Triumph street triple suddenly slowing issue

[Powerslave]

Hi everyone,

 

I wonder if anyone can give advice...? I have a Triumph street triple RX (2016) i have an irritating issue with the bike slowing suddenly for no reason at all. This happens when I accelerate to around 6000 revs and then drop off the throttle, the bike slows normally with engine braking but then something else kicks in and slows the bike suddenly for a second or two and then drops out again. It's like the front brake is being applied but I'm not touching it! This is sporadic and I have no idea why it's happening. Triumph ran a diagnostic and said they couldn't find anything wrong. I spoke to my local mechanic and he said he thought it was something built into the bikes CPU to do with meeting emissions targets. I've had this issue since I bought the bike from a dealership, they also said they couldn't find a fault!

Anyone got any thoughts on why this is happening?

[Mississippi Bullfrog]

A lot of modern bikes run very lean and this can cause engines to snatch at low throttle settings. It's not clear at what speed / rpm you are experiencing this issue. You could try fitting a booster plug which fools the ECU into thinking the engine is colder than it is so the off throttle mix is richened slightly. It certainly made my Bobber 1200 smoother on the over-run.

[Powerslave]

Hi Bullfrog, thank you for your response. It happens when I throttle off at between 6 and 8000 Rpm. So the bike is effectively coasting...as it slows (no throttle at all) to around 3000rpm the sudden slowing or braking issue kicks in for about 2 seconds and then drops out again. It doesn't happen everytime but the more aggressively I ride the more noticeable it is. I can counteract it by adding a tiny bit of throttle but i shouldn't have to do this. It's pretty frustrating!

[Ian Frog]

I know this may sound really stupid but do you happen to know if these occasions when it happens coincide with a full or empty tank or are random?

It may be worth checking the simple things like fuel tank breather mechanisms before starting down any path that leads to expense.

My reasoning is that during deceleration the engine still has a requirement for fuel but the amount is greatly reduced and during the same period the fuel can be moved to the front of the tank.

Just a thought.

Cheers

Ian

[Powerslave]

Hi Ian, no it doesn't make any difference if the tank is full or otherwise it's always there...if i'm just commuting or taking it easy you don't really notice but if i give it some stick then it really becomes irritating. It feels like someones feathering the front brake even though i'm not touching it, it almost pulls you forward...it's just plain weird!