Throtte Shaft Seals a necessity to change?

Sometimes the floats stick... You can try to get them to unstick with a gentle rap on the bowls with a screwdriver handle.

 

Whether accidentally overfilled with oil or by sticky/leaky float valves, the crankcase is obviously too full. That's why you have oil or fuel-polluted oil surging into the airbox via the crankcase ventilation tube.

 

The idle is so high I don't like to run it for too long.... Needle/seat is new, everything new on the carb except for throttle shaft seal (which i did not soak in carb dip). I can't imagine that is allowing so much air through to idle this high, and even at that, to idle this high I need increased fuel+air mixture. If it was just increased air it would run lean no? but not idle this high.

Before I worry about the idle though I have to stop this oil leak.

I will smell for gas in the crankcase, but whats coming out looks entirely like oil.

I hear almost a swooshing sound when I kill the engine. Like some fluids are bouncing around.

How would one check the oil level, in the glass gauge in the right side crankshaft I can't see anything. If I take a dipstick and dip in the crankcase could I measure like that?

thanks guys... this forum is a godsend

 

A little air leak at the throttleshafts or at the intake boots can send you racing to 5k rpms or more....

Please listen when we tell you stuff----

 

As Hogfiddles states... if we tell you what it is please listen and follow advice OR get results you have now ....it is your choice and your $$$ and having a nice paper weight

 

Your right this is true. Well listen, I'm not experienced in this stuff yet, what I reason logical to myself might not be accurate in practice.

Well thanks for your help so far.

From what I could gather, I need new airbox to carb boots, and throttle shaft seals.

And probably a good idea to drain the oil out, and replace. I think there's too much. I added a tad, when I first started messing around with the bike, because I had no clue how much was in there and for sure didn't want the bike to ever start with not enough oil.

 

Ok, you're forgiven

No prob- that's why we're here

If they have shrunk and/or become so hard that you can't get them on the carbs anymore .... yes. Otherwise they are probably still ok.

It's the carb-to-MANIFOLD boots that usually develop the cracks and leaks that we talk about.

Throttle-shaft seals.... definitely replace.

Not 'probably' a good idea----- 'DEFINITELY' a good idea. Open the filler cap and sniff... smell gassy? Polluted oil. Not smell gassy? Old oils with what you added mixed in... you can run for a bit, but should at least put it on the center stand and view the oil sightglass to check level. If overfilled, drain some.... but if you're draining, may as well just finish the job all the way.

 

It's not that they have shrunk, they've expanded if anything. Maybe i'll just replace the clamp ring around it.. It doesn't really seal anything anymore.

Quick side question: what do you guys use to seal the carb bowl gasket? I would like it to stick permanently to the bowl, Ive tried a few things so far but find they always either get destroyed by gasoline, and then leave glunks of stuff in the bowl (which I would imagine to be terrible, that would clog the jets real fast)
Or is it best to just leave them bare?

 

some after market needle/seat replacements just don't work right.

even though they weren't soaked in the dip, if carb cleaner were to get in them and set for awhile it won't do them any good

 

Bingo!

 

Bowl gaskets - bare clean surfaces both sides.

Throttle shaft seals--I'll say it only once......whether they shrank or expanded, hardened, melted, etc...... They are over 30 years old. They need to be replaced. If you tear down far enough to separate the bodies, REPLACE THE SHAFT SEALS AND THE FUEL SUPPLY TUBE O-RINGSIDE. If you don't, you'll tear everything down again soon to do them and wish you did them the first time.'

That all said, it's up to you. Do what you want. We've recommended certain things to you enough times now

going radio-silent,

Dfox

 

No no no no I'm talking about the airbox to carb boots..... I've more than understood now that those throttle shafts need to be changed... and for good reason. Maybe they were sealing (ok) before the rack was broken, but after I broke it, POPULAR OPINION is they're useless.


I understand, I shalt repent of my sins.

 

I misunderstood, my bad.

