Occasional stutter at 4-5000rpm | GTAMotorcycle.com

Occasional stutter at 4-5000rpm

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stangn99

Well-known member
Hey all,

I recently did the required 20k maintenance on my bike, which included:
  • new spark plugs
  • new air filter
  • valve adjustment
  • head bearing adjustment (also re-greased)
  • etc, etc
After doing all the work I rode the bike 2-3 times with no issues.

I rode it again yesterday and noticed a slight stutter at around 4-5000rpm. I think it happens when I'm slowly decelerating. I also notice my throttle wasn't "snapping" back like it normally did.

I checked and re-adjusted the throttle nut adjusters under the tank (I had to remove the throttle wire bracket to do the valve adjustment), and now it snaps back to 0% like before, but the stutter remains.

As well, after filling up gas at the station yesterday, the bike started kind of strange for the first time ever. It kind of wanted to stall for a split second, then stabilized itself right away.

I ran a scan and have no error codes.
Confirmed throttle bodies are balanced via TuneECU and DealerTool.
I'll have to do a bit more riding to see if I can reproduce the issue, but wondering if anyone has any suggestions on what I can check in the meantime.

15 Street Triple Rx
20,100km
Slip-on


Thanks
 
I would check the spark plugs gap and wires
 
ToSlow said:
I would check the spark plugs gap and wires
Click to expand...
I can't check the gap because they are dual electrode plugs (stock, purchased from dealer), but I will check to make sure the coils are pushed in all the way later today. I remember them being a pain to both take out and put back in when doing the valve adjustment.

I read there is also a 12 minutes adaptation procedure that can be performed on this bike (basically letting the bike idle for 12 minutes without touching anything). I'll try this out too but I'm skeptical.
 
Has it gotten any fresh gas this year yet?

Edit: I did read the entire original post, there was a delay in my mental mail. The bike does have fresh gas
 
GreyGhost said:
It got worse right after you got new gas? I'd drain a bit and let it sit to see if it separates.
Click to expand...
No, no. It's just that after I went to Esso to fill-up, starting the bike (engine at operating temp) was strange. It's never done that before. It almost stalled for a split second then corrected itself.
Gary said:
Gas line pinched / kinked?
Click to expand...
I've checked this, but will check again when I make sure the coils are in the plug tight. I routed literally every wire and hose exactly the same way it was from factory. Nobody has worked on the bike but me, so I know it's all back to stock routing for wires and hoses.

TwistedKestrel said:
Has it gotten any fresh gas this year yet?

Edit: I did read the entire original post, there was a delay in my mental mail. The bike does have fresh gas
Click to expand...
It has. The tank I just filled yesterday was the second fill-up this season.

I stupidly put 93 octane in it for it's first fill-up. I always put 89, but the first tank I filled up after winter storage got 93. I already pressed the button on the pump and was too impatient to wait for it to reset and start over.
 
stangn99 said:
No, no. It's just that after I went to Esso to fill-up, starting the bike (engine at operating temp) was strange. It's never done that before. It almost stalled for a split second then corrected itself.

I've checked this, but will check again when I make sure the coils are in the plug tight. I routed literally every wire and hose exactly the same way it was from factory. Nobody has worked on the bike but me, so I know it's all back to stock routing for wires and hoses.


It has. The tank I just filled yesterday was the second fill-up this season.

I stupidly put 93 octane in it for it's first fill-up. I always put 89, but the first tank I filled up after winter storage got 93. I already pressed the button on the pump and was too impatient to wait for it to reset and start over.
Click to expand...
Street triple is 89? Interesting
 
Evoex said:
Street triple is 89? Interesting
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I think the manual actually calls for 91 RON, and from what I remember it translates to 87 (or 89) octane. I've been putting in 89 for the past 4 years without issues...until yesterday. I can't imagine 93 octane would cause stuttering though, especially when it only happens between a specific RPM range.
 
