Problems Starting~Cleaned Carbs

[DaMax]

Hey eveyone this is actually my first post. I have recently cleaned the carbs(with the help of Sean) and decided to install the carbs this evening. Well I got hooked up with a quite unique problem....

For starters, the choke did not seem to work at all. When I would try to start the bike, I had to mostly play with the throttle to keep the thing running once I got it started. The bike only ran for 30 seconds and during that time I noticed that the diaphragm slide on carb #1 was not moving at all while all the other slides were. She died when I stopped playing with the throttle. After she died I noticed smoke coming from the back of the engine where the exhaust hooks up and it smelled like burning oil. I tested how warm the engine was and cylinder number one( I think or which ever cylinder is under carb #1) seemed the warmest and the front cylinders were not warm at all even at the headers. I am really stumped and was wondering what you guys think.

Cheers

 

[bazwell]

Um.... Something is wrong!

First step from me would be turn the float bowl drain screws and make sure all the carby's have got fuel in them.

 

[DaMax]

Update....I finally had time to stop by the warehouse to see if she was getting fuel by unscrewing the fuel drain srews. Only carb #1 had fuel running out out of all four. I checked the rubber T fitting that connects carbs 3 & 4 and tested if fuel was coming out of the brass T fitting and there was. Are the carbs at fault? Do I need to pull them apart again?
:ummm:

 

[ninjaneer]

was it working before the rebuild? if so, when you reassembled the carb rack, did you put the synch springs in correctly? when you were rebuilding them did you mess with the idle screw? how 'bout float level? how 'bout the afr screws, what are they set at. the chokes valves on each carb come in and out all together?

what i'm getting at i guess, is 1) make sure your choke plungers are working, 2) make sure your afr screws are set accordingly, 3) make sure your floats are at spec, 4) you more than likely will have to do a initial synch on the carbs just to get the rack firing., 5) make sure the idle screw is set to where it belongs.

those are my initial thoughts based on my experience of rebuilding my carbs only once. i make no claim that my diagnosis skills will directly help you zero in on a resolution, but perhaps your response or my questions will spark the proper debug path.

 

[naughtyG]

Two things:
- are you trying to run it without its airbox? (won't run well if at all that way)
- how far out of sync are the carbs? You should try to get them as close as poss on the bench, or on the bike have a look at how together (or not) they open as you first twist the throttle and try to get them close.
Of course it'll still need syncing once it runs.

 

[DaMax]

Alright I have pinpointed it down to the floats. I have the A/F screws out 2.5 turns and so fourth. The bike ran fine before the winter season, but those emulsifier tubes were pretty dirty. So I pulled the carbs off and tried to spray a little starter fluid in the brass elbows where the fuel comes in and something is plugged up in their or something so I am going to take the carbs home, take them apart for the third time and measure my floats and find out what is plugging them up.

Thanks again for all your helpunk:, I?ll keep you guys updated!

Cheers

 

[[email protected]]

Typically the pilot jets, in the jet block, in the float bowl, get plugged.

 

[DaMax]

Took the carbs apart again and noticed that the float needle was blocking fuel from getting in. Does this mean when I purchased the carb kit from ebay I got a cheap part? Is this normal?
:ummm:

 

[06VMAXIMUS]

Float needle should block fuel from getting in....when the float is pressing on it. Verify that the needles move freely in the seat, and check float heights for correct setting. Carb parts other than Yamaha OEM have been said to be a bad choice.

 

[one2dmax]

Depends on which carb kit you got.
Here's pictures - Note the bad part vs the good part
http://www.facebook.com/media/set/?set=a.282802178678.144229.282702488678&type=1

Sean

 

[bazwell]

Took the carbs apart again and noticed that the float needle was blocking fuel from getting in. Does this mean when I purchased the carb kit from ebay I got a cheap part? Is this normal?
:ummm:

If you are certain that fuel isn't getting into the carbs, then that would be a fault for sure!

On the bench :
- With the carb upside down and the float fitted the needle should block the fuel.
- With the carb right side up and the float (and the wire clip) fitted the needle should not block the fuel.

My guess is either the wire clip isn't pulling the needle down, or the needle isn't moving free.

If the new needles are sticking, get your old needles and look at the pointy black bit with a magnifying glass. You need new ones if the black bit isn't rubbery any more, or if there is a mark on it where it seals into the little hole to block the fuel.

 

[dannymax]

Took the carbs apart again and noticed that the float needle was blocking fuel from getting in. Does this mean when I purchased the carb kit from ebay I got a cheap part? Is this normal?
:ummm:

What kit did you get...who is the manufacturer or what is the kit part #?

Is it by any chance #48-1996? :ummm:

 

[DaMax]

No the man. # was 18-2879. But anyway got the carbs hooked up and got fuel in all bowls now. But that rear left cylinder is still smokin. I might hookup the air box then vac. synch them and see what happens. She wasn't smokin like that before I put here away.

 

[dannymax]

Could very well be sync.

 

[DaMax]

Alright I pinpointed out where the oil is coming from and there seems to be residue on the bolt of the clamp where you connect the rear exhaust to the engine on the left side. Hope this isn't serious. One thing to mention is that I do not have the air box on yet.