Airbox boots-- if they've expanded, that's ok. Easier to fit--- lol. More likely, though, that the ring clamps have been stretched, so THEY aren't sealing correctly..... if the problem is the airbox side. Otherwise, check the manifold-side boots---- the thick heavy ones....

 

I apply RTV to the gasket and apply it to the bowl , let it dry completely and apply grease to the face of the gasket that faces carb body , Doing this the bowl can be removed without sticking to the carb body and stays attached to the bowl . I have removed bowls a couple of times and reinstalled no leaks either.

 

Hello, I am back.. after a long winter of a garage too cold to work in.

I hope you guys are still following this thread ( if not i'll make a new post).

I appreciate everyone's help thus far...


I have changed the throttle shaft seals, have bench synced the carbs (used two pins to set the butterfly valves all the same, and set the float levels to 3mm below the top edge of the bowl).

And the bike starts up, but same problem I had before... Extremely high idle.

So high, that I'm afraid to run the bike for more than a few seconds a time, in case i might crack the cylinder head, as the engine is cold, and hasn't run consistently in 10+ years.

**Video for reference:


From info I found online, and logic (hopefully), seems like there is a massive vacuum leak.

Things that I have ruled out:

1. Throttle shaft seals
2. Butterfly valves (the idle adjustment screw is pretty much all the way out, small little sliver)
3. Fuel levels ( i used clear plastic tubing to check the levels, they're 3mm +- 2 below the top of the bowl, I have read that high float levels can cause high idle, but even 3mm from the top of the bowl seems pretty high to me)

I checked the manifold boots, they look good, still flexible, but how they look must be deceiving. The leak is obviously not coming before the butterfly valves, as they are closed.
I bought heavy duty gear clamps that seal the boots pretty good, and checks the nipples for noticeable leaks.

Before I replace the boots, as they would cost me close to 600 bucks with exchange rate (damn the canadian dollar) , i want to rule everything else out.

Might be a poorly sealed head gasket, but there's no black deposits around the engine.

I find it hard to believe the engine runs this fast with just a vacuum leak. Where is it drawing the fuel to run? I would imagine this would be such a lean mixture the bike wouldn't even start.


What do you guys think?

 

I see you're playing in the choke. Just to confirm, are you trying to start it without choke and you receive the same results? how far out is your idle adjustment screw? I'd turn it all the way out to where you can get the bike to run at a decent enough range. from that you can then run your vacuum tests.

 

Have you sprayed starter fluid around to see where the idle might race more?

Have you backed the idle screw down?

Have you done a running sync?

 

me too
start looking at the throttle linkage. disable the ignition so it doesn't start, get a battery charger on the battery and do a running sync with just a starter.
15sec on one minute off, at least. two or three 15 sec shots should be enough to see if the sync is way off.
with the idle screw all the way out it should stall, try that

 

When the bike is cold, turning down the choke starts to stall the engine. After a few times starting it, choke up/choke down, does the same thing.

I want to check for leaks with starter fluid/propane torch, but I really don't want to run the bike for a more than a few seconds at a time.
I'll try to back down the idle screws and see what happens.

I currently have no battery, its hooked via jumper cables to my car.

You mean run a the carb synch tool? one with the gauges? I haven't purchased one yet.

Is this a synch issue? I understand if its running rough, but this just accelerates up like the throttle is open halfway. The throttles are close.

I was thinking to try to start the bike with a propane torch, and see where pointing the torch would cause difficulty starting.

 

Ah, I see what your saying. If one of the intakes produce much less vacuum than the others, theres a leak. Too much free air flow to produce a strong enough vacuum.

 

1. You won't crack the head by letting it run on like that, just don't let it go past redline for long (or at all if you can avoid it).

2. A vacuum leak can make the engine run right up past redline. I've had expereince with that.

3. Improper synchronization can make the idle quite high as well. I find that using pins is great for getting all the throttle plates even, but it's not at all good for getting them in the right place. They should cover about half of the idle fuel outlet in the carb throat. It's possible that you have the baseline set far enough off that backing the idle speed screw out won't let it drop to the proper idle.

