Top end rebuild (Stuttering, Elec. Issues Prior) (Pic heavy)

Stay tuned -- I'll be checking all this stuff today and will return with a thorough report

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

Still trying to find time to do this today, but let's do some thinking in the meantime:

Unfortunately all I did was slap the air filter and try to ride the bike. I couldn't do any tuning because I had to give the air filter back (someone let me borrow it). However, I went ahead and bought an OEM filter and when it shows up, I'll colortune and sync.

That's definitely something I would not have noticed. I did replace both the chain and sprockets before the trip, so there's a possibility something could be amiss down there. New thrust washer, too. We'll find out when I pull off the chain and front sprocket.

You're right, my mind tells me based on the stuttering miles I've put on this XJ that the problem is fuel/air related -- but driveline is one of those things we have not considered.

The headers and mufflers were both off when doing the head rebuild. There was no sound of anything loose in there (rocks, debris, baffles, or otherwise). I'll get a flashlight in there to see what I can see.

As far as any other things we haven't though of or discussed...Thinking out loud:

Electrical? Everything has been replaced. Lets work up the food chain:

Spark plugs ---> boots ---> coils ---> wiring harness/fuses ---> pickup coil ---> CDI

Stator ---> reg/rect ---> battery

Safety relay is missing from that list, going to check.

----------------------------

Fuel/air? What I've touched:

Compression is good ---> rebuilt head w/new gasket ---> lapped valves ---> stem seals ---> valve clearances in check ---> timing is correct ---> chain tensioner is functional

Intakes and o-rings ---> carb boots ---> correct jets ---> float levels correct ---> no tears/rips in diaphragms ---> they go clunk ---> emulsion tubes in good shape ---> fuel pump and lines ---> petcock and vacuum tube ---> tank and cap air inlet

Carb to airbox boots ---> air filter

As you suggested Fitz, throttle shaft seals are not in that list. Plus, the airbox is two-peice and there's a gasket/seal between them. Perhaps that seal is disintegrating. Also, as Mr.Etobicoke suggested, I did not try and sync/tune with the OEM air filter.

UPDATE:

Ok, there are two relays on here. The right one is the flasher, the left one I'm assuming is the safety relay. I can find it on the parts fiches but can't find anything that tells it's purpose. Not even in the manual. Well I'mma gank it and see what happens.



The side stand area is pretty nasty. The switch back there could probably use some cleaning.



UPDATE: The bike doesn't start without the relay on the left

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

Driveline check:


Nothing out of the ordinary at first, but there was a little play in the sprocket. I hammered the lock washer back, and the nut just spun off with no socket...Looks like the lock washer did it's job. That explains the chain vibes, I bet.


I didn't put it on backwards, lol


No unusual wear


No damage to the spindle


While I'm waiting for a new lock washer, I'm going to finish up these carbs. Might even try to score another parts rack off ebay since I've got two racks, but only one complete set of internals.

 

I love getting emails about this topic.... everytime it's like christmas...

I open it up hoping for the best present ever, the solution


Only to be disappointed by a pair of socks.....

I think it's something to do w/ the fuel system going to reserve and back... I really do

Thinking about it today at work... your problem came up when you switched it... I noticed it when I was switching back and forth, since then I've nailed my mpg and haven't had to use my reserve on my rides. Just plan to stop when I know I'm 5miles or less til reserve....

But, the flash I had was the last time I had this problem... I had switched to reserve, drove the .7 miles to the gas station, gotten gas, and when I went to pull away it started to bog down/stutter...

With my fix.... a tap of the #1 spark plug, pull in the clutch and give it a lil gas, it seems to clear up...

but now thinking about it.. i wonder if it's more like the inside leaf that is only being sucked up when it has been on reserve... IDK

like I said, Damn pair of socks!!!

 

If you can't find the safety relay...just unplug the side stand switch and bypass the wiring harness there. It will be interesting to see how the bike runs with the front sprocket tight. What spark plugs are you using?

Kenneth

 

Come get your socks!

Haha I know what you mean Koi...the Christmas solution is coming, don't worry

Yea I'm curious what will happen with a correctly fastened driveline. Although I'm still convinced the stuttering is fuel/air related. One thing at a time I suppose.

Spark plugs -- NGK CR8-E

 

Stuttering is definitely fuel/air/spark related.... though i'm saying fuel more then air/spark.... just my intuition though I can't see how we've missed it so far...

anywho... damn you and your socks....

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

You don't like them?

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

No,,,, these are more my style




8O

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

Dang Koi, you must have been working out!

ANYWAYS

Forgot to mention: sidestand relay unplugged, bypassed at the harness, there was change. That was the last electrical thing to diagnose.

Last night I got the XJ home from work, which is about 20 miles. Couldn't really start pulling things off while it's at work.

