82 XJ550 Maxim Running Lean

I have a 1982 XJ550 that I've been working on for a little while. When I first got it, it would rev too low and die if i didn't constantly give it some throttle. I opened up the carbs and cleaned them. When I reinstalled, the bike ran well. However, the idle was pretty high at 1500rpm. Now, if I turn it on, it will start out at about 1000 and slowly make its way up until it's at about 5000rpm and won't lower until it cools. I have tried adjusting the idle speed screw to no avail. I'm right in the middle of adjusting the valves, but I wouldn't think that would cause this.
The caps on the little metal nipples for synching the carbs are pretty hard, and I've read that can cause vacuum leaks. I also left the carbs together and dipped them when cleaning, which I have read can damage some seals between the carbs.

Anyone have advice on how to fix this idle?

 

You have a vacuum leak (or more than one).

Start with the easy things. Replace the vacuum caps and the vacum line to the petcock.

Since you dipped the carbs with the seals in place you should not be surprised if that does not remedy the problem.

Once the carbs are eliminated as the problem you should examine the intake boots for deep cracks. Carb cleaner methodically sprayed around each boot in turn will identify any that are cracked clear through. There is a budget-friendly repair if you can't afford to buy new replacements, or if you're hesitant to remove the bolts that hold the boots on (they can break pretty easily).

Carbs should be first though.

Read This First

Inside your Carbs

IN THE CHURCH OF CLEAN

Cleaning your Mikuni carbs

Why you should replace butterfly (throttle shaft) seals.

Replacing your Hitachi throttle shaft seals (The same info is applicable to the Mikunis as well).

Setting the fuel levels (this is a critical step that is often overlooked during carb work).

 

I replaced all intake manifold boots when I got the bike because they were cracked and ripped all over. I'll order shims, the vacuum caps, the vacuum line, and throttle seals from xj4ever and re-clean the carbs while replacing the seals.

Thanks a ton for the help.

 

Normally you would do a bench synch to align all the butterflies, using the transition hole nearest closed to do this, then set the idle screw to allow the least crack of light through them.
Did you do this?
Did you set the float levels and then check them on the bike?
This should get it close enough to do a running sync using vacuum gauges (both my seca and maxim 650s run well enough to use by using this method).
Lastly, did you do the valve clearances?

 

How about slow down and take things in order?

Replacing throttle shaft seals in Mikunis is a bit of a major project, and while I'm not going to argue that it's not necessary, or will be at some point, you're still coming at this backwards. Let's don't rush into breaking the rack just yet.
First thing, before any carb tuning can begin, is to get the valves in spec.
Then, once cleaned, the carbs need to have the float levels accurately wet-set and a careful bench sync done before they are returned to the bike. At that point, a running vacuum sync is in order; which could be affected by a vacuum leak if said leak is bad enough. So far, a vacuum leak, while quite plausible or even probable, has not been diagnosed, just immediately assumed based on symptoms. Symptoms that are not unexpected with unsynchronized carbs and/or wonky float levels as well.

You can't just clean the carbs, throw them back on the bike, and hope it will run. Mikunis are very sensitive to being disassembled and reassembled; wet-set float levels and a bench sync are absolutely a must anytime you have them apart.

One more quick note: On the 550s, the intake manifold bolt holes are "blind" that is, they don't go all the way through like on the bigger bikes. As such, they are less prone to becoming corroded in place, and easier to remove (carefully) without breaking. Replacing the manifolds on a 550 is nowhere near as scary as on one of the bigger XJs.

 

Well, I have throttle shaft seals on the way, as well as new pilot jets and pilot mixture screws as when I took the carbs apart the heads of those were in pretty terrible shape. If I take the carbs apart to replace these, should I still leave the rack intact and leave the old throttle shaft seals alone? I doubt they've been touched in a long time. A lot of small rubber pieces like that on this bike so far have been practically rock hard. Especially the ones that are hard to get to, or out of the way. Thank you for helping me see this from a different angle and please give me more advice on this part of the carbs.

I've been busy working on the camshafts of the bike today to easily get the valve shims out (I took one out and rotated the engine so I couldn't get it back in), and now I have the shims I need coming.

