What did you do to your Yamaha today?

That might be too bright

 

Good call. I’ve decided to go with fireflies in a jar strapped to the bike with an old belt I don’t use anymore.

My first carb rack. Hats on Friday.

 

Adjusted the injection timing, to what's a first guess of what should be about ideal. Ran some more street dyno and updated most of the fuel table. Also tweaked warm-up and acceleration enrichment a bit. Starting, idle, and driveability are all pretty good right now, as is mid and high end power. Definitely curious to see how fuel efficiency looks on longer trips. Next step, once the weather's a bit more predictable and the lock-down is not as strict, is a ride up to Cripple Creek (10000 feet or so) to check how well dialed in the altitude correction is.

Also hooked up the B/W that used to connect to the TCI to the ECU so I could re-enable the side stand safety circuit. Now it works just like it used to: cut the ignition if the clutch is out, side stand down, and not in neutral.

 

I got a couple stable-mates for (the rest of) my xj’s.....both have good titles
They will both come back to life

 

My bike was manufactured 7/81. Some PO painted the gas tank a heavy metal flake gray. It’s pretty hideous, it also has a large dent in the left side. I’ve had the tank off for a month and it’s marinating in EvapoRust.

The underside of my tank is that ^^^^^ color of red. What’s that called and is there a code for it?

 

It would help to know what model your bike is.

If it's a Seca 750, it's called Yamaha Brilliant Red.

Sounds more like you have a Maxim, though. No idea on that color name.

 

I thought it might be easier to move the whole bike if, by a long shot, I could get it up start... tank smelled ok. I hooked a battery, hit the button——
Slow R-r-r-r, let go of button. Then about a second or two later... GURGLE GURGLE GURGLE.

??????

Starter button again—-


rrrrrrrrr

gurgle gurgle gurgle


Looked around—- hmmm.... oil pouring out of the bottom of the airbox making a big mess.

tried one more time, just to try and clear it a bit...


Rrrr.... click. Hook up aux power... click.

Well, time to push it up to the shop.
Guess it sits there for a bit .

lol

 

1983 XJ750 Maxim models proudly wore the Code 7J "New Ruby Red" color.

 

Today, so far, I am updating this list with what I did yesterday: modified the AFR table and went for a ride with my laptop under the cargo net to apply those changes to the VE table. Also made some manual changes to the VE table outside the typical Auto-tune area. New tune cleans up a couple of spots where I wasn't getting as smooth a response as I wanted when just starting out. Definitely better now for puttering around just off idle. Feels great for mid/upper power, but still might need to be leaner for highway cruise. I also disabled noise filtering, which I'd had on forever on this tune. I don't think it's needed anymore - if it ever really was - and having it on adds to the processing load for the ECU, which can make it a bit glitchy when data logging or auto tuning. Even with it on, though, the 15 minute or so auto-tune run I did was fine.

I do wish my data logging app included speed. It does include latitude and longitude, but no speed. Anyway, net net is I think I'm still around 13.5 or so when cruising at 65MPH. Will probably do some more data logging over the weekend to better isolate where I am on the map at 55 to 75 in fourth and fifth gears, and lean those out to somewhere around 15.

 

Figured it out. It’s Black Red (002J). Gonna change to Frost Silver.

 

Hello all, first post for a new member. This has been a really cool thread to read through. I bought my 1982 Maxim XJ650 about 5 years ago from a young man that "... rode it until it stopped working." Named her Loretta because of her attitude.

To get back on subject; Today I rebuilt the front caliper and master cylinder. I am in the process of an "as is" restoration; make it mechanically sound but not aesthetically perfect. I like to ride and she's just gonna keep getting dirty, lol. Take care and have a good evening.

Toe-Knee

 

Took about a 60 mile ride (first day out of stay at home order in Colorado) up to Woodland Park and back. Woodland Park is about 8500' elevation, whereas I live at about 6000'. I wanted to see what I could learn about the accuracy of my altitude compensation curve. Well... the bike ran really great... just smooth, good throttle response everywhere, good midband power...

