Hard starting

Leckbass
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Re: Hard starting

Post by Leckbass »

Lechy wrote:Try this:
No choke, no throttle, crank for about 5 seconds, no choke wide open throttle, crank again for about 5 seconds, wait a few seconds then try to start as normal, choke and no throttle.

[emoji41]
Interesting... never heard that one, but I'll give it a try in 2 weeks

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Fred
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Re: Hard starting

Post by Fred »

What you have is insufficient fuel, any engine needs fuel and more of it for cold starts.

Have you cleaned the choke jets where it pics up fuel from the float chamber.

On the rear carb bowl face is a hole and a drilling about 1/4 inch that goes to the bottom. Now bottom of a float bowl is not a nice place to be.

The front is a brass tube,, cleanliness is essential running magic snake oil does not clean these parts.

Lechy
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Re: Hard starting

Post by Lechy »

What Fred is describing is the transient (temporary) fuel enrichment jet on the rear carb, the front is different. This jet is normally fixed and cannot be removed for cleaning, nor can its air jet. If this is blocked, the choke will be useless and you will have a popping in coasting and a bad lag on sudden acceleration.
[emoji41]
Grow old disgracefully young man.

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Fred
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Re: Hard starting

Post by Fred »

Lechy wrote:What Fred is describing is the transient (temporary) fuel enrichment jet on the rear carb, the front is different. This jet is normally fixed and cannot be removed for cleaning, nor can its air jet. If this is blocked, the choke will be useless and you will have a popping in coasting and a bad lag on sudden acceleration.
[emoji41]

No-- I am talking about the fuel supply jet for the enrichment system (choke)

The transient enrichment system has 2 air jets and both are removable. One of them is disabled by the transient diaphragm valve. Cut the air from one and it will enrich.

Lechy
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Re: Hard starting

Post by Lechy »

No Fred. the 2 systems are connected this is true. One air jet feeds the low/idle. the other feeds the enrichment which serves 3 functions depending in the vacuum in the throat 1. feeding the choke enrichment 2 enriching the mix in throttle chop/coasting 3 taking the place of the accelerator pump in hard acceleration (all 3 jets are active in this),
[emoji41]
Grow old disgracefully young man.

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Fred
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Re: Hard starting

Post by Fred »

What the f are we talking about here the choke or transient or transition.

Every one is all fucked up on these three words.

Lets simplify this by calling coasting, choke and accelerator.

Choke is one system --it gets fuel from the bowl all on its own,-- no fuel --no choke. It goes through a large valve and dumps it down the venturi. No finesse in this short use system.

The other 2 coasting and accelerator is all part of the idle circuit, talking fuel from the idle jet in the bowl. Hence a much larger jet size than bikes with comparable displacement.

There is 2 air jets that are removable,-- on both carbs one of them is in the throat, the second air jet is under that coasting valve on one carb and the other is under the main slide diaphragm. I forget which carb has which.

The coasting valve shuts off ONE air jet making is slightly richer stopping popping. Putting washers behind it will delay the operation of the valve making it worse. ( I have removed my valve, I use 2 air jets all the time yes it pops --so what)

The accelerator jets ( 3 holes in the venturi) are fed fuel through the idle jet, this emulsifies with air in a large chamber above the venturi. This feed fuel and air on demand from throttle. ( yes all these systems sucking fuel through one idle jet that why its BIG.

None interfere with each other as when you accelerate you don't need coasting and when your coasting you dont need accelerator.

This large chamber also feeds the adjustable idle mixture screw.

Hence your idle mix is neither air nor fuel but air and fuel already mixed.

NOW---for bad starting you need fuel. The choke gets fuel from the tiny hole at the bottom of the bowl or on the FRONT carb through the time brass pipe that goes down into the bowl.

No fuel no choke. The choke will only work with throttle closed so it sucks through the choke and not the venturi.

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