What did you do to your Yamaha today?

Spent the wee hours running wires and configuring a Bosch relay for the lower fog light, power is via #14AWG from the battery via 10 amp fuse then to a 30 amp cube relay and feeding a 130 watt H3 bulb. I had to pull apart the RH controls and physically repair the light switch, one lead came off and the contacts were jazzed so it was 45 minutes of surgery. Might add a flasher function to the fog as an attention-getter and add a select switch where the blank plate is on the hand control.
Thursday afternoon was spent sync'in & balancing carbs getting things dialed in then a good jaunt. Felt better off the line, confidant and controlled while the midrange remained just as strong... 1981 Yamaha SECA 750=1
Crusty Older Honda V4 sport bike=0
No mercy spankin' this one up and down hwy 47 several time.
Tonight is all about anti-seize on the exhaust studs and ordering up some Heli-Coils for the cam cover bolts as two have pulled the threads on the ends and is now weeping a little oil. Going to make a drill & tap alignment block to keep everything straight this weekend

 

Okay so question for the group; has anyone ever actually verified the accuracy of their electronic tachometer to a known accurate source? I did just this and here are the results of my tachometer on an 81 SECA 750 after it had been re-capped & resoldered. For some reason my handwritten page won't rotate despite formatting before I uploaded it.



I also watched the input current using a Motorola R1011B high current power supply and compared this with the resulting spark, the RMS current remained constant at just over 5 amps but the spark itself began to get weaker around 110hz and got stronger past 130Hz staying fat & strong to the roll off point of about 215Hz where it stopped completely. No buzz from the coils so I suspect this is the limit of the TCI itself.

Overall this is a very strong ignition system (ask me how I know) that will function down to about 10.5 volts for a reliable spark, the TCI dropped out at 6.5 volts and the turn-on threshold was found to be just under 7 volts. A good 1/2 inch spark with plenty of bite!

I was properly supervised for the duration of the test.

 

130W bulb!!!

 

Yeah, if they can't see it then they are blind.

 

True, but I'll bet that many accidents are not caused by a lack of seeing, it's caused because "they" aren't even looking........besides at the latest tik-tac video on their toy phone.

 

And that is the problem... possibly addressed with a set of stainless brake lines, what's the total for the two long & anti-dive lines?

 

So firstly, no, I had no idea verifying the accuracy of the tach to a known source was even a thing....but it's minutiae like this that I appreciate. Everybody has their own reasons for enjoying an antique hunk of steel, aluminum and rubber bits, and these odd and arguably unnecessary procedures that suit me. Now I'll waste time scrolling ebay for a function generator....

Also, the clipped bulb picture made me think Hella's slogan should be "Come Hella high watta..."

 

Just sent you that info in a private message........

 

Chacal: I got your PM, thanks for the info.

So... today. Another 200 miles on the SECA doing a round trip to Brainerd and back with an average speed of just over 52 MPH and only got 34 MPG and this brings me to my question: does the pilot adjustment screw affect only the idle or all the mixtures entirely? Floats are set on the high side of the book spec, #122 main jets and #42 pilots. The motor is "breaking up" at full throttle above 6000 but if I back off to say 2/3 it really pulls hard passing the century mark in 4th and keeps pulling hard thru 5th. It "feels" lean at full twist and the breakup reinforces this but before I drop in a set of #124's I'd like to know more about that pilot adjustment as the factory book gives nothing more than "optimized for emissions & performance" which to me spells compromise.
Carbs have been balanced & sync'd with 2-3/4 turns on the fine thread pilot screws and the idle is smooth with good pickup on the throttle, no hunting or sputters.
Ran all day with the 130 watt fog going, put the bike on the center stand running with the light on and took a look for myself a hundred feet back in my car. A big gain in the visibility factor so it's going to remain on during the day.

My 81 SECA at my tower site east of Brainerd MN

 

Yes the idle mixture screws contribute at all throttle openings, but I would suggest the effect is tiny, given the size of the jets etc.

 

That's what I thought as well. Pulled the plugs out and found they're still running lean despite the floats at spec so it's a jump to #124 for the mains, running #122s now and the pilots set rich for the off-idle transition.
This weekend is the fork seals, both leaked oil out and down into the brakes. Our local cycle shop had them in stock so I'm about to get medieval with the front end.

 

Started the workbench construction to aid in the revival of the Midnight while sorting and waiting on shims that count?

 

Oh sweet bike! I really dig the contrast.

 

Spent the day fixing all the stripped out holes. Fun with HeliCoils.

 

Got a stubborn tire that won't give up the bead? I used a small vacuum pump and it took less than 15 seconds to pull the sidewalls and... schhoopp! sucked them right in. Took me less than 20 minutes to swap out the rear tire. That 130 tire leaves only 15 millimeters of minimum clearance to the swingarm.

 

Spent the day going back to my old ways of making my own jets and tuning them, used to do this with my Yamaha YZ250. A little solder and a handful of wire size drills, got rid of the flat spot at 6500 and it stays crisp to the redline.

 

I wouldn't worry, it's 14mm more than you need.

 

I will say the change to the 130 tire made a world of difference, wow does this thing ride nice!

 

Attempted a seat recovering today. I won't call it a professional job, but maybe a sight better than the duct tape massacre it replaced.

 

I could park my fat... on that seat all day. Very nice job.

So I've been working on my SECA for the past few nights, last night was the speedometer and the damage caused by the death scream as the bushing was burning up. It turned a pile of shavings up the shaft and locked everything up and destroyed the wheel drive, I found a good used one but USPS decided to send my package on a US tour and it ended up getting stuck in Connecticut. It's a govt operation what can I say?
The big thing I'm waiting for are the correct fork seals. Our local Yamaha dealership sold the wrong ones so I went with K & S after confirming both the part number and dimensions. They're set to arrive via UPS today and once the wheel drive arrives the work will begin.
The last run of the bike seemed right on with the mixture, no flat spot or breakup but I'm only getting 38 mpg. Going to swap the #122 mains back in and stuff a small camera in the airbox to record the slide movement as the engine transitions across the power band, my goal is to see where the slide is sitting at 6000 RPM and how it relates to the needle taper in real time & load. If anyone is interested I will post the complete video with sound. My hypothesis is the flat spot is near where the taper becomes more pronounced and steeper.
It's been raining here since monday evening and so far picked up 1.37" in a coffee can with a 30+ mph east wind, great weather for focused work on the bike.