Slightly altered 83 XJ750 Maxim

Have a question for someone that knows more about XJs than I do.

I just checked logs from today’s ride and it shows my max RPM were 12,873?

Is this even possible?
Tach seems to function fine and RPM matches speed at least when I look at it. But such high RPM kind of throws me off. I didn’t even know these engines could spin that fast.

 

this says it's possible
http://thefirstgensite.com/code/maxrpm.htm
i think it voids your warranty though
750 stroke 2.22 inches

 

Received new gas cap today, but I didn’t want to use two keys (1 for ignition & one for gas) so I ended up taking parts out of new cap and swapped them over to my original cap. New seal, new springs, new locking mechanism. Greased everything inside and it seems to operate very smooth. Will have to do some testing to see if this fixed my problem with spilling fuel, but so far after tipping bike to the side until foot pegs touch the ground there are no leaks.

 

I cave in and ordered new rear wheel and new tire. Should be here in a week or so.

 

Rust-oleum played a joke on me today....

I decided to paint back side of my frame to prevent it from rusting until frame goes in for powdercoating later this year. Stripped the bike, masked everything off, degreased the frame and started spraying, everything went smooth, no runs, no dust. Waited around 8 hours for paint to harden and then slowly started putting bike together. The way I modified my bike, parts have to go back in exact order, otherwise nothing can be fitted since “tolerances” are quite tight. Once I was half way done, I mounted rear wheel & brakes and said WTF out loud! At that point sun started making its way into garage and I realized that what was supposed to be BLACK paint, was actually the darkest GREEN I ever seen!

Let’s just say I was beyond pissed!

Stripped bike back down, masked it all off again, degreased it once again and proceeded to paint with different satin black paint.
Now it came out exactly how I wanted it. Left it as is and will be putting it back together tomorrow.

I’ll include a few pictures.

 

Spent last couple of days working on my XJ. Back half of the frame & rear brake plate received paint (temporary until it all goes into powdercoating) and did paint correction on the gas tank.

New rear wheel and tire should be coming in sometime next week.

 

The few race bikes that were built ran the redline at 12k.
The rules about what's safe change a bit when prestige is on the line instead of warranty claims.

 

Went on the longest ride so far, 155 miles. Bikes performed well, but today was first hot day riding and I will be going up in jet size. Bike runs a bit lean.
Besides that, I also rode through a full tank of fuel and was able to put 140 miles on it before having to switch to reserve, good range imo considering that tank is a lot smaller than stock. Also, achieved a milestone of 500 miles on the bike in its current form.

 

that's a seca 550 tank correct?
4.2 gal total 0.9 reserve

so about 42 mpg not bad.

 

Correct on the tank model. My tank sits at slightly different angle than it does on XJ550. So I willed up I think around 3.7-3.8 gallons. Calculated 38MPG.

 

and I'm thinking you do not ride conservatively

 

Lol
Not at all! That’s another reason i sold 1000CC sport bike and bought old XJ. It’s plenty of fun to ride and keep it at somewhat reasonable speed. I am not responsible enough to own fast bikes. Haha

 

Received new rear wheel and tire today. Will be dismounting old tire that new wheel came with and painting new wheel tomorrow.

 

Love the look of your bike so far. The rattle can green is the same colour as an IKEA couch I have and my son swears up and down it's black.

 

View attachment 35132 New rear wheel and tire mounted. Didn’t make as much of a difference as I expected but still an improvement.

 

Ties the front and rear togeather nice looks like it was ment to be.

 

Swapped in new jets yesterday since I felt like it was a hair too lean and went for a ride today. Well, I think I went too rich as for the first time in it’s life bike started bogging on low throttle. Needless to say, I will be going back to what I previously had.

 

Update.
Spent most of Saturday messing with carbs, swapped Jett’s, synced them and now bike performs flawlessly! Super steady idle at 1k rpm, zero bogging, great throttle response, no popping on deceleration, drops down to idle from redline instantly, exhaust sounds smooth and deeper.

Also, this morning went to Sears point raceway to get my suspension adjusted and fine tuned. What a difference that made! Bike is very smooth on imperfect roads, absorbs impacts mid corner without getting upset. I would highly such tuning service to anyone with adjustable suspension!

 

Out of curiosity, what jet combo did you end up with?

 

43/134

 

Achieved a milestone of 1000 miles on the build.

 

Oh to live in a good weather place.... rain and cold off and on here the way it going I'll be lucky to put 1000km(!?!) On my bike this season.

 

What you need is an "Aerostitch" cold weather suit, amazing stuff. It's not cheap, but neither is a motorcycle that you can't (hardly) ride.
Cheers, 50gary

 

Went for a ride today and snapped couple of pictures of the bike.

 

Decided to take a bike for work today instead of a car, due to it being Friday and it was during rush hour traffic. On the way back I ended up going through a tunnel and did 2nd gear WOT pull, bike sounded orgasmic in the tunnel!

 

bet that made them look up from their cell phones

 

Ever since buying my XJ, I always disliked how quiet horns are on this bike (not sure if it’s just mine or all of them) and after yesterday’s ride through traffic I realized that cars probably can’t even hear my horn. So I swapped out stock 2 horns for original single horn from my 2006 R1 donor bike.
Now I finally have horn that’s beyond adequate!

 

If you can find room for them and make them look nice..
https://www.amazon.com/SoundOrigina...n&qid=1561240559&s=gateway&sr=8-1-spons&psc=1

 

Room is one thing I don’t have much of. Fitting electronics and hiding wiring on this bike has been an issue due to the luck of space and not disturb minimalistic look of the bike.

