Dies on quick WOT

SGM
I think you said at the start of this thread that if you crack it open it would die yes, as if you had hit the kill button. if you keep it WOT does it eventually pick up or will it continue to die until you close the throttle and open it more cautiously allowing the revs to pick up? i only ask because mine does this as its about to come to final temperature or about four miles on the road, if i crack it open it will hesitate and die and if i keep it at WOT it will eventually come to a stop, once its done this its ok for the rest of the day. As you say if your bumbling along you don't notice it but if your giving it some you do notice it, could be the same fault. When you find out what it is let me know, mines a 550 by the way.
Happy days, you know a shiny new husa has fuel injection, i reckon that might fix it.
Jockular.

how come you say it used to be ok but now you are changing the jetting? that's changing the rules of the game????

that's unfair!

in that case rais the needle one clip and it'll be gone.

rules is rules (sulk)

regards

Taffy

SGM said:

The fuel squirt from the AP is standard, and I can't help assume there for a reason. And I can't see how I am to limit its duration, there is no way to do this without modifying the carb (and as I'm fairly sure this problem is new, I'm not really into adding new potential issues before sorting this one).

Click to expand...

Again, the fuel squirt is still way too long. The stock FCR carb is not really designed for a large single cylinder engine for use on the dirt according to Dale L. In fact Dale recommends disconnecting the AP entirely. One easy method for reducing the squirt duration is to replace the original short pin AP diaphragm with a long pin Honda diaphragm. This effectively reduces the squirt down to a second or less. At least this is the way many KTM folks accomplish this, without the need of adding a leak jet.

Apparently the FCR was developed originally for road racing fitted to 750-1000 fours, ie up 250cc cylinders. The small cylinders don't get enough vacuum happening at low rpm so the ap gives a hit to get it happening. Hence as cylinder size goes up, the ap squirt can come down, all other things being equal. Snap throttle bog can either be lean or rich and its not always obvious which.

I fitted a Lineaweaver kit to my 650 and disabled the ap as per instructions, but found that some ap was still beneficial. With the kit 1 mm stroke was good, but after dyno tuning it was way too much, so its now about 1/3 - 1/2 mm.

I made it adjustable for no cost, just a bit of time and a small bolt and washers I had lying about.
http://www.husaberg.org/index.php?set_a ... _photo.php

Set up like this you can adjust it externally without any stuff removed from the bike, just need a 8mm spanner, makes testing really easy.

I also did the Taff mod to the MK1 FCR I fitted to my 501.
http://www.husaberg.org/index.php?set_a ... _photo.php.

So, if your jetting is spot on, some AP is still good, and less than standard is an indication of good jetting. If you are using higher revs all the time then you have enough vacuum and the need for the ap is not really evident (road racing, dirt/flat track, but snapping from closed/small throttle opening from lower revs the ap is helpful (trail, enduro).

Steve