Topic: Cranks but not starting, I really need some help.

[vonvendetta]

I am a complete noob, this is the first time I attempted anything like this. I want to get this going before I lose interest or give up.

I bought a cb500 '72 about 3 months ago now and it wasn't running. It actually sat since '95 in a garage. The wiring was in rough shape and the gas tank along with carbs needed a good clean. So far I cleaned the carbs, rewired everything but the regulator and rectifier and ran new fuel lines along with some cosmetic work.


When I got it. Didn't try to actually start it because I was worried about the old fuel.


As she stands today.

So I bought the small lines that come out of the carbs on the bottom, think they are for vacuum and then I ran two new lines from the petcock to the carbs between 1 and 4. Do I need to attach a hose to the top engine cover and what else am I missing?
Bought 4 new plugs and the spark seems to work well. I might have the coils backwards or something? I did however take all the carbs apart, soak them, replace all the seals, and needles.
 

[dave500]

those four lines are over flow lines,attach a hose to the rocker breather long enough to reach down to the rear bottom of the engine and leave it open,use two throttle cables,dont only use one,it wont start with the throttles just sitting closed youll have to open them slightly,,they wont just start on idle from cold.

[vonvendetta]

those four lines are over flow lines,attach a hose to the rocker breather long enough to reach down to the rear bottom of the engine and leave it open,use two throttle cables,dont only use one,it wont start with the throttles just sitting closed youll have to open them slightly,,they wont just start on idle from cold.

I held the throttle slightly open while pressing the start button. I could hear it sucking in air and the starter cranking.
I know it needs spark, air and fuel. It is getting spark and I hear it sucking air, not enough spark? I am guessing vacuum or fuel might be the problem? Are there any vacuum lines and is there any way I can check to see if the carbs are getting fuel? I imagine I could just suck on one of the over flow lines and hope to taste some gas.

[Vinhead1957]

You could lower one of the bowls and look or better yet pull a plug and smell it. Hope you used fresh fuel

[vonvendetta]

You could lower one of the bowls and look or better yet pull a plug and smell it. Hope you used fresh fuel

I did, made sure no old oil was left in the motor and replaced with new of course, new oil filter, new gas, new plugs, new fuel lines. I might try that. At least that way I can make sure it is getting fuel in.

[MoMo]

Did you take the carbs apart?  Were the emulsion tubes taken out?  All the Honda fours I have worked on that sat for a long time with gas had clogged emulsion tubes, your bike will not start if they are clogged...Larry

[vonvendetta]

Did you take the carbs apart?  Were the emulsion tubes taken out?  All the Honda fours I have worked on that sat for a long time with gas had clogged emulsion tubes, your bike will not start if they are clogged...Larry

I took out all the needles but emulsion tubes... I don't think I changed those. :\

[MoMo]

Did you take the carbs apart?  Were the emulsion tubes taken out?  All the Honda fours I have worked on that sat for a long time with gas had clogged emulsion tubes, your bike will not start if they are clogged...Larry

I took out all the needles but emulsion tubes... I don't think I changed those. :\

They do not usually need to be changed just cleaned along with the chamber they sit it. Requires removal of the slides and needles then using a soft rod to tap the emulsion tubes up and out.  Part 3 on this microfiche  http://www.mrcycles.com/fiche_section_detail.asp?section=2450215&category=Motorcycles&make=Honda&year=1975&fveh=131064   sorry I do not know how to copy the image only the link...Larry

[harisuluv]

Looks like you used duplicolor rattle can on your entire carb setup, including manifolds?  Hope you taped everything off well...

Did you clean all the jets well?  You emphasized the needles but what about the idle jets?

[vonvendetta]

Looks like you used duplicolor rattle can on your entire carb setup, including manifolds?  Hope you taped everything off well...

Did you clean all the jets well?  You emphasized the needles but what about the idle jets?

I did make sure the jets looked good. The carbs actually had no build up and looked really good. I did soak them in carb cleaner anyway.
I did you duplicolor and clear on the carbs, vht engine paint and clear on engine and vht manifold on the exhaust. Everything was sealed 100%. Emulsion thing I might need to check, I can't find what or where in the carbs they are though.

