390 intermittent hard to start, poor running

[jlamb4483]

I’ve had it happen one time while out riding where I had poor throttle response off idle, and they motor wanting to die when pulling in the clutch. The motor wasn’t hot, indicated around 170 degrees. I performed the altitude reset where you allow the bike to idle and get to 180 degrees, shut off, then restart and it was good all day.

I rode Foresthill trail 6 last week, which is a very slow technical trail. The bike was definitely running hot, the trail tech actually stopped receiving signal so I don’t know how hot it was, I think the signal to start the fan wasn’t functioning because the fan was not running. No boil-over but could feel the heat on my right leg. My friends bikes were boiling over. I began experiencing the same symptoms where to the bike would die when pulling in the clutch and having the rpms drop to idle, as well as it wouldn’t start without giving a ton of throttle and the keeping it revved high to keep running.

After taking a break and letting the bikes cool, the trail tech began working again (it wasn’t recording mileage either) and the bike started normally and ran great even when getting hot again and the fan running.

Any suggestions are appreciated. It’s a 2017 390-rrs with 25 hours.

[firffighter]

When you did your reset did you begin with a stone cold motor?

Have you tried the stepper motor reset? Start with stone cold motor, no throttle at all, idle approximately 10 min. and/or 215 degrees, hit kill switch.

I had a day riding where I didn't let my bike warm up at all and temps were in the low 40's/high 30's. Bike ran funny all day. Next time out I did stepper motor reset and bike performed perfectly.

[jlamb4483]

I did not start from a cold motor. I will perform that reset before my next ride.

[firffighter]

Seems to consensus that cold motor and do not touch throttle during any part of process is key.

Keep us up to date on how it goes.

[jlamb4483]

I rode the other day. Warmed up the bike from a cold motor to 215 without touching the throttle and turned it off (performed the reset). It ran great all day. It was cold out and the engine temp never got above 180.

I think the poor running was a combination of going up in altitude and not letting the bike warm up, and then also the engine temp was really hot. Wish I knew how hot when it didn’t want to start but both my friends bike’s coolant were overflowing and i did see temps on my bike above 230.

We’ll see how it goes. Going to let the bike warm up for at least a few minutes without touching the throttle for now on.

[firffighter]

Glad you were able to diagnose the problem. The warm up seems to be key to the bikes running at their best.

[rjfyrman]

I have a brand new 18 390 with 4.5 hrs on it and it did this exact same thing the other day. I went from sea level to 3700 ft and when I got near the top is when it wanted to die and start hard etc. I will do the reset described and let you know, as this ride is right in my back yard in Santa Cruz. Other than that slight hiccup...bike is phenomenal!! Be Safe!

[hawaiidirtrider]

Big radiators and an overflow bottle and a higher pressure radiator cap sound like good add ons. .. and maybe a water . Cooling mods always are good to have.wetter

[aviatrix]

I'd like to resurrect this threat, as I am having a similar issue with my 2016 390, except it won't stay running longer than 30 seconds. I am trying to perform the stepper motor reset as @firffighter describes, but without success. Any other ideas?

[aviatrix]

UPDATE (for those of you who may experience a similar issue): After checking the load on the battery during start-up (fine, evidently they pull a lot of power initially once started - even if it sounds strong at first) and checking the fuel injector (fine, took it into a shop and had them test it in an atomizer), I discovered tiny bubbles coming up through the fuel tank during start-up, indicating either a bad fuel line or worse, a bad fuel pump. Turned out to be the fuel pump due to the bike sitting for a few years, not being run and bad gas. All the seals disintegrated when touched, more than likely due to the ethanol in the fuel. Thanks to APEX Sports in Colorado Springs and the service manager there, Jim, for taking the time to troubleshoot with me the other day. On the bright side, my 1200GS did quite well on the trails of Penrose Commons.

Keep this in mind when you buy a 4-year old bike with only 29 hours from a private seller. Bike ran fine when I went to look at it. Bought it a few days later, brought it home and it started having issues within 15 minutes.