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Hard starting in warm weather

5K views 25 replies 15 participants last post by  fishguy 
#1 ·
I have a 2016 tw 200. My tw has always started without the choke. It didn't matter how cold it was out, it never needed the choke. The bike has always run well once warm and doesn't seem to have any lean symptoms like backfire on decel etc. It still runs well once warm.

Just this week in socal our temps have hit the upper 80's. Now all of the sudden when I get to work, shut the bike off for four hours, it doesn't like to start up again without the choke. Not sure why.

I'm going to start experimenting with bigger pilots and the fuel screw, but usually when my bikes have been lean I can tell during cold starts and backfire on decel or similar running symptoms. These warm weather starting issues are new to me. Anyone else experience this?


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#3 ·
Hi. I have a 2015 that was doing exactly the same as yours. I remember that opening the fuel mixture screw 2 1/4 or 2 1/2 turns out solved the problem. I would recommend doing it if you haven't done it yet.
Remember that in order to access the screw you will have to remove the plug, not a big deal! You will find instructions on this Forum if you look for it. Based on my short time I've been searching here I can guarantee that you won't find better help anywhere else, it is satisfying to see how many members are willing to help out in all kind of "situations" sharing their own experiences.
 
#4 ·
Yeah I've had to drill and remove the plug on several bikes so it shouldn't be a issue.

It just ran so good in cold weather I thought it was pretty much dead on.

Did you simply adjust the fuel screw or did you do both the pilot jet and fuel screw adjustment at the same time?
 
#5 ·
So I broke out the $60 service manual and from what I could find, there's absolutely no reference to the fuel mixture screw location. Maybe I'm missing it but it's certainly not easy to find. So I got down to carb level and I'm suspecting the screw is located on the front bottom of the carb. I was hoping not to have to pull the carb to pull the plug out, but it looks like I may have to.


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#6 ·
Front bottom of the carb...yes...that's it bro.
 
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#9 ·
sounds to me like your low speed circuit may be a tad too rich. Since cold air is more dense than hot air, your intake is drawing more air molecules per unit of volume in cold weather than in hot weather. If it ran well in cold weather but now struggles to start with warmer weather, you're likely a bit too rich (less air mixed with same amount of fuel.) If the choke doesn't help starting in the warmer weather, that reinforces the rich condition. If this is indeed the case, opening the pilot screw further (adding more fuel to less air) will only exacerbate the problem. Just my 2 cents based on your symptoms
 
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#11 ·
That was my initial thought as well since it starts so well in cold weather without the choke. It's been this way since I bought the bike which has been mostly during the colder season. Now that we've had warm weather, all of the sudden I need the choke to start it, when it's above 80 out.

So here's how yesterday went.
I went out in the garage at 6:45am. Temp was 49 degrees outside and my garage was 60ish. I pushed the bike out in the driveway, hit the starter button with no choke and it started and idled perfect within one second of hitting the start button. Drove a couple miles to work, parked it, and went in. At 11:15am I walked out to go to lunch. I unlocked the disc brake lock, put the key in and hit the start button. It turned over a few times and nothing. Did it again for maybe 5 or 6 seconds and still nothing. Pulled the choke half way and it lit up in a second or two.

It ran perfect all the way home. Shut it off when I got home. Decided to try and start it again within a minute and it lit up immediately. Parked it in the garage and ate lunch. An hour went out to start it and it turned over a bunch of times and needed the choke to halfway again. Started and ran perfect back to work.
 
#12 ·
Thats very strange. It seems totally backwards. i assume you turn off the petcock each time you park? Seems like one of the carb circuits (idle?) is plugged when hot.

I wish I had your weather, but I am glad I do not need a disc lock, I am 15 miles from the border of Detroit and I leave my key in my ignition ll the time. My parents (lived in the same town I do now) didn't even have keys to the house when they sold it, never locked the doors :)
 
#13 ·
Same area and I have my TWs at almost 3 turns out. Both start immediately when cold, with the choke all the way out and no throttle. Then push the choke/enrichment in to the halfway point.
I usually let them warm up for a minute or two but mostly because of inexperienced riders use one of them.

If they are warm they will start without the choke, and no throttle, right away.

I was surprised on Sunday when I went riding that they both needed the choke to start since it was probably already 75F outside.