 

Got spotted by a friend today.
Crappy picture but you can tell the size of the bike.

 

Run out of gas today and had to push bike 3.5 miles to nearest gas station. I guess I ridden it little harder than usual since I run out of gas 15 miles sooner than ever. Anyone has suggestion on how to modify or what petcock valve to get in order to get reasonable reserve? I am not sure if something is wrong with my petcock valve or if it’s due to the angle of the tank but I only get 1.5-2 miles on reserve.

 

depends on the tubes in the tank you could make the reserve taller and the on tube taller end up switching over earlier

long ago I used to carry a canteen full of gas

27 oz
https://www.ebay.com/itm/27-fl-oz-U...=123669257847fe0efc6a2aec456c9c320128839b401d

 

https://www.ebay.com/itm/6x16-End-F...395276?hash=item234587fc8c:g:vhQAAOSwo8hTqffS

bottom of page has smaller tanks would be good for longer trips make it detachable.

do you have room to reshape underside of tank?

relocate petcock or add second one to front of tank a low point.
or a tap to manual shutoff.
like a balancing tube with tee in it.

 

Do you remember the thread where you mentioned leveling the tank?
Well, that's the result; a smaller reserve.
I don't think you'd want to alter the pickup level for the reserve since that would leave you with almost nowhere in the tank for water and detritus to settle out.

If I were going to alter the tank it would be on the topside, and somewhat a PITA to layout, cut, and fit (who am I trying to kid? It'd be cut rectangular and I'd make it ugly on purpose). Making the tank about 2" taller would add enough volume that you could use a manual petcock with brass feed tubes cut to your desired heights and not only gain more reserve but gain more overall range.

A 1 liter MSR bottle would look good strapped to the rear downtube. Mine lives in the left storage-tube that I made (which would not look good on your bike at all). MSR botttles solve all sorts of problems (like not having the patience for rolling compound curves into steel sheet).

 

Most definitely don’t have any space what so ever under the tank, since that’s where my buttery, front control connectors, horns, starter relay, all the grounds and the rest of the wiring resides.

 

I do remember that thread, but you know what... no RAGRETS! Hahaha (misspelled on purpose)

I most definitely don’t want to modify tank or shape of it. Extra frame mounted bottle of fuel isn't a bad idea, but I feel like it’ll mess with lines on the bike. :/

Conclusion will be to stick to ~100 mile fill up intervals. I was used to 135-140 mile fill up until today. :/

 

Coolness has its price.

 

100% agree!
I am willing to pay it!

When I started building my bike I fully realized that it won’t be 100% polished out version of a motorcycle that Yamaha intended it to be, but after making so many changes and the only negative is almost inexistent reserve, I am ok with that. I did better than most.

 

Here's a thought, and it would solve your sliding-off problem too.

At one point (pre 1940) there were several manufacturere of smaller displacement machines who incorportated spare fuel tanks into their designs. Some ugly, others fairly good looking. There are also long-distance riders who have developed a market for auxillary fuel tanks (none would be suitable for your machine though).

SO...

Tail cowl. Possibly detachable. Also fuel tank.

Downsides: Would have to be fabricated to suit. Adds weight to the rear. Could be plumbed into the fuel system so you can switch to it without needing to use it like a gas can.

Upsides: No more sliding off the seat. No more pushing the bike to a gas station.

 

Done longest/furthers ride on this bike today.
Bikes performed as expected. Covered first 98 miles before stopping for fuel in 1 hour and 8 minutes, calculated Fuel economy and came up with 30mpg, which isn’t bad considering the style of riding I do. RPMs were in the range of 6000-9000+ Most of the time and didn’t have a single issue. Really curious to check oil level once bike cools down and oil settles, since it’s first time when it was kept at high rpm for such long time.

 

Sooooo...

Went for a ride today and when coming home, stopped at stop light and idle first was stuck at 2k rpm. This was news to me since before that moment I haven’t had any issues with idle. Pulled into garage, same thing. Did some diagnosing and came up with leaking throttle shaft seals. :/

Already emailed Chacal for a set of new seals.

Perhaps beating on the bike brought on a light on this issue.

 

it was all that working of the throttle that did it

 

you went 98 miles in 68 minutes, give it about 15 minutes and those throttle seals will catch up with you

 

98 in 68 is very fast. 86.47
Cheers, 50gary

 

And now I am paying for it. Haha
Parts should come in on Monday. But I probably won’t be able to get to do it until Tuesday or Wednesday.

 

Update. Recieved parts from XJ4EVER yesterday and put them in today.
Bike is back up and running as should.

XJ4EVER emailed me a link to DIY on how to change throttle shaft seals. It’s very detailed DIY however I am the type of person that can’t follow directions and if DIY has more than a handful of steps I get confused and start to overthink the whole process. So I went in it and tried to figure out on my own.

From what I have read before made me believe that doing this job will be very complicated, however after doing it myself I must say it’s a lot easier than I though.
From start to finish it took less than 2 hours.

One thing I must mention is that for some reason after replacing seals and fuel line O-rings between carbs I had to turn fuel mixture screws out half a turn to make bike run right.

 

Out half a turn is weird. Normally you'd need to lean them up.

 

That’s my exact thinking. After replacing seals (which were providing air leak) bike actually started to run slightly lean. Makes no sense to me but that’s what I did.

 

Mocked up a windscreen to clean up the front end. What do you all think? I am not completely set on keeping it.