Topic: Carb/Airfilter and Ignition Wiring Questions

[wrndgls]

Hi newbie here,
Just got a 81, cb650 block from craigslist and bolted it to a table. Using it for a custom project but I wanted to get it running first. (Don't have a frame yet...) I got the headers on there and hooked up the carbs. I'm assuming compression and valves are fine for now because I don't have a comp tester and I don't want to take the head off just yet.

I retrofitted a set of carbs from an 83-85 with some hose and cleaned them up real nice, I have plenty of experience with the japanese carbs and plan on tuning them to the 81 block. My question is, don't the cv carbs need a good seal to run at all? The CV slides/needles won't move (engine won;t run right) if theres not an airbox/filter on the outside of the carbs right? (air filters are expensive and I don't wanna drop the 120 yet.) I like the look of 4 filters, but if someone can convince me that the stock airbox can perform the same I'm all ears. 

After the carbs and pipes were hooked up I started messing with the wiring. which I don't know much about. I found a good wiring diagram, along with the free manual online and got to work plugging stuff up. Today I was able to jump the starter motor off of my truck and hear it turn over (nothing is seized!!), but I could not get a spark from the coil. I don't have the right hand controls, so I shorted the connections in the wiring harness with a paperclip, connection black to black/white. This is what the killswitch does when it is in "run" correct? Why am I not seeing a spark when the engine turns over? Also to engage the starter I am shorting the big red on the starter relay to the starter + cable. Why can I not use the paperclip trick on the right hand control harness connecting the yellow/red to the black? This should do the same thing as a starter button but nothing happens. Have tried both "run" and "start" paperclips at the same time, still nothing.
I have ordered right hand controls (killswitch) and they are on the way, but according to what I tried today I am not confident it will help... I think something else is up. What are some common problems/mistakes that I could be making?

Sorry for the overload just wanted to give you the details.

[74750k4]

For starters: (no pun intended)

1) Get a meter, DVM, or analog, and learn how to use it, so you can test, instead of guess. You will save yourself hours of "messing" around with your wiring.

2)Lose the paper clips, and buy some short test leads. They work better than paper clips, and since they usually come insulated on the alligator clips, they are safer. Plus the alligator clips are handy for other things.

Once you complete both of these initial steps, you will be telling us why, instead of asking us why.

[fdbrat]

Get it running stock so you know everything is right then mod it. I like pods too. But they need attention and time to get them right.
Also if you go to pods you will need to rejet the slow jets. Which is hard.

See the 650 has friction fit slow jets. They are easy enough to remove with a bit of twist and pull. But it's hardto find any one who carries them.

Tho I found some. Write a place called SCI (Sirius Consolidatd Inc). sci@siriusconinc.com

Ask them if they have part this part in stock. And if they don't ask when they might get another order in. Keep checking in with them. I think they get them made in Canada. And when they have them. Buy them fast. Cause they don't last long.

Subject: Friction fit jet / press in jet
Part No.
KHS-49A042

[Powderman]

The stock air box will not perform the same. It will hands down run better unless you spend considerable time tuning "pod filters" unless they are a quality brand like K&N. I know others who had said they have gotten pods to run good. That is subjective when judging performance by the seat of your pants. I have yet to see a single dyno report that shows the pods ran better than the stock air box. They look cool, but that's where the benefit ends.

[wrndgls]

haha well I don't any kind of filter yet since I am building from the block up. I will probably eventually use pods and tune the to them (seat of the pants style.) Once I get the spark issue figured out, can I hear it run without having a filter? My thinking is the cv carbs need a filter of some kind to generate a vaccum and open up the slider/needle jet.
Could a couple inches of manifold/runner between carb and filter make the pods perform more like the stock airbox?

[wrndgls]

747 thanks for the advice man. Used the #$%* out of the meter today, got a much better understanding of what I'm doing. and traced the problem to the neutral switch. Once I had a complete circuit I was able to turn it over and see all four plugs fire today.
I wrestled with some ngk plugs I got from advanced (idk if you guys know the ones but they are wider than the champion plugs so you can't fit a socket down in there to thread the things in!)

Tonight me and a buddy took off the rocker arm assembly and got the ngk plugs snugged down. I filled up a ghetto rigged tank and went to start it, but nothing we did would get it to fire. My thoughts are...

1) Carbs need some backpressure/ filters or an airbox to suck the right amount of fuel. (after several attempts they were feeling pretty dry)
2) Leaky T joint in the middle isn't getting gas to the outside cylinders.
3) newer model carbs are too far off in jetting to supply enough fuel.



anyone have any insight on this CV carb stuff? I really don't wanna shell out for air filters but tomorrow is my last day to work on this thing before I leave town for the holidays and it would be great if I could start this bad boy and spend the break looking for a frame. thanks guys.

again sorry for the rambling but it helps to think outloud....thanks everyone for the input this is my first bike build so I will be needing all the help I can get!

[bjbuchanan]

CV use vacuum to move those slides, pods will make that considerably trickier. It isn't like the ealier style carbs that just flow less fuel because of less "pull" thru the carbs or side winds creating lean/confusion mix situations. This can be masked/overcome to an extent that streetability is acceptable, CV is harder

I would suggest some type of box with a calm air plenum, even if it is some kind of custom bread box thing. Individual filters will be a real headache and it isn't like jets are cheap. Sucks to drop 30$ every time to NOT be what you need.

[lucky]

Carbs come LAST, after all other issues are resolved.

[wrndgls]

This can be masked/overcome to an extent that streetability is acceptable, CV is harder

Can you elaborate?

Yeah I'm not really looking forward to jetting this thing, but I really don't want to run the stock airbox. Anyone know of any simplified custom intake solutions?