Sent from my SCH-I535 using Tapatalk 2

[harisuluv]

Well, spark, fuel, air....  You'll have to figure out which one. Sounds like you have spark. You should at least unscrew a drain plug and see if there's actually gas in there.

Also, make sure your kill switch isn't off and set for run.

[dave500]

and the fuel tap/valve is on,some people have gotten its position wrong.

[vonvendetta]

Well, spark, fuel, air....  You'll have to figure out which one. Sounds like you have spark. You should at least unscrew a drain plug and see if there's actually gas in there.

Also, make sure your kill switch isn't off and set for run.

Will it crank if the kill switch is wrong? I did wire it from scratch and used a zx636 start/kill switch.

Sent from my SCH-I535 using Tapatalk 2

[Xnavylfr]

IF you rewired it correctly , then the starter shouldn't even spin with the kill switch OFF. You say you are getting fire/spark at the plugs , and I see you have POD filters. Have you tried starting with the choke closed then if it starts slowly open the choke. If the carbs are NOT jetted correctly for the pods then they tend to make a bike VERY hard to start because they don't restrict the air enough to pull up fuel.
I know most people HATE to try starting fluid because the chance of a fire but if you use a SMALL amount in each carb filter while trying to fire the engine and it starts for just a second then you have fuel flow issues.

Xnavylfr(CHUCK)

[vonvendetta]

IF you rewired it correctly , then the starter shouldn't even spin with the kill switch OFF. You say you are getting fire/spark at the plugs , and I see you have POD filters. Have you tried starting with the choke closed then if it starts slowly open the choke. If the carbs are NOT jetted correctly for the pods then they tend to make a bike VERY hard to start because they don't restrict the air enough to pull up fuel.
I know most people HATE to try starting fluid because the chance of a fire but if you use a SMALL amount in each carb filter while trying to fire the engine and it starts for just a second then you have fuel flow issues.

Xnavylfr(CHUCK)

Great, then I did wire it correctly. It had velocity stacks and super sport exhaust on it but I think it had the stock size jets in it, 100 and 40? The velocity stacks weren't in good shape so I got these filters for like $20 instead. I will take the overflow pan off and see if it has gasaline like someone else suggested and if it does I will try the starter fluid.
Thank you!

[dave500]

umm?the starter will spin the engine with the right hand kill switch in either of the off positions!!it just wont start,it will crank over and over but wont fire,the bar mounted kill switch switches the ignition (coils)on or off only.you better check the zx switch hook up?

[vonvendetta]

umm?the starter will spin the engine with the right hand kill switch in either of the off positions!!it just wont start,it will crank over and over but wont fire,the bar mounted kill switch switches the ignition (coils)on or off only.you better check the zx switch hook up?

No, it wont crank in both positions. It will only crank when in the kill switch is in position and the coils only get juice when key on ignition. So I do get spark and it will crank. Do the coils have to be attached in a specific order for it to start or will it just sound rough? If so, can someone shoot me a quick picture?

[tlbranth]

Pull a plug, hook it up and ground it. Crank engine. Spark? If no, figure out why. If yes, put small amount of gas in the plug hole & replace plug. Open throttle a bit and crank. Fire? If yes, fuel problem. If no, mechanical or timing problem.

[dave500]

umm?the starter will spin the engine with the right hand kill switch in either of the off positions!!it just wont start,it will crank over and over but wont fire,the bar mounted kill switch switches the ignition (coils)on or off only.you better check the zx switch hook up?

No, it wont crank in both positions. It will only crank when in the kill switch is in position and the coils only get juice when key on ignition. So I do get spark and it will crank. Do the coils have to be attached in a specific order for it to start or will it just sound rough? If so, can someone shoot me a quick picture?

ok so youve wired it up different to how it was with the honda switches?the stock wiring allows the starter to spin the engine even with the kill switch on the bars in the off position,follow the wire from the 1/4 points,they should be connected to the 1/4 coil and the 2/3 points should connect to the 2/3 coil.

[vonvendetta]

Thanks guys, after a second look at the carbs I noticed the idle (slow) jet was clogged to hell. Cleaned it up and got it to start, almost 10 years later. 

Honda cb500 with gsxr swap First start