Compatible Parts for different xs400 models

[BCven]

Hey guys. I'm hoping to do some restoration of my 1982 xs400j this winter so I've been on the hunt for a parts bike to use as a source for some this and that. I have found a 1982 xs400sj heritage special in my price range, but I'm thinking that not many of the parts would actually fit. I know the first 3 letters of the vin is supposed to be the parts codes and these two are different (mine is 12R and the parts bike is 14V). Are any of the parts between these two bikes interchangeable??

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[xschris]

Sounds like you have a dohc bike. The 82 heritage was a sohc bike where none of the parts will work for your bike.

 

[willem]

look for a seca or maxim. That's a xs400r or xs400j, they can be recognized by the frame: the engine sits inside the frame on SOHC's (so there are frame pipes running in front and below the engine) whereas the DOHC's have the engine hanging from the frame (they are a 'stressed member' of the frame). The Seca looks quite different from your Maxim, but 99% of the parts will fit. They have the same frame, just different styling and the Seca has 6 gears instead of 5.

Good luck!

 

[BCven]

Oh, I see. That's quite an inherent difference! Thanks for the quick replies. Happy Friday.

 

[16VGTIDave]

The Seca looks quite different from your Maxim, but 99% of the parts will fit. They have the same frame, just different styling and the Seca has 6 gears instead of 5.

They have similar frames. There are differences, such as the pivot point for the rear brake lever is further back on a Seca. Many parts won't interchange between the Seca and Maxim.

 

[willem]

sorry listen to dave, not me

 

[BCven]

You guys are unbelievably helpful.

All my research tells me that a XS400K would have matching parts to my XS400J; both having the 12R parts code. Can anybody back me up on that?

Thanks in advance!

 

[Lou Ranger]

I think the only difference is model year. The 81/82 seems to be the 'J' and the 83 seems to be the 'K'. Mine is a 1984 and I always thought it was a "J".
But I don't think there are any changes over the run of Maxims exported to N.America.
Don't know if there were changes from '85 - '89 for the ones exported to Europe.

 

[BCven]

Thanks for the response! That is what I have come up with as well. I was just looking for some extra confirmation before I spend any money!!!

 

[Lou Ranger]

Other than the transmissions (5 & 6 spds respectively) the engines in the Seca and Maxima are identical so all those internal parts, plus the techniques & schedules for adjustments, maintenance, oil changes etc., are interchangeable.

 

[BCven]

I'm finding out that I'm pretty sure PO put a different tank on my bike. Any way to know what tank I have? I came to this conclusion after ordering parts according to my vin and them not fitting (petcock rebuild kit). I also decided the distance from petcock to carbs is weird and seems to short AND the actual way the tank sits on the frame works but doesn't secure as well as I think it should. Either way I can't get my petcock to work for me at all and I need to look into replacing but I have no idea what to look for since my tank doesn't seem to be for my model bike. Thanks in advance.

 

[xschris]

The pics of your bikes shows that you have a sohc xs400 tank on a dohc bike.

 

[Lou Ranger]

Chris would be right about your tank, I'm sure.
Below is a pic of what a stock Maxim 400 tank looks like.

Also below are a few pics of various Yamaha petcocks. They are NOT all the same. My Maxim's sequence is different from my old sr 250's and the 650 which I rode this summer, so maybe it's just a matter of picking the right one.
Perhaps your PO put the Maxim petcock on the sohc tank and it doesn't work right.

The Maxim has OFF at the 9:00 position, and RES at 12:00 - whereas the 650 had RES at 9:00.

 

[BCven]

Mine is like the third picture you have there from the xs650. What do you guys think I should do? I'll shop for a tank but I can't spend a fortune either. I might start with a rebuild kit for a xs650 petcock to see if I can get my fuel flowing correctly... Although I still don't like the short distance from cock to carb. I'm open for suggestions though for what to do next. I'll have to bounce this thread over to carb talk when I finally get my fuel issues worked out!!

 

[Lou Ranger]

If you want to restore the bike into an all "original" Maxim, then buying a new tank and the plastic side pieces etc. will be necessary. But if you just want to enjoy riding a good, reliable bike, why not simply improve the way the tank is attached if you don't think it has been done properly?
Judging by the views in your photo album, the bike and the existing tank look really good.

As to the short distance between the petcock and the carbs, could you post a picture of the left side of your bike? On the xj650, for example, the distance is very short yet works just fine. If it's even closer than that on yours, could you not simply loop a long fuel line around?

 

[BCven]

I'm not going for the all original look necessarily, but I am interested in having the right tank. I happened to find an affordable OEM tank on ebay so I went for it. The existing tank looks good on the bike for sure, but I'd like to have the xs400j tank either way. I'm hoping I can sell my existing tank and come out about even anyways (and give a needy xs400 a good tank!). My problem with the short distance is that I have a filter and when I couldn't get the petcock to function properly I installed an inline fuel valve... and that made things pretty tight! I don't have a picture handy, but one section my new hose is about 75% kinked after the valve and I don't like it. Either way, I'm excited about the new tank and petcock. while I wait I'm going to clean my carbs real good again (I was having some carb issues before the fuel issues). I just hate taking my carbs off and on. I feel like I have to cram them back in every time and the air box boots are starting to show the wear. Any suggestions? I know this post belongs elsewhere... and I'm sure this has been asked before, but I'm curious if there's a trick out there that I haven't tried.

Thanks everybody!

 

[Lou Ranger]

There is a dohc trick which allows one to tip the engine forward and down without detaching it. I don't remember if this is to facilitate valve adjustment or carb removal (or both).

You put a jack under the engine and then remove all of the mounting bolts except the bottom one. Then you can lower the jack and the engine will pivot down and forward. I hope it will help.

 

[willem]

I wouldn't pivot the engine, it's not really necessary I think. Also I don't have a jack so I wouldn't be able to actually. Sure the carbs are not the easiest to take off, but what I usually do is loosen the airbox inside the frame so you can slide it back an inch or two, bolt the intake boots onto the carbs and the cylinder first, and then stick the airbox back on the carbs and bolt it down again. It goes easier every time. As for the valve adjustment, you can manage fine without pivoting the engine as well.

 

[Lou Ranger]

I wouldn't pivot the engine ...

I wouldn't either - I'm sure I'd never be able to get it up afterwards .
Your patient method is likely the best bet, however, BCven did ask if there were any tricks he hadn't tried, and rotating one's engine is pretty tricky

 

[BCven]

Sounds a little more complicated than I'd like to mess with... although the idea of it sounds so simple and got me a little excited to try it for a minute.
I've loosened the air box and that only gives me like an inch... Maybe I missed a bolt or two that would free up some more space. I'm planning on diving back in this evening... maybe I'll find a magic button that moves everything out of the way and disassembles the carbs for me.