Some 790 Maintenance Musings

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

AfricaOffroad

Race Dog
Joined
Jan 26, 2006
Messages
2,467
Reaction score
759
Location
Debbin
Bike
Husqvarna (all models)
So a couple of rides back I noticed the 790 start to limit it’s revs , particularly at high rpm.
Given it was on the dirt, I thought it was the traction control and related to the new knobby fitted.
Tested it on the tar and bike seemed fine so I didn’t think anything of it.

Next ride I lent it to a friend. He too complained about the rev limiting ( not a misfire).
Initially I thought it was the setting he had the bike on, but back of my mind I was remembering the limiting I had felt on my ride a few weeks back. So we stop for a break, jump on the bike, quick blast down the road , it feels fine?

The day ride continues, he is complaining more and more. We swop bikes, yes it’s noticeable, now bike won’t rev much past 5000rpm. There must be a sensor messing round, it’s like the traction control is over compensating. Secondly I can’t switch it off no matter how I try. I put rally mode to 1, still no difference.

Eventually I get onto tar, figure with no wheel slip the bike will rev. Nope, not a chance. I can’t even get the bike up to 100km/h !!! When one switches the bike off and then on, it seems to rev a bit more, but within a few 100m the bike is flat again.

So we limp home the next day and bike goes to Ktm. Btw, no warning lights on dash.
They plug it in, find some software error on a control module.
I think ah great, hopefully the problem is simple, although I’m a bit annoyed by the frailty of the bikes software.
They suspect a voltage spike may have caused the corruption.
So that gets sorted and bike goes out for a test run.

Aaaagh, it’s no different.
Now I’m starting to think $$$$$$.
We surmise it must be mechanical.
The technician ( who is really really good) decides to swop fuel tank over.
BIKE IS BACK TO NORMAL !!

So he strips the fuel pump out, and here we find the problem.
There is around 300ml of water in the tank, and the strainer and filter is totally gunked up.
I really don’t know where I might have picked up the contaminants, with the fuel range on the bike I normally fill up in Salt Rock for my day rides. It’s possible it happened before I bought the bike and it eventually found its way into the filter 🤷‍♂️.

Then onto my Scotts damper. Friend complained about a really bad headshake. I thought he was being a woes, the previous ride when I fitted it, the bike felt planted. Anyway, on one of the rough roads I took the bike and had a scary as shit headshake, and I was waiting for it. Yes he is right, the damper wasn’t working properly. So it got flushed yesterday, definitely it’s maintenance was overdue. I didn’t know condition of damper, had been given it years ago and only fitted it now. A warning to all those who buy second hand dampers
 

Attachments

  • D4A32FA9-215B-48AE-9304-5A869CD63669.jpeg
    D4A32FA9-215B-48AE-9304-5A869CD63669.jpeg
    861.5 KB · Views: 0
  • AB884AFF-214D-44BC-8CEB-51F33956039B.jpeg
    AB884AFF-214D-44BC-8CEB-51F33956039B.jpeg
    880 KB · Views: 0
  • 77266345-925F-484F-A1D0-8F3AA2C725B3.jpeg
    77266345-925F-484F-A1D0-8F3AA2C725B3.jpeg
    982.4 KB · Views: 0
  • B2E967AF-9EE5-4968-BC38-5439E028AA46.jpeg
    B2E967AF-9EE5-4968-BC38-5439E028AA46.jpeg
    1 MB · Views: 0
  • 9298DC68-0832-447C-90CE-660EA9275FEC.jpeg
    9298DC68-0832-447C-90CE-660EA9275FEC.jpeg
    1.6 MB · Views: 0
Top