What did you do to your Yamaha today?

The top end of the damper rod should look like below (XJ650 on the right)

 

The top of the damper rod has a fairly shallow 12 point socket-like fitting. Probably is difficult to see down the tube with some old black fork oil on it. This is from a 750 with the adjuster. The 650 doesn't have that piece, plus the snap ring. Double nuts on a piece of 1/2" all thread will fit this...no need to buy a special tool.

But the damper rods are retained by the Allen head bolt on the bottom of the fork tube. An impact gun will usually get them out without the all thread tool, but you'll need it to reinstall.

 

Whoops, Dan already answered that one!

 

That's all I did with mine. A bit of fiddling to make them, but haven't had to touch them since.
It was a bit of a pisser, because the original caps on the 850 were properly adjustable, but the replacement GS1000 forks were air. "No problem, I'll just swap the caps over."
Nah, different thread - same internal size of tube but different fracking thread. Why?
Just had to make my own.

 

Yup

 

beanie screens... little dome shaped screens that are press fit above the inlet needle valve where it screws into the carb body, good at catching the junk that somehow always gets around that Checkpoint Charlie. Saves a ton of headaches when the needle gets hung up and bleeds the tank into the airbox. The little screens I omitted on my carb rack that could have saved me from pulling them apart Monday afternoon to clean out a chunk of the adhesive used to secure the paper filter element inside the filter itself, silver lining in this was setting the floats again and swapping main jets to #124's... no more 6000 RPM breakup.

 

Thankyou @Brhatweed

 

Today I finished replacing the forks with a pair of ~1982 vintage ones I got from @Fuller56. As I said earlier, I went with the original "heavy duty" springs and replaced the air fittings with bolts that will probably just be used to vent the air out when changing fork fluid next year. Had I been more ambitious, I would have dismantled the original 1980 forks and re-used their inner tubes with the later sliders, as these 1980 tubes are low-mileage cream puffs and the replacements do show some wear. I will put the old ones away someplace safe, and if I ever decide the new tubes are showing wear, I will swap them.

Couple notes: first, re the advice to slip a 5/8" spark plug socket onto a string of extensions "backwards"... doesn't work with any of the sockets I have, which cannot be used that way. So I instead bought a 7/16" coupler nut (5/8" outside size) and used it to connect my spark plug socket to a regular 5/8" socket. New tool; I should patent it...


A little ductape holds it all together.

Second, the top plugs did not want to come out easily after I removed the snap rings. I popped it out eventually (launching the cap on a flight across the garage that led to a half-hour search) and after some fooling around concluded there was a burr (possibly from the tubing cutter at the factory) at the top of the tube. A little dressing with a file, followed by a good rinse with carb cleaner, got rid of this. I think. With any luck I will have no reason to pull these plugs out for a long time...

 

Traded saddles with a buddy and put some miles on his FZ-07. First thing he did was complain about how hard my clutch is to pull in... Asked if he as a man or a mouse. I will say the FZ has plenty of go but being all gears it really wasn't any faster than my SECA regardless of the rider. All bark and no bite, really nothing more than a gum job on the ankles. Honestly I have nothing nice to say about the FZ. Better road manners maybe with the butter smooth ride and it corners well but I don't feel much sport in this bike.

 

I'm shocked, would have expected to hear "nimble, fast, light, easy to change direction" etc.
They certainly look the part.

 

The burr is more likely due to years of compression of the circlip against the upper lip of the groove.

I have a tool that is a bolt welded into a pipe. I ground the bolt head faces ever so slightly so each face is just barely tapered. It slides right in, and can’t get jammed.
Some people just jam a broom handle down, but I’d be concerned about it breaking off in there.

 

Had hopes of great progress today and started well, but ran into this on the clutch where one bolt had backed out and worn down. Not one I had on the shelf. Trip into town and back, got it fixed, but now it's too damn hot to continue.

 

Good you caught that, use red loctite on your new bolts.

