[TREKsportMK3]

I guess it's a habbit I learned from a manual-transmission car. Going downhill doesn't need any power, so why not "coast?" Still, on a motorcycle, it doesn't save that much gas when I usually get 55mpg anyway. Obviously I don't do it now because of this whole post. If it somehow affected the clutch, then I would have issues with it not staying in gear or slipping out of gear. It's never had an issue. Not sure how pulling the clutch with the engine at 5000 rpm would make it randomly start dipping down below idle rpm. If 1300 is the "set" idle rpm, then no matter the rpm beforehand, it should still stop there.

 

[Bikenut]

I guess it's a habbit I learned from a manual-transmission car. Going downhill doesn't need any power, so why not "coast?" Still, on a motorcycle, it doesn't save that much gas when I usually get 55mpg anyway. Obviously I don't do it now because of this whole post. If it somehow affected the clutch, then I would have issues with it not staying in gear or slipping out of gear. It's never had an issue. Not sure how pulling the clutch with the engine at 5000 rpm would make it randomly start dipping down below idle rpm. If 1300 is the "set" idle rpm, then no matter the rpm beforehand, it should still stop there.

I grew up, and learned to drive from my gas mileage conscious father, in a very hilly part of Michigan's Upper Peninsula. Slipping the car into neutral on downhills was the normal way of driving and I've done it all my life. With bikes going to neutral isn't wise but pulling the clutch works equally as well. Actually with my bikes I pull the clutch and coast up to stop signs/stop lights letting the engine idle as I downshift according to how much I slow the bike with the front brake.

So... as far as the engine is concerned once it is disengaged from the drive train it doesn't matter how fast the bike is still moving the bike and engine essentially become separate and it makes no difference how fast or slow the engine is spinning in relation to how fast the bike is moving.

As such.. when the clutch is pulled and the throttle is returned to idle the engine should idle. And it should continue to idle until more throttle is applied. If it doesn't there is something wrong with air flow, or gas flow, or ECU programming, or something else in the ignition system. Just a weird question... what do your spark plugs look like?

 

[Grantman]

A bit confusing when you seem to contradict yourself.

Any help would be appreciated and it's nothing major or horrible. I can down-shift without going into neutrel and only pull the shift lever to go into neutrel right as I stop and it causes no issues. Even if the rpm drops like it's stalling, it rarely ever fully dies.

Not quite. Say I start the bike in a parking lot, like at work. If I drive to the end of that parking lot, or hit the road where there's a stop sign, I have to stop. You can't stop the bike while it's in gear or the engine dies/stalls out. You have to pull the clutch lever to come to a stop. Even if it's in 1st gear where you're at 4000rpm or trying to take it easy slowing down to 2000rpm, as soon as you're trying to slow down to come to a stop and you pull the clutch lever, THAT'S when the rpm drops down very low for a few seconds, or the engine dies.

Dropping to 1000rpm is a non-issue. The bike stalling and cutting out during normal stops is an issue, if it's doing that which is still confusingly unclear.
This bizarre coasting technique forces your clutch pull rod bearing to work a lot more than normal riding. I'd say stop doing that.
Seems a fat non-issue to me unless it is stalling at normal stops.

 

[Billy Red]

If it’s really bothering you maybe it’s time to go see a dealer because no one is going to be able to give you a cure just by your problem description. Most problems can have several different causes and even if someone else had the same problem they may need a different repair. Good luck whichever way you go.

 

[TREKsportMK3]

Just a weird question... what do your spark plugs look like?

I used to get off the interatate and just hold the clutch lever while lightly hitting the brake 'til I got to a red light or something. Now I have to downshift with the clutch still connecting everything. It is cool to slow down without using the brakes, but it's a habbit I'm used to from my last 2 bikes. Haven't checked spark plugs, though I was planning to at 20,000 miles. I'm at 19,000+ now, so should be soon. I changed the air filter around 11,000 miles. Replacing it didn't fix the issue, but the stock one was barely even dirty, so made me feel pretty good about the air-flow. I'd think if it was an air or fuel issue, it would always be an issue somehow. To only sometimes have an issue when pulling the clutch lever while moving makes me think it's gotta be something connecting the air/fuel and clutch with idle being thrown in. TPS sensor makes sense in some ways, but it just seems weird that it would only have a problem when riding and pulling the clutch lever while moving and nowhere else. As I said earlier, revving it in 1st gear, while not moving, with the clutch lever held in the whole time, drops the rpm back to 1300 no problem. But as soon as I'm coasting through the parking lot and pull the clutch lever to come to a stop sign is different. Then it wants to drop to 1000rpm for a couple seconds or possibly stall. Just weird.

 

[TREKsportMK3]

If it’s really bothering you maybe it’s time to go see a dealer because no one is going to be able to give you a cure just by your problem description. Most problems can have several different causes and even if someone else had the same problem they may need a different repair. Good luck whichever way you go.

You might be right. Usually most issues have been figured out by someone at some time and there's something to look for or something to change. But this seems odd enough that there may not be a simple answer. I guess I was hoping for "Oh ya, here's this issue. Replace this part and you'll be fine!" But maybe something is having an odd problem that most people have never to dealt with.

 

[kieran]

Hi, I have had the same thing happen to me about 12 times over a 5 year period of ownership of the bike, My problem is like to yours which I will try to explane. If I am traveling at 50 MPH and see traffic lights in the distance, I pull the clutch in to let it free wheel up to the lights when getting nearer the lights I would look down at the rev-counter and see it on ZERO, so the first thing to do would be to let the clutch out before I stop so it bump starts it, But it will be compleatly dead and will not start, so i would walk it to the side of the road then use the starter motor and it will fire up straight away, its a good job there has been no one behind me for being tail gated. As I said It has only happened about 12 times in 5 years, So I have leaned to deal with it.

