1978 XS400-2E

[nico]

Hey all,
I just bought this bike and plan on restoring/cafeing/bratting it. Just overall getting it running excellent and then make it look good. Just wanted to introduce myself as I am sure I will be on here quite often asking for advice and help. So far I have replaced the spark plugs because it wouldn't start two days after I brought it home even though I drove it an hour to bring it here.

I have new mufflers and pod filters on the way as the current pipes are rusted thru in a few spots.
Nick

 

[Martis]

Welcome to the forum

 

[xschris]

Welcome! Any pics to share?

 

[chkm8]

if there are no pics, it must not exist!

 

[nico]

I apologize for the double thread and for the no pics. Should be quickly amended. In other news, I have replacements on the way from Dime City Cycles : http://www.dimecitycycles.com/vinta...parts-24-inch-megaphone-muffler-80-84013.html And I ordered some pod filters as I think those just look pretty darn sweet.

I apologize if this has been asked/answered, I did search but didnt find the answer. I am curious on how rejetting works. It allows more or less gas to flow into the carb with the air to mix properly, correct? So if I am putting clean smaller filters on, will this allow more air therefore I need more gas, therefore... larger? jets? Which brings me to my next question. Is it something I "adjust" or is it a part that is replaced?

 

[bcware]

Some adjustment can be made, but you will need larger pilot and main jets for exhaust and pod filters.

 

[nico]

Ok, I will order them then, oh and also my petcock does not have an off just RES, ON and PRI and the guy that had it before me put in a filter and an on/off valve. Could I replace the petcock with one that has an OFF or will that matter? I plan on removing the on/off because it is not stock and cleaning out the fuel lines tomorrow but I don't know if leaving the fuel on will hurt anything, it didnt on my last bike but it wasn't this old. And what does the PRI stands for? Primary fuel? Prime?

and...until I can take some more shots, a picture from when I first brought it home:

and sorry if I seem stupid to all this...I am!

 

[bcware]

PRI is prime. It will allow fuel to freely flow even without vacuum from the engine (when the engine is off).

The manual shut-off may be a band-aid fix for a leaking petcock.

If your petcock is not leaking leaving it "on" is fine; it operates via vacuum from the engine in the "on" position. Fuel will not flow while the engine is off in this position unless your petcock is leaking.

 

[nico]

That is good to know. I imagine that was the fix because it smells of gas and had a lot of gunk under it and around the engine. I am going to give the lines a thorough cleaning and maybe the petcock will just need cleaning/new seals? hopefully. I'll try to remember to take some pics during the process and keep posting cause I know we all like pictures

Thanks for the quick responses. Nice to know there are helpful people on here

 

[bcware]

Consider replacing the petcock for a few dollars more than replacement gaskets/seals; myself and a few others went with a universal manual one from partsnmore and we have had great success. Install an in-line fuel filter as well if you don't already have one.

 

[nico]

Which one did you go with? And on the jets what size would you recommend?

 

[bcware]

For pods and exhaust I would buy 45 and 47 pilot jets and 145 through 155 mains. To save myself time I ended up ordering all the main jets available from 137.5 (stock for me) to 160, but it is unlikely you'll need more than a 45 or 47 pilot. Shipping is relatively expensive for such items, but the jets aren't too bad. I didn't want to find out I was 1 size small and have to wait another week for a new set...

 

[nico]

Also what kind of petcock did you get? Will any universal work?

 

[bcware]

mikesxs for jets (large round type); partsnmore for the petcock.

Info with regard to my 1978:

http://www.xs400.com/forum/showthread.php?t=4844&highlight=petcock+partsnmore&page=6

 

[nico]

I need gaskets for my carbs right? Should i get the kit? There are just gaskets and then the kits. And is the float bowl gasket the only one? Sorry for the noob questions.

http://www.partsnmore.com/parts/yamaha/xs400/?filters[fitting]=custom#product-48-1407

 

[nico]

I ended up getting the petcock repair kit and the carb kit with the gasket. So now I just ...wait. I got the bike tore down today. Tank, seat, carbs, air filters, pipes and brake and shifter off. Couldn't do much besides clean so thats what I did all day.

during taking everything off:

with dirt/gunk:

without:

end of the day:

 

[bcware]

Yikes; what's up with those carb boots? Good job on the cleaning by the way!

 

[JARichmond]

Don't forget to clean off the seats in your petcock with scotchbrite, or it will never seal properly. Also, sand all mating surfaces with 600# wet/dry sandpaper. I have a write up done recently for an OEM petcock rebuild that you can follow. I have the same one as you do lying around somewhere, and they are almost identical in operation.

 

[nico]

Bcware: the boots are removed and I have the openings into the motor covered. What you are seeing is black duct tape.

Today I got the carbs tore down and cleaned thoroughly. Now waiting on the new jets and gaskets to get in so I can get this all back together!

 

[nico]

I posted this in another thread but I'll try it again as I'm needing to get some ordered.

The Shinko 712s don't look too bad but are tubeless. The Kenda Challengers don't have correct size in the rear tire but have it in the front tire. Will it be ok running a front tire on the rear? The tread looks to be the same on both.

Also, my bike has a 100/90/18 on the front instead of the stock 90/90/18. I didn't notice til I looked at the size, can I just keep using the 100? No clearance issues i've noticed nor handling.

So, if I ordered the Challengers, i'd be getting two 100/90/18 front tires. Does this sound ok?