What did you do to your Yamaha today?

That might be some reflective "wheel rim" tape that someone applied.....easy enough to find on eBay, etc.

FORK OIL: you can always mix "weights" (viscosity) oils of the same brand oil to get a "custom" weight suitable to your liking.

PITTING: yes, about the only "fix" (besides re-chroming or replacement) is the epoxy solution, it works well if done correctly, and it would be a long time before epoxy is affected by oil.....the biggest challenge is getting the fork metal really, really clean enough for the epoxy to stick properly, and then getting the epoxy sanded to a truly round curvature. Takes time and quite a bit of patience!

 

My idea for this weekend is to take a wire wheel on my power tools to the rust (if it's really bad) or otherwise just wet sand it and epoxy.

My wire wheel was pretty good with the brake pedal to remove the rust.

It's all a short term fix anyway, since I want to upgrade the forks to dual rotors in the future anyway

 

This is what I did to my Yamaha today...

 

Cross your fingers... I may have solved the problem of my #2 carb overflowing. I rummaged through my spare parts and replaced the aftermarket, metal-tip float needle (and its corresponding seat) with one of the 46-year-old original equipment ones I took out when rebuilding the carbs when I first started reviving this bike. Did the same in #1 because I thought that one was overflowing last October... though, given the way gasoline moves around, it might have actually been coming from #2 and just finding its way across the rack to #1. Set the levels in both carbs, took it out for a spin yesterday afternoon. The improvement was immediate: I could hear all four cylinders firing, a nice even howl rather than the very distinct parallel-twin sound it had been making. Rode it about 20 miles, pulled into my driveway... and it stalled and wouldn't restart. Finally I tried putting it on reserve, even though the trip meter said 80 miles. Started right up, ran fine. Flipped it back to "on" and within half a minute it was running on two cylinders and then stalling. Back to reserve... all four again.

This morning I took it to the gas station and filled it up. 2.7 gallons, which (according to past fill-ups) means I was indeed out of the main supply and into the reserve. MPG worked out to something like 33.4, which is about 25% under what I typically see (mid-40s). Well, there was a lot of raw gas just going through unburned... Took the bike for a 70-mile ride. It ran... much better. It still doesn't want to idle properly (a synch will probably help with this) and undoubtedly needs some fine tuning. But... it is at least rideable again. And a fair amount of fun.

 

Update to the above: I got in another 50 or so miles yesterday afternoon. Still rode great, and I was able to check fuel economy on the way back. It is somewhere between 45 and 50 mpg, depending on how much gas went on the outside of the tank, the hot engine, and the pavement at the Sofa King Bad Exxon Station, who had the clever idea of putting a spring on the "vapor recovery" nozzle's hold-on tab so that the thing doesn't shut off when you release the trigger.

I think I need to replace the throttle cable. With the "Daytona" bars, the stock Maxim cable (for the buckhorns) is way too long, it's rusty, and even though I have the adjuster set all the way in, there is absolutely no slack in it. This may or may not be contributing to the erratic idle speed, but I think it's something I should replace before spending too much effort going into further adjustments that might just be frustrated. Am I correct that a cable for an XJ650RJ Seca would be a proper fit with the "standard Japanese bike" handlebars?

I also need to do a better clutch adjustment, I think. 1-2 upshifts are a chore above 6000 rpm. 2-3 and beyond are no problem, but winding it out in first gear leads to a major battle to upshift. I copied the "Full Monty Clutch Adjustment" procedure and will try to do it next week. And while we're on the subject, is there any consensus on whether/which choice of oil delivers the smoothest shifting? There seems to be a consensus that the Royal Enfield Himalayan 450 likes Motul 7100, and my experience seems to match that. Or is the Yamaha like most UJMs, pretty indifferent to lubricant?

 

ohhh, an oil thread! How fun. Me, I use 15W40 diesel oil for the protection the extra zinc gives the cams. But that reasoning comes from almost 300k miles on Kawasaki ZG1000's that have notoriously bad camshafts. It has worked well in my XJ's. About the time for an oil change (I do 3k miles) the shifting starts to get less easy, not hard but less easy. Fresh oil and generally better shifting. I figure it is just the XJ's way of asking for fresh oil and attention. Fresh oil is more important in my thinking than the weight or brand, within reason of course.

