Problem at starting

[oli36]

Hi guys,

im new here. I just bought a xs 400SH 1981 last week !

Today, when I tryed to start the bike is didnt started and i saw smoke coming out of that hole ( You can see in the picture). The bike didnt start. The hole is located right under the connection of the two carbs *

I dont know if you guys can help me out with this problem
Sorry im from quebec so im not that good in english.

Thanks for your help !

 

[16VGTIDave]

There should be a rubber hose that connects that fitting to the crankcase vent tube that appears to be right behind it in your picture. Make sure everything is very clean as you don't want dirt getting into your carbs or engine.

There are plenty of threads here on this, but for a cold start you should pull the choke knob out all the way and NOT touch the throttle. Once the bike is running, you can push the choke in to the 1/2 position and let is warm up for a minute as you get your helmet and gloves on. By this time you should be able to ride gently away and once underway push the choke in all the way.

 

[oli36]

Thanks a lot 16VGTIDave for the answer !

And is it possible that the hose that you are talking about is just behind that hole in the picture ? Because the hose right behind the hole is connected to the crankcase

 

[arfstrom]

Yes, I see the squeeze clamp on the bottom, and the top should be on that nipple. (with a second squeeze clamp, like the bottom.

 

[oli36]

Allright ! Thank you guys i just realized my mistake !

But now a second problem occured. After plugging that hose in te right spot i tried to start the bike and it didnt and there was smoke coming out of the pods air filter ? Ive read the same issues on other topics. I know that i need to adjust the vavle but is this could cause the bike to not start ?

 

[16VGTIDave]

If the valves are so tight that you can't get the bike to start, then yes! When you try to start the bike, does the engine sound/feel like it has compression? Or is it just spinning over very quick?

It is easy enough to adjust the valves on the SOHC engine that I wouldn't put it off. You may have to replace the sparkplugs if the engine has been flooded. At least clean them.

 

[oli36]

If the valves are so tight that you can't get the bike to start, then yes! When you try to start the bike, does the engine sound/feel like it has compression? Or is it just spinning over very quick?

It is easy enough to adjust the valves on the SOHC engine that I wouldn't put it off. You may have to replace the sparkplugs if the engine has been flooded. At least clean them.

Thanks again Dave, the bike has compression. In fact, it starts on full chocke, put i need to pull the throttle a little to help it. And once it's started, i got to pull the throttle to keep it alive.

Do you think this coul be caused by a problem with the carbs ? Cause there's pod filters on the bike but i dont think the carbs has been jetted for this. If i put the stock air filter back on it, would this possibly solve the problem ?

 

[oli36]

So there's the problem. At 0.44 you can hear the valves clacking and you can also see in this video that i need to pull the gas to keep the bike running. So do you guys have any ideas of where's the problem from ?

because, the past last week the bike what starting at the first try and was running well ?

 

[oli36]

I juste realized that all of my problem started when i let the petcock valve on PRI for a night ( I forgot to put it back on fuel and it stayed that way for a night or 2 )

Is my problem to start the bike could come from that ? If yes, what should i do ?

 

[brockd]

I'm certainly no genius (yet) but it sounds like you have the same problem I had last week. I didn't realize my petcock was in need of fixing so I had a constant fuel flow into my carbs, causing them to overfill and spill out into the engine. Only figured this out when I drained out the oil - which came out waaaaay too runny because it was thinned with fuel - and could smell/see the gas.
Drain your oil, fill it back up, and try again! And don't forget your petcock.

 

[oli36]

I'm certainly no genius (yet) but it sounds like you have the same problem I had last week. I didn't realize my petcock was in need of fixing so I had a constant fuel flow into my carbs, causing them to overfill and spill out into the engine. Only figured this out when I drained out the oil - which came out waaaaay too runny because it was thinned with fuel - and could smell/see the gas.
Drain your oil, fill it back up, and try again! And don't forget your petcock.

Ok tanks ! Do i néed to replace anything on thé petcock ?
I"ll drain my oil ans make sure to not do that again.

 

[arfstrom]

The trick with the petcock, is you should be able to unplug the bottom of fuel tank, with the petcock in any position but pri, and nothing but a drip will fall out. If you find it is draining on you, then you could consider a rebuild the gaskets. for about 15 usd.

http://xjbikes.com/forums/threads/rebuilding-the-yamaha-vacuum-fuel-valve-w-pics.25058/

http://www.amazon.com/Outlaw-Racing...&qid=1430525150&sr=8-1&keywords=xs400+petcock

1980-1981 Yamaha Special XS400 SG/SH K&L Fuel Petcock Repair Kit #18-2699 (ebay for 30) I did K&L

Mental note, The manufacture made this for others, Good luck (so look things up by the name on the product, is how I found this site.

 

[oli36]

The trick with the petcock, is you should be able to unplug the bottom of fuel tank, with the petcock in any position but pri, and nothing but a drip will fall out. If you find it is draining on you, then you could consider a rebuild the gaskets. for about 15 usd.

http://xjbikes.com/forums/threads/rebuilding-the-yamaha-vacuum-fuel-valve-w-pics.25058/

http://www.amazon.com/Outlaw-Racing...&qid=1430525150&sr=8-1&keywords=xs400+petcock

1980-1981 Yamaha Special XS400 SG/SH K&L Fuel Petcock Repair Kit #18-2699 (ebay for 30) I did K&L

Mental note, The manufacture made this for others, Good luck (so look things up by the name on the product, is how I found this site.

Allright then ! I think the petcock is OK since i removed the tank today and let in on fuel and nothing came out of the hose ( a little drop)