| Author | Message | ||
     Thatdudejoe |
I finally got around to changing the failed crankseal on my 98 S1 and on the test ride, I noticed that it sputters (actually, it shakes rather violently back and forth) at exactly 3K rpm every time I quickly accelerate under about 80+ percent throttle. It does not have this problem at all if I roll on the throttle, only when the throttle is quickly opened a large amount, say full for example. I know that that mainshaft nut is known for coming loose, but it only does it (and consistently at that) at EXACTLY 3K rpm. Once it passes this spot (around 3,250 or so), you can snap the throttle open as much as you want without any problem at all. Thanks, -Joe | ||
| Brinnutz |
LOL, seems to be a lot of these threads this year. Check front isolator, all exhaust mounts, rear isolators. Report back. | ||
| Thatdudejoe |
By the way, I WAS riding open header but it has been off before and never had this problem. -Joe | ||
| Thatdudejoe |
All three of those things look to check out. I just rode the bike right before I started on the seal a couple weeks ago and it did not have this problem at all. I was thinking that it is more of an engine or ignition problem because the sputtering is coming from the motor it seems like. It does this in every gear, and once again, exactly when it hits 3k rpm, like clockwork. -Joe} | ||
| Psycrow |
Sorry for the thread hijack but I have a question. When anyone posts about a vibe at 3k everyone responds with Front ISO and with good reason as Ive recently discovered myself... but WHY 3k? whats going on with this engine that 3k is the magic vibe zone? I thought these engines smoothed out after idle? Is there anything that can be done to reduce the 3k vibe zone to help the New ISO? Psy | ||
| Preybird1 |
The only sure fire thing is to split the motor cases and have your crank assembly balanced! My friend has one that has been balanced and you would not believe the difference. The sputtering is probably intake seals going bad or head temp sensor! I Had similar problems until i changed out the o2 sensor head temp sensor and all the throttle body and intake seals! | ||
| Thatdudejoe |
Yes, but this is kind of an "all of a sudden" problem, and the sputter is more of a hesitation, my apologies but I was unsure of what word to use to describe it. What happens is the bike accelerates hard, hits this troubled spot like a brick wall, usually gets through it depending on which gear you are in (e.g. tall gears take longer to get through the spot), and then continues to accelerate at its normal rate throughout the rest of the powerband. I was thinking it may have had something to do with a part that was effected during the seal change process by mistake or something. To reply to that last statement, there were no balancing problems with the bike "last week" so to say, when I rode it right before the repair. I know that failure or wear of a part is possible, but I am not so sure is is probable in this case as I strongly believe it is related to the repair. However, I am not a professional mechanic (20 y.o. college student) so I could be wrong. Also, due to my schedule (summer classes are worse than the normal semester, in that they hold you accountable for 4 months of work in 6 weeks), it is unlikely that I would be able to do an extensive inspection such as taking the motor out and splitting the case, not only because it would be extremely time consuming, but also because my resources are limited. Regardless, I GREATLY appreciate all of the insight you guys give on a daily basis! | ||
| Brinnutz |
Yeah, my bad...I read sputters as it shakes kinda thing...That'll teach me to drink and try to help | ||
| Thatdudejoe |
Haha no problem, like I said I enjoy all the insight I can get from you guys. Everyday with this bike is a learning experience for me! | ||
| Sparky |
I see yours has a Thunderslide kit. Have you done any work recently on the carb to change any of its settings? The other thing that can have an effect on throttle response at transitions from heavy throttle to part throttle is the Vacuum Operated Electric Switch (VOES) plugged into the carb which advances the ignition advance curve at part throttle and relaxes the curve at full throttle. If the switch is not working, let's say it does not advance when it should, there could be a hesitation effect at mid RPMs at about the same time that the carb slide is opening when RPMs rise. So, you might make sure 1) that the VOES is connected and plugged into the carb and 2) that it works. You can check it out with a multimeter and see if it has continuity with a little vacuum applied, 5 to 6 in. mercury. | ||
| Skntpig |
Have you tried running it with the whole exhaust connected? An open header might give you that stumble around 3K. | ||
| Thatdudejoe |
I just put the can on and rode it up and down the street a couple times and it did not sputter. However, I did not notice the problem last time until about 15 min into the ride. Unfortunately, it is about to rain here in MD so I will not be able to go for a ride today to really make sure that is what the problem was but I really hope that it was just my lazy neglect to slip the can back on that was the problem. I'll post back tomorrow. | ||
| Skntpig |
You probably did this in different weather last time. It just isn't jetted for no can and the weather. At least you fixed it. You could also try the A/F screw if it still isn't right. Google Sportster CV jetting. | ||
| Skntpig |
Oh yeah, you could search here for carb jetting and find tons of info. |
