New Stutter issue

[Boog]

Calling for knowledge and insight from all you Doctors of Rocketology.

Issue: After filling up, the bike stutters and dies.

I usually fill up every 2-4 days. The last two fill ups have been around 4pm on very hot days (around 89°-93°F) at the same station and at the same pump. The bike is at running temperature after about 40-45 minutes of riding at both freeway speed and stop and go. The tank was low with adding over 5 gallons on each fill. I am using premium as the operator’s manual dictates. And, I top it off almost to the filler cap level.

When leaving the station, I go right into stop and go traffic for the last few miles home. On these last two fill ups, the bike begins to stutter within a few minutes of riding and will die when I let off the throttle. If I keep the throttle open, the bike will have a few power fluxes but keeps going. When this happened last Friday (the first time), I thought maybe it was overheating. I was in stop and go traffic, so I just left it off for a few minutes to cool down and pushed the bike along with the cagers. I started it when a side street came along, got out of the traffic and took the long way home. Within a mile, the issue was gone and no other problems with it. Then yesterday, after filling like previously described, the same issue hit again. I executed the same route and made it home.

Questions:

1. Because both fill ups are the same pump with the same gas, is the fuel causing the issue even though it is several days apart?
2. Is this an ambient heat related matter?
3. Is this an engine/fuel system heat related matter?
4. Am I putting too much fuel in the tank?

I have thought that maybe the filter is dirty but after riding the bike for hours with TDragger last weekend and then to work each day this week showed no issues, and riding to work this morning after yesterday’s fill up showed no sign of the stutter; thus, I would not think the filter is the problem.

I anxiously await your comments as I am riding to Sturgis in a couple of weeks and do not want any issues on the road. Thanks in advance.

 

[tdragger]

Bobby, you better check the manual again. I'm almost certain that it calls for Regular (87 PON) rather than Premium (93 PON). This may be your whole issue.

Check page 31 of the manual. 87 octane using (R+M)/2 method (also known as PON or AKI). The 91 listed is RON which is what most of the rest of the world uses.

Another thought is that the vent line is blocked somehow. If the tank can't vent when full, the vacuum can be significant in a short amount of time. Once you burn off some full and the air pocket is larger, there's less vacuum as full is further burned off.

 

[Boog]

Bobby, you better check the manual again. I'm almost certain that it calls for Regular (87 PON) rather than Premium (93 PON). This may be your whole issue.

Check page 31 of the manual. 87 octane using (R+M)/2 method (also known as PON or AKI). The 91 listed is RON which is what most of the rest of the world uses.

Another thought is that the vent line is blocked somehow. If the tank can't vent when full, the vacuum can be significant in a short amount of time. Once you burn off some full and the air pocket is larger, there's less vacuum as full is further burned off.

You have taught me something new James, Thanks! I just checked the manual again (Page 30 for the R3T) and this is what it reads:

 

[RKTNMYPKT]

I ran nothing but 91 in my R3T for 5 yrs and am currently running it in my Roadster with out any negative effects,
Although CA gas seems to be different than what the rest of the civilized world uses, My gas mileage increased and my bike ran better on the RAA trip as soon as I left CA.

 

[cusso ken]

You have taught me something new James, Thanks! I jsut checked the manual again (Page 30 for the R3T) and this is what it reads:

How about you try just half filling the tank a couple of times if Ok, then fill to maximum and if the stutter comes back you can investigate the venting system ,just a thought ,may isolate the problem.

 

[Boog]

I ran nothing but 91 in my R3T for 5 yrs and am currently running it in my Roadster with out any negative effects,
Although CA gas seems to be different than what the rest of the civilized world uses, My gas mileage increased and my bike ran better on the RAA trip as soon as I left CA.

Thanks Jim. I normally wouldn't think going to a higher octane than required would cause anything negative and I have only used premium for these first 11K miles without any other issue. Another thread talks about getting bad gas from premium pumps due to the lower usage than the other tanks at the service station. I suppose that could be part of the matter.

 

[Boog]

How about you try just half filling the tank a couple of times if Ok, then fill to maximum and if the stutter comes back you can investigate the venting system ,just a thought ,may isolate the problem.

Thanks Ken, I will indeed test that idea.

 

[tdragger]

An old professor of mine who's life work was on octane requirements was adamant about running the proper octane that the engine was designed and tuned for. He was particularly critical of the myth that premium is always better than regular.

Back in the carb days, it didn't matter quite as much but with digital fuel injection systems of today, the tune is expecting a certain octane level. Flame front propagation and other properties of the fuel affect the timing and efficiency of the burn. Premium has a slower flame front propagation than regular and may result in unburnt fuel at the end of the burn stroke and the unburnt fuel ends up in the exhaust system. In the low compression tractor motors that we have, regular is the proper gas.

 

[Boog]

An old professor of mine who's life work was on octane requirements was adamant about running the proper octane that the engine was designed and tuned for. He was particularly critical of the myth that premium is always better than regular.

Back in the carb days, it didn't matter quite as much but with digital fuel injection systems of today, the tune is expecting a certain octane level. Flame front propagation and other properties of the fuel affect the timing and efficiency of the burn. Premium has a slower flame front propagation than regular and may result in unburnt fuel at the end of the burn stroke and the unburnt fuel ends up in the exhaust system. In the low compression tractor motors that we have, regular is the proper gas.

Thanks again James, this is all new to me. I love knowing the science of such things!!!

 

[Rocket Scientist]

I always stay below that metal thing with the holes in it when I fill up.