What did you do to your Yamaha today?

Picked up 10 gals of 100LL AvGas for $85.00, I was filling the bike with KwikTrip 91 ethanol free but the bike seemed "off" so I drained the tank and pumped in the airplane juice for a good run tomorrow, other things took up my afternoon and now I don't feel like dealing with the evening commuters. Bike starts the same, 1/2 in on the enrich lever gets things going with only a couple of puffs of the starter and the idle settles right in like it has so maybe I had a load of bad gas. Weather-wimp is promising us 50F highs so I will get some miles on the clock, at 37F now and a dark shade helmet I'm not up for it this evening.

 

So Monday after work pulled bike out and went for the first official ride , onlt went six miles...the temp was great 74 degrees...but wind guts were 35 miles an hour , hit two gusts that almost put me off the road so called ride short. Today temp is 40 and windy

 

Dropped a set of new plugs in and went for the redline on several plug chops running the 100LL, running a little fat but I think it's dialed in well enough. Clutch held well but still has a grab point on the drop-in that's abrupt, at some point in the near future I will dissect the basket and check the steels replacing the friction along the way.
Had to wipe my @$$ after the runs down the road, not only does the motor sound mean above 7000 it really pulls like stink all the way to 9500... all I can say is WOW! For a shafty this one has some real bite to that bark. It just wants to keep pulling and hard.
So what to b!tch about... Still have to do the fork seals at some point and replace the rear tire, a question for the group: what is the biggest or "best" alternative rear tire size for the 750RJ? I have a line on some 130/80 tires but I'm concerned with the wider tread rubbing than the aspect. Eyeballing with a vernier caliper says the 130 would fit but I'd trust past member experience more. Don't worry about being polite about tires, I'm not politically correct.

 

Today was another hundred miles of just cruising along, I did pull the plugs for a quick check and they're a darker tan but nothing offensive. Got a few complements from fellow riders about the nice survivor and got to thinking about possibly painting things up, I can't find the Yamaha brilliant red in the PPG database so I might jump off the rez and go with the GM 92U which is a dark cherry that's used on my '05 Impala. I have a pint of base now and the mix is 5:1 so this could cover things well, I'm already set up for HVLP. Depends on my ambition level which isn't the same at 54 years of age.

Here are the two side-by-side to get an idea of the color, the Impala needs a wax.

 

Was going to ride today but stuck my nose out the door and said... nope too cold. I keep forgetting we're in early march and normally its in the low-30's. Maybe this weekend as the weather wimp is promising upper-50s. Tomorrow is get a Bosch Day/Night vision camera looking on the bike parking pad with a motion light, small town has some new riff-raff now and they're learnin' the ropes.

 

No from me. original colour is better

 

Have to agree with Minimutly on this one. I played around in GIMP (LinUX Photochop) doing various color fills & overlays over the stock colors and nothing screams 80's Yamaha better than that brilliant red so I'm going to look into a custom match. The only change I made on paper was removing the YAMAHA badge from the tank and going with gold tuning forks and a carbon fiber pattern to the lower edges of the side panels in place of the flat black.
The closest red I can find is what was used on the 1988 Gen-II Mazda RX-7, I had a Turbo-II car long before climate change and found a stray can of touch-up on the shelf, if time allows I may do a mix with some metallic and spray a swatch or two. The color is still available... for $50/pint!

Have to take the carbs to church this weekend, I filled the tank with 100LL AvGas and I think it dissolved some crud in the tank and that has settled into the #4 pilot passage as I get nothing at idle unless I put my hand over the inlet to pull up some raw gas. I religiously turn the fuel valve off a block from home and run the carbs dry before parking, there's also a new automotive style filter down there. Give me something to do this weekend as we're going to warm up for the week and I want to get some miles on. Also threw a new spare clutch cable & bulbs into the rear cubby, not if but when I need them.

 

Went to crank the bike today, and the carbs started flooding out, gas everywhere. Thought the petcock might not be working right, and was letting gas continue to flow in the ON position. Tried a different fuel delivery method, and gas continued to leak out of the carbs. So, pulling the carbs off tomorrow to take a fresh look. Might have a petcock problem, definitely have a carb problem. Seems like a new one as well. I didn't replace the floats when I rebuilt the set, I did replace the float needles.

