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    1978 Yamaha XS400

kmac's Achievements


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  1. Good job! Everything takes longer than you think it will. But getting there is half the fun isn't it? Glad to see colortune plug works well, been thinking about getting one.
  2. You should find out what year the engine is if possible. The first first 3 numbers of the the number stamped on the crankcase (1L9 for example) would be helpful. I converted my 78 xs400E which had points to use an electronic ignition from an xs400G. So upgrading an xs400 engine from points to electronic would be easy and only require removing the points and mechanical advance then replacing them with the pickup coil and rotor from the broken G engine. I would figure out what engine you actually have though. That said, if the pickup coil plate fits properly and the 2 coils physically occupy the same location as the points once did, it should work. The pickup coil plate from the electronic ignition engine should be exactly the same size (diameter) as the plate that holds the points on the new engine.
  3. There is no problem with grounding the plug on the head while you crank the ignition to test for spark. Just make sure that the plug doesn't lose contact with the head and that both coils have a spark plug in place when you turn it over. Sorry if I caused confusion.
  4. Welcome! It looks right. Looks like mine which is a 78 400E. Yamaha parts catalog says that 80 and 81 (and 78) use the same chromed fender. This will come in handy: http://www.yamaha-motor.com/sport/parts/home.aspx
  5. Yep, you're right, it is TCI. The coil spec was 3 ohm so I just matched that. I looked in the yamaha manual G model supplement and they have a block diagram showing the driver transitors inside the ignitor box.
  6. I installed some Dynatech DC3-2 mini-coils on my 78 XS400E (US). Had to fabricate a couple of brackets to hold them but they do fit under the gas tank nicely. The spark energy was noticably better than my 30 year old coils. They are being driven from the 1980 CDI ignitor box that I installed awhile back. The coils are 3 ohm primary like the old ones and have not killed the CDI after a couple hundred miles. If you want to use new coils on your bike, this could be an option. I'm using the same resistor cap plug wires that came standard on the 78 US model. And platinum tip plugs. http://hollymchone.com/tmppx/index.html
  7. I used the POR-15 motorcycle tank kit quite a few months back and can recommend it. No rust, no flaking. Very solid material once dry. I did have to drop the bowls on the carbs and clean out the pilot jets after the first tank of gas. But nothing since. I didn't rinse the tank after it was done. Maybe if I had put some gas in the tank and given it a good rinse before trying to use it would have been a good idea. But has been no problem since. And yes, another use for duct tape! Oh, and if you are going to have your tank repainted too, I would do the POR-15 first. It can be messy if your not careful.
  8. Sorry! Got it and responded. Must have had the wrong goggles on.
  9. I think drewpy pinned the instructions and parts list in 'xs400 links'.
  10. kmac

    electric kawasaki

    To build a bike like this is on my short list of projects. I want to use a yamaha xs250 or xs400. I have so many parts already. Should be a fun project. I've seen some people use up to 7 or 8 smaller 12 volt batteries to get the voltage up. Anyway, this fellow was pretty resourceful.
  11. If mikesxs.com is out of the sizes you want to try, you can also find main and pilot jets on denniskirk.com. They have them for the same price. I ordered Monday and they arrived today. They had the ones in stock that mikesxs was out of. I added a mac 2 into 1 exhaust going through the tuning process too.
  12. To upgrade my xs400e I used parts from 80 or 81 xs400 machines: o Pickup coil - 4R4-81671-10-00 o Rotor 3F9-81673-10-00 (will need longer bolt) o Ignitor assembly 4R4-82305-10-00 o Ignition coils 2F3-82310-60-00 (you could use aftermarket high energy too) o Ignition cover: 3F9-11157-00-00 (yep, your points cover is too shallow) You can get part numbers from: http://www.yamaha-motor.com/sport/parts/home.aspx If you want to make installation easier, get these too: o Battery box - Ignitor mounts on the bottom. Easier than adapting old one. o Wiring harness - untape an 80/81 xs400 wiring harness and lift out the wiring for the ignition coil plugs, ignitor plug and the pickup coil plug. One snip each for power and gound and you have all the wiring and plugs to add electronic ignition to your bike. o xs400G Wiring diagram. After you remove the points and condensor, there will be a red/white power connect left hanging. Use that to power your new circuit. It comes right off the kill switch. Add a connector to ground wire and find a place to bolt it onto the frame. Make sure you have a good battery. You're adding more load and you want to keep your voltage up when using electric start. Mikesxs has a maintenance free battery I have ordered but not gotten yet that has 170cc amps. Some ebay sellers say that the ignitor box from 82 works as well. But that is the year the xs400 went to DOHC. Don't know if that makes a difference, but I just kept looking if it came from an 82. There was very little or no retooling to the cylinder head from 79 through 81 so parts will fit nicely. Don't forget to set timing. Most parts are no longer available from Yamaha. But everything can be found on ebay with patience. I suggest getting spares if you go ahead with it. Have fun!
  13. The prefix indicates the model number. 3M1 indicates that it is a MX100F. Here is a link I use to cross reference part numbers to the bikes they come from. It lists the prefix in ascending order with corresponding bike model. I haven't found it wrong yet. http://www.johnnystoybox.com/parts_cross.htm
  14. Thanks, will check that out for sure! Very possibly the problem. Probably won't get to it until this winter. Love the MikesXS.com site. Bought a stainless brake caliper piston there that works in xs400. Nice.
  15. Not sure. They were cleaned in a solvent bath I know. Could smell solvent and exterior oxidation was removed and they looked quite good. But don't know beyond that (a long and disturbing tale of outsourcing carb repairs that you should do yourself). I think some 25 year old gunk is still in passageways. I am getting a used ultrasonic soon. Big enough to clean one carb at a time. Will give that a go. Also, I read in another thread that fishline works well for those hard to reach places. I had bought a xs400 engine from a guy off of craigslist a few months ago for cheap that included carbs. He had said that a high school student had rebuilt the carbs some years back. Tried not to roll my eyes as they didn't look like they had ever been off the bike. But...now...I decided to remove them from the spare engine, drop the float bowls and take a look. Clean. They had not been boiled out but at least they had not been sitting around for many years with old gas in them. Not sure what the kid did to rebuild them. After installing them on my bike's engine, and turning over...a few snorts and pops (old dust??), it fired up and ran pretty well after the engine warmed up. They too will need to be ultrasonic'ed. But at least I know that dirty carbs are my main problem.
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