want to confirm next steps after smelling gas from oil filler opening

Sorry for the long post, but I wanted to err on the side of providing as much detail as I could.

Also, thanks in advance to every for their help. I'm quite handy, but not really a motor guy. Since buying an older motorcycle, I've had a chance to learn a ton and your expertise and encouragement are appreciated.

The background:
I picked up a 1982 XJ650 Seca in autumn 2016 from a shadetree mechanic that works only on older bikes. Rode the bike the rest of the season without any issues. To winterize it, I made sure the tank was full of treated, non-oxygenated gas, I ran the bike a bit to get it into the system, shut it down, drained the carb bowls and topped up the tank. Put a tender on the battery and put it to bed for winter.

In February, we had some record weather and I started it up and took it out for a spin. It didn't fire right up, but it didn't take much coaxing, either. I did not notice anything to indicate any problems.

The symptoms:
Weather got cold again and after sitting another month on the battery tender, I fired it up. No, I had not re-drained the carb bowls. It started well enough, but got a bit rough as it warmed up and was incredibly sensitive to choke and throttle. Exhaust 1 & 2 were cold, so I shut it down and pulled the plugs. They were wet. I left them out to dry things up, started searching on the forums, and can confirm I smell gas in the crankcase. So, if I read anything correctly, I likely have stuck floats on carbs 1 & 2.

I want to add that last fall, a friend's Honda CB350Four had two cold cylinders after we cleaned and reinstalled his carbs. That evening, when I started mine up, I felt the exhausts. 1 & 2 were cold while 3 & 4 were warm. But, 1 & 2 caught up and were eventually hat and the bike ran smoothly.

Next steps:
I plan to rebuild the petcock and then address the carbs (rebuild/clean/set/synch).

Questions:
Anything else I should be looking at?
I have heard people talk about tapping float bowls to release the floats, any more detail as to what this means or when its necessary?
When I put the bike on prime to get it going after draining carb bowl, how long should I be on prime? Should I automatically tap on the bowls? Put another way, how do I prevent this when I reinstall the carbs or next spring?
I assume I should immediately drain and replace the oil.

Thanks again.

 

tap or rap the float bowls with a screwdriver handle when first filling them to make sure they do not bind as they rise with the fuel.
prime 15 to 20 seconds close and repete. I would advise using translucent fuel line so you can see when the bowls are full (no air left in line)
I run the last few tanks of fuel for the season with non ethanol high test and do not drain the bowls you can add your brand of stablizer if you want on the last tank fill.

as long as you can see an air bubble in the sight glass do not drain the oil until you can confirm your carbs are not overflowing then change oil
unless it is going to be months spring is just around the corner

 

Do not leave petcock in PRI if you have stock petcock. Leave in ON if it is still vacuum petcock . As long as it is not leaking this should keep you from filling crankcase .
^^^+1 tap float bowls with handle of screw driver see if it helps.

 

And replace the oil and filter AFTER you fix the fuel problem

 

And don't start/run the engine until you have fixed the fuel problems!

 

your original rubber brake line

if you had a clear inline fuel filter you'd know right away

check the oil level, if it's only up a few ounces, you can start it to work on it. but change it before you ride it. you might not fix the floats the first attempt, then you wasted the oil

 

Parts from XJ4Ever are on their way and I spent time today getting the bike ready. I hope I can get it running smoothly again. Today was the nicest weather since last October and I had to resort to riding a friend's Honda.

 

got 10 inches of snow last night

 

My sympathies. I'm in Minnesota. Snow will remain a possibility for a couple more months.

 

Beautiful day here, had garage door open while working on a bike.
13c and sunny

 

I just started a new job, so progress has been slow. I'm in the middle of rebuilding the gas tank cap and the petcock valve right now. With everything going on, it'll be a bit before I tackle the carbs.

 

I finally cleared up some time where I could focus on the bike and get the carbs off. This was my first time removing the carbs (on anything) and with everyone's tips on heating and loosening the air box and tucking the boots in, it took me a lot less time than I feared to remove the carbs. As well as it went, there are some things I wanted to run past this group:

• Some of the clamps were incredibly loose and most of them are bent in some way. Assuming I can tighten them up well enough, do they need replacing?
• The carb boots are flexible enough and I don't see any cracks, but they are caked with thick grime and grease. What's the best way to clean them?
• The bike ran great last season and I was planning to do just to the carb lowers to cut my teeth and save a full rebuild for this fall. I'm the farthest thing from an expert, but the guts seem to hint at biting the bullet and do the full rebuild now. Thoughts?

Thanks in advance.

 

Not a bad idea, but those carbs look remarkably clean inside, any history known about their service record?

