2006-2009 Suzuki 450 (LT-R450) Engine Idles Rough

2006-2009 Suzuki 450 (LT-R450) Engine Idles Rough

Suzuki 450 ATV engine idles rough refers to when the Suzuki all-terrine vehicle’s engine runs poorly while out of gear or disconnected from a load. The following information details symptoms and possible causes as well as remedies you should follow if your Suzuki LT-R450 (LTR450) won’t idle correctly.


2006 2007 2008 2009 Suzuki 450 (LT-R450) Engine Idles Rough

  1. Cracked or damaged vacuum hose. Inspect hose and replace if necessary.
  2. Vales not seating correctly. Either replace or repair the valves.
  3. Damaged or defective valve guides. Replace with new guides.
  4. Worn down camshafts. Install new camshafts.
  5. Spark plug gap too wide. Adjust gap to factory specifications or replace. See repair manual for gapping specifications.
  6. Defective plug cap/ignition coil. Replace with new parts if needed.
  7. Defective crank shaft position (CKP) sensor. Use a multimeter to test sensor, replace if necessary.
  8. Defective throttle position (TP) sensor. Test sensor and replace if needed.
  9. Faulty fuel pump. Replace with a new unit.
  10. Cracked or damaged vacuum hose. Replace hose.

It’s highly recommended to use the downloadable repair manual when performing service and repairs to the Suzuki LT-R450. Additional information regarding engine idles poorly is included in the ebook.


  1. Can someone tell me the base setting (turns out) for the idle air screw on a 2008? I don’t see it in the manual.

    • If you are referring to the fast idle or high idle, a lot of people just blocked it off. Adjustment procedure is on section 2-12 in the manual.

  2. I have ltr 450 and idle is fix @ ~ 1500 rpm and cannot be adjusted. The idle is rough and stuttering. When I turn the idle screw the ATV engine goes directly with a big bang out. The other rpm’s are fine.

  3. My all-terrine vehicle 08 model ltr-450 has rough idle and won’t stay running. I have full Yosh exhaust cherry bomb and Rekluse clutch. I have checked all the sensors and replaced the stator, set tps, cleaned injector, installed new spark plug and have checked valves but I haven’t been able to figure out the problem.

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