Project Oliver; 1980 xs400 build

[SuccubusJuice16]

Hi guys, so ive had this bike for about 6 or 7 months now, and ive started working on it and getting it running.

so far ive got it running well mechanically. one of the previous owners shopped the exhaust how you see it in the pics, so i rejetted (after an extensive carb clean) and finally got it up and running. i put semi-synth yamalube and my clutch seems to slip a little, so i may go to full conventional soon. Other then that, the front shocks could use a rebulld.

i bought the bike as a work in progress, and a lot of stuff is jankey imo but for the most part dosent seem too bad. ill be uploading photos too.

Edit- figured i should give my goals for the build as well:
make headlight mount, wire LEDs for running/ turn signals front and rear, relocate battery and some wiring, & possibly make new seat

 

[SuccubusJuice16]

this is pretty much the condition i bought it in. I've just taken off the side covers and air filters, and added a cutoff valve and clear filter on the fuel line, (i cleaned the tank and rebuilt the petcock. the in-tank filter was MIA, and i didnt feel like sourcing one :/. Also my floats are not adjusted correctly- i think- hence the shutoff valve.)

in retrospect, i should have just got a replacement petcock off of mikesxs.

 

[SuccubusJuice16]

made some brackets for the headlight out of scrap metal i had laying around.




i decided to incorporate a blinker on the headlight mounts, and will be using a couple of small LEDs as running lights.



My turns will be pretty damn bright, so i figured its OK that they are kind of tucked away a bit.

 

[xschris]

Welcome to the forum. You may want to put some air filters and exhaust on the bike It will run and tune much much better and last a long time.

 

[SuccubusJuice16]

Thanks, yea i actually bought some cheapo moxi brand pods for the time being. as for the exhaust, i plan to leave it chopped as is. (although, its almost hysterically loud)

 

[motoTrooper]

Another thing to consider - I got some advice from a motorcycle tech (40+ years experience). He cautioned me against running engines without exhausts mounted or without enough back pressure as that can burn exhaust valves...

 

[SuccubusJuice16]

@Mototrooper

I have heard that too about back pressure issues while running a straight exhaust. I've actually heard things from both sides of the fence, and from people that have personally ran successful with it. I have not yet however come across a someone where engine failure was a direct result of running a straight exhaust, other than it running lean due to improper jetting.


If anyone has input (or can testify to personnel experience with success/ failure) i would be interested in hearing what you guys have to say! i have heard a few guys running the same setup i have in regards to chopped exhaust, and +1 size on the jets with stock air filters removed.

 

[Edgee2004]

Running open exhaust will cause excessive scavenging of the exhaust gases causing the exhaust valves to operate at a higher than normal temperature eventually burning them. Which is really them just wrapping.

 

[SuccubusJuice16]

Thanks for the info Edgee. What would you say is the "life expectancy" if the bike's motor under "normal" riding conditions? (no hooning, canyon running, etc.) just regular riding around town/ fwy.

im assuming it wouldn't be a sudden failure, but a gradual decline in motor performance, correct?

 

[SuccubusJuice16]

Well, ive been gone for a couple weeks for work, but ive made some progress recently:

Got a shitty battery box made up real quick, did a lot of wiring and crimping over the last week. i got all of the bullet connectors from Cycleterminal.com. The guy that runs it is super cool, great customer service. also got the mini fuse holder there, along with diodes to keep feedback from going through the brake/turn wires for the rear tail lights.

Here are some pics



















i added those wave looking gussets because i had to bore out a relatively large hole on the frame tube to fit the tail light wiring harness through, and i felt safer with some added support.

 

[Unkle Crusty]

Not on a Yamaha four stroke but: I have not been sold on the idea the engine needs back pressure. The theory was to get the exhaust gases out the most efficient way possible.
So we used expansion chambers ( very noisy ) on the two stroke GP bikes, and megaphones on the four stroke bikes.
I ran two megaphones on a 750 Norton engine. 32 inches from the head to the beginning of the megaphone. That was a critical dimension. Just about everything had been tried and tested by Axtell and Libby in CA. The maximum horsepower of 85 was a known quantity. Even today many think around 70 is all that can be had. They are not checking the right sources. After a large amount of changes, to the engine and frame and suspension, I reliably ran 85 hp for a few years. Ultimately the crank breaks from too much piston speed. But I did not have any exhaust valve problems. We ran three angles on the valve seats, and a thin contact area. Also ran a large oil cooler. From memory, I would re-seat the valves when the compression dropped to about 183 PSI.
Still have some main jets in my tool box. Think they are around 185.

Unkle Crusty

 

[SuccubusJuice16]

Well, i tentatively finished the bike. Ill be posting up some pics soon. I got it running pretty good, took it out to run some errands the other day. Noticed the LED license plate light had already gone out (cheap light from Amazon, shipped from China) luckily they came as a pair, so it didn't take long to swap out.

unfortunately, i shot myself in the foot; the starter relay doesn't have a rubber cover over the positive lead, and it grounded itself to the chassis. (Edit- i had initially wrapped it a few times with electrical tape- i didn't leave it completely exposed. I got lucky it didn't short while i was riding it) I didn't realize that happened until i smelled it cooking. Now i don't have any power to a any lights, nothing happens when the key is turned.

I've already begun to trouble shoot it, but wont be able to work on it more until later this week.

Here is what i know so far:
-battery became discharged to approx. 9.38 Volts, so the first step is getting that back up.
-there is a large voltage drop on the positive lead of the starter relay to ground- it read about 6.2V. ill be double checking wires all have good connection first on this.
-all lights work when hooked direct to a battery
-no fuses were blown
-no wires appear to have melted or become burned/exposed (other than the obvious positive lead to the starter relay)
-starter switch has been swapped with another to verify the switch has not been fried

my next step will be to swap out the starter relay with one that should work.

ill be posting pics of the current state of the bike, as well as progress on troubleshooting this electrical problem.

 

[SuccubusJuice16]

Here are a few pictures of it "put together"













yes, the seat is super uncomfortable, but that's how the bike was when i picked it up. the battery is a bit low for my comfort, but it was $35, so i cant complain too much.

 

[SuccubusJuice16]

forgot to update: indeed, it seems i burnt out the starter relay upon it grounding itself out on the frame. I had a second hand one that a swapped in, put in a new battery, cut some old water hose to wrap around the terminals to give them a nice thick protective cover and zip tied/ wrapped it all in electrical tape. Starts right up again! I plan to take it out this weekend for a little cruise if time permits.