I don't know why you'd need the choke with warm weather but not when it's cooler.
 
#17 ·
I was thinking maybe the float is out of adjustment and when you close the petcock overnight or leave it sit, it comes up to the right level, but when the petcock is left open it some how doesn't come to the right level? I really have no clue, just thinking through possibilities with you. You should always close it off when you park it btw.
 
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#18 ·
Ok so I think I may have noticed something today. Usually when I get to work I'm running late so I speed through the parking lot and coast to a stop killing it before it has time to come to a smooth idle. So today I gave it maybe 15 seconds of idling before turning it off and it started perfectly every time. So I'm definitely thinking now it's probably some kind of a lean condition that probably has to do with the pilot circuit / fuel screw. Strange cause I do this in cooler weather it has no effect on starting, on in warm temps. We have to leave town this Friday for the state wrestling championships for my son, but when I get back I'm going to mess around and adjust fueling a bit.


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#19 ·
I would be interested to hear if turning your petcock on and off at the beginning and end of each ride changes anything. I remember years ago a friend left his petcock on on his motocrosser. The engine and expansion chamber FILLED with fuel. I remember removing the pipe and dumping out a large amount of gasoline... like a couple of cups. Perhaps a small similar leak is causing your odd rich condition at cold starts on a bike that is notoriously lean on the idle circuit.
 
#22 ·
Update. As of a week and a half ago I was still experiencing very difficult warm weather starting if the bike's engine was cold. Once engine is warm it always started immediately and operated normally. I did open the fuel screw to 2 1/2 turns out with the stock 31 pilot. That had no effect. Then changed to a 34 pilot and that had no effect either on those starts.

So strange, nearly every day I left for work at 7am 50 degree ish and it would start no choke. Ran perfect to work. Shut off and at 11:30am I'd go and try and start it and it would turn over for at least 30 seconds with nothing. Even the choke made no difference. I had to give it a tiny bit of throttle and it would slowly start. It was embarrassing especially when people were watching me trying to start an almost new bike. They would ask what's up with it not starting?

Anyways last week I finally fixed it. Unfortunately I changed two things at once so I'll never know which one fixed it, but at least there's no more starting issues. I do have my suspicions though.

So I ran out of gas in the gas can and tw last week. It was a fresh mix of 91 octane with Stabil marine 360 ( which I recently started running in all my engines that sit, switching from Stabil regular red). This time I decided to try 87 octane back with regular Stabil red with no 360 or vapor technology. Now the bike starts instantly anytime, any weather with no choke and runs perfect. So my guess is probably the Stabil marine 360 and the vapor technology, and maybe being parked in the hot sun. Something must be going on there.

If you're wondering why I run fuel stabilizer it's cause I don't go through gas very fast and I've always run it in all my engines including my Ktm with no problems, but just recently switched to the marine. So I'm switching back to red from now on and going to stick with 87 octane. Just glad it's back to normal now. Sometimes weird things happen I guess. Had me chasing my tail for a couple months.
 
#23 ·
That is interesting about the gas. I just bought some stabil 360 and put some in a can of non ethanol gas from Utah. So right about now So Cal switches gas formulas from winter to summer. The different formulas have higher and lower volatility.

Summer-Blend vs Winter-Blend Gasoline: What?s the Difference?
 
#24 ·
Yeah the starting issues were literally every day without a hitch till I switched to 87 with standard Stabil.

One other incident that concerned me was with my 16 ktm 500 exc. Two weeks after switching to Stabil marine I had a high pressure fuel line split on the inside and weep fuel out the threads to the edges. The split was about 3 inches long and only on the inside. This fuel line was only as old as the bike which is about a year and a half. Maybe a fluke, but also had me wondering if something in the marine formula was a little hard on rubber hoses. No way of knowing though.
 
#25 ·
Anything more than 87 octane is generally a waste in a TW.
 
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#26 ·
I stopped using red Stabil. As far as I know, the "red" does nothing to counteract the adverse effects of ethanol. I have thought about trying the "marine" grade. Now I will not.
I run 87 octane (my TW HATES 91). I add Seafoam (a little bit all the time) and/or StarTron to neutralize the ethanol and for winter storage. She starts every time.
 
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