Jets and Pilot need resized?

[ChazAWillis]

So my bike was in the garage for about a hear without starting up so I took the carbs out and cleaned them (soaked them in cleaner for 24hrs about 3 times and used compressed air in all of the passage ways).

I rebuild it this weekend and put all the original sizes in as the PO had a 125 instead of the 142.5 in the pilot screw. I know I am going to have to resize. But I am not sure what size to go to.

Currently the bike wont even Idle. It will stay running if choke is held or throttle is held. Air screw is at 3 out. As soon as you let off choke or throttle it dies instantly.

Has pods instead of box air filter. And there is another pod that comes from the right side of the engine and im not sure if it was originally like that or hooked to the box. It had aftermarket pipes on but I found and bought the original exhaust and put it on.

Now I am kind of stumped on what else to check. I replaced the vacuum line so there is nothing wrong with it. Intake boot has no cracks. Sprayed it and it didnt effect the rpm.

 

[XS NEWBIE]

I just did pods on my 79 and just got it running good.. via 150 main jet size.. all other jets are stock... and I think they are about 3 turns out.. and a lot of playing with the idle stop thinger. Also just set the timing and valves.

 

[Jeff0133]

I went with 145/45 jets, 2 1/2 turns out on the brat...starts right up, idles ok, hangs a little after revving.
Still needs a little tuning.
The pod on the right is used to cover the crankcase breather which used to be connected via a hose to the h-pipe.

 

[ChazAWillis]

Alright I know this is going to sound stupid but I think I know what I am doing wrong. The bike doesnt have a choke line anymore so I was pressing the rod over (which is open) and I thought I was choking it but when I let off it was closing (choking). Is that how it works? So somehow I'm going to have to find a way to keep it open if that is correct.

 

[xschris]

So you have a dohc bike? Post some pics as a sohc bike and dohc bike are jetted different.

 

[ChazAWillis]

Sorry I havent been home the past few days. The bike isnt at my house right now but I can get some pictures tomorrow. How can I tell if it is DOHC instead of SOHC?

I do have pics of the carbs though.

 

[SoraXS400]

Sorry I havent been home the past few days. The bike isnt at my house right now but I can get some pictures tomorrow. How can I tell if it is DOHC instead of SOHC?

I do have pics of the carbs though.
View attachment 28958 View attachment 28959

0. Bike identification *
Before anything, find out if you have a DOHC or SOHC model bike, as the bikes are very similar in many ways but have distinct differences when it comes to a number of jobs. Also, parts are usually not interchangeable so keep an eye on compatibility when you order anything.
If your bike says "Maxim", "Seca", "DOHC" or "YICS" anywhere, it's likely to be a DOHC bike. These are the later model XS400 (1982-1989), of which the Seca has 6 gears instead of 5. Both the Maxim and Seca have (unless limited due to local laws and regulations) slightly more hp than the earlier XS400's. If your bike does not have any of these marks, it's likely to be a SOHC (1975-1982). If it says "Special" anywhere, it's definitely a SOHC. Of course, there has been endless modding and chopping on a lot of these bikes, so if you really want to know for sure, post some pictures on the forum and we'll help you ID your bike.
Further info on the different models of XS400's can be found here

In the second quote (written by Willem) shows to tell the difference.

 

[ChazAWillis]

It is a Maxim and it says YICS on the left side on crankcase

 

[SoraXS400]

It is a Maxim and it says YICS on the left side on crankcase

You have a DOHC bike then. xschris can take it from here, as I'm not good with these bikes quite yet.

 

[xschris]

I don't own a dohc bike so what jets to use will have to be answered by someone that owns one but I can say you are missing the washers that go between the needle jets and the main jets.

 

[ChazAWillis]

Yea I got them out atm. Waiting for a few more parts on carbs before I assemble it completely. Jets are just sitting in there until I get the new ones.

And this is the choke thing im talking about.

When its in resting place the hole seems to be covered (I'm assuming this is choked):


But when I press it to the left it is opened:

 

[xschris]

Opened is enriched. These really don't have a "choke".

 

[ChazAWillis]

So if it is closed all the time it wont matter?

 

[xschris]

When it's closed the enriched circuit is off. Usually you do this after the bike is warm enough to ride.

 

[Jeff0133]

I went with 145/45 jets, 2 1/2 turns out on the brat...starts right up, idles ok, hangs a little after revving.
Still needs a little tuning.
The pod on the right is used to cover the crankcase breather which used to be connected via a hose to the h-pipe.

I have two dohcs and that is my setup you could also ask 16VGTIDAVE ...for his setup but I think it is about the same...

 

[ChazAWillis]

Thanks! Also does anyone know a good place to get intake boots at? Mine are fine atm but would like to have an extra set in case something happend. I have searched around a but but havent found any for the '83 XS400K.

 

[Jeff0133]

JBM industries...

 

[ChazAWillis]

Do you know if the 650 carbs are identicle to the xs400 on the bs34 carb model? I can find stuff that will fit the carb but not the engine side.

 

[Jeff0133]

Same bs-34 carb...But I would email them to be sure

 

[xschris]

The 80-82 sohc xs400 uses the same slide/diaphragm as the 80-84 xs650. The 82-84 dohc xs400 also uses them. There are other components in the carb that are NOT the same. Because they are bs34 don't everything will swap over. Remember that these bikes all have different fuel needs.