4. There probably are multiple issues contributing to the high idle, so change one thing at a time and then see what effect it has before proceeding to the next item.

 

There is only ONE idle speed screw--- between carb 2 and 3. The knurled knob on the air box side of the carbs us what you need to turn counterclockwise to bring the idle speed down. If that's the cause, you're gonna have to turn it out quite a way.

If you don't have a carbtune, or similar, set of guages, you'll have a tough time balancing the carbs. No, we're not talking about the sync tool called the "YICS tool". You don't need that.

Is it a sync issue? Maybe... maybe not.

 

if you see a big difference it's probably your sync. count on getting some kind of sync gauge, dials, tubes, or water but you'll need one before your done

 

Back idle knob out if it is not touching then there is a problem .

 

If it's not touching, then most likely a butterfly is way out of wack and holding things open. I did get one carb rack to rebuild one time where a butterfly was actually bent and holding things open as well… A sticky shaft could also hold things open too. Any way you look at it, if The idle speed screw is not touching then you have other issues like jetfixer said---

 

Didn't finish typing had to catch train...if butterfly plates are not perfectly centered this can cause problems, first time I did carbs one plate was slightly off it does happen so please don't get insulted when asked . Did you do a bench synch with 2 business cards cut in half , put one under each butterfly adjust synch screw 1&2 till card has slight drag, do 3&4 same you will have to bring idle knob till you get a drag on all 4 cards , this should get you in ball park. A running synch will need performed I use a 4 vacuum gauge synch manifold adjusted till 1 and 2 and 4 equaled 1.5 hg and then adjusted idle knob up till all 4 read 1.5hg and idle was 1100rpm .I have no popping of the exhaust and runs great .....disclaimer your results may vary

 

Sometimes pictures can help. You should be able to back the idle screw out so that the result looks like the pic on the left, and all 4 should look this way with a good bench sync.

 

That's the way I'd do it, it will be close enough to ride if you take care with it.

 

It takes so long to bend the paper clips out, or cut the business card straps etc. etc.… I can have a rack bench sink by the time you get the business cards cut. You don't need to go through all that. Turn the idle screw in until carburetor number three butterfly top exposes the complete hole. Now it just the other three butterflies to just uncover the same hole in their carburetors. Now back the idle screw down until the holes are half covered , Then fine-adjust so all four holes are half covered now your bench sink. It takes only a minute or two to bench sync

 

I didn't see it before… Rooster explains it.

 

Makes sense. There's 3 idle holes on the carbs though, half cover the middle one.

Carb # 3 is the master. So first set that before setting others. What's the order if them again?

When I tried starting it last, both holes were uncovered at idle.

Will try this, see what difference it makes, and update.

 

For bench sync, I open til the middle hole on #3 is totally uncovered. (that way they are all open far enough that a different butterfly won't hold anything open or close too soon). Now ai adjust the remaining three to match. Doesn't matter what order. Once all match, I back the idle screw out til butterfly 3 covers half of the middle hole. Fine adjust the remaking three to match. Order doesn't matter. I snap them open a shut a few times, then check. Adjust if needed. install. Start up and do running sync.

My preferred order -

1. Balance 4 to 3
2. Balance 1 and 2
3. Balance 1/2 to 3/4

 

Priceless info, and so simple. It works too, better than a bodged running sync.

 

There is one idle hole (the one closest to the slide, also the one the the idle mixture screw controls), one transition hole (the middle one), and one enrichment hole (the one furthest from the slide, which also acts as a transition hole).

 

There you are, good explanation, and really, you should be able to see which order to adjust them - just work outwards from the master.