 

[TREKsportMK3]

So I have leaned to deal with it.

I have too, for the most part. Nothing I can do, honestly, but even trying to rev it up a little when coming to an uphill stop usually keeps the engine running. Recently, when it did stall at that uphill stop, I restarted it and it seemed to not wanna start as quick as usual. Then again, I had just started it up a minute before that since I'd just gotten off work. I'm sure the battery was weak to a point, but it always makes me wonder. Any time I restart it, it never has an issue, but it's at least good to hear that someone else has dealt with the stalling. Even though I hate that it's affecting you, too. If you ever figure anything out, be sure to let me know!

 

[TREKsportMK3]

Ok, so I'm still thinking it's somehow the battery. Yesterday I tightened the clutch cable up; it was a little loose, but nothing major. Figured it would make some kind of difference. Started it up today for work and after I got ready, I got on and backed out of my area. Right next to the highway, my entrance is very downhill and at a curve. As I started down slowly (in 1st), I pulled the clutch lever and started pressing on the brake some to slow down to a stop. The bike died. But when I tried to restart it, it seemed to struggle and crank a few times before starting back up. That's why I think it's somehow the battery as it's weekest after a cold start. It wasn't an OEM battery, but the bike shop said it was one of their best and the cool thing for me was that it didn't need to be charged or pour acid in or anything when I bought it. Not lithium, but somehow different than a "pour in the acid then charge it up" battery. Then again, I also noticed a slow/extra-cranking startup after having the bike down for a few weeks. The battery was only a few weeks old at this point, but it seemed like it didn't have the normal start-up power I'm used to. Any thoughts?

 

[Rich T]

Can you measure the battery voltage right now? If it is 12.8 volts, it is fully charged. If it is not, then you will need a 1 amp trickle charger to charge it overnight, and then you will need to measure it again -- but you can't measure it immediately after charging, or you can get a false reading... You either want to turn the ignition on for a half minute and then measure, or let it sit overnight (off charger) and then measure... If you have a fully charged battery, your next step it to check the charging system -- start the engine and rev to 4k RPM and while revving, measure the battery -- it should be 14.4-14.8 volts or so -- that tells you your charging system is working.

 

[TREKsportMK3]

I guess I was also thinking, if the engine was still cranking with no delay or hesitation, it may not be the battery at all. Spark plugs may be an issue since they have close to 20,000 miles on them, but I've had no acceleration issues or missfires at all. It's probably time to replace them anyway, but unless it's a weird shut-off-valve type issue, I think fuel and air are good. Maybe dude was right and I should just take it to a shop. I guess I've just always been the type to try and fix things myself.

 

[Duckman]

Blown head gasket. Definitely a blown head gasket. Did it make a "poomph" sound the last time it started?

 

[TREKsportMK3]

...? Pretty sure a blown headgasket would have very different issues.

 

[Pmack]

...? Pretty sure a blown headgasket would have very different issues.

That's just @Duckman throwing some tongue in cheek noise at you for a chuckle.
See the "What am I missing" thread by @Tracy .

 

[TREKsportMK3]

Although being parked in idle and revving the engine causes no issues, if it's not battery related, it's gotta be fuel or air. Spark plugs and fuel injectors as well as the air or fuel filters don't make sense since I have no issues anywhere else in driving. My thought would be something that controls air and/or fuel when coming to or being in idle. However, when I got home, after being on the imterstate, and in my parking area, I tried to ride in 1st and randomly pull the clutch lever. At work, when it's first started up and cruising, this is when it drops rpm or stalls, but this time it fell back to 1300rpm no issue. If not battery related, my only thoughts would be on "heat" as the bike would be fully warmed up after being on the interstate. Could it be something to do with the idle being slightly higher when it's first started or a temperature sensor that wouldn't have any issues when the bike is warmed up? I guess my thought would be that maybe when it's cool after just being started up, when the rpm drops when going into idle, it's dropping lower than it's supposed to. I wanna say heating-up rpm is 1500-1700, but if it's dropping as low as 1300 or lower, maybe that's why it struggles or stalls out.

 

[TREKsportMK3]

Any other thoughts on my newest update? I've always been the type to try amd fix things myself, but sometimes I just don't know enough.

 

[Duckman]

These bikes stock have a fuel cut mode. When you chop the throttle while riding it will cut fuel for a while. Perfectly normal. If you have your ECU flashed for performance this fuel cut can be disabled.

You should not be pulling in the clutch and coasting at speed.

 

[Bikenut]

Intermittent vacuum leak?

 

[TREKsportMK3]

You should not be pulling in the clutch and coasting at speed.

Now I don't do it because I can't, but my plan now is just to pull the clutch lever when coming to a stop. I just want to be able to do that without the bike stalling out. What you're saying makes sense and sounds like something I can work with pretty soon. My questions would be: if it was cutting fuel, wouldn't I notice this all the time? If it's only an issue close to start-up, could the fuel cut only be noticed here instead of all the time? Also, if my bike has always been this way, why did this issue not start happening until it had many more miles. When I first got it at around 1000 miles, it never had an issue like this. Not saying you're wrong by any means, but I'm always curious.

 

[TREKsportMK3]

Intermittent vacuum leak?

I could see that as a possible scenario, but to only have a vacuum leak when it's "warming up" and not all the time makes me question this. Unless there's only a vacuum leak when the bike is first started or warming up, I wouldn't think that would be the issue. I could be wrong, though.