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1984 XS400 DOHC


xmastree
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So, I have this old XS400 DOHC, which has been idle for a few years. I've fettled it to a point, and it's on the road, but not as good as it could be.

Pics here

During the fettling, I had the carbs off and had them ultrasonically cleaned.

Firstly, starting is a pain. It tends to fire up instantly, then die after about two seconds. After that it takes a lot of cranking, it will catch, but I can't get it to stay running. Any throttle action and it just dies. Mostly, it's one cylinder doing all the work, and this post caught my eye. I would like to check the valve clearances and ignition timing but I have no data to work from.

Also, I should replace the spark plugs, but rather than assume it has the right ones fitted, I would like to know what they ought to be.

The speedo reads really slow. Following a friend at 30,40,50,60 on his, mine reads 20,25,30,40. The trip counter seems to be reading low too, suggesting the problem lies with the speedo drive rather than the speedo itself. In 6th gear, at 6000rpm, the speedo reads 65mph, but it feels much faster.

The tacho is very sluggish. At standstill I can rev it up to what sounds painful, and back again and the needle only reaches 2000. Holding it at 4000 then killing the engine, it takes 4 seconds to drop. On the road, up through the gears and it hardly moves. As if it's full of oil or something.

What tyre pressures should I use? Dunlop Arrowmax, 100/90x18 and 120/90x18

Does anyone produce a manual for this thing?

Edit:

Any idea if this will be any good? At £17 it's a tad expensive, and at 20 pages it isn't going to be a workshop manual either.

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So, I have this old XS400 DOHC, which has been idle for a few years. I've fettled it to a point, and it's on the road, but not as good as it could be.

Pics here

During the fettling, I had the carbs off and had them ultrasonically cleaned.

Firstly, starting is a pain. It tends to fire up instantly, then die after about two seconds. After that it takes a lot of cranking, it will catch, but I can't get it to stay running. Any throttle action and it just dies. Mostly, it's one cylinder doing all the work, and this post caught my eye. I would like to check the valve clearances and ignition timing but I have no data to work from.

Also, I should replace the spark plugs, but rather than assume it has the right ones fitted, I would like to know what they ought to be.

The speedo reads really slow. Following a friend at 30,40,50,60 on his, mine reads 20,25,30,40. The trip counter seems to be reading low too, suggesting the problem lies with the speedo drive rather than the speedo itself. In 6th gear, at 6000rpm, the speedo reads 65mph, but it feels much faster.

The tacho is very sluggish. At standstill I can rev it up to what sounds painful, and back again and the needle only reaches 2000. Holding it at 4000 then killing the engine, it takes 4 seconds to drop. On the road, up through the gears and it hardly moves. As if it's full of oil or something.

What tyre pressures should I use? Dunlop Arrowmax, 100/90x18 and 120/90x18

Does anyone produce a manual for this thing?

Edit:

Any idea if this will be any good? At £17 it's a tad expensive, and at 20 pages it isn't going to be a workshop manual either.

in usa = 1983 Yamaha XS400K

found this on motogrid for you

http://www.motogrid.com/pages/parts/viewby...d/2/yamaha.aspx

enter the above date etc and the service data there as well as part numbers. it is also known as 12n model which was very popular in Germany, which is where you will see most parts on ebay.

http://translate.google.com/translate?hl=e...hl%3Den%26lr%3D

uses google translator, you can pick up what they are on about (usually) unless you speak german and then you're quids in :o)

drewpy

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in usa = 1983 Yamaha XS400K

found this on motogrid for you

http://www.motogrid.com/pages/parts/viewby...d/2/yamaha.aspx

enter the above date etc and the service data there as well as part numbers.

Interesting, thanks. Although the service data isn't the most legible scan I've seen... :angry:

By enlarging it, blurring slightly and squinting at it, I can just about make out:

valve clearance (cold) Intake/Exhaust | 0.51 ~ 0.58mm / 0.15 ~ 0.20mm

5701valves.png

The exhaust I can believe, but I'm not sure about the inlet.

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Here's the spark plug you should have for it.

http://www.ngksparkplugs.com/part_finder/m...08&type=reg

Hmm, that link doesn't work, and going from the top to search for my XS400 reveals that they don't exist after 1982 (the SOCH model) and they don't even have plugs for that one...

ngk.png

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What I ought to do is try the local Yamaha dealers, they should have a big book saying what needs what. They may also be able to advise me about the valve clearances, so long as I promise to buy the shims from them...

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  • 1 month later...
  • 2 weeks later...

That would be really helpful to me, as i can't get hold of one by my preferred legal means!
Well my conscience is now clear, as I have just splashed out on the real McCoy on eBay. :D

Not cheap though, at £25 + £3.50 p+p. :angry:

I'd post the link, but there was only one available.

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Well my conscience is now clear, as I have just splashed out on the real McCoy on eBay. :D

Not cheap though, at £25 + £3.50 p+p. :angry:

I'd post the link, but there was only one available.

hi there well seems to me theres an opportunity here if you have a good scanner and can reproduce the manual I too have had loads of trouble locating one for my 400 seca last one I found I bought from canada but alas it never arrived.

if you can help i would be most grateful. Ken

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  • 6 months later...

hi there well seems to me theres an opportunity here if you have a good scanner and can reproduce the manual I too have had loads of trouble locating one for my 400 seca last one I found I bought from canada but alas it never arrived.

if you can help i would be most grateful. Ken

Hi, I am new, I am looking for the same manual :D

Maybe sending PDF......paying it?

Riccardo

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