Pumba the XJ750 project

uhh that is the cleanest bike i have ever seen for 600

 

sorry..don't mean to hijack. It IS nice looking. I think I'd be crazy not to pick it up. The same guy just sold a good looking '77 cb750 that I was a day too late on, because I couldn't get off of work. I've been emailing back and forth with him non stop for days. Just a cool 50 year old dude that really loves bikes. He also has an '83 gs1100e and xs1100 that look sweet, but they aren't up for sale.

I'll start my own thread when I get this in the garage. I want to chop/bob it. Not 100% sure on the direction I'll be taking, but I'll be reading a TON on here to help me figure it out. Great site.

Sorry again for the hijack

 

The gauges are Koso...
Can be found here koso

 

Found time to work out the wiring connections for the replacement bar switches, and fit new sealed connectors.



Love the way they look too


Now its strip down the wiring and audit out some of the crap and replace most of the connectors.

 

That's wiring hareness looks like a bowl of spagetti gone wrong!!!
Those weather-pack connectors are the answer for sure. Using them along with die-electric grease and your connections are sealed tight.

 

Ok
In the middle of the wiring, and noticed no headlight relay, so I will add one.

Will keep the neutral and clutch switches operational, but get rid of the sidestand switch.

Changing the flasher unit to electronic, so I can change to any globes or LEDS at any time
Next question.
My new switches have a hazard light switch, should I keep it as a spare switch or wire up hazard lights?

 

I don't see a need for hazards, but I guess that would just ber personal preference. I personally wouldn't use it.

 

Oh, and I have a '90 gsxr 1100 with a rats nest for wiring. Would you like to come redo mine while you're at it? It's looking great.

 

For those who are trying to tidy up behind the headlight area, today I
went from this;



All that junk was removed/edited/modified


And now we have this;


Indicators are not terminated yet.
As soon as I get some tidy bullet connectors for the indicators and a changeover relay for the headlight its test on the bike time 8O

 

Is there a fuel gauge with that instrument cluster and will if work with the sending unit from a Seca tank? Just wondering> Thanks!

 

Yes there is a fuel Gauge in the instruments, can be programmed for a 100ohm or 510ohm sender.
I will probably be slightly modifying the sender to get it to work correctly.

 

Great! Let us know if/when you get it to work then. I searched high and low for a gauge that works with our senders, and ended up finding one on line (automotive kind - $25~) But haven't got it just yet. Trying to figure out where I can mount it so it's not so goofy looking on the bike, like the one I have now (mounted on the handlebars)

 

Did a mock up of the wiring and gauges on my second start up.
The gauge reads opposite, so after a quick reversal of the internals of the sender it was time to test again.
Full = full
Half = half
Empty = quarter

Research continues 8)

Today I also got the final shims and finished the valve clearance and balanced the carbs

Wiring is almost there.

Here is todays run up for those interested;
Pumba runs

 

Alright....I'm not too crazy about the sound of the bike. I'm glad it started and it's all working great, but what are some popular exhaust mods to make these things sound a bit meaner?

 

That's coming along great! The gauges and controls look excellent.

 

I agree the exhaust note is not inspiring, but after it is registered and on the road I will be considering changes. The project has many months to go

But as for unique exhausts, Pumba is a long term project with multiple stages.

Pumba MK II is the bit I cant wait to do!

Spent time today after work machining brackets for the dominator headlights

Could not find any headlight brackets that I liked, so I decided to make my own :!: 6 hours labor later i'm halfway there.
I sure hope they turn out the way I imagine them in my head :wink:

Fuel gauge update;
Sender will not work as is with the Koso gauges, although I can get a full reading, but tank empty is 1/3 on the gauge. Through my contacts (automotive instrument tech) I have ordered an internal winding to suit a Honda that I will try to convert into the XJ750 sender.
I expect this to work, and will document the progress. I am not sure others will go to as much trouble.

But with this project, the enjoyment is in the journey, as well as the destination

 

"But with this project, the enjoyment is in the journey, as well as the destination".... Like any good ride should be, that's not merely from A to B.

 

Version 1 of the headlight brackets. Not that happy with them. Still need to round off a few edges and polish up, but they did not turn out anything like what I visualized they would.
Being multiple pieces allows later changes :?

 

The Koso instruments have 2 fuel gauge options. The options are to suit either a 100ohm or 510ohm sender. Evidently 100 ohm is common Yamaha and 510 is common Honda.
The first thing I noticed was the sender read the opposite way, and this was quickly fixed by reversing the senders internal resistor. This gave me a Gauge that read full correctly but read empty at 1/3 tank level (510ohm setting)

Over the last few days I have rewound the sender and shortened the resistor wire to convert it to be a 100ohm sender. Testing will happen this weekend and I expect it will perform correctly (resistance tests are ok)
If it works ok, is it work putting up a separate how to? There seems to be a few people looking for alternative gauge options, and modifying the sender to suit a more common yamaha gauge may be of interest?

 

Ok The Koso dash's fuel gauge requires either a 100ohm or 510ohm sender to work properly.
The XJ750 is 320ish ohms and also reads backwards.
The first mod is to remove the actual windings by bending the tabs open;



And then flipping over the windings so the ground is at the other end.

After trying this connected up to the gauge full was spot on, but the tank was empty when the gauge read 1/3


Time to go deeper into the problem;

Resistor windings were unsoldered and removed


And then unwound. Resistance was checked along the length, and it was cut at 110ohms



Then carefully rewound.
First resistance test showed problems, but once the path the wiper runs on was scraped clean to remove any insulation, it now works perfectly.
Next week I will do the same to my spare sender