 

Well, yesterday was quite nice so I decided to go fly fishing, then decided to take the X and save some gas and enjoy a ride. I put around 75 miles on it and hit two lakes. I almost forgot how hard you need to hold on when you wind it up to 10K on the tach in 2nd gear.

 

Something really fishy about that post...

 

Very nice. Did he get a ride home to (be) supper?

 

Nope, she went back in the water like the others I caught.

 

Knew there was something fishy!

 

Hrm...

Now what? Had to hit her with some map gas to get to this point lol

Edit: got both off. I'm slightly concerned about this middle chute thing, but the new hi performance bearings are in the freezer and I'll install those in a bit.

Guessing I don't need moly grease since these bearings have seals on both sides?

I have no idea how this inner tube connects, is it just pressure?

 

Installing the new bearings with a 32mm/30mm impact seems like it might be cracking the metal

 

We're finding the 15mm bearing remover tool is not expanding enough to try and remove the high performance bearing with the tool for the bearings. Basically because of that, we can't remove the bearing to try installing it again.

We hit the bearing with the tool correctly for a minute, and pick up the tire and hit the rod and the whole 15mm piece comes off.

Edit: we measured the distance of the race to see if it was installed uneven and best case it was .01mm off, so instead of trying to remove it, we installed it and it went in finally.

Had to buy a harbor freight "bearing race and seal driver set" tho.

 

Day two, I cannot get the left fork tube off

However, the right fork tube, which is leaking, happens to come right off

Edit: apparently complaining about the thing, is what helped to get the fork off? Yay

Edit 2: this also doesn't look like the manual... Air pressurized??

Edit 3: it doesn't unscrew, the whole thing inside seems to spin, and I can't press it down much

 

I'm not really sure what to do at this point. I have the fork tip as seen above soaking in kroil but it doesn't want to come out

Edit2: I moved on to the other fork and that air plug is removed without any effort. Figures. That's the one that's fine. I don't have a vice so I'm using the triple tree to hold the inner tube.

Edit3: the left fork is disassembled, though I can't seem to get the oil seal out. Maybe I should just leave it there?

Two hours later and I still can't get this dumb air stem removed

 

Holy shit I got it!

I had to apply tension to the spring seat and then use a wrench to forcibly keep the seat stationary

Now I'm struggling with the oil seals in the forks, they do not want to come out. Tempted to just use my new Dremel and cut them out

Edit: didn't need to cut them out, they just took a LOT more force with a flathead than I thought.

Some rust inside, used the deburring tool to remove what rust I could find.

 

Now that everything is disassembled, I've been wet sanding the inner tubes with 800 and 1000 grit and honestly, I don't think I need the epoxy. It's pretty smooth now

 

I remember my dad dealing with a scratch on the fork of his Triumph Bonneville years ago and he said it was a matter of getting the "channel" out of the metal and smoothing down enough so the lip of the seal could follow the surface. Guess it worked because it has not leaked in over 45 years that I know of, still has the bike to this day.


I see I've received eight likes so far on my SECA 750 turning over 50,000 miles, I'm sure there are others who have passed this mark on the original motor. Thanks for the recognition, I'm hoping to post the odometer rolling over 75,000 at some point.

 

Ok, here's the recap of everything I did to the bike this weekend (mechanically, in order) and some various observations:

• Took off front tire, detaching the speedo cable first, then the tire, then the caliper (which was way easier to do, because the tension of the caliper felt like it really locked onto the front rotor). Note: (At this point the brakes felt very strong and responsive.) I then took off the fender. In retrospect, the manual says to take off the fender and the caliper and then the tire (iirc) which seems goofy and harder.
• Removed both wheel bearings using 15mm spreader tool which was very useful in getting the originals out. The wheel bearings seemed to be undamaged, but they're likely 44 years old, and the tire came off, so may as well.
• Removed both front forks off the triple tree. The left fork was not leaking, but the right fork was. The leaking fork came out of the triple tree by simply removing the tension of the bolts holding the inner fork tube. The non-leaking fork tube was stuck in the triple tree and had to be yanked with a lot more force than the right one, ironically. Saw some signs of rust on the inside of the triple tree, which is probably why it was "stuck".
• Planned to upgrade the brake lines and both stem bearings, decided to do that another time.
• Reinstalled two "hi-performance wheel bearings" in the front, but when things looked like it got stuck, we tried using the 15mm wheel bearing spreader tool, and realized that the spreader wasn't actually spreading and when we would lift the tire to pound the long bar so the wheel bearing would be removed, we realized the spreader tool and rod would just, fall out as if it didn't do anything. I should have measured the inside race with a caliper to see how the dimensions differ, but based on the behavior, I have reason to believe that removing the "hi-performance wheel bearings" in the future is going to require a 14mm tool instead of a 15. the 15mm absolutely goes inside the inner race, it just doesn't expand, and thus, the tool doesn't work on them.
• Added https://www.oreillyauto.com/detail/...-wheel-bearing-grease/mp02/90374?q=red+grease to the outside of the wheel bearings. These ones are enclosed, with no way to open them up without potentially damaging them, so I just added some on top amongst the pins (seen above in images)
• Added same grease to speedometer hub. The manual says white lithium? which I guess is just slightly less dense? than this. I suppose it should be fine.
• Disassembled both forks, finding that the leaking fork, has an air pressure valve, which was a pain to remove. The non-leaking fork pressure valve was not a pain to remove, because of course.
• Using the damping tool, and a hex wrench, I was very easily able to remove the inner tube from the outer tube on both forks. I did not need to apply more than an arm strength amount of pressure to do this, and frankly, not even that much.
• Cleaned the inner tubes with the long plastic wire brush tool, and wet sanded both inner tubes (which had some slight surface pitting but nothing drastically deep) with 800 and 1000 grit sandpaper). I also used the deburring tool on the top Inner part of the inner fork tubes, where there was some pitting that was a little worse. This is in the area where the inner tube plug sits.
• Cleaned some rusty stuff and debris from the top of the Outer fork tubes. The Lower fork tube circlip was rusty on both.
• Damping rod plastic washer was fine, but replaced it anyway
• Oring on inner tube plug was fine, but replaced it anyway
• Did not replace the inner air valve the kit came with, as I have no idea how to get inside the schrader valve to replace it. rubber oring seals on the outside of the valve seemed fine
• Both old oil seals have a spring along the underbody, in a star pattern (as if the spring has gotten has gotten twisted every half inch?). The new oil seals do not have this issue, the spring along the inner fork seal is a circle.
• Installed oil seals with the oil seal driver tool, very handy!
• Replaced lower bolts with new ones, even though the old ones seemed fine
• Replaced lower crush? washer, even though old washer seemed fine.
• Replaced drain screws, as one was a bit stripped from previous owner. Lower drain seems to have a plastic non-removable insert? Put the drain o-rings from the kit on top of the plastic around the drain screw cause I couldn't figure out how to remove them. There were no drain o-rings to begin with, on either fork.
• Reinstalled spring (making sure to put the denser part of the spring on top, as the manual says)
• Reinstalled spring seat and spacer
• Used graduated cylinder to try and fill 278ml worth of 10w fork oil, but the graduated cylinder has two measurements on it, and one of the measurements starts lower than the other. I think I got about 275ml or so, but I am really not sure, because the cylinder wasn't very accurate.
• I got a tool that was supposed to be used to "take the top off" extra oil as to not overfill, but I couldn't find a good instruction on how to use it, so I gave up and moved on.
• Added some fork oil to the top of the oil seal and circlip, and moved the inner tube up and down to make sure it was lubricated and to prevent further potential debris, per manual
• Added fork tube dust seal, using the aforementioned oil seal driver tool, because that was a pain to get on there without it.
• Added Gaiter (accordion) boots to the lower part of the front forks to prevent further damage
• Installed both forks into the triple tree (as I have no vice) got another person to press down with a flat screwdriver on the top plug cap, after I installed the spacer, and installed the circlip afterwards. Having a second pair of hands for this specific step is a godsend, because it is a massive enormous pain in the ass to do yourself. Can I do it? Yes. Do I ever want to do this again? No!!
• Reinstalled the pressure valve on top of both forks, and attempted to add some pressure to each fork, but Yamaha says don't add more than 17psi or you will risk ruining the fork seals. The internet and the manual seems to suggest around 5.7 psi, within 1.4psi of each other. I have absolutely no idea how this is possible. I have a ryobi inflater that I use for my car and I use it for the tires of the bike, it's relatively simple and accurate. Filling often shows digitally several PSI, and when you stop filling it will give you a readout of the current PSI before you remove the latch (which always loses some PSI from having done so). The smallest blip of this gun brought me easily to 11.5psi, allegedly. I did this on the other one, and it's about 9.5psi or so. That's about as close as I can get without easily blasting over the extremely small range. This was done with no tire on the front end, fully suspended. Me and the gf went to the store to try and find a regular bike inflater (you remember the old step to pump ones? Though you can use your arms if you're feeling strong) but even those seem to go up to like a hundred psi. What tool should I be using for this??
• Reinstalled front fender
• Reinstalled caliper, applying anti-seize to the back of the retaining clip that "retains" the top part of the brake pads, and applying anti-seize to the back of the brake pads, where the piston touches the brake pads. (I know to do this on my car, so I figure the same behavior applies here).
• Reinstalled the pin and clip that holds the brakes in place
• Reinstalled front tire, with enormous difficulty. Apparently, the middle axle rod has a spacer that goes between the right fork and the wheel hub, and getting the whole thing properly on there is a massive pain in the ass.