 

I don't have any history on service. I bought the bike from a mechanic that was actively riding it on weekends. This was one of the newest bikes in his shop.

 

I think I measured the valve shims correctly and have identified the replacement shims I need.

Intake
(carb; clearance; current shim; replacement)
#1; 0.09; 285; 280
#1; 0.10; 285; 280
#1; 0.10; 285; 280
#1; 0.09; 285; 280

Exhaust
#1; 0.18; spec
#1; 0.16; spec
#1; 0.14; 275; 270
#1; 0.18; spec

Is it common for all the shims to be the same size? I was wondering if it was possible they are original. The bike has 23k miles.

 

Are we talking clamps on the intake side or the air box side? When I had the carbs off last season, I noticed my air box side clamps were loose even when the tension screw was completely against it's nut. I took an old bicycle tube and cut strips the same thickness as the clamps. Then I used contact cement to bond the rubber to the inside of the clamp, effectively lining and thickening the inner diameter of the clamp(s). Worked like a charm!

I'd imagine if the PO was a MC mechanic, he'd have checked the shims and swapped the ones that needed changing... but you never know...

 

The clamps for carbs 2, 3 & 4 on the airbox side and the clamps for carbs 2 & 3 for the intake side. I'm guessing someone was too lazy to reach in there and find the screws.

As for the mechanic, I think his focus was making them run, not necessarily the fine details. Still, I was happy with it before I started digging into it; I'm hoping it's even better when I'm done.

 

Unlikely. The most common way for that to happen is an idiot (make tham all the same, paying no attention to the clearances). The second (and more desirable, but quite rare) most common way is the head having been built by someone who's really, really, overly, incredably focused on getting things too perfect. In order for all the shims to be the same size, and have all of the valve clearances in spec, a fella would have to grind the valve stems amd/or be really (pointlessly) accurate when putting in new valve seats.


I just thought of another way. If somebody had a bunch of the same size shim, but not any of the sizes needed, that fella might grind the shims to suit. Check the shim thicknesses with a micrometer or caliper.

 

I was getting ready to replace the valve seats and noticed a distinct difference between the old ones and my replacements from Chacal. The replacement (on the left) is 13.75mm tall, while the old on (on the right) is 15mm. Also, the size of the fitting on the end for the screens are completely differ shapes and size.

Can anyone tell me which is correct?

Also, the old valve cover lifted up easily, leaving the gasket stuck fast to the engine. Any tips to remove it? I don't want bits of gasket to get into spaces it doesn't belong..

 

I can, me, me (waving hand wildly in air, in the back of the room)!

 

Thanks, Horshack! It's not so much that I doubted you. It's just that this is my first time doing more than a simple oil change (on any kind of motor) and I've always been a "trust, but verify" kind of guy. Once my latest order arrives, I can get teh screens on and reassemble everything.

Any tips on removing the old gasket without creating confetti and getting it into the engine?

 

Which gasket?


In regards to the float valve issue, the seats and screens, etc. are different because they are made by different manufacturers:

- original fuel inlet - float valve brass seats had a fuel inlet boss (where the inlet filter screen sits) of either 5.10mm (and thus uses the HCP9855 flat screen) or a 6.57mm boss with a 7.30mm "capture lip" (and this style float valve seat uses the HCP869 domed screen).

- The HCP10 (current OEM) kit comes with a screen. The screen boss on the seat is 5.10mm OD and it comes with the HCP9855 flat screen. The needle is the same length as, and is rubber-tipped, just like the original. The float valve seat washer is made of copper as original.

- The HCP18795 kits (aftermarket) comes without a screen. The screen boss on the seat is 5.10mm OD and it accepts the HCP9855 flat screen. The needle is the same length as the OEM needle and is rubber-tipped just like the original. The float valve seat washer is made of aluminum rather than copper.

 

the seat and needle are a set, the fuel level is what counts. the size of the parts that make the level right doesn't matter.
if they came from Len, their right

 

The valve cover gasket. It's almost as if a previous owner read the airhead valve adjustment post and then did the opposite.

 

Gasket scraper tool, single-sided razor blade, rags stuffed down in the cam chain tunnel, positive karma.

That figures.

 

As you have found Len/ Chacal is a trusted source . . .

Good for you for seeing something was not like the others and asking questions.


P.S. Avoid gouging into the head whilst using the razor blade - scrape, scrape, scrape. I found pulling instead of pushing to be the best.

 

I ran into problems setting floats today. As I started to fill the carbs, gas was dripping down off carb 4's float bowl. At first I thought I had not sealed the bowls to the bodies. As I let the gas run into the carbs, I saw gas also coming off the carb 3 float bowl. I tried a few things and still couldn't stop it. Finally, I left the bowls off carbs 3 & 4, remove the floats and needles and plugged the seat with some borrowed fingers. It appears gas is leaking from the fuel inlet tee.

