, too.

The most important things are :

1. totally redo all carbs
2. totally redo petcock
3. totally change oil/filter

4. now to bench sync the carbs before putting them back on

5. now sync the carbs on the running bike

6. colortune/sync/colortune/sync til you're happy.

Now that those are done, Now you can address everything else:

Check rear brakes
check/rebuild master cylinder and front brakes
check all electrical connections
probably need to replace old tires by now, too.

Ok, get those all done, then let us know EXACTLY what you have done, and we'll go from there....................

Sounds like a lot, and it is.......but----if you want a safe and reliable bike, you have to undo what years of neglect/ abandonment/simple ignoring/etc..... WILL do. In your case, you're ahead because you know where it's been, and you have been reading. That's all good.

Don't worry. You can't screw it up too badly. If you get concerned, we're here to help.

Take your time ad work carefully. We will get you through it, and on the other side, you're going to know your bike inside and out.

Dave Fox

 

Just replaced my petc**k with an on-off-res. tap from Len (chacal)...works great....the delux is only a few more bucks than a full rebuild kit....and I can sleep at night without having to worry...as long as I turn it off!

 

Thanks for the input!

Eventually, I'll get to all those things you listed, hogfiddles. I know there isn't a "need" to sell the bike. the task ahead just looked very daunting / time consuming. But even if I sell it later, I want to getting it running right first. My guess is, I'll become so attached in the process, I'll keep it!

I didn't have access locally to the replacement seals / extra parts needed to even make an ATTEMPT at rebuilding the carbs (or the petcock) yesterday, so that's why I made myself some short-term goals. Saturday afternoon I was able (almost) to accomplish what I planned in my steps 1 thru 6. For a guy who is completely green to doing anything with engines other than oil changes, that's a success! Here's what I did:

I removed top covers from carbs #1, 2, & 4 - while on the bike. However, I was unable to open up carb #3 at all. One screw head started to get mashed with the phillips screwdriver. Geez, those screws sure are soft! I intend to upgrade to stainless and/or Allen style (or buy those "special" Japanese Phillips screwdriver sizes), but that will have to wait until I completely rebuild the carbs.

From the left, #1, 2, & 4 carbs all looked VERY clean inside the top, the needles look mint, and the 3 rubber diaphragms I checked seem to still be supple (due to the Seafoam, perhaps?). As far as going CLUNK ...Can this only be achieved when the carbs have been fully removed so there's no vacuum? #1 CLUNKED, but it seems #2 & #4 were working against air pressure while everything else was still hooked up.

I put the top covers back on the carbs, and made sure to reassemble everything I took apart.

I installed the temporary ON/OFF fuel valve: $2.99 at Home Despot... It works, at least until I can rebuild the petcock.

I drained the oil (there was about half a liter, or maybe .75L of dirty, black, gasoline-smelling oil. The engine always had a slight oil leak near the tach cable.

I installed a new oil filter, and added 1L of Castrol 4T 20W50. (How much should be in there? The engine block has a stamp that says 2200cm3, but does that mean it needs 2.2L of oil?)

Two weeks ago, what was left of the 5 year old gas was a tiny amount in the bottom of the tank. (So, the bike started on 5-year-old gas + one can of Seafoam.) Since then, I have filled up once with premium, but I'd say now there's about 1/3 of a tank in it. I'm going to fill up again today. Should I add more Seafoam?

...

Well, that's what I've done so far. With some fiddling on the throttle & " choke", it started last night!

As far as the next step, a couple of the items you mentioned ...I really have no clue how to do yet (i.e. electrical connections, valve shims, rebuild master cylinder

I live in Canada, so I know it might take a bit longer to get the parts I order from Len (chacal). And I want to minimize the hours that the bike is non-driveable, so I would rather buy everything I "might" need ahead of time, rather than pulling things apart & waiting to receive ONLY the parts that "need" replacing. Here is what I plan to order:

-complete petcock rebuild kit
-inline fuel filter

-2@ 3 x 4 cupcake pans
-complete carb rebuild kit (including replacement stainless screws, o-rings, seals, etc.)
-enrichment circuit twist drill (I've got tons of tiny, TINY sizes at work, and several hand-held pin vises. What diameter is this well, exactly?)

-K&N "foam" air filter (unless mine can be "refreshed" somehow.)

-upgrade the factory oil filter system with Chacal's screw-in adapter

-valve shim tool (or make my own?)
-valve shims? (I've read that I won't know what to buy until I open them up & measure.)
-digital caliper
-gasket kit - or whatever is needed upon reassembly after checking the valve shims
-tool for hand-turning the engine?

-ColortuneII plug kit
-YICS tool (Or has a DIY design been perfected?)

-check rear drum brakes & order replacements if needed. (I haven't read anything on this yet.)
-new front & rear tires (Based on a few threads I've read, I'm thinking of Battlax BT45, or Dunlop D404. Are tires / wheels something I can install myself? If so, which specialized tools will I need?)

Extras:
-rubber grommets / fittings which attach the plastic side covers to the frame
-YAMAHA tank badges
-Maxim 550 side badges
-chrome polish? (What's the best?)

BTW, is there a way to lube the throttle cable? I bought a cable clamp / aerosol lube system, and it worked great on my clutch. How do I remove the top end of the throttle cable?

 

Ummm...

You haven't remedied anything.

The floats that stick and dump gas into your crankcase have NOTHING AT ALL to do with the needles you can get to by pulling the hats off the tops of the carbs. You looked at your throttle slides, jet needles and diaphragms. Your problem is on the opposite (bottom) side of the carbs.

Here's an "exploded" Mikuni, you need to worry about the FLOAT NEEDLE valves, which are accessed by removing the float bowls. http://xjbikes.com/Forums/viewtopic/t=31061.html

Oil capacity is indeed 2.2L; you actually need about 2.4L in total. Oil level is checked with the bike on the centerstand and the motor OFF for at least 10 minutes beforehand.

Valve clearances: http://xjbikes.com/Forums/viewtopic/t=14827.html
Part Deux: http://xjbikes.com/Forums/viewtopic/t=29209.html

If you have a float that's badly stuck, it can "dump" fuel even when the bike is running and you could end up with gas-polluted oil again.

All that taking shortcuts on the carbs is going to cost you is having to do it over and over, changing the oil multiple times, etc. You're not saving anything with your current approach.

 

The inline fuel valve is installed, so the petcock leak isn't an immediate issue. Plus, the puddle of fuel is no longer stinking up the garage, and causing a fire hazard, so I'd say I've fixed THAT at least.

But I hear you, bigfitz. Thanks for the input. I've read here that if you're float needles are sticking, tapping the carbs with a rubber mallet can dislodge them, and solve the fuel-leak issue (at least temporarily). I misunderstood?

Today I drove the bike to work, and back. Other than throttle hesitation off the line, it functions well. And there's no more gas smell in the crankcase (or very little).

Thanks for the Exploded View of the Mikuni carb! That will really help me when it comes time to rebuild.

I put 2.2 or 2.3L into the bike, and tried what you said about leaning it over to check the oil window, but somehow it didn't work. I'll try again, when a friend can do the leaning, maybe.

I'll do a search for links on "syncing" the carbs? Either bench, or on the bike.

Have I missed anything significant on my prospective parts / tool order?