My new XS400 special II


XS400 Enthusiast
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Herefordshire, UK
Howdy to all,
I'm an XS400 noob, only collected her today ... she's pretty but needs a bit of tidying up and small jobs doing. I had her out for a quick spin and I'm actually really impressed by her handling and responsiveness

She's a numbers matching '80 4R5 (Special II)with about 12,000 on the clock and she's running really nicely. I can't wait to do a full tune up and have a decent ride ... I think she'll be a real stunner, gotta love that metallic blue ! ...

This forum is a really great resource ... I've already downloaded the Haynes and factory manuals. I'm sure I'll have a boatload of stupid questions as they arise.

Welcome to the forum. The bike is actually a 81 model. Nice find looks in good shape.
Thanks ... she's in pretty good condition, a previous owners done some odd mods though. The seat is now bolted on and the lock unit removed, no idea why. I think she's gorgeous anyway

She's registered as a '81 ...
Had a few hours to tinker on the XS today ... changed the oil, checked through a few bits and pieces, ordered some parts then I took her out for a ride ... boy was I surprised, I'd found the buckhorns a bit awkward around the yard but they are lovely on the road. She feels light but solid and nicely planted on the road, she's got relaxed handling in the corners but she's no slouch ... had her up to 70 in 5th on the little backroads until the bumps and my nerve forced me to ease off ... :devilish:
Never got to try 6th as I was only on backroads and twisties, she's got plenty of get up and go all the way up through the box. I feel 4th is really nice and wide and I could chug into slow corners and still pull away nicely even without downshifting ... over all a very nice ride and definitely better than I'm used to.

More tinkering today, I've identified a few niggles to fix.
1. Brake lights, the front switch is pretty worn out causing an intermittent fault )
2. Fuse box is heating up the main fuse to the point of melting

I've ordered a new front switch and a 4 way blade fuse box to replace the old one. So I'll get started on replacing that tomorrow. I'll solder the connectors for extra security.
In the mean time I've taken the carbs off, dismantled and cleaned them. They are in fairly good condition and she's running well so I'm not going to retune them (yet). I've reset the floats though as they seemed well out of adjustment.

I'm amazed the previous owner hasnt fitted an in line filter so that's another job worth doing (bizarre as the clearly cared enough to fit a secondary tap on the fuel line)
Re: the fuel system.

The tank interior is spotless, so that's a plus, the previous owner obviously replaced the old petcock with a new vacuum type petcock (similar to the original) but it's clear he either found it didn't work or didn't trust it as he's fitted a secondary inline tap. This sounds ok but I'm pretty sure the original worked fine but as he reused the original vacuum hose he experienced problems ... it's got a hole in it :laugh: ... it's always funny how people spend time and money but cheap out on stuff that can ruin a project ;)

So I've replaced that hose, it'll be interesting to see if it fixes the petcock.
Thanks XSCHRIS, done :) ... I went with the 26mm as advised on here for the brass floats. Once they're back on I'll check the actual bowl fill level.

One thing I'm unsure of, my bike has replacement carb boots with the vacuum ports on each side ... is there any benefit to creating a Y junction to the petcock using both ports instead of just the left side?

Easily done ... not sure if there's any point ? ... I'd appreciate any opinions :umm:

Today I replaced the fuse box, replaced the vacuum hose, added an in-line fuel filter, put the carbs back on and fitted a new throttle cable.

Once I opened the fuel taps and fed her a little extra fuel through the intakes she fired up nicely. Warmed up well and settled to an idle of about 1400/1500rpm ... since cleaning the carb and fitting the new throttle cable she's even more responsive. Really happy with the result of some time well spent.

I've still got a little bit of work to do to get her up to scratch. I really want to sort out the rear light cluster and brake light. It's been rewired (badly) in the past and I know I can do a whole lot better ... :)
Thanks :) ... I love her so far ... just getting it all set up nicely.

Spent ages getting the clutch set up to perfection today, went for a ride and broke the clutch cable :laugh:

Bump started her and drove home very cautiously, soldered it but I've ordered a new one :thumbsup:

Can't wait for a nice warm day !!!
Looks like you are off to a great start Mac. That blue looks really great! Those carbs looked pretty clean, a hell of a lot better looking inside then when I opened mine up! Yech! Plus I had to use single strands of copper wire to chase all the jet holes/orifices and passage ways before I could get any engine speed changes out of my idle jet screws.
Thanks Tstidham:) ... I think she's beautiful.

Looking at her history I reckon she was dug out of a barn in 2014 with about 4000 miles on the clock and has been kept on the road since and had another 8000 miles put on her. She's had a recent carb rebuild kit, but I didn't trust it ... carbs were pretty clean but definitely not spotless.

I'm pretty happy with how she runs and she really rides well with very snappy acceleration. However there are a few things I'd like to adjust ... Throttle is hard to regulate between 1800 and 3500rpm ... tends to just ramp up from 1800 straight to 3500 its hard to control smoothly. I've still not synced the carbs and I'm sure they've got uneven main jet sizes...

On the plus side, I think I've nailed the clutch adjustment. She's now much more progressive...
Another constructive day ...

Went for a ride ... really enjoyed it :)

She really rides so well and accelerates brilliantly, however, I still feel the carb issue is letting down her slow speed maneuverability. No point is syncing the carbs further or experimenting with needle positions until I get the main jets sorted (they are definitely different sizes) ... My gameplan is to start off with 135 main jets and balance them, then if I'm still having issues I'll work with needle positions. The idle circuit seems perfect, she likes 1 click of choke to start when it's really cold but that can be switched off within a minute and she'll settle down to a cold idle at about 1400rpm and when good and warm (20 minutes or so) she'll settle to a steady 1200rpm ... the issue hits on switching to the main jets.

I took the afternoon to adjust the TLS front brake... I'll be honest, I didn't even look at the manual :unsure:, I just used my normal technique of adjusting primary and secondary arms and it's worked a treat ... I actually dialled the brakes back a bit as they were a bit sharp :bike:

While they were off I polished the front hub (doesn't show in the pic) and cleaned and greased everything. Then I repainted the front Yamaha decal, as the missing black background was really annoying me.
135 is stock for your bike. If everything else is stock those should work. A proper carb sync with a manometer is a must for a good running bike.
Thanks XSCHRIS :) ... 135 was what I had thought too. She's got standard air filters and I want her running stock. Totally agree about syncing the carbs ... I'm interested to see how the 135 jets and manometer syncing affects performance as she's already got fantastic power.
Only had a couple of hours today ... I removed the gauges for refinishing/cleaning and I replaced the gauge bulbs ... they are wedge type bulbs and I happened to have some LED ones from my old Chevy truck dash ... they fit and work perfectly. I also dropped my forks in the triple tree as they had been set 1" higher than stock.

I've started repainting the gauge housings and I've got to replace the rubber grommets ... I will admit that the bike looks way better (IMHO) without those massive gauges.
Thanks buddy ... she'll get there :bike:

I'm waiting for the carb jets, got the carb sync tubes all set up but I'm not free to work on her until the weekend ...