1978 Yamaha XS400 Chop replacement thread.

[SaddleTramp98]

Im starting this thread to replace my other. if they ever get the missing threads back this one can be deleted or I may just use this one now. Heres my 78 Yamaha XS400. It's got around 2K miles and hasnt been on the road in about 40 years, hopefully I can change that.




I polished the carbs with Brasso then the carb bowls and top caps with 220 grit sandpaper up to 1200 grit, and polished them with Brasso. I then cleaned the carbs inside and out and changed the jets and lots of the internals. I also added some pod filters but I may change them








I got the bike running tonight I just used the stock jet sizes and settings for the stock airbox. It would idle decently but if I gave it gas, once it got past 2k rpms it would stall and die.

I'm gonna mess with it some tomorrow and see if i can get it to actually rev up and run steady. Then after I get my garage organized a little better and my tig setup for my welder I'll start tearing it down.

[SaddleTramp98]

Still working on collecting Tig welding supplies and my hardtail kit. I'm just thinking ahead and I ordered some parts since Lowbrow was having the 20% off 4th of July sale. I got some plug wires and the old style screw on metal ring terminals, a gas tank and some stuff for my other bike.

My bike has these coils with the plug wires built in...



They work but I need to switch to something else that can take my new plug wires and they need to either look good or be able to be hidden.

I'm running a points ignition. If I switch to an electronic ignition for my year bike, the instructions I read said you still need to run 2 single fire coils anyway so the whole placement/ looks aspect wouldnt change.

I think I read the Ohm's should be around 4-4.5 for the coils but I'll have to go back and do some more reading to check. What would running say a 3ohm coil do vs a 4-5ohm coil? I suck at math and I'm kinda new to wiring and electrical and points ignitions but I can learn pretty quick if I try. Sorry if these are dumb questions.

I was wondering if I could use any of these coils instead, the top 2 Dynatech's would be on a Harley I'd assume and the last ones would be found on Brit bikes. A coils a coil right?







Mikesxs also sells coils that are direct replacement but something better looking, better quality, easier to hide is what I'm after. But I can make them work they're black and the plug wires screw on them.

[TriNortchopz]

look here at available options:

Ignition: Systems, Coils, Plugs, Switches, Hardware
https://www.heidentuning.com/xs650-s...-hardware.html
(check out their 880cc big bore kits while you are there...)

ya, looks like Mike has several options too;
https://www.mikesxs.net/motorcycles/...n-systems.html

[SaddleTramp98]

look here at available options:

Ignition: Systems, Coils, Plugs, Switches, Hardware
https://www.heidentuning.com/xs650-s...-hardware.html
(check out their 880cc big bore kits while you are there...)

ya, looks like Mike has several options too;
https://www.mikesxs.net/motorcycles/...n-systems.html

Those are for the XS650 though TriNortonchopz. I think the coils would work though they should be interchangeable as long as they're 4-5 ohms. I don't think the 880cc big bore would match up though, I didnt see too many threads on the xs400 forum about big bore kits besides custom stuff people have done.

I think I'm just gonna get 2 of these coils, and try to stash them somewhere, I just dont want a whole lot of wires showing looking like a big rat's nest.



Seems like not as many people working on the 400s vs the 650s. Mostly just cafe racers and drag bikes compared to all the XS650 choppers I've seen. I did find one thread that ended up being dead and unfinished, but this is kinda the look I'm going for minus the solo seat. I'd rather try to make a small king and queen seat or score one on ebay.

[mcknzAlex]

Looking nice, it seems like you are getting all the parts that you need.

[jervinLX]

Good info here. We'll be working on a XS400 soon