Inbound:

OEM air filter
Throttle shaft seals
Lock washer for sprocket

 

Quick tip, from looking at the pics: When you re-fit the countershaft sprocket, lube the splines with a nice high-temp grease. Running it "dry" like that will accelerate wear on the splines, as you can see by the red dust.

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

Come get your socks

Thanks for the tip, Fitz. I was curious where all that rust dust came from.

While waiting for the parts to show, I wanted to make sure the carbs were in tip top shape. Taking into consideration this is literally the 10th time I've taken them apart this year, I still found some things that were not to my liking.

Check out the o-ring on the valve seat. It wasn't like this last time I got my carb on.


The o-ring on the idle mixture screw isn't disintegrating, but it's kind of flat. Not sure if it's supposed to be like that.


The is the main jet tube. There's a little tiny o-ring that goes on the end of the jet, and presses up against the holey mistifier tube. As you can see, it's time for a new set.


Going to soda blast this rack today. It's the one I've been using to diagnose with while I'm rebuilding the original rack.



Either I didn't catch this stuff before, or something caused it recently. Regardless, it's something else that needs to be done properly before I can even hope to get the bike running right.

 

Don't soda blast the insides of the carbs unless you're breaking the rack. You don't want to drive soda dust into the throttle shaft seals from the inside.

The inside of that jet tube is pretty interesting...

and no, the o-rings on the idle mixture screws aren't supposed to be flat like that.

 

So, just throwing out there the latest stutter on my bike...

Went out for a ride the other night with some friends, had ran 135 miles on the first tank ((5-10 short of reserve)) and then 139 miles on the 2nd tank ((1-5 miles til reserve)) On the third tank of gas we went to dinner, no problems, ran fine..

And oh by the way, I replaced the stupid chrome fgt looking screaming gayh pipes with a set of stock exhaust I got off ebay.. run's smoother but there's a bigger gap in the middle of the power band around 6500rpm... anyway not the point

I was riding home after dinner, probably 38 miles into the tank of gas and was attempting to get on it a lil bit to cut through some slower cars, well when I romped on it, 5th gear, but was being lazy and not downshifting to 4th so it was a lower rpm, 5-5500? I got the bog/stutter/1/2 an engine feel.

Immediately got off it, reached down to trusty #1 spark plug, tap tap wiggle wiggle, no worky... Sh*t....

So I downshifted into 4th, still boggy, pulled in the clutch, revved it, smoothed out and never bogged again....

for the remaining 5 miles I thought about it and previous times and I can say the romping on it in a higher gear might be a reoccurance but I don't remember, never thought about that part of the situation til this last time...

Not saying it helps at all... when I got home it was running fine, I was full and tired, so when I got up in the next morning and put it on the stand, did some checks.. of course I couldn't find that big red arrow pointing to the answer...

Going to pull it apart in a few days before a major ride on the 28th to the redwoods... will take pics and show you how ugly my bike is internally compared to your clean lil princess....

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

Interesting. Sucks you're having issues, though.

Gah!

Here's where mine stands. I got completely new o-rings and throttle shaft seals for the whole thang, and it idled better, sounded better, but still stuttered. Don't have the new air filter yet. But there are not-good noises coming from under the valve cover. I need to pop the cover and double check everything. Might even take the head off again.

I'm just keeping my open for a parts bike, really.

These are the little main jet o-rings. Old on top, new on bottom.


I used the back end of a small drill bit to press them in


O-rings for the valve seats


New idle mixture assemblies


Old on top, new on bottom


And then for some reason my XJ decided to molt? Maybe it will come out bigger and stronger as a XJ900. The way I had my tank in "storage" while wrenching caused some motion lotion to reconfigure the color. What's next.

 

Before you go yanking the head, just triple-check the cam timing and then the valve clearances; and run another compression test.

 

How did this conclude... I've just read the entire thread -- no resolution to-date?

Thanks

 

I am equally interested in knowing what happened.

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

Ahh, I've been meaning to update this thread. Turns out (to no big surprise) it was carb related, more specifically the throttle shaft seals. Those suckers would allow air to sneak in when the engine was drawing the right amount -- half throttle.

By the time I figured it out, I had three racks of XJ600 carbs in the garage and I would use the same internals (jets, diaphragms, ect...) in each set, but only one set I tried actually worked. The other two sets that didn't work had throttle shaft seals more shriveled and crusty that a raisin crossed with a hobo.

However, I should make a new thread for this particular XJ, because it has been getting a complete rebuild...

 

Re: Top end rebuild (Stuttering, Elec. Issues Prior) (Pic he

THANK YOU!! So good to know from a PREVENTATIVE perspective as I am doing some rebuild and tear down work this winter

Thank you!! p.s. looks great keep up the good work and post as you go.