 

Replaced seat cover 1982 650 maxim. Came out pretty nice if I don’t say so myself lol.
Also pulled rear tire and did battle with the bearings. Finally sliced a carriage bolt down the middle and it worked for removal. Thanks to this site and information from members .
This 42 year old bike will be on the roads of New Hampshire can’t wait

 

More like nervous than nimble but maybe it's because I'm spoiled coming from a long history of big liter bikes. It "feels" fast with the high RPMs climbing thru the gears but don't watch the digital speedometer, even a VW Rabbit has a lightweight snap. I does feel sportbike-ish don't get me wrong and it has a very smooth and refined ride but it's not going to run with the big dogs. I expected it to run circles around my SECA being lighter and more advanced but that little twin seems to run out of breath despite having 4 valves/jug. Changing direction is no problem, clamp the fronts hard and kick the back around. This thing has instant on brakes with plenty of control and it really hugs the corners almost too well. We traded again Friday and I got a better opportunity to really whip it up around lake Mille Lacs. Plenty of hard curves once you get past the lumbering RV's and big cruiser bikes but hard as I tried the SECA inched past at full twist. My old bones don't sit well in that cramped up position so it was back to the SECA on the top of county-19 where my camera failed to cooperate, there will be a next time.

Also finished my buddy's VTX-1800. Cruises like an early 70's plush-mobile with a motor that pulls like a freight train. Damn smooth for a V-twin but what a pain in the backside. Now it's for sale and I'm trying to talk him into something more sensible like a Maxim but he's a bit apprehensive over the carbonators.

 

I bought several items from an eBay seller last year including a NOS brake master cylinder, EBC brake rotors, SS brake hoses and a nearly new looking set of exhaust header pipes. I did the brakes last year and finally took care of the exhaust this July 4th weekend. Very happy for the $100 I spent on the pipes.

 

Got this 750 motor slapped together today. My goal was to make every mistake possible, and I believe I succeeded.

Gearshaft bearing in backwards
Pistons in the wrong order
Piston backwards
Forgot O-rings between jugs and case (thanks Haynes)
Forgot to chase threads, resulting in separating the case halves two more times. Somewhere in here is where I ran my finger between the clutch gear and case and had to do a rapid bandage wrap of blue tape before the Yamabond dried.
Plus halfway through I decided the primary chain was too slack (new tensioner, old chain) and tore apart another parts motor to grab its chain which was in much better shape.

And it must have been 600 degrees out today, so I blame that for all the brain fog.

But it's together. Going to put it on the engine stand for the head and side covers.

 

Clean motor.

 

Drilled and LH thread tapped one of the carb hat screws that had sheared off on one of my 900Fs Mikuni carbs. It just screwed in on the back cut, the opposite of what I expected, but I'll take it. Cleaned all the m5 threads out with an m5, good to go.

 

Took bike out for an hour ride!
Hot day out!
Bike still running smooth over a year after resurrecting it.

I have 5 bikes now, rode 3 of them yesterday 1hr each. Nice thing about having that many bikes is that I MUST regularly ride to keep them exercised.
I have not been taking the XJ650 on group rides but I think I may do so the next time we have a 3-4hr group ride.

 

Keeping them exercised is going to be a full time job.

 

My buddy has a VTX-1800. What a beast. I've only ridden it once, a couple years ago when my only active ride was my WR250R. A larger difference in rides is hard to imagine. I was always amused riding with him - over 2L of displacement but only 3 cylinders between us. At least on the Seca I contribute a few more CCs and double the jugs. Not sure he'd have bought it for himself, but his wife surprised him one birthday (she bought it off a friend/neighbor) after he'd been without a bike for 2 decades. His last was a 1985 V-Max, so, yeah, he liked big . . . displacements.


As for me, nothing too exciting lately, just commuting when I can. Hope to get a weekend ride in soon.

 

They were begging to go outside and play......

 

Got the oil pump and pan, shifter, clutch and side covers on. I've been contemplating painting it black with a bare aluminum head, so this is probably the stage I need to paint before proceeding.

I took all the disassembled case parts of this motor to be hydroblasted some time ago. While it did make for a nice finish, and cleaned up a fairly oxidized and stained motor, I won't do that again. Cleaning the grit out is very laborious, and even after all that time I'll still run a bolt into some threads and get some crunchiness from some leftover grit.

It would be a good process on an assembled motor so the media only touches the outside.

 

I've been rollin' the miles on my 750 like it's nothing. Two trips to Brainerd MN so far this week, each is 165 miles round trip plus the everything else going on. Totally rock solid without a problem and I can hit the century mark without trying. Been averaging 46 MPG on these runs according to the gas pump & odometer math and maybe a quarter of a quart of oil over the past 4250 miles I've been riding it. I keep looking at the topic and honestly I don't have much to contribute, only thing I can think of is pulling the front off the ground in 2nd doing a stoplight shootout with my neighbor in is 2023 Mustang... its fast but I still got him.
Nothing like starting out smooth then pouring the coals on taking it to the redline on each shift, love that sound!

