Bought this project a few days ago, got her fired up and running and took her for a spin around the block. Won't run without choke. Pulled the carbs apart, it has 147.5 main jets and the other two were stock. I cleaned every thing up and ordered 137.5 jets. I assume that's what was causing the bike to only run half or full choke. Too big of jets. It does have a open exhaust and small pod filters. I also bled out the front brake line and it was a pretty nasty color. The caliper does function but won't fully release, it is definately contacting rotor. I hope I can get a rebuild kit or new caliper.
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1980xs Brat Project
- Thread starter Noah
- Start date
No your front end is not from a xs400. Not sure what it's off of so ordering parts will be hard. Disc brakes will drag a bit. That's normal. As long as you can turn the wheel easily you should be fine. What pods do you have. Pods directly on these type carbs is a bad idea making the bike run poorly.
Calipers say Japan and have a 8823 in white stamped under where the piston is and a 87r stamped into the metal. They do work good when I press the brake lever, I'm just worried they are going to lock up or not disengage when I need them too. The pods font seem to have a brand. What do you suggest for filters? Also do you think the 137.5 main jets were approximately the right size? It died on me during last ride, I think it is dumping ok much fuel with the huge 147.5 that someone put in there before.
Could be a lot of things causing your issue. Stock intake setup is best but using the stock H-pipe and 6" black foam uni filters would be the next option. Lot of threads on carbs and filters in the forum. You may also want to start with basic tuning and maintenance first to rule out any other things.
I haven't been able to get spark after she died yesterday. I checked all the wiring, I'm thinking its a points or ignition module problem. I definately got a project, it was so much fun to ride.. For all 2 minutes, so I know it will be worth it in the end,
Tried using the spare bikes ignition module, no luck. Still not getting spark. The previous owner boogered the Phillips head screws on the pick up coil on the spare bike so I haven't removed that one to see if it will work. Not sure what else could have just suddenly quit. Maybe the ignition coils themselves?
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I would try new plugs first. If your bike was running bad they could be fouled. Testing the trigger pickup to easy and it don't need to be removed. The manual has the specs for that. Your poor wiring/grounds may also be the issue.
Found my issue, previous owner left me quite the project. Someone installed an afternmarket flywheel and it grenaded. Sprocket chain shredded the wires that connect to the stator, neutral switch and oil pressure sensor.. There's a plate with timing marks on it that is free spinning behind the flywheel. Ill have access to flywheel puller monday. I'm hoping I can use the stock flywheel from the spare bike with no issues. Worse case scenario, I will run a compression test on the spare motor and if it checks out. Ill swap all the parts over to that one. I'm using the factory harness from the parts bike to redo the ghetto wiring. If I hadn't heard the motor run before, I would he a lot more worried after seeing this. Ill keep you posted. Thanks
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I would look at the motor that is still stock. All the marks should be still correct for that one. Someone did a PMA conversion with the other on which removes all the marks. These motors are not really setup well for this type system. The xs650 is more suited for this. The stock xs400 system is a very good system as there are no brushes or parts to wear out. The winding's can go bad but because everything is in oil from the motor they will stay cooler and less pron to drying out. My 79 still has its original charging system and it works perfect even after 35k+ miles on it.
https://www.mikesxs.net/yamaha-xs650-xs400-standard-overhaul-gasket-set.html
Edit: ordered my jets from Mikes and they got here so fast. Is getting the whole gasket set my best bet?
Thanks for the help Chris, I appreciate the knowledge. I would really like to keep the Motor stock, I don't need any extra power. I'm glad to hear they were built with the reliability. Do you know where I can get a stator cover gasket? I've only seen them for sale with kit. I looked online and it appears to be a 16 mm flywheel puller?
Edit: ordered my jets from Mikes and they got here so fast. Is getting the whole gasket set my best bet?
Thanks for the help Chris, I appreciate the knowledge. I would really like to keep the Motor stock, I don't need any extra power. I'm glad to hear they were built with the reliability. Do you know where I can get a stator cover gasket? I've only seen them for sale with kit. I looked online and it appears to be a 16 mm flywheel puller?
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The last time I got jets from mikes they where china made knock offs of mikuni. They are not as well made and the sizes are not correct. I use only real mikuni jets ( they will have a square within a square marked on them). Jetsareus.com has real ones as well as most yamaha dealers. It will make tuning much easier.