 

so update. I fixed the idle screw to where it should be at, i read somewhere before that you adjust it that you can just see a sliver under the butterfly valve, but obviously my 'sliver' was too much. Backed them all to where they cover most of the middle hole.

so now the bike idles at 3000 rpm, at a range which i can work with.

when i get my hands on a fire extinguisher i'm going to try a propane torch and see if the idle changes.

I'll even turn the idle more out, and see if that makes it better.

I also find after i start her a few times and she runs, when i leave it for a few minutes it ceases to start again. engine flooding? Not sure why that happens. it starts well cold, then after i turn it off, then try to start again it fails, no matter where the choke is.

When this bike gets up and running, i'm FedExing you all a case of beers

 

I don't do the 'sliver' or the 'card', or the 'paper clip'. I do the 'half of the hole' for the INITIAL SETTING and then Carbtune Pro from there to balance.

Have you BALANCED them yet? That will help a lot with the idle. Keep in mind that you WILL be adjusting the idle as you Carbtune, too, as part of the process.
Small turn,blip the throttle, let settle....small turn, blip the throttle, let settle.....repeat,repeat, adjust idle up or down depending on if it starts to get too low, or starts to race too much....l
Etc......l

 

The carbtune works the same as the other synch tools right? Like the gauges.. tests how much vacuum is going into each cylinder.

Don't I need the yics tool to properly balance the carbs. As it blocks off the airflow between the cylinders.

I'm going to try the propane torch today, if no noticable change in idle, I can rule out vacuum leaks. Then go from there.

Thanks again for your help.

 

Carb tune works like all the others........only better. Yes, you're basically balancing all the carbs to whatever one has the lowest vacuum. You're simply BALANCING them.

No, you DON'T NEED the YICS tool. I"ve never once used mine. Ever. When you're riding down the road, your passage isn't blocked, so whatever you balance with it blocked is going to be slightly different anyway. As I said before, unless you're going for picky amounts for racing, don't bother. These aren't high-tech micro-monitored engines anyway.

 

1. Carbtune is a brand of vacuum gauge.

2. The YICS tool is optional.

3. Propane doesn't always catch intermittant vacuum leaks (such as might be had with throttle shaft seals not always sealing). I prefer to use carb cleaner because it hangs around for a bit longer.

 

Ha, I always thought the yics tool was absolutely mandatory.

Unless I did any modifications (air pods, aftermarket exhaust) , should I worry about something like a colortune? I have the pilot screws set at 3 full turns out.
I will still check the plugs to see what color they become.

My main fuel jets stock are 120, but i have 122 jets installed, I did fit a K&N filter however. Pilot jet still stock at 40. Reading through Len's catalog, he suggests for every +3 main jet, you should increase pilot jet by +1. so i should be good?

 

You should be good, if not a tad rich. Most people end up at around 2 3/4 turns out. Keep looking at the plugs (the heat change on the ground strap, not so much the insulator color), and as you go leaner (if you find that you need to) listen for backfiring on deceleration (at which point you are too lean). Fuel economy is also a good indicator, but that will vary some with weather and road conditions. If you're getting less than 40MPG then she's very much too rich.

Having said all that, the priority is to get the idle down to no higher than 1500 RPM (and be able to kill the engine with the idle speed knob backed all the way out). If you can't do that, then there's still something not set up correctly.

 

Would this work for HSC33 carbs? Can you elaborate on the #11? What size is it and is it in inch or metric? Best, Nikolai

 

I got these. Have not tried them yet. I sent the dimensions l found on the forum to the supplier. They are the same dimensions l believe as the ones some XJ owners were ordering from the American supplier McMaster-Carr.

 

I used the X rings on my XJ700 carb throttle shafts. They work so far. They seem a loose fit into the carb body but so do the original C rings.

 

Good to know cheers.

 

I just stay with the throttleshaft seals from xj4ever

 

I would - without doubt - go for that option if I was located in the US. Shipping, import taxes etc just makes it too complicated and expensive.

 

Yes so would l if l lived in the USA. I am going to try the X rings because they are a good fit on the throttle shafts.