Bonneville America Forums Forums Technical Forums General Tech Cranks, but won't start.

The situation: I bought my new (to me) bike with aftermarket carburetors and pipes on it. I decided I wanted to change these out in the interest of reducing noise and increasing fuel efficiency. Saturday, I finally managed to get the stock carbs back on. Everything seemed to be hooked up fine, and I was able to start the bike. Then - whoa - big fuel leak! Turns out that I had connected the fuel line to the overflow fitting. Gas was shooting out the fuel inlet fitting. I fixed that, and the leak stopped. I started the bike again, and it ran fine for a few minutes. I was adjusting the idle when it slowed down and eventually died.

Since then, I haven't been able to get it started. The lights come on when I turn the key, and the starter cranks, but the engine won't catch. I have verified that fuel is making it to the carbs.

Any ideas what's going on here? My only real thought is spark. Could the spark plugs have gotten fouled in just a few minutes since I started the bike? If so, how and why?

Is it possible you turned the idle down too far? Have you checked for spark? Does it try to start or just nothing but crank? Have you checked what jets you have? Have you checked the pilot screw adjustment? Open the bowl drains to verify you are getting gas into the bowls?

I've tried turning the idle screw back up again. No go. Haven't checked for spark yet. Carbs definitely getting fuel. Jets are stock. Nothing but crank.

I would check for spark then. You need air,fuel, and spark for the engine to run. Those are always the first things to verify. Once you are sure you have all 3 then it's time to do some finer checking. If one of those is missing then you know where to start looking.

That's what I was thinking, too.

what carbs u had before?

The RC racing carbs.

CR special keihin? no difference with fuel consumption and and on long runs even better!!!

How two hoses can hose you


Since you connected the fuel supply to the breather T, where did you connect the breather hose? i bet you connected the vent line to where the fuel line would go. Ya had em mixed up. When you aware of the mix up you corrected it. The vent line has a check valve in it. Fuel may have collected in the vent line and effectively stopped it up or betterer, messed it up. Solution: clean out the vent hose. i,e, detach it and lower it to see if fuel comes out. Blow through it.

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I didn't connect the breather hose to anything.

is it connected now?

I connected it to a hose that I found on the bike that wasn't connected to anything at either end. But I don't see what difference it makes. The bike didn't start with nothing connected to the overflow, and it doesn't start with that hose connected.

Here is what I gather:
The breather hose was not connected to the RC racing carbs.
The stockers sat unused for an extended period of time
you have not tried to start the bike with the breather hose disconnected. (it ran after you had connected the fuel line correctly and connected the wayward hose. The bike fired up and ran out of fuel, while the fuel and breather hose were connected.) The bike never really ran for any extended period of time with the stockers on.

Just tying to brain storm this tis all.

Having replace the RC racing carbs, and replacing them with the stockers, a question arises as to how long the stockers sat on the shelf? Perhaps the float needles are gummy? Once you have ascertained spark and full flow, then I would suspect a can of carb cleaner and some compressed air may be in order, i.e., clean the carbs. at the very outside, the floats may be full of gas. The carbs idle circuits which are drilled passages are great gunk collectors.

yup. Pull em. in the immortal words of our fearless leader dinqua, "...Once you have done this a couple times, it gets easier. I can pull my carbs in about 15 minutes now, that includes the tank and all the extras as well..."

Quote:

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The bike didn't start with nothing connected to the overflow, and it doesn't start with that hose connected.

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yes it did start once you had corrected the fuel dumping on the floor issue. you said what's up and got the info to correct it. At the time of correction you connected up that hose that was all by it's lownsome. thus the idea that the breather hose might be the culprit. Have you disconnected the "hose that I found on the bike that wasn't connected to anything at either end" and tried to start the motorsickle?

In summary four items given fuel flow to the bowls and hot plugs:

Breather hose
Varnished carbs
sticky float needles
incorrect float height adjustment.

If those carbs sat for any length of time with some residual fuel in the needle and the pilot passages they would become gummed up. The breather hose if not connected for all that time may have an obstruction in them too. Mud wasps love small hoses like that and are very good at clogging them up.

I'll check it out.

That sounds like fuel isn't getting into the bowl. Classic sign of stuck float or dirty float needle or seat. Both have to be stuck though or it would fire on 1 cyl. Clogged breather would also do the same not allowing gas into the bowls. I suspect those 2 since that is the last thing you did. It could also be dirty screen on the petcock or clogged hidden filter, this filter is a likely candidate if the carbs sat on a shelf with that open to collect dust.

Thanks for the clarification! Sounds like it ran long enough to dislodge varnish and clog things up.

And after all the trouble you had just getting those carbs on, I know the last thing you want to do is take them off again!

yeah. But I learned something from Joe's tribulations. If I ever get a set of used carbies, I'll clean em up before the install. (I am with the dinq on this: It is really easy after ya pull em several times.)

The toughest part is

Okay, I pulled the spark plugs. They were pretty black. I cleaned them up as best I could, and checked for spark. I got one. Probably not the strongest ever, but at least it's something. I pulled the carbs again, and unscrewed the bowls. There's some whiteish/yellowish residue on the sides of the bowls. Is this the "varnish"?

I'm going to clean them up good. Anybody got any special tips for this?

varnish lis a kind oif yellowy brown color to an almost carmel color. White is usually water.

Sounds like both varnish and water.
Couple of cans of carb cleaner, Q-Tips, and paper towels.
Don't use wire, or anything metal to try to poke things out.
Toothpicks, or straw from a broom, won't scratch parts.
Old toothbrushes are handy too.

Good Luck! Keep us posted,
Uncle Charlie

With that result I'd be draining the tank, too. Then, after the carbies are spotless, a refill with fresh mid grade gas and a double dose of Seafoam to scrub those lines clean.

I already drained the tank. Didn't put any seafoam in, though.

A little dry gas to disperse any water left in the first tank of gas.

put your CR back they low maintenance carbs

U will regret that decision anyway good luck to make it work with old carbs

yeah, well, I'm sticking with the CVKs

I offered to buy them too.

So, from the "One Mystery Begets Another" file, check this out:

I put in an order with Brent today. I ordered new jets, hex cap screws and thumb screws for the idle mixture. When I got home from work I started disassembling the carbs to clean them. So, the insides are a little grungy, the jets are a little grungy, but nothing spectacular.

I drill out the caps on the idle mixture screws, and just out of curiousity I decide that I want to see where they're set. So I start turning them to the right to seat them and... nothing.

The idle mixture screws were turned all the way in. How could they have gotten that way? I thought they were set at the factory.

Might be why the former owner went with the CRs, thinking the CVKs were crap...

Could be. So here's a question: would the closed idle mixture screws cause the problems I was having?

It would probably make it hard to start at the very least and then it wouldn't idle right.

what did you do?