 

Yep, the hydroblast people seem to be really negligent (lazy?) in regards to the after-processing clean-up, had that same issue with 2 different companies that do that process, and the 2nd job I made sure to explain in advance that they need to come back clean-clean-clean with no leftover slurry in them.......turned out it was like talking to a wall.

 

And P.S.: once that slurry dries and hardens, it's a beast to remove...........

 

Yes for sure. Before I had this done, I talked to the owner about my concerns, having read varying opinions on the grit removal. He said the parts were thoroughly cleaned afterwards, but I believe "clean" is relative, depending on who does it.

Still, it is hard to get that level of clean between the cooling fins and other difficult to reach spots. But if I were to do this on an assembled motor, I'll probably just do it myself with the grit siphon attachment for the pressure washer.

I also searched for a place that would blast with dry ice, but couldn't find any that were semi local.

 

Had a weird problem today, cruising along not suspectin' nothin' while inching my way past 5000 RPM's when the engine started to breakup and the tach was jumping all over the range. Backed off the grip and things mellowed out so I started with the mental diagnostics... trigger pickup, TCI itself maybe a pinched or chaffed wire while making my way off the road and under about 4000 things smoothed out and sanity prevailed until I passed the 5000 mark again only this time it smoothed out towards 6000. Weird. Got the bike home and started really looking around for the problem and decided to run it up in neutral. It was getting dark by this point and I just happened to be looking near the TCI while revving the motor and saw the blue flashes under the seat. What's happening is the airbox cover was resonating right around the 5000 mark hard enough to shake the fuses out of the clips and it was the fuse for the TCI that was jittering the power and arcing, explains the jumpy tach as well. Tomorrow I'm going to fashion a damper and reinforce the plastic lid and see how that works out.
Thought I'd share this with the group.

 

If you have the original Yamaha fuse setup change it for a bladed one. The clips get weak and break. They cause electrical problems on our older bikes. The airbox cover won't be able to shake the fuses out of a blade type fuse box.

 

Got this done this morning before it got too hot. Out with old greasy (and bum starter clutch). Not quite ready with the new one to go back in.



Once again my lashed on 1/2" pipe removal method was easy, and a one person job. Maybe 2 minutes from starting to lift to setting the motor on the dolly.



And the other motor looming in the background. I got a coat of paint on it last night, but need to let that cure and also get the starter and alternator cover painted, then file off the paint on the fins and YICS. Guess I should adjust the valves while it's out as well.

 

Actually I did replace what was left of the OE holder with an Amphenol design that is used in telecom equipment and the clips have a very firm grip, the resonance of the lid is quite strong but it wouldn't capture well on video. Too damn hot out to do much of anything today. 91F with a 74F dewpoint. That little circuit on the top is a +12 to +5 bucking regulator for the Garmin GPS, far more stable than the lighter socket adapter.

 

so how do you do that 1 person engine removal with the pipe method?

My guess, having studied the pic again is you lift the whole bike onto the pipe using a pair of stout stands, then having removed the engine mounts lower the bike and move it sideways, but what holds the engine level as you move the bike?

 

The pipe is lashed to the back of the cylinders. The timing chain tensioner is removed.

One end of the pipe is suspended by a engine hoist, or in this case the chainfall hooked to the rafters. Then you lift the other end of the pipe by hand, so you're picking up a bit less than half the weight. Leaving the pipe long enough let's you swing the whole thing sideways. And the pipe just behind the cylinders is a good balance point so you can lift it one handed and twist for rotation, leaving the other hand to give the chain hoist another turn, or wrestle with the drive shaft boot. The bike doesn't move during the whole process.

 

Whew! Thought I would have to he-man this one...

 

Sounds worth a try!

