New member 79 XS400! HELP!

[domc]

Hello all...

First off, I'd like to say thanks for any input I receive...and I do mean ANY! I bought my bike about eight months ago with plans of getting it running and doing a café/brat build. So far, I've accomplished about 95% of it, and I can't wait for the day I can really get out there and enjoy it. I completely stripped the bike down, pulled the harness and engine, did some fab work to the frame, and refinished things how I saw fit. End result is a bike I am becoming more and more proud of every time I show it off.

There is one thing that has been kicking my ass since getting it running, and that is the oh-so-rare BS34's that I am ready to burn the bike to the ground because of. I originally had sent them to a local shop (who is now out of business), to have them gone through/cleaned. $180 later, I got back carbs which were no better than when I sent them in. Fortunately, I have another friend who has a shop, and I sent the entire bike over to him. Come to find out, the carbs needed to be overhauled, and again I opened my wallet and bought two master rebuild kits (Yamaha NOS) to the tune of another $150. Now I have clean, overhauled carbs and the bike drops the right cylinder at about 3500rpm. I pulled the spark plug, and it reeks of fuel. I have tried adjusting the mix screw on top of the right carb and it doesn't seem to change anything. Yes, it has pod filters and aftermarket bullet-style mufflers. I can't see jetting being an issue because it is running rich. This is super annoying because the bike kicks right over, idles beautiful, and revs freely in neutral. I replaced the coils thinking they may be the problem, but the conditions haven't changed at all. I am at wits end with this thing instead of happily cruising around on it...again, ANY input is appreciated and thanks in advance!

 

[BBS360]

I'm no guru, but...

I can't see jetting being an issue because it is running rich.

I believe the rule of thumb is if it takes more than 4 turns on the mix screw to fix things, change the jet.
Did either of the shops that worked on the carbs change the jetting to account for the changes to the intake?

There are some good guides on carb jetting on the forum.

 

[xschris]

If you are running emgo pods directly on the carbs, those type block the vent holes in the front of them. Those are the worst filters made. Post some pics of your setup and also confirm the jet sizes you are using.

 

[domc]

If you are running emgo pods directly on the carbs, those type block the vent holes in the front of them. Those are the worst filters made. Post some pics of your setup and also confirm the jet sizes you are using.

I am using the Emgo pods. Is there anything I can do with those besides toss them? I believe the jets are stock, but the shop had drilled them out. I'll check that with him and keep you posted.

 

[rshutchinson]

I would never drill jets unless in an absolute pinch for whatever reason. You'll never truly know what size they are and for $6/pair it's just not worth it.

I could be wrong but I believe the 78-79 carbs used smaller jets from the factory than the 80-81 but a +2 main and +1 pilot is usually where most end up when using pods and shorty mufflers. I ended up with 145 mains and 42.5 pilots and many others did as well (maybe a slightly smaller or bigger main after testing). Someone else can say for sure on whether those bikes used smaller jets.

You can dremel the out the part that is blocking the jets, I think there was a few threads somewhere that show it, I'll have a look.

Or you can just buy new good ones that don't have that problem like Mikes XS, K&N or UNI foam pods.

 

[domc]

I would never drill jets unless in an absolute pinch for whatever reason. You'll never truly know what size they are and for $6/pair it's just not worth it.

I could be wrong but I believe the 78-79 carbs used smaller jets from the factory than the 80-81 but a +2 main and +1 pilot is usually where most end up when using pods and shorty mufflers. I ended up with 145 mains and 42.5 pilots and many others did as well (maybe a slightly smaller or bigger main after testing). Someone else can say for sure on whether those bikes used smaller jets.

You can dremel the out the part that is blocking the jets, I think there was a few threads somewhere that show it, I'll have a look.

Or you can just buy new good ones that don't have that problem like Mikes XS, K&N or UNI foam pods.

Awesome...thanks for the reply. I'm at work, but hopefully tonight I can get some more answers!

 

[ensoroni]

get rid of the egos. mikesxs.com has a set of s400/360 pods that will not block the passages. It cleared up a lot of my issues when I had the s34's on my 360.