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keons5 · 07-08-2008, 04:42 AM

I have a 1978 Honda CB400 Engine on a gokart (Picture below). The pet**** valve broke, so I replaced it with a brass elbow fitting from a plumbing store. The question I have is whether or not the pet**** valve has a diaphram/vacuum. My on/off valve is a radiator clamp on the hose. When I turn the fuel on, it seems to flow into the cylinders. The other day it filled the cylinders all the way.

About a week ago I was getting too much fuel so I cleaned the carburetors. After that, the engine fired every time I kicked it but wouldn't start. It seemed like a lack of fuel. Now, it just floods like nothing I've ever seen.

longride · 07-08-2008, 05:40 AM

Flooding carbs has nothing to do with the petc*ck and everything to do with your carb floats and float needles. Check for cracked floats and replace the needles and seats with new ones.

keons5 · 07-08-2008, 06:13 AM

Quote:

Originally Posted by longride

Flooding carbs has nothing to do with the petc*ck and everything to do with your carb floats and float needles. Check for cracked floats and replace the needles and seats with new ones.

So you don't think the problem has anything to do with the missing petco*ck valve? I guess I'll have to go through the carburetors again. Thanks for the info,

Anyone else have input?

keons5 · 07-08-2008, 06:15 AM

I don't really get how both carburetors all the sudden flood. What's the chance that both of the floats/needles are bad all of the sudden?

pushrod · 07-08-2008, 08:07 AM

I'm trying to figure out how he determined the jugs were full.

mscuddy · 07-08-2008, 08:36 AM

I wondered what happened to all those old CB400 twins...sounds like you should go to the salvage yard and get another vacuum operated fuel valve. You might of mixed up the lines and put the gas line into the vacuum line port, thus flooding the cylinder with raw gas.

keons5 · 07-08-2008, 08:54 AM

Quote:

Originally Posted by mscuddy

I wondered what happened to all those old CB400 twins...sounds like you should go to the salvage yard and get another vacuum operated fuel valve. You might of mixed up the lines and put the gas line into the vacuum line port, thus flooding the cylinder with raw gas.

There is no vacuum line port. I was reading a manual and it stated that the vacuum operated valves were on 1980+ Models. Maybe I didn't read it correctly. I will post a picture of what it says.

I got quoted $125 for a fuel valve locally. The cheapest I found was $34 plus shipping online. I don't want to put the money into one unless I know that is the problem.

I knew the cylinders were full. I turned the gas on and cranked over the engine about 8 times, then it locked up. It scared the crap outta me. I thought I locked the whole engine. I pulled the plugs out to look, and I tried to turn it over and gas shot out all over my garage. It even hit the ceiling. I have the carburetors off right now, and I will take another look at them after lunch.

Thanks for all of the interest guys! Keep it coming

keons5 · 07-08-2008, 09:11 AM

Here's what the manual says.

Cliffs: The vacuum operated petc*ck valve is only on the 1985-newer models.

seruzawa · 07-08-2008, 09:15 AM

Quote:

Originally Posted by keons5

There is no vacuum line port. I was reading a manual and it stated that the vacuum operated valves were on 1980+ Models. Maybe I didn't read it correctly. I will post a picture of what it says.

I got quoted $125 for a fuel valve locally. The cheapest I found was $34 plus shipping online. I don't want to put the money into one unless I know that is the problem.

I knew the cylinders were full. I turned the gas on and cranked over the engine about 8 times, then it locked up. It scared the crap outta me. I thought I locked the whole engine. I pulled the plugs out to look, and I tried to turn it over and gas shot out all over my garage. It even hit the ceiling. I have the carburetors off right now, and I will take another look at them after lunch.

Thanks for all of the interest guys! Keep it coming

Sounds like keons5 lucky he no smoke or have patchouli oil candle burning when he work in garage.

longride · 07-08-2008, 09:17 AM

The job of the floats and needles is to fill the carb bowls and shut it down when they are full. Unless you have positive pressure in your gas tank, there is no way the petc*ck will flood the engine. Simple as that.

07-08-2008, 04:42 AM	#1
keons5 Registered Member Join Date: Jul 2008 Posts: 11	Motorcycle Powered Gokart - Help! (Honda CB400) I have a 1978 Honda CB400 Engine on a gokart (Picture below). The pet** valve broke, so I replaced it with a brass elbow fitting from a plumbing store. The question I have is whether or not the pet** valve has a diaphram/vacuum. My on/off valve is a radiator clamp on the hose. When I turn the fuel on, it seems to flow into the cylinders. The other day it filled the cylinders all the way. About a week ago I was getting too much fuel so I cleaned the carburetors. After that, the engine fired every time I kicked it but wouldn't start. It seemed like a lack of fuel. Now, it just floods like nothing I've ever seen.

07-08-2008, 05:40 AM	#2
longride Super Duper Mod Man Join Date: Nov 2001 Location: Anywhere they let me Posts: 10,484	Flooding carbs has nothing to do with the petc*ck and everything to do with your carb floats and float needles. Check for cracked floats and replace the needles and seats with new ones. __________________ I'm a knucklehead

07-08-2008, 08:07 AM	#5
pushrod Founding Member Join Date: Nov 2001 Location: Baja 'Bama Posts: 3,478	I'm trying to figure out how he determined the jugs were full. __________________ You would not understand, this is not how I am... I have become - Comfortably Numb.

07-08-2008, 08:36 AM	#6
mscuddy MODERATOR X Join Date: Jun 2007 Location: Next to my still checkin the temp. Posts: 5,444	I wondered what happened to all those old CB400 twins...sounds like you should go to the salvage yard and get another vacuum operated fuel valve. You might of mixed up the lines and put the gas line into the vacuum line port, thus flooding the cylinder with raw gas. __________________ A gun is a tool, Marian; no better or no worse than any other tool: an axe, a shovel or anything. A gun is as good or as bad as the man using it. Remember that.

07-08-2008, 09:17 AM	#10
longride Super Duper Mod Man Join Date: Nov 2001 Location: Anywhere they let me Posts: 10,484	The job of the floats and needles is to fill the carb bowls and shut it down when they are full. Unless you have positive pressure in your gas tank, there is no way the petc*ck will flood the engine. Simple as that. __________________ I'm a knucklehead

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07-08-2008, 06:15 AM	#4
keons5 Registered Member Join Date: Jul 2008 Posts: 11	I don't really get how both carburetors all the sudden flood. What's the chance that both of the floats/needles are bad all of the sudden?

07-08-2008, 09:11 AM	#8
keons5 Registered Member Join Date: Jul 2008 Posts: 11	Here's what the manual says. Cliffs: The vacuum operated petc*ck valve is only on the 1985-newer models.