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Hi.

I am helping my dad with his newly bought 2000 VN 800 Drifter.

It doesn't run good, probably bad jets which is usual of what I have seen on different forums regarding the VN 800.

I have already cleaned the carbs once, this helped quite a bit before it soon got bad again. It's popping, backfiring and surging when riding it. No anomalies when accelerating hard etc.

So we've ordered new jets and a new float valve. Stock was:

Pilot jet: 48
Main jet: 135


The new we ordered is:

Pilot jet: 52
Main jet: 155

However, I went to hell and back getting the air box mounted last time I had the carburetor out for cleaning, because of the hoses that you have to connect to the backside of the airbox.

There are three of them; a large one, a normal one and a small hose going into it. I was simply wondering if I can clog a couple of them with plugs/screws, or at least reroute them down below the engine with filters etc.

Any suggestions?


 

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Some hoses can be capped, some can not without capping other things.
There is a wealth of info on the 800 here: http://www.angelfire.com/ak5/russwolf/airbox.html

Study those PDFs on grampsizing/scooterizing and they'll explain all the hoses you're dealing with.

BTW, With those larger jets you will likely run too rich unless you open up the intake and exhaust accordingly. Also, its usually best to fix a known issue before trying a performance mod, but we dont judge!
 

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Hi.

I am helping my dad with his newly bought 2000 VN 800 Drifter.

It doesn't run good, probably bad jets which is usual of what I have seen on different forums regarding the VN 800.

I have already cleaned the carbs once, this helped quite a bit before it soon got bad again. It's popping, backfiring and surging when riding it. No anomalies when accelerating hard etc.

So we've ordered new jets and a new float valve. Stock was:

Pilot jet: 48
Main jet: 135


The new we ordered is:

Pilot jet: 52
Main jet: 155

However, I went to hell and back getting the air box mounted last time I had the carburetor out for cleaning, because of the hoses that you have to connect to the backside of the airbox.

There are three of them; a large one, a normal one and a small hose going into it. I was simply wondering if I can clog a couple of them with plugs/screws, or at least reroute them down below the engine with filters etc.

Any suggestions?


you dont get "bad jets". someone may have fitted some that are too big, but the stock ones are fine untill you alter the airbox and the pipes. if you have stock filter and pipes, put the originals back.

the most likely cause of your problem is air leaks on the rubber hoses.

the rubber tube holding the carb to the bike is a bitch to get back on and resealed correctly. you need the tank off to see if its fitted all the way around and to do up the bolts evenly. start looking there.
on the carb, is a small hose with an elbow that goes nowhere, what have you done with this, its important.

on the carb, the small hose from the top of the body goes to the fuel tap. if this is blocked, kinked or perished, you will get no fuel, which describes your symptoms.

one hose into the air cleaner back comes from the engine breather tube, mounted right tight against the carb on the side of the rear cylinder. DO NOT BLOCK THAT PIPE.
the small pipe from the bottom is a drip tube into a little bottle that should be down by the right foot. a lot of the bottles get lost, but that pipe is a drain for excess oil from the breather. if you block that, the excess oil will get into the engine and also cause similar symptoms.
 

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I'm going to echo the above here, it should run perfect with the standard jets and air filter housing. If it doesn't then something is wrong. The petcock has a habit of failing on these and doesn't open correctly under vacuum. It has three positions, normal, reserve and prime. Stick it in the prime position as this is a permanently on state and doesn't require vacuum to open it. Then see how the bike runs.

Always start with the basics. Clean carb, good fuel supply, good condition of rubber items such a diaphragm and pipes, all secure, correct fuel height in float bowl, good spark.
 
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