 

Impressive I read some posts by members and it blows me away how knowledgeable they are .
Good work

I just started a barn find June 2024 it ran idled and super clean tank 500 bucks . Has not been registered since 2017 replaced tires, bearings front and back, brakes front and back clutch cable, replaced seat cover, It seems that the more I clean the more it needs more cleaning lol. Ran the bike today just in driveway about ten minutes. Throttle response was great idle no problem but seems I have an oil leak. Noticed smoke from under motor on pipes. Kind of bummed out. Maybe I am in over my head with this project.
But it’s nice to read posts about projects going well for people. Very informative

 

Don’t panic over “smoke from under the engine on pipes.....” it’s likely simply just oil that has seeped out while sitting, and/or gas leered out from the valve cover gasket (regardless of whether it LOOKS like head-gasket or not..... appearance can be deceiving), And now that you’re running it— the oil is just burning off. It’s NOT A big deal.

 

The knowledge on this forum can't be measured by the weight of gold, some really sharp cookies in this jar. Personally I've been on 2-wheels since I was a little kid and always had a knack for small engines. Now I'm in my mid-50 and still learning, always someone here with a good pointer, suggestion or reminder that comes from their own experiences and I learned to trust them very early on.

I put another 250-some miles on my 750 SECA this afternoon without a problem, I credit the others here for keeping me in line. I picked my 1981 SECA 750 up in a number of boxes and milkjug crates and spent over a week straight working 10 hrs/night putting it together, both the factory manual and xjbikes forum were within arms reach. The technicals are right on the money.


So today was a ride up to the north shore seeking some cooler weather and a hard running return trip down the interstate sometimes running 80+ for extended periods. Didn't find any relief from the heat & humidity but had a good ride. Seems my endurance in the seat is slightly shorter than the fuel tank but I managed and got a headlight full of bugs. A good day on the SECA.

 

So, took the 83 XJ650 for an hour long ride. First full ride with the new standard bars. Really makes the bike feel like a whole new bike.
The relaxed feel of the stock buckhorn bars are comfortable but the smooth higher reving sound of the 4 cyclinder 650 just does not match for the Japanese cruiser look of the bike.
Before I got going I had a run away idle event. It was at 8K and tried stopping and starting several times, raising and lowering throttle while bike was off.
Looked at the carbs and the butterfly plates were moving with the throttle. Shut off the choke and still was reving high.
Then I realized I had tucked the throttle cable some today and then looked at it and it was a bit kinked. So pulled it out and yup, that was it.
2 things. I should really re route that cable long term as well as lube it.
next I marked the idle position of the butterfly axle on the right carb. vertical is the current idle position and fully twist is just shy of 90 degrees.
What might have clue'd me in would have been to push down on the throttle couplings where the carbs connect together to verify the butterflys where closing.

It was a good ride and currently happy w/ the new bars. More UJM than before.

 

Thanks for the info
I will be degreasing the engine next weekend
And looking into it.
Paul

 

I had resurected an 82 xj650 this winter. When I purchased it I told him he had an oil leak as I saw oil all on the lower and side of the bike.
I guess he got sloppy w/ the oil change cause after running it for a few times, the smoke stopped and after wiping up the engine, it did not come back.
Like Hogfiddles says, the pipes also smoked some for a while after getting it running and then stopped.

 

I got my Yamaha a bit dirtier today.



Nice 100 mile ride followed by a not so nice 30 mile ride. I stopped for gas about a half mile after going on reserve. Filled the tank. Started the bike, it was balky (which it usually is not). Sounded... off, like it wasn't running on all cylinders. I started home and it was missing, sputtering, but running. It would go 65mph but still sounded like it wasn't running on all four. It seemed to sputter, then up around 7000 rpm it would suddenly smooth out and yank my arms out of my shoulders. Got it home and took a look at the plugs. 1, 2, and 3 were the normal light tan, but 4 was sooty black. So I figure it's not an ignition problem (since 1 and 4 are on the same coil), but cylinder 4 running way too rich. Trouble is... what brought this on? The bike's been running just fine for the last thousand miles, and just like that, after buying gas, I've got a carbon-fouled plug and it's running like crap. Just coincidence? Ingested something into carb #4? Hmm...

No time to mess with it now (it's too hot anyway). FWIW, I left the gas on for a few minutes and the carb didn't overflow, so it's probably not a stuck float valve. Any thoughts...? Wanna place bets on whether I'll be pulling the carb rack... again...?

EDIT: before I pull the rack I'm going to pull the hat off carb #4. I am not an expert on CV carbs but understand enough theory to think that if the piston/needle gets stuck in the up (or even partially up) position, the carb would behave like a butterfly carb with a huge jet dumping fuel into it... which would kinda replicate the symptoms I experienced. Tomorrow. Time for Italian dinner...

