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1978 XS400 CAFE Build

132K views 521 replies 39 participants last post by  AKyammy 
#1 ·
What's up bros, I'M BACK!!! Sold my GSXR project a while ago, I was sure it would be a long while till I had a bike again. I was wrong. Recently I had a cool dream about riding a little CAFE bike, the next day I watched the trailer for "The Girl With The Dragon Tattoo" in it she was riding some sweet little 2 cylinder CAFE bike and I thought to myself, I've always wanted a Small CC, 70's Japanese bike to CAFE out, but where can I get one that isn't burnt out or expensive. I remembered my good friend Brian said he would sell me his since he bought an RX7 and he doesn't have time to do both. So here she is, a 1978 Yamaha XS400. Beautiful condition, sat in a shed for 15 years. 17,xxx original miles bone stock, new tires, battery, and fuel lines and he already cleaned the carbs. I pick it up Friday, here's some pics of it I snapped tonight in his garage:






Bike starts right up and runs with the occasional pop, I checked the carb boots and sure enough they're cracked, replacing those will most likely fix that. Other than that it needs a good cleaning and then I can start the build. Here's my plan:
Clip ons
rearsets
leather cafe seat
2 into 1 exhaust
rear gas shocks
LED Blinkers/taillight/headlight
Hidden mini cell battery
custom gauge cluster
strip it down to the bare essentials
a little re-painting
possibly switch to disc brakes if I can find them on spoked wheels
Let me know your thoughts and ideas.
 
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#493 ·
Venturesomerite (Brian) stopped over last night and we finished up the top end, torqued it down and adjusted the valve clearance, all that good shit. Everytime he comes over I learn about 10 new useful things. Here's a few pics he snapped of me when I was workin.




Sweet revenge for Brian. A close up nose shot like the one I took of him the other day


What's the torque setting???


Tonight I'm going to adjust the gear selector and maybe put the motor back in the frame.
 
#495 ·
The cover had a very stuck cap, I still have the lines on my arms from holding it down while he used that breaker on it.
 
#497 ·
That is sick looking, is that a turbo???
 
#499 ·
Any more pics or info on it? The headlight is gay but everything else looks awesome.
 
#500 ·
I see, there's a link to his build under the picture. Nice
 
#501 ·
Starting tearing down the cm450 today, AND free'd the motor. I poured Marvel Oil down in the sparkplug holes and let it seep in for a few hours. I went to the top of the hill by my house, started rolling and dumped it into 1st gear and pop. Shot Marvel Oil across to each house on both sides of the street :D I can hear the compression, sounds good. I threw some dirt bars on it too, I think I'm going to build a little chopper out of it. My Dad never ended up taking it so I'm starting the build. Heres some pics, and a special "running video" I had my neighbor shoot for me...





If you listen closley you can hear the chain running along the swinger
 
#502 ·
those bikes take to the brat style really well! get some short shocks on the back and lower the triples down the forks a bit, then chop that tail!
 
#503 ·
Hell yeah Matt, sounds aright to me. My Dad still really wants the bike so I'll just build it here our at his house and he'll fund the parts, works for me. Got the top end off today, some light rust on the rocker casts but cleaned up nicley, valves, springs and shit look great. Pistons and cylinders look good, not scarred or anything. Just some staining on the cylinders where the pistons were stuck. Bottom end looks nice and clean, both pistons fire at the same time on this bike. My Yamaha alternates, I thought that was cool, what do you call that?



 
#505 ·
Really? cool
 
#506 ·
New issue:mad: Motors back in and I got the valves dialed in very nicley, almost silent. I woke up early Saturday morning to go for a ride since it was soo nice out, starts right up and idles fine but once it warmed up I revved er a bit and the rpms got stuck at 3k. Sounds like a vacuum leak right? New vacuum line for the petcock, carb boots and gaskets are new. Pulled the carbs apart and re-cleaned the slides, needles, jets passageways, choke parts, checked out the diaphrams, everything. Put it back together and still the same. took the carbs back off to really inspect the choke because I remebered this happeing a while ago while the cholke was on but it would stop with it off. I'm thinking one of the seals might be fucked up on the choke plungers, with the carbs off when i pull the choke (rail style connected to the bodies) I can hear a vacuum noise from one side but not the other. What yall think??? Thoughts???
 
#507 ·
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#508 ·
Wow, great advice thanks Ants! I took apart the petcock before putting the motor back in to see why fuel was creeping into my carbs, the leak stopped but I might have put the petcock diaphragm back in wrong. I'll have to try this.
 
#509 ·
Hanging Revs can also be a bad synch, more likely a vac leak of some sort. Doesn't take much either. If you want to synch I have synch gauges at my shop.
 
#510 ·
I second the bad sync.
 
#511 ·
Guess what I bought today. :D



1980 xs650 special II, went with Venturesomerite to pick it up. 11,XXX miles, carbs are in the box on the sissy bar rack, motor's free and everythings there but the intake boots. $200!!! I still can't believe it, that was my first offer he didn't even flinch. It needs some lovin for sure but I'm happy as hell. Build thread coming soon...
 
#514 ·
for 200 you'll make money if you build the bike or end up parting it out! Good buy!
 
#515 ·
I'm building this bike for me, my xs400 is for sale on CL right now. Got a few bites, one guy offered an AR-15 with a bunch of accessories for a trade.
 
#516 ·
Think I found the carb problem, I checked the synch with guages and they're dead on. I pulled them apart one more time because I wanted to check something I havn't touched yet, the A/F mixture screws. Here's what I found:

The tip is still stuck in the body.
 
#518 ·
use a snapped off end of a really small drill bit as a press tool. get a bolt and a acorn nut that will just barly fit in the carb screwed together then drill a hole in the top of the acorn nut with the drill bit you robbed a piece off the chuck end. put it in place and unthread the nut and press the screw bit out with the drill bit end.

did this with two screws in my XS1100.
 
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