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Discussion Starter · #1 ·
Hi!

First thing first, bike is a 2007 Daytona 675, stock except for Annitori QS, rearsets, levers, upgraded suspension and K&N air filter.

Weird issue happened yesterday while at a track day. Exiting a somewhat fast left corner before short straight, 3rd gear, I thought I had lost the rear when accelerating past the apex and kept it upright by miracle but upon getting back on the throttle with the bike now in a straight line, "it" started again.

"It" was the same as hitting the rev limiter (engine cutting off) but I was only at 8000 RPM. I did not push to see if would have gone away at a higher rev but as long as I kept it under 8000, everything was good. I did not know at that time that this was its limit. Quick check of the bike showed no leakage or smoke so I completed my lap at a much slower pace (arm raised, off the race line, etc.) but on a later part of the course, I was in 4th gear at the time, I hit than same behavior around 8000 RPM also and was able to reproduce it a couple more times.

My next track day is in about 4 weeks so I have some time to look for the issue and fix it.

First of all, has anyone here experienced this issue? What was causing it and how was it fixed? I had in the past an issue with the coolant temperature sensor acting up but although the bike was also giving the feeling that the engine was cutting, it was also showing other signs I did not have this time (high RPM, weird temperature display, impossible to start, flooded engine, etc.).

My plan to troubleshoot this new issue is to have a look at:

  • Quickshifter: starting the bike in the pits on race stands and playing with the shifter rod did not cause a problem. I'll try to bypass it if I still haven't found the issue next time I am at the track (or on a Dyno if I can find one around here).
  • Fuel pump/Fuel filter: bike is a 2007, this was never replaced or serviced. Not a bad time to look at this as I was to switch with another gas tank I have anyway. Is it possible to replace just the fuel filter? Can't find a part# for this, just for the whole pump assembly.
  • Clutch: looking for warped plates. In the pits, 1st gear almost at idle while going/coming from pit exit/entrance, bike was somewhat jerky, not smooth as usual. Sign of a clutch slowly dying that finally did later on the track?

I am open to suggestions!

Thank you!
 

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Discussion Starter · #2 ·
Followup

Looks like this was a popular subject but no reply...

Update: Issue still present after having:

  • Checked the QS, no issue with it, even bypassing it still show the same problem
  • Checked and adjusted the EXUP valve, was not seized, cables look to be stretched a bit because adjustment was not easy to do (matching the arrow to the stopper using TuneECU), did not disable it to rule it out
  • Checked the sidestand switch, cleaned and greased the stand, no issue there either, did not bypass the switch to rule it out
  • Fuel tank connections, one vent was disconnected, all the other connectors were in place so replaced the vent, no luck issue still present
  • Was a little more "persistent" this time, it helped that I was testing it off track and after the problem was repeated at around 8k rpm, once over it, engine is running fine

Still to check:

  • Fuel pump, I doubt very much the issue would it be there as revving the engine past 8k rpm (more like 9k or 9.5k) doesn't show the issue anymore
  • Clutch, I doubt very much again that this would be the issue as it was in neutral for the off track testing (on race stands)

Still open to suggestions! There is a great volume of knowledge here, from multiple forum members. I have not given up.

Tks! :thumbup:
 

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Check to see how much free play you have at the clutch lever. I've seen this a few times, on track especially. If you don't have enough free play at the lever, when the engine/clutch gets hot, it can start to slip, which feels like hitting a rev limiter.
 

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Discussion Starter · #4 ·
Update #2

So, after more work on the bike, it was found that bypassing the QS "resolves" the issue. That's between quotes because I am not convinced (maybe I should) that the issue comes from the QS itself. By bypassing, I mean to disconnect the QS and then connect the provided bypass plug to the coil loom.

After reading some posts about other QS "failing" where the cause was sometimes the charging system and not the unit itself, I am leaning toward testing it to rule it out before buying a new QS.

I've found this page (https://www.triumph675.net/forum/showpost.php?p=463591&postcount=1) to help in testing the charging system but is there something else I should be doing differently or in extra? I haven't read the whole 1000 posts in that thread, let's be honest.

Thank you!
 

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Discussion Starter · #5 ·
Check to see how much free play you have at the clutch lever. I've seen this a few times, on track especially. If you don't have enough free play at the lever, when the engine/clutch gets hot, it can start to slip, which feels like hitting a rev limiter.
Nice suggestion btw but it was possible to reproduce the issue on race stands, in neutral.

There is enough free play at the lever for the clutch to operate as designed.

Tks
 

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Strange. Best guess is that vibration at that rpm causes the qs switch to activate and remain on. If so, it's probably the switch on the shift linkage.
 

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Update #2

So, after more work on the bike, it was found that bypassing the QS "resolves" the issue. That's between quotes because I am not convinced (maybe I should) that the issue comes from the QS itself. By bypassing, I mean to disconnect the QS and then connect the provided bypass plug to the coil loom.

After reading some posts about other QS "failing" where the cause was sometimes the charging system and not the unit itself, I am leaning toward testing it to rule it out before buying a new QS.

I've found this page (The Definitive 675 Charging Diagnostic/Upgrade Thread) to help in testing the charging system but is there something else I should be doing differently or in extra? I haven't read the whole 1000 posts in that thread, let's be honest.

Thank you!
Did you eventually get it fixed? I am having exactly the same issue today on track. Found this thread and unplugged the QS connector and it worked, although I did see the provided bypass connector, simply just pulled it out.
 
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