 

Well if it has stuck up it will be weak, not rich...

 

Really? I would have thought that with the needle pulled all the way out of the jet the carb would be dumping fuel into the throat like mad. But, as I said, I am not a CV carb expert. We'll see when I start taking things apart, I guess.

 

What pulls the fuel out of the jet? Vacuum. No vacuum no fuel. The point of the slide is to regulate the vacuum seen by the main jet/needle assembly. In a correctly working carb, as the volume of air increases the vacuum below the "closed" slide would increase (non - linearly), by connecting this vacuum to the top of the slide (via the hole in the bottom) the slide lifts against the spring until it reaches equillibrium (hence CV or constant vacuum). All this means the design and operation of the needle is simplified, and the carb cannot "fall flat", or overfuel.
By changing the size of the hole in the bottom of the slide you can change the rate it rises, and how it responds to pulses. By changing the rate of the spring you can change the vacuum at the needle, and also when it reaches fully open.
Simple eh?

 

Simple, maybe. I'm not an expert on the specific carbs used in the XJ series, or on multi-carb systems (I have years and years with the big single Kehin CV carbs used on Harleys and Buells and KLRs).

Of course, the dirty plug could be a red herring. It definitely is running too rich on that cylinder, but it was dry (no fuel or oil on it), not bridged (as my old two-strokes were prone to do), not covered in fluffy ash... just black with carbon on 3/4 of the insulator. So out of adjustment on that cylinder, but maybe that is an independent problem.

The obvious direction to look is something related to having gone on reserve and filled the tank just before the bike started running badly. When a bike is running perfectly, then I do something, then it runs horribly, there's reason to suspect the something I did was related. So what did I do? Flipped it to reserve for maybe half a mile (I was coming into town with the intent of buying gas, about 110 miles on the tank, and the engine sputtered a bit as I pulled up to a stoplight). Filled it up, switched back to main on the petcock. Went inside to answer the call of nature. Came out, popped the seat and got a wrench out of the tool kit to tighten a loose bolt I had noticed on the front fork. Put tools back, closed seat, went to start bike. It was reluctant to start and sounded wrong, more like a twin than a four. Seemed slow and rough, sputtered and surged, seemed to smooth out and run properly when I had it up over 7000 rpm. Stopped at one point to see if maybe the fuel tank was vacuum locked (I had recently replaced the cap with an aftermarket one and thought maybe the vent was bad, though it had gone a couple hundred miles without incident on the new cap). This involved shutting off the motor, and it almost didn't restart. Continued running horribly till I got home, about 30 miles in all.

So I suppose the flip to reserve might have allowed it to ingest something that clogged the fuel supply, though I had cleaned the tank as part of reviving the bike. The petcock is converted to manual operation, and the only mode in which it could fail (the spring-loaded vacuum plunger opening) would cause it to not fully shut off, not restrict flow. There is a screen on the petcock, but not an inline filter.

I guess I will start by removing the fuel line and making sure fuel flows. Next step might be to clean or replace the plug and see if it runs any better (on the hypothesis that prolonged rich running on #4 fouled that plug to the point where it coincidentally started running badly. And then (sigh) start looking into the carbs themselves...

But first... today is dedicated to brewing beer. The bike will have to wait until tomorrow, unless the brew goes unusually quickly.

 

Continued, during a short break while the enzymes do their thing...

I quickly dismissed the easiest possibilities. The petcock flows plenty of fuel, and the slide in #4 was in its proper position. So much for that. Now I am making hypotheses and testing them. Let's look at the plugs. I mentioned #4 looked badly carbon fouled. Here's a picture of #1 and #4:



Even #1 looks a bit dirtier than I would like after only ~2500 miles, but there was a lot of screwing around and adjusting in that period. #4 is covered with soot, and smells of unburned gasoline. If I understand the secondary circuit correctly, either both #1 and #4 fire, or neither fires, because they are in series. Izzat so?

Which causes me to wonder... has the #4 plug been getting dirtier and dirtier, and just happened to reach the point yesterday where it wouldn't pass a spark except at high rpm? And in that circumstance, would #1 also get no spark at all, or a weak spark? Questions, questions... and these BP7ES plugs are getting hard to find... I really oughta convert over to non-resistor caps and resistor plugs...

Back to the brewery. Enzymes are done for now...