We then lowered the bike off the center stand (we used floor jacks on the frame while it was on the middle stand to secure it upright) and tested it. the front forks felt like they were a bit soft, but I have no idea if this is because there's not quite enough oil in it, and my measurements are off, or, if this is because this is what 10w fork oil behaves like, or if the air pressure is wrong. I don't think I installed the spring backwards, they certainly were resistant enough to hand pressure, but hand strength is different than bike weight. I had my gf test the forks by sitting on the bike and manually pressing the forks in, which looked like they compressed a lot to me (unsure if it was more apparent by the gaiter boots squishing, or if it's normal). They just seem like they're softer than before, before it leaked anyways. The previous technician didn't work on the front forks, so I have no idea when the last time this was done. I also have no idea what the existing fork oil was in this, other than it was ruby red. I have no idea how much air pressure was in these, but I'm guessing probably close to 20 based on how long it took to drain each pressure valve. I'm guessing it had 15w oil instead of 10w, but I have no idea. Eventually the gf seemed satisfied with the front forks, though they, by comparison, are extremely soft compared to her 2025 CB750 Hornet.

More importantly, it appears that the front brakes are now extremely soft. I had her take the bike up and down the hill, and the rear brakes are working well, but the front brakes are not working very well. They work, but they are engaging very slowly, as if there is air in the lines, is my guess. I very specifically did not remove anything with the brake lines, except to remove the caliper and just had it rest on the "crash guard" all weekend, so that it wouldn't hang on its own cable. The technician said that he rebuilt the front brake caliper (back in october), so that has been done (though there is some rust and corrosion on the caliper piston, and in a few places). The only thing I can think of here, is the "twisting" of the caliper did so in a way that perhaps there was some air added to the brake lines, though I did not detect any leaks of brake fluid anywhere. Thankfully, I have replacement brake lines and crush washer, and bleeder valve, and union bolts, so I can do that next weekend and hope that solves it?

Finally, I dialed back the idle speed mixture screw, and started the bike again, and let her run for a minute or two, and then took a laser thermometer to the headers. If the left most (while sitting on the bike) is cylinder 1, and the right is 4, then these were the approximate temperatures of the headers from left to right: 250, 450, 350, 450. Meaning, Cylinders 1 and 3 are running rather cold to the rest of the system. I replaced already all spark plugs and caps with brand new ones (5k caps, resistorless plugs). Could the ignition coils be going bad?

That's a long post but let me know if I did a stupid or what I'm missing here, or if I did a good job for having never done forks before (wheel bearings I've done before, technically. I wish I had a dang press for wheel bearings in the future)