Do you have links to guides on how to check float levels and bench synch? I have seen guides for these tasks before, but sometimes I lose things like those and can't get back to them through much searching. I'll definitely do this stuff before I put the carbs fully back together.

 

Okay, small problem. In my manual (Clymer XJ550), for removing the camshafts it says to remove the tensioner, bring the cams to the T on the crankshaft, remove one bolt from each sprocket. Then rotate the engine counterclockwise until the bolts on the other side of the sprockets are visible and remove those.

However, later on for reassembling the clams, it says to make sure the cams are still in TDC position. My engine is no longer in that position because I rotated it as instructed. What do I do to proceed with installation?

 

Upon further reading, it looks like it wants me to take the cylinder head off the engine and then rotate it back to TDC after the head is off. I don't have a reason to take the head off. With the chain, sprockets, and camshafts removed can I turn my engine back to TDC without removing the head first?

Thanks for all the help everyone

 

yes. remove left side crank cover where the pickup coils are located. you will see a square "nut" turn that the whay the wheels turn . on the pick up plate you will se a T that is TDC turn motor untill pointer is pointing at the T.
remove spark plugs first to make turning easy

the cams have a mark on them and cam caps have a mark that you line up for the cam install

when you reinstall the cam chain tensioner you will see a C on the same plate that is where the pointer points when you release the cam adjusted

 

I see that. Is it okay to turn with the camshafts out and the cam chain hanging above?

 

yes as all the valves will be closed. just remove sparkplugs to avoid compression.

cam chain may rotate if it is still on sprocket on crankshaft.

 

Okay, the cam chain I think is on the crankshaft underneath still. Do I just help it through my zip tie holding it by the frame and rotate to T? Sorry for sounding apprehensive and careful, I just don't want to damage my engine and I know you guys are experts.

 

When I reinstall the camshafts, do I have to time them? I see they have some sort of spiral gearing, will this time them properly for me?

 

I have an update. I went ahead and pushed the cam chain along slowly and turned the engine all the way around to align the T with the mark perfectly.

Does this mean that my cylinders are in a good position now and I can put my cams back on safely? I understand how to follow the manual procedure to do this.

Also, I still need to know how to set my float levels and bench synch my carbs. Could somebody send me links to guides on these subjects?

Thanks everyone!

 

That I did not know. Those details are a large part of why I appreciate you being able to return to the forum.

 

how-to-bench-synch-your-carbs.6366

 

Awesome link. Now if anyone had one about how to set float levels that would be awesome, I'm pretty sure I need to buy some cheap hardware for that and I'm about to go out to the store tomorrow.

 

So h0w did we get to camshaft removal again? Just to replace shims? Valve shims can easily be changed without removing the cams.

Yes, the "T" mark is TDC on the crank and is used for properly timing the cams. Cam timing is very important, as the pistons could hit the valves if not set up properly. Not sure why you're now contemplating removing the head, my advice there is DON'T. I'm still unclear as to why the motor is coming apart this far, seems a bit unnecessary.

Float levels: http://www.xj4ever.com/setting fuel levels.pdf You have Mikuni BS28s, so the spec is 2mm +/-1mm bellow carb/bowl joint.

 

I had to remove the cams because I removed a shim and then turned the engine without replacing it, so using the wire method I couldn't seem to get a new shim in its place. Therefore I removed the cams to make this shim job easier. I'm now waiting, with the head remaining on, for new shims so I can put this engine back together.

 

Gotcha. Another reason the "holding tool" method is a better than the "wire down the plug 'ole" method.

Advice: if you plan to keep this bike, spend the <however much it is these days> and get a valve bucket hold-down tool. Makes the job much easier.

Also, and again if you plan to keep this bike, invest in a factory shop manual. The Clymer, while "OK" is chock full of misinformation. (Which is not to absolve the factory book of questionable procedures either...)

 

Thanks for the advice. I'll invest in both of those next season. I do plan on keeping this bike, all this time alone in the garage with it sure builds up the sentimental value!

I've been working on the carbs while waiting for parts to come. Last time I did these carbs, the heads of the pilot jets had been mangled by the last guy to open them up, but I managed to get them all out with a screwdriver. I have new pilot jets coming on Friday. Now, I can't seem to turn any of them. I sprayed some WD-40 on them last night, but I doubt that will help too much.

