Let’s help this guy fix his bike

[oz1961]

Hello everyone
I hope you are all well

This poor guy has tried everything to fix his bike except change his coils but it seems like a fuel problem to me

Please give me your thoughts so I can pass them onto him and help him back on the road

Thanks always
KR

 

[oz1961]

Here is another video of it
It’s strange how all four carbys are reacting the same at the same time

 

[Mr. Max]

Fuel delivery to carbs (filter, pump, clean tank, fresh gas no water). If fuel pump is clicking a lot when it gets power it's a sign it is not pressuring the system up. First start of the day it is normal to click quite a bit, but.. Well, you know what's normal and what is not.
I assume there is stock jetting, if it has been tuned for more gas it's getting too much.
Just my 2 cents, don't know but following.

 

[marsmax85]

First thing I do is what Mr Max said and I would add a sync job with a shotgun and pea shooter ...
might have to get into the carbs easy things first I say

 

[oz1961]

I thought exactly the same as your thoughts yet he told me that the carbs were professionally rebuilt and put on another bike which ran perfectly to test them before fitting to his

He fitted a new petrol pump filter and hoses

Pump is pumping 1 liter a minute

Please keep your thoughts coming
I really appreciate everything you suggest

 

[one2dmax]

Is he running with an airbox in place? Does he have air correctors installed (from a dynojet stage seven or our Muscle kit)? It sounds like it's running on two cylinders anyway but sometimes video is hard to get clear sound from it

 

[oz1961]

Hi sean
I spoke to him this morning again
He bought it at an auction and it was running like this

He had the carbys rebuilt and no change

Swapped a set of carbys from another running bike and no change
Fitted a new air filter fuel filter and fuel lines
No change

Ran it with filters on and off no change

The only things he hasn’t done is the coils

 

[DMAN999]

Hi sean
I spoke to him this morning again
He bought it at an auction and it was running like this

He had the carbys rebuilt and no change

Swapped a set of carbys from another running bike and no change
Fitted a new air filter fuel filter and fuel lines
No change

Ran it with filters on and off no change

The only things he hasn’t done is the coils

You say air filters (multiple) and not air filter (singular). Does he have a pod air filter on each carb and not a single air filter in the stock air box?
If he has four pod filters, that would imply that he has a Dynojet stage 7 kit installed. If so, that is important information. Does he also have a full aftermarket exhaust?
This is information that will help members more knowledgeable than me help you diagnose the problem.
One tip that I can suggest is that he cut about 1/4 off of the plug wires at the coil end to ensure a good connection.

 

[oz1961]

Hi and thanks for your imput

The carburetors were all returned to original specifications and run on another vmax working perfectly

He has put all new high voltage leads and plugs

Now it has a single factory air filter and factory air box

Cleaned the fuel tank
New fuel lines

Only thing unchanged are the coils

So I’m thinking it has to be them
What else can it be?

 

[marsmax85]

Did you cut 1/4 off spark plug wires ? green build up inside wires will cause malfunction

 

[oz1961]

Did you cut 1/4 off spark plug wires ? green build up inside wires will cause malfunction

All new leads

 

[christopher509]

Hello , I wonder if there is a restriction in the tank air vent slowing down the flow of fuel . Remove the fuel tank cap and try again .

Regards Chris.

 

[El Canadiense]

Check the temperature of the head of your exhaust pipes to verify similar temperatures among the four pipes. If 1 or more are low, you probably have a problem with the corresponding carb/spark. I did this previously and found 3 of 4 diaphragms had holes in them but can be used to trace other problems as well. A mechanic in Mexico City showed me this by just spitting on the pipes. The spit doesn't disappear as fast on the non-firing cylinders but a temperature gun will give a more accurate reading.

 

[Fire-medic]

A mechanic in Mexico City showed me this by just spitting on the pipes.

Old-school for sure, but it does give an indication of low-temperature headers. I used to use a spritz bottle. Now I have a HFT digital readout thermal gun that is handy for this type of work. If a pilot jet isn't flowing, the idle temp will be significantly-lower, but run RPM's to mid-range and hold it there a bit, and the low-temp header will soon climb to a temp much-closer to the firing at idle headers.

 

[Hipnip]

Had a similar problem, fresh carb rebuild, new fuel pump. Upgraded fuel lines........or so I thought. Turns out the fuel line from tank did not seal completely & was sucking air. Installed new oem fuel line & problem solved.

 

[one2dmax]

Check to see if air correctors are installed. With the stock airbox they will not allow for full acceleration if they are in place. If the pod filters are in use then it requires them
With them installed
.

Versus without

 

[oz1961]

Did you cut 1/4 off spark plug wires ? green build up inside wires will cause malfunction

Yes and no

He completely replaced the leads with new high tension leads

 

[oz1961]

Is he running with an airbox in place? Does he have air correctors installed (from a dynojet stage seven or our Muscle kit)? It sounds like it's running on two cylinders anyway but sometimes video is hard to get clear sound from it

Here is a photo of his carbs
Can’t see if they are fitted or not sean

 

[oz1961]

Check to see if air correctors are installed. With the stock airbox they will not allow for full acceleration if they are in place. If the pod filters are in use then it requires them
With them installed
.View attachment 85124

Versus without
View attachment 85125

 

[oz1961]

Here is the photo of his carbs Sean but I can’t see if they are fitted or not