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Discussion in 'Parallel World (790/890)' started by 2whlin, Oct 8, 2017.
Fuel filter/pump. Might want to pull it and check.
When the engine/tank is hot and around a half tank vapour lock has been an issue for some people. Either a stuck check valve in the gas cap or the valve is too small/restrictive... I don’t think we’ve collectively decided as a forum. Usually presents as a fuel delivery problem that causes cuts and surges under load.
That said, opening the cap (thus releasing the pressure) and filling up with fuel (cools down the tank) has always cleared that one up for me. Some people have pulled the valve in the stock cap and others have gone to an aftermarket cap.
Next time it happens try popping the cap open and riding like that. If the problem goes away it’s the check valve, if it doesn’t go away then it’s not the check valve (pump/filter/injector?).
Is cooling system TOO efficient?
It takes a while to get 790 to operating temperature (i.e. four bars on the dashboard).
5 minutes on idle when weather is warm.
This morning, 12 – 15 °C, I waited seven minutes to get three bars, lost my patience and rode to work. It climbed to fourth bar (“engine warm” says the Repair Manual) only after I hit the city traffic 22 kilometres later.
I feel it’s naughty to ride so long on cold engine. Idling longer however...would be faster to drive :/
Idling until the engine is warm? My neighbors would kill me.
I start the bike, put on my helmet and gloves and off I go.
In my opinion the engine should be warm before you demand max. power from it, but gentle riding within the city limits is a different story...
I just wait for one bar and then move
I think the cooling system is fine. I do let my motors warm a bit but never wait for them to reach full operating temp unless I'm going to be hammering the motor right off the bat. I doubt the 790 is using forged pistons though dont know for certain. Cast piston are much more dimensionally stable and multi viscosity oils are very effective. It's not 1969.
That's my 2 cents. :)
If I waited for my truck to reach full operating temp before taking off I'd be waiting a good 15 minutes or more in cooler weather.
4 bars minimum
Also no swimming for one hour after you have eaten.
And most importantly no running with scissors
Thank you guys! It just looks like the bike will never reach the full operating temperature from September to May (except in the city). I'll go back to my usual solution: masking tape over the grill.
I do it the other way around.
Put on helmet and gloves, get on the bike, start and ride off.
Good chance I've got it all backwards but I've been told that it's actually better to warm the engine on load as it heats up and spreads the oil better.
Anyway, I'm not going to intoxicate myself letting my bike sit there idling in my basement garage.
Nah; safety third!
Live life dangerously.....always run with scissors......
A bigger problem with the little KTMs (and maybe these too) is blipping the engine too quickly at a high rpm and the still thick motor oil crushes the paper oil filter. KTM has revised the filters several times to make it more idiot proof, but where there is an idiot, there is a way
I stop at one bar. Then ride to the second bar. Then the third. Going to the fourth bar may not be such a good idea.
True. The 1190 dash which uses the same oil filter would flash angrily early in the rpm range until the motor oil was above a certain temp.
I take it easy on cold motors and dont feel the need to rev them while the motor is first warming up. I see a bar or two pop up on radiator temp and I call it good to go with a bit of mechanical sympathy for the fact it's not at operating temp yet. My little 250 XC-F I let warm up much more for the first run. Opinions vary. About the only thing most (but not all) agree on is dont run the snot out of a cold motor.
After doing at least 5 minutes of extensive internet research on this I am an expert.
It used to make sense to warm the engine before riding because:
1. Cold oil flows slowly and some parts might not be properly lubricated.
2. Carburated engines don't run well when cold.
3. Parts fit together a little differently when cold.
Multi-vis oils take care of 1. Electronic fuel injection eliminates 2. Better materials and manufacturing tolerances mostly takes care of 3 so go ahead and ride when the engine is cold but take it easy at first.
It's actually bad to idle my car when the weather is cold because the engine will never warm up. It just sits there condensing gasoline on the cylinder walls and diluting the oil.
Changed to a stainless steel oil filter for this reason, plus better filtration and easier oil changes. Rottweiler sells them.
But the engine never warms up while cooled by stream of air, while riding. Course the question is what else doesn't warp up while stationary.
Your reasoning stands, we've all seen the "driveway warming not necessary" infomercials. It's just too warm now to wait for revving till first few stoplights. I live in the country...
(reacting to sluagh)
Um, ever heard of a thermostat?
My bike would consistently be at 4 bars within a couple of miles at moderate or low throttle (city traffic). Ever since I had the cruise control installed it takes much longer to get to 4 bars. This is without using the cruise control. I wonder if the CC install also remapped the ecu and somehow made it richer?
I'd guess that most riders have some "sympathy" for a cold engine, but when discussions like this develop I'm reminded of a factory tour we took in Mattighofen a few years ago. Amongst the many other fascinating things we were privileged to see was the start to finish engine manufacture of the (then) new twins that were going into the Adventure bikes. The process of taking a hunk of Aluminum to a roaring engine in spce of a couple of hours (more or less) was (to me) amazing. One of the most astounding things we saw was at the end of "the line" where a tester took a freshly assembled engine, hooked up the oil, water, electrical system, exhaust and various monitoring connections then hit the start button. After running Briefly, the engine was then immediately run up to 5K rpm and monitored for a few moments then shut down and sent on the bike assembly line. Done....Ready to Race. This experience and that of speaking with a race motor builder, has tempered my "sympathy".