Sounds like you are looking in the correct direction , you need to get the fuel pressure checked.

 

If I was to guess, It almost sounds clutch related, maybe a weakened or broken primary spring.
Or a bad belt.

 

if it was a bad belt slipping I'd be hitting rev limiter at a lower speed though?

I just don't see my clutching affecting a low rpm limit. but I'll check it out as well.


Eric@HoldersDiesel

 

I'm seeing correct pressure at key on motor off. 53ish. maybe a tad low


Eric@HoldersDiesel

 

My XP1K with SLP slip on has the 4500 rpm burble as well, but as far as the rest I have not experienced those other issues.

 

Try calibrating your clutch. If you have big tires (just guessing) or other factors affecting load and running too low of RPM on the clutch it will never get over a low RPM. The max HP is around 8400 RPM so running less RPM is also lower HP. Adjust the clutch to run at 8200 +/- first. If it won't go there it is not the clutch. Just my $.02 worth

 

my clutching is tuned in to my old 30s. I'm running a tad heavier 31s now but prob have ~200 miles on them with no issues tuned how it is.

I'll def check it out though. thanks everyone for the input.


it's loaded with power until that rpm and literally just dies.

Eric@HoldersDiesel

 

Not sure if I am understanding the situation properly but it made me think of this video I saw the other day, good luck

 

I've had similar issues and it's the engine derating. you won't see any check engine light coming on. First time for me was packing from the exhaust plugging the spark arrestor and the second time was a plugged air filter. I updated my clutch cover to the 2015 high flow cover with the new intake screens and got mud on the air intake and that derated the engine as well. The first time it happened to me I took it to my dealer and they had it for a week rebuilt my clutches and got it back only to have the same issue. I remembered reading on here about packing plugging the spark arrester and checked mine and found it to be 70% plugged.

 

How do your rollers look on your secondary? Check your weights on your primary???