Topic: Carb pic - what am I missing here?

[Rddmm2]

I was cleaning carbs on my K5 cb750 and I noticed the float bowl is missing the brass pinhole fitting in the bottom right of float bowl on #4? Please see right side of pic.  Is this a big problem? Carbs 1 to 3 had one brass pinhole fitting on each side and I'm not sure what purpose these serve.
( I know that the idle jet and float needle are missing in pic - They were taken out for cleaning when I took the pic.)

NOTE: I have not been able to get the bike to start now for 2 weeks and wondering if this would be a reason. Last time it was running I had to keep blipping throttle at the light to keep it going until it finally quit on me and hasn't started since.   
Thanks

[Brown Bomber]

Nothing missing there, if you look at the outside of the carb body, you'll see that channel is not machined because it would be another vent hole if it where connected to another carb on that side.

[754]

Need more info, sounds like your slow jet.. where in the pic do you mean?

 If it fell out, should have been in the float bowl..where did you empty that??

[Rddmm2]

I'm only wondering about the brass vent hole on far right side which is empty. ( I have the slow jet and float needle)
Nothing else was in float bowl and clearly someone else had cleaned carbs not too long ago.  Bowls 1 to 3 had a brass vent hole on both sides but #4 only has the vent hole on left side -that's what I'm wondering about.
Thanks

[Spanner 1]

Where's your slow jet !!!!... the center jet = main jet?

[Spanner 1]

Duh!!.( about the slow jet ).. yes, the #1 and #4 carb don't have the second vent 'port' as 2 and 3 vent both to #1 and #4....

[Johnie]

Brown bomber and Spanner have it correct. 1 & 4 carb do not have the brass fitting on one side. Can you get us some more info on what you did to the bike? Did you do a bench sync on the carbs? Did you check the spark and fuel flow?

[Rddmm2]

I spent winter getting it ready to be certified and on the road, - the frustrating thing is that it was running before I started and now that its insured and licensed and on the road I can't get it to start. I'm a bit discouraged.

I/m not the most accomplished backyard mechanic. The stuff I did was electrical, including fixing signals, installing a clutch switch and safety starter switch and nos handlebar switches, since I wanted it to be original - it started a few times since I did the electrical stuff - also new tires, rear brakes, steering bearing, rebuilt starter, replaced a muffler, patched another and other odds and ends all with the help of the sohc4 site. Hasn't run long enough to know if the muffler patch is going to hold up   
I cleaned inside of tank using electrolysis and I thought this was the root of the problem since draining the floats would show some sediment and I never sealed the inside of the tank. Also, this is when it started running rough after about 7 miles and then finally quit. It hasn't started since.  This is when I had to blip throttle when idling to keep it going.  So i pulled the carbs thinking some crud had worked its way into the carbs but I did not see any obvious signs of dirt plugging holes or needles - used carb cleaner and compressed air - carbs were kinda clean without any varnish whatsoever so someone must have done this not too long ago.  I did not adjust floats. - oil, filter and new plugs. - actually i thought i smelled a bit of gas in crankcase so I put in fresh oil after cleaning carbs.
re Fuel Flow: cleaned up petcock  - the float bowls fill up quickly if thats any indicator. I did not sync carbs but that would be next if I could get it to run. 
re Spark - all I have done is test plugs against side of engine and some spark, although can't say for sure how strong.
that's about where I am.

 
 

[Johnie]

OK, that was a good synopsis of what you did so far. For being a backyard mechanic you are doing good. You learned a lot by doing all that yourself. Now you start the process of elimination to locate the problem. When you did the carbs it appears you did take them off the bike. To bad you did not bench sync them, but if they ran before and you did not change the slide height they should run again. Also to bad you did not check the float height. I hate to say this, but you might want to start by taking the carbs back off to check the float height and then do a bench sync. That is a starting point. If it does not start after that then you have at least eliminated 2 items and we move on to the next. Have you taken a plug out to see if the plug is wet with fuel? And you can see light through the slow jets when you take them out? Have you thought about putting in some in-line fuel filters just to rule out the clean tank that just might have some crud in there. Take a look at the pic below. I found this after I cleaned my carbs. The previous owner was running it with this stuff in his tank. You could look in the tank and it looked fine. But when I dumped it out look at what I found.

[Rddmm2]

Yeah, i know i should have checked float levels - damn - not sure why I didn't - using a clear hose to check float levels while the carbs are held in position in a bench vise good enough? or do I need a proper gauge. 
- what do you mean by change the slide height?
i've synced carbs with a Morgan Carb tuner before but not clear on what a bench sync entails
i did install an in line filter
definately saw light through each slow jet and ran compressed air through each - #2,3, and 4 had a small screen filter over slow jet but #1 did not.
After a few kicks I pulled #4 plug and it seemed wet.
Thanks

[medic09]

If you synched with a Carbtune on the running bike, then you're already past the bench synch.  The bench synch is done with the carb rack off (on the bench), and you use it to get the slides pretty darn close to each other's height.  But if you synch a running bike with a synch tool like the Carbtune, you've covered it anyway.  If you adjusted the carbs at all during the synch, then you were adjusting slide height.

[Rddmm2]

Still won't kick let alone start.

Review:  Last time it ran very rough and had to blip throttle at red lights to keep it from stalling.  I got home and shut it down and it hasn't started since - not even a kick.

1. It could be something simple that I'm overlooking? - Clutch switch must be ok since the bike won't turn over unless clutch in - b) Neutral light is 'On' but could neutral switch still keep it from firing if it was faulty? not sure how that could be. c) it has a safety starter unit installed. d) Fuses are all good

2. Re: Ignition - Kill switch is ok since power from Blk/wh to ignition coils (+) is  'on'
ii. There is power on both Yellow and Blue (-) from ignition leading to points,  and power at end of blue and yellow at points plate. ( intermittent depending on which set of points is open or closed)
iii. Points must have been recently changed since they look new without pitting or burns.
iv. Clearly good spark on plugs 1 through 4 ( I set each plug across the engine and saw a strong spark on 1,4 and reasonably strong spark on 2,3 )
Open to any comment on whether it still could be a points issue. I do not have a MM.

3. Re Fuel Delivery - I was convinced this was the problem since it ran so rough and I recently cleaned tank and saw some small black deposits when I drained floats. 
i. Review: I pulled carbs and cleaned all jets and passages with carb cleaner and compressed air - the carbs/slow jet looked fine and saw daylight but I did it anyway - however, I did not adjust float heights.
ii. I recently backed air screws to 1 full turn out on each carb (360)- However, still will not kick. ( note: all 4 air screws were sitting at 1/2 turn out only...)
iii.  I recently checked float level while carbs on bike and fuel is about 1 cm down from top lip when i remove the float bowl with fuel still in it - no indication that float heights are drastically out of whack.
iv. Boot Clamps seem tight without any air leakage at engine but not sure how to test this if not running. 

SHould I try 'Quick start" through air box to see if I get a kick?
Any further comment would be great - very frustrating - I'm so close but obviously so far from taking it for my inaugural cruise

 

[csc]

+1 on trying the Quick Start  start fluid, use a good dose of it , if it starts and runs for afew secs you have elminated all the simple overlooked items{ kill switch , clutch switch , fuse etc}...  Then its on to checking the other, fuel delv & ignition..