I didn't break the rack or dip the carb bodies and this wasn't happening earlier. The tee seems to have a slight amount of left/right play. It's possible that all the fuel connectors leak, but I didn't run the gas long enough to confirm.

 

If you didn't break the rack, I can pretty much GUARANTEE that's where it's coming from. AND- I can pretty well guarantee after you get it all back into the bike.....again.....you're gonna find you have vacuum leaks at the throttleshaft seals---so you'll get to take it off AGAIN! The reason for that is so you can get really good at removing and installing them. 'That way, when you finally decide to do it ALL at once, then you'll be able to pull them right off, and then when it's time, be able to pop them right back on like it was a piece of cake

 

Yeah, I've already been kicking myself over it. The bike ran without an issue, none of the carb-related symptoms I've read about on the forum. Then, I try to fix one "little" issue and it's been snowballing from there.

Well, this will give me the chance to replace some chewed up jets and idle mixture screws, while I'm at it.

 

Brake calipers are rebuilt, master cylinder is rebuilt, and stainless steel brake lines are in stalled. Everything is torqued to spec and ready to fill. Brake lines seem to be the original. I didn't see any cracks, but they're pretty gunked up.



Nothing left on my list now except go back and finish the carbs with the throttle shaft seals and gas tube O-rings.

 

I may have spoke too soon. Micrometer came from Amazon and I put it on the front rotors. 4.5mm on the nose. I'm thinking it'd be best to replace them, since the rest of the brake system has just been rebuilt or replaced.

My wallet is crying, "Uncle!"

 

Spending a few hundred dollars more is better than dying because you can't stop. You'll still be ahead on what it would cost to buy a used motorccyle that doesn't need any work (like those even exist).

Why You NEED TO REPLACE Original brake lines w/pics

 

Carbs are completely disassembled (again) and soaking.

As I looked at the needles, I noticed that a couple of them "lean" to one side. The needle itself is not bent, but there appears to be a small tab in the base of the diaphragm cylinder that keeps it from sitting flush. I've not seen reference to anything like this in any of the reading I've done.

Is this normal?

 

Normal and intentional.

 

Correct, the only question is "why?"............Mikuni needles are not offset like the Hitachi needles are.

 

To make foreigners ask questions.

 

Gross!

 

Carbs are cleaned, refurbished and reassembled. Fuel levels are dialed in and they're bench synched. A few more bits to finish up before getting them back on the bike and then it's colortune and running synch.

I've shared a lot of what I've learned with a friend who has a '73 Honda CB 350 Four. He says it runs better and with more power than he ever remembers and it's been with his family since '75. He took it up to 75 mph for the first time ever and said he still had plenty of room on the tach. I was happy with the bike before, but, given his success, I'm excited to take it for a test ride. Probably another week, given my schedule.

 

You did, of course, take note that he posted the snow comment on Apr 2, right?

 

Been lucky here. It's been so long since there was snow that I can't remember when.

 

Hah, no, missed that. Sadly, being Canadian, getting snow in June isn't unheard of =/

 

Today was the big day - reinstalled the carbs. It fired right up with choke and ran well. All 4 exhausts were warm, gas wasn't flowing into the crankcase - off to a good start.

After I took the choke off, the RPMs really took off. They'd come back down only to rev up again. I'll be reviewing tonight how to do a running synch and use the Colortune plug. I think I've read somewhere on this site that the synch and colortune will clear up the revving issue. That happens tomorrow.

Couldn't have gotten this far without everyone's help and Len's fast service.

 

Don't feel bad. Many of the less-traveled passes across the Rockies and Cascades down here aren't open yet.

 

Sometimes. Sometimes it's a vacuum leak.

 

If vacuum syncing and color tuning does not clear it up.....then most likely you have a vacuum leak

 

I haven't dealt with a vacuum leak on these bikes, but if it's anything like cars and such simply spraying some propane or other gaseous fuel around vacuum fittings will cause the idle to change when you get near the leak. Pretty easy to troubleshoot really.

 

Vacuum leaks are usually confined to the area of either the intake manifold boots or their gaskets , airbox boots, vacuum caps on intake manifold boots or the fuel vacuum line itself.....

Never had to perform the propane test...good luck with that.....just make sure all boots & gaskets are in good condition & tight.

 

Does anyone know if there is any reason not to try the propane test before I try to synch the carbs? I am thinking it might be easier than worrying about high revs while trying to synch the carbs and adjust the idle mixtures.

 

Or the throttle shaft seals, which are often overlooked.

 

None at all.