What's the best method for removing these stuck jets? I got an easy out kit with a #1 size easy out that seems small enough for the jet. However, I am concerned. The couple times I have used these tools before have been unsuccessful. Is the metal of the jet going to be too soft and get ground up by the easy out before it grabs hold and loosens? Please give me advice on how to continue

Cameron

 

First off, don't use WD-40 to loosen anything, it is not a penetrating oil.

 

My bad, I have commonly seen WD-40 referred to as penetrating lube.

 

Buy some PB Blaster or even Liquid Wrench. The WD in WD-40 stands for Water Displacement. Common mistake though, you are not alone.

 

can you get the outside with pliers
heat it up a little, like boiling water hot

 

I'm taking it to my step-dads shop, so I'm sure we'll have PB blaster or something.

What do you mean the outside? What should I grab with pliers, the carb body around the jet? I don't think anything will grab this jet anymore.

When I tried to remove the jets again, I already knew the heads were on their last legs. I pushed the driver really hard and turned, but it grinded away everything left to grab. It's stuck. I have to modify the jets in some way e.g. drill into them to get them out.

 

I think Polock meant can you grip the outside shoulder with vise grips to try turning the jets out.

 

There's no way to turn them out, pushing and turning a flathead counterclockwise in the head never catches on anything.

 

I'll respectfully disagree. The problem was that he turned the engine without a shim in a bucket. The same can be done with the holding tool in place, and a different sort of damage can result.
I've changed shims both ways, and for me the holding tool is clumsy. At the end of the day using the tool that works best for you is what's best, so long as it's suited to the job.

 

True, and had the tool been in use there could have been irreversable damage. However, when properly used, the tool always keeps the bucket held down far enough. My biggest concern with the wire down the hole method is disturbing the carbon deposits directly adjacent to the valve seat or on the head of the valve itself. Using a piece of insulated solid #12 wire is less likely to cause such disturbance than a zip-tie, but I'm still not a fan of poking about blindly in the combustion chamber.

 

I meant clamp the shoulder of the jet with the vise grip pliers. Not the carb. No screwdriver needed.

 

What do you mean by the shoulder of the jet? The jet is down about a 2 inch hole in the carb.

 

Sorry, I was not paying attention to which jet you were referring to. My advice is no good for your issue.

 

Agreed. My fear with the zip-tie is that it has edges sharp enough to act as a scraper. Carbon is really tough to remove, but a sharp edge of any kind can disturb it.

 

I'm confused about which jets are stuck. Can you post a pic please? That will help with recommending how to remove without damaging the carb body.

 

Here is a photo of one of the jets. They all look like this. They look pretty normal in the photos, but the parts of the head that the screwdriver blade would grab are rounded down.

 

OK. Those are the ones I was thinking of.
Use an e-z-out after soaking in a proper penetrating oil.
The only bad thing that might happen is the hole in the jet gets mangled enough that the e-z-out loses its purchace.
Don't use the small one that you have to fit the existing hole though. It won't be srtong enough and may snap off.
Drill the hole as big as you can without hitting the minor diamater of the threads. If it still wont' budge then you can step up the drill size so that you cut the body of the jet away from the minor diameter of the threads and can then use a dental pick to remove the remainder of the threads from the hole.
If you have a set of left-twist drills use those. Fairly often the fastener will catch on the drill and back out without needing to do anything else.

If you feel at all sketchy about the proposition grab a box of doughnuts Monday morning and head over to a local machine shop with the carb body.

 

Are you sure a screwdriver that tightly and squarely fits the jet won't pop 'em out? If you already had them out once, they shouldn't be so tight as to require drilling or EZ-Outs or anything. Lots of soft metal involved here, don't be going all medieval unless absolutely necessary.

 

It doesn't matter how carefully I line the blade up or how hard I push. The driver just spins around on the head of the jet.

 

I got the pilot jets out using an easy out. This is pretty exciting.

Tomorrow I get parts in the mail so I'll rebuild the carbs, set float height, and bench sync before installing. I'll let you all know how this goes.

Thanks a ton, everyone.