Motorcycle Repair/07 crf450r



I recently got this bike and it was running great, aside from the difficulty starting when hot. I purchased the boyesen QuickStart3 and installed it today. This made a world of difference for starting the bike and its much easier now, hot or cold. The problem is the loud, excessive backfire in deceleration now, which was not an issue before. I've tried making minor adjustments to leak jet(adjustable w/qs3), idle, air/fuel mixture.. I can't figure it out. Any ideas? Any knowledge on this subject will help. Thanks.

Brian, My son had this same bike. His however was more noticable with the after matket FMF pipe. He did not have the hot start set up but it may be an annoying problem thats the "nature of the beast" thing. Try checking the cylinder to pipe seal as they can suck air and do similar things.

Motorcycle Repair

All Answers

Answers by Expert:

Ask Experts


Gary Blake


I have built from ground up race winning motocross bikes and atvs as well as atv,s for flat track and TT racing. I am starting to take on the utv challenges now for racing. This is a new area for me so Im in a learning curve.


I have extensive experience in off road motorcycles and atv,s.I also work on street bikes and personal watercraft, Some experience was self taught and some was factory trained. I have been working in the powersports industry since the mid 70,s I hope I can help. Thanks Gary

Was a sponsor for K.O.R.R.(kansas off road riders) and now I am working with ROMEO,s (retired old motorcyclists eating out)and was in charge of the Quad Wars for the monster truck series in Central Kansas

Factory trained Kawasaki Heavy Industries. Factory trained GasGas motorcycles and atvs worked as a technician and was as a dealership owner.Kaw.Suz,Honda,Aprilia,Arctic cat,See Doo,Can Am, Bombardier,Yamaha,GasGas,Qingi,TM,Moto Guzzi,Harley,s

©2017 All rights reserved.