I know nothing about street triples but doing a valve adjustment on a multi carbed bike like my ST1100 means you should re-syncing the carbs as the timing changes slightly. I assume your bike is fuel injected, but is there be some type of adjustment or fine tuning required to your FI system or other system post valve adjustment?
 
ReSTored said:
I know nothing about street triples but doing a valve adjustment on a multi carbed bike like my ST1100 means you should re-syncing the carbs as the timing changes slightly. I assume your bike is fuel injected, but is there be some type of adjustment or fine tuning required to your FI system or other system post valve adjustment?
Click to expand...
@stangn99 did the valves get adjusted or checked?
 
ReSTored said:
I know nothing about street triples but doing a valve adjustment on a multi carbed bike like my ST1100 means you should re-syncing the carbs as the timing changes slightly. I assume your bike is fuel injected, but is there be some type of adjustment or fine tuning required to your FI system or other system post valve adjustment?
Click to expand...

The only thing I'm aware of is throttle body syncing, which I've done using the Triumph DealerTool (and TuneECU to make sure they were all in sync).

GreyGhost said:
@stangn99 did the valves get adjusted or checked?
Click to expand...
I had to adjust all of the shims on the exhaust side (well out of spec on the tight end).
Intake side was okay and within spec.

I even used the OEM timing pin tool to lock the gears in place, and cable tied the intake cam to prevent any chance of the chain moving around.

At the end of the job the alignment marks on the cams lined up perfectly with each other (which I suppose means the cam chain is not stretched as I had initially thought).


TK4 said:
I'm still thinking water in the fuel. Run another tankful or two through it and see if the problem persists.
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The tank I have now is 89 octane. I'll run it dry but I doubt water is the issue. My garage is also heated and averages 17-21 degrees throughout winter, if it makes a difference.


I also just finished checking the spark coils - all three are in nice and tight.
All hoses are in place and not pinched in any way.

I'm going to try the Triumph Adaptation process later today to see if it helps at all.

Thank you all for the suggestions so far.
 
Hmmm? ALL the exhaust were lot of spec? Very strange. I think this may be where the problem is. How far out were they?
 
The spec is 0.325mm to 0.375mm

I measured/felt anywhere from 0.29 to 0.31. I re-shimmed all 6 valves to anywhere from 0.34 to 0.36 depending on the shims available from the dealer.
 
I have never heard of an engine going that far out of spec in 20k. Especially on just one side. Something is not right there.
 
Wingboy said:
I have never heard of an engine going that far out of spec in 20k. Especially on just one side. Something is not right there.
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My old ninja 636 was the same. All 8 exhaust clearances were well out of spec on the tight end, though that motor had 31,000km on it. All intake ones where within spec.

Perhaps it's my riding style? I don't know ??‍♂️. My bikes never see redline. Only reason I immediately noticed the stutter at 4k rpm is because that's usually where I'm at most times. I usually shift and hover between 4-6k rpm.

Edit: meant to say 8 valves, not 16
 
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Always shim to the loose side of the spec.
When you take it out and hammer on it clearances can tighten up because you've blown off whatever minimal, residual carbon buildup there may have been on the valve seats.
 
Quick update: looks like problem may be solved.

I ran the "12 minute tune" as per TuneECU instructions. I actually left it to idle for 20 minutes for good measure.

I've done about 50km so far without any stuttering. Rolling on and off the throttle also seems to have gotten slightly smoother. I'm not sure what exactly the 12 minute tune does, but I'm hoping the problem is fixed. From what I've read I think it may have reset the TPS forcing the ecu to re-learn everything.

From TuneECU:

The 12 minutes tune:
Ensure the transmission is in neutral.
Ensure the ECM has no stored faults (DTCs).
WITHOUT TOUCHING THE THROTTLE, start the engine and allow it to warm up to 90°C .
Leave the engine to idle for a further 12 minutes.
 
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