So, I got to WP, and pulled into a parking lot, and checked what the ECU had to say at idle... aha! -9% of compensation from the O2 sensor. So, I dropped that part of the curve a bunch, and was still even about 3 to 4 percent rich, but I left it like that and headed back. When I got back home I checked it, and was kind of shocked to see I was running about 12 to 15 percent rich. Shut it down and let it sit for a minute, then restarted, and was initially lean, but shortly balanced back to pretty much right without O2 correction. So, I don't know why that is. I put the old curve back, because it looks like it wasn't terrible, regardless, and I plan to instead head up Pikes Peak this weekend. 14100' at the top there, so I should get a much clearer indication of how much compensation is needed for the low pressure end of the curve.

Plenty of options here for high altitude tuning, but not much for low. There is a spot in NE Colorado that's about 3300'. I'll probably take a drive out there in a few weeks to try to better define the upper half of the curve. I've done a lot of retuning since my trip to Alabama last summer, but during that trip things were far too rich at sea level, and I think that's probably still the case. Half-way to sea level should give me a decent idea of how far off I am, still, I think.

 

Slowly but surely. Waiting on Len’s Fusebox replacement. That’ll be interesting. This bike has no fuse box, the PO apparently threw it away and just twisted all the wires together with zero circuit protection.

Cleaned up the battery ground, didn’t realize it was copper coated until I started cleaning it. It was varying shades of apparently 38 year old rust and dirt.

Does anyone have a good closeup picture of the XJ650J starter relay? My ground wire from the starter relay is a big hairy woven steel cord, its a mess. I’d like to see what it’s supposed to look like.

 

Engine dismantling process going well. Cylinder head moving slightly but two seized broken studs on exhaust side of head. Having a beer then go back tomorrow with blowtorch and have another cautious attempt to remove it. Patience is critical so as not to damage parts.

 

So, it’s interesting what you can learn by tearing apart a parts bike—-

I bought an ‘82 750 maxim a couple summers ago...

a guy bought it to get running, but: no title, no key, engine set up because it’s stopped running for a PO in 1985, and was left outside with one spark plug out. (I doubt I’ll be able to get it to turn, but I’ll try for a bit).

Anyway, I thing I found out why —— when I pulled the kickstand off, apparently a couple of wires had gotten moved, and the front point of the kickstand had cut them. I guess that would do it, and would be tough to locate the issue.



so, now I have a bunch of 750 maxim parts available let me know what you need.

dave fox

 

Rode to the top of Pikes Peak (14110 feet). It was an interesting ride. Definitely going to do it again. Maybe in a bit warmer weather next time. Mainly did it to do high altitude tuning - baro adjustment. Learned a bit... mostly that there's a lot I still don't understand about how MS2/Extra's baro adjustment works.

This photo was not at the top, but a bit down from there. Maybe 13000 feet or so.

 

Interesting.....not much air pressure at 14,000ft. What is it using to read pressure? Is it reading atmospheric pressure or is it reading pressure somewhere in the engine?

 

Interesting......not much air pressure at 14,000 ft. What’s it using to read air pressure? Is it reading atmospheric pressure or is it reading air pressure somewhere within the engine?

 

The setup uses two MPX4100A 1 bar MAP sensors. One senses pressure in the manifold, the other is in free air for ambient baro data.

 

Still trying to remove cylinder head. The two studs on the exhaust side are sheared off and I have tried the blowtorch on them and the blowtorch holding on the fastener securing the cylinders to the crankcase. They probably have not been out since the bike was assembled at the factory. Going to try more heat and penetrating oil. The rest of the disassembly and reassembly should be straightforward once I get these corroded fasteners out. Not surprising really as they are the ones with all the road grime thrown on them. Time for a beer and go back to it tomorrow.