How does a quiet insert effect jetting?

10 replies to this topic
  • rmcr250r

Posted September 17, 2010 - 04:07 PM


currently have a fmf ti4 slip on on my 09 running it with a 165 main and the bike ran great. Since i installed the quiet insert it runs pretty rough. Poping and hard to start. Would putting an insert in create a lean condition?

  • grayracer513

Posted September 17, 2010 - 04:51 PM


It can be a little hard to guess sometimes which way it will go, but yes, sometimes if the insert interferes enough with air flow though and out, it can cause a lean condition by softening the strength of the intake vacuum in the carb. Once you get it running, see what happens if you back the fuel screw out a ways. That will tell you (and it may be all you need to do).

  • YamaLink

Posted September 18, 2010 - 07:29 AM


This doesn't answer your question, but I had the same convo with a friend on his 09 with a quiet insert; not the same brand as yours and his jetting is a tad different.

It did affect his but just minimally, not poppping and not lean. His actually became a tad richer down low and he lost some high end rpm. I left his place late and he did not turn the fs so maybe he'll have a report at the end of the weekend....but I'll be in Italy and won't know of his final tune findings.

  • rmcr250r

Posted September 19, 2010 - 04:48 PM


Messed with the fuel screw and it seemed to run alot better. But it was also in the 70s today whereas it was in the 50s last time at the track so maybe that made it run leaner.

  • rmcr250r

Posted September 26, 2010 - 04:01 PM


Ok had the bike at the track today and it staight out ran like crap. Wont start easily lots of popping. Once it does start it bogs immediately and stalls. Is this a rich condition? I really cant tell for myself.

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  • grayracer513

Posted September 26, 2010 - 07:53 PM


Is it better or worse with the choke on? Or the hot start?

  • rmcr250r

Posted September 27, 2010 - 09:19 AM


Starts up ok with choke on but hot start didnt do too much to help re-starting.

  • grayracer513

Posted September 27, 2010 - 09:37 AM


Does it run better with the choke on while it's running?

  • rmcr250r

Posted September 27, 2010 - 11:16 AM


Yea seems like it does. Once i take the choke off and give it gas it will stall. Takes like 10-15 kicks to get it started once its warm and the hot start doesnt seem to make a difference in making it any easier.

  • grayracer513

Posted September 27, 2010 - 11:21 AM


Sounds lean then, since making it richer helps, don't you think? Has the bike stood around unused for a month or two at some point before this started?

  • rmcr250r

Posted September 27, 2010 - 12:42 PM


Sounds lean then, since making it richer helps, don't you think? Has the bike stood around unused for a month or two at some point before this started?

It gets ridden usually every other weekend. Like i said bike ran 100% before this insert was installed. Ill mess with the clip position and see if that helps at all.

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