1vj air box
 

Hi
I,ve just bought a 1vj, and want to adapt the air filter box. I understand that the boxes are the same on the 3aj and the 1vj, but that the back lid/cap on the 3aj has intakes that
draw air from under the seat. Is this the case, and are the two caps exchangeable?
Thanks Dave

yes, the caps are exchangeable.
it is strongly recommended to close the two original air intakes of 1vj airbox (above cylinder head).
instead of changing the rear cap, you can simply leave the air filter box open.

best regards
klaus
xt600.de / tech. dep.

Why is the Klaus? Is it do do with lack of air flow under the seat?

Charlie

no, there is enough air under the seat.
the only use of the cap in this place is to reduce noise ( but imo this is a very nice sound ;-)

regards
klaus
xt600.de / tech. dep.

Thanks for the advice. That saves me £14.
I understand some people also move the oil cooler to aid the free flow of air to the cylinder head. Where do they attach it?
Dave

if you block the origional holes and leave the rear cover off, do you need to adjust the jetting? why is this better than the way yamaha made it?

No need to change jetting as Yams are standard pretty rich, this operation will make a run a bit leaner but better. I happened to do this on a test bench (3aj) and it gave me 4 Nm, which is 10% more torque. Just by leaving something off!

It is better than original, for three reasons:
1. Air is drawn from a cooler place than just above the hot head, which counts especially at low speeds or standing still
2. Under the seat is a far less dusty place than just behind the front wheel
3. The inlet area towards the filter is far larger than with the two original suction stumps

In general the Yam engineers do a very good job, just once in a while they are slightly off. Just to erase any doubts, the later 3aj models have the same air box but draw air from under the seat in exactly the same way as Klaus describes!

Auke

So my understanding is that on the 1VJ airbox, you leave the rear inspection/cleaning panel off and so leaving the sponge exposed?

Thanks

Yep.

Do you then replace the filter sponge with another type of filter or is the OEM filter sufficient?

Do you have to clean the filter more regularly with this setup?

Is there a K&N filter that will fit the 1VJ, what is the part number?

Thanks

yes, stay with OEM filter, for two reasons:
- cheap
- easy to clean everywhere (some fuel will do)

no need to clean the filter more often than usually (depending on conditions, of course)

if you want to waste money, you can use the k&n filter for XT600 34F, 55W, 34L, 2KF, 2NF.
it will fit with small mods (http://www.xt600.de/xt_werkstatt/+ba...1VJ/index.htm#)

best regards
klaus
xt600.de / tech. dep.

with regard to 1vj's running rich , aren't they designed that way to help cooling - solved on the 3aj by using deeper cooling fins on the cylinder ?