 

Seems like a weekend for carb work, guess we need some church'n up

Just bought a new Kenda K657 Challenger for the rear, gonna need it sooner'er later.

 

Sudden carb flooding has more to do with rusty bits than carb faults - time to empty and wash out the tank?

 

Spent Saturday in church and followed the factory bible to the letter, what I found was the AvGas I'm using softened the adhesive inside the fuel filter and was dissolving it causing the paper element to break loose. Found the dissolved glue puddled on the bottoms of the bowls and plugging the enrichment passage leading to the air throat. Spent sunday morning cleaning and passing little wires thru all the passages followed by an acetone based cleaning spray to clear everything out then wet set the floats and wrestled everything back on the bike.
First twist of the starter and it was running, throttle is crisp but hot idle has more of a "random" thump exhaust note like a cammed vintage V8 and no amount of fiddling with the pilot screws settles it down. Vacuum is even and balanced and the flame color is a soft blue, I'm at a loss with this one. Before it was much smoother, ideas?

 

Did some test spot cleaning of the engine on the 82 XJ650 this weekend with some of that "totally awesome" dollar store cleaner.
Seems like any other cleaner. Nothing special to me, just cheap. Way too cold to do it outside so waiting for it to warm up.

Weather warming up here in Maryland this week!
And with clock changes, I foresee daily after work rides again in my future.

 

Opinions? Cyls 4-3-2-1 looking almost perfect

 

I was thinking that I needed to drain the tank into a coffee filter and see what's floating around and pull the carbs off and see if anything is clogged up.

 

Today I removed the head from a "spare" 750 engine - the camchain was broken, so I expected to see bent valves, but they were ok?
Anyway, the cam bearings looked dreadful, like the oil was full of metal bits, otherwise I wouldn't have lifted it. one thing I noticed was the bore wear - i could feel it..
One of the bores was oily, one had water ingress, all felt worn, but I haven't measured them yet. I have a strong suspicon that this engine is scrap.

 

one thing I noticed - the head gasket overhangs the bores (by a mm or so) - is this normal or has someone slung on a 650 gasket?

 

Never seen a head gasket intrude into bore space. It wouldn't last long.

 

Worked on the bleeding the front brakes. After removing the bleeder valves and let sit overnight. Then used a body messager on high on the lines to get air pockets out. Still can't get any pressure going on the brake. Just like getting some wrenchen on the bike in at-least.

 

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@Secacsm89
This thing is great for bleeding!

 

That vacuum bleeder is the easiest way. Here's why it is so difficult to build pressure from a dry system that has just been opened, replaced, drained, etc.

The brake fluid exists in a few areas inside the master cylinder. Area "A" is where you dump it in the top. There are two orifices in the bottom of the reservoir bowl. Area "B" is where the high pressure to your caliper is built when the piston moves forward. The high pressure is contained by the front seal. Brake fluid only enters this area through the small orifice. Area "C" is low pressure fluid that is always open to the reservoir and easily exchanges fluid through the large orifice. When the brake lever is release and the piston relaxed, the spring pushes it all the way back until the first seal is parked just behind the small orifice. As soon as the piston moves forward, the small orifice is blocked and the high pressure is contained and pushed further forward. This orifice is intentionally small so that pressure can begin to build as soon as possible during the stroke of the piston, and so the lips of the seal are not "splooshed" out of the hole by the high fluid pressure. Any leakage past the first seal winds up in area "C" which returns it to the reservoir.



When the system is dry, and you fill up the reservoir, this is how it looks. Area "B" is still full of air because the brake fluid doesn't like to flow through the small orifice, even when the orifice is clean. Pumping the brake moves the fluid in area "C" back and forth, but it is not generating any pressure. A couple things will prevent area "A" from ever filling. If your brake lever adjuster is too tight, the piston will be parked too far forward, blocking the small orifice. If the small orifice is dirty or blocked, it will never pass fluid. And it is so small that even left alone with gravity, it just won't fill or will take forever. That is why using the vacuum bleeder helps so much. It will forcefully draw fluid out of the reservoir, through the small orifice, filling area "B". Once you get some fluid in there, pumping the lever can help due to the vacuum of the retracting piston (you can watch tiny air bubbles emerge from the small orifice), but the vacuum bleeder is still a faster way to get there.