Question about 2002 Honda CRF 450 R

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2002 crf450, rough running, back firing, hard start

Hard start, back firing, sudden onset problem, valves? coil? replaced sparkplug but same.

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  • wsg29 Feb 20, 2009

    difficult to kick start, back firing, dificult to start when hot

  • Anonymous Mar 15, 2014

    it run good until gets hot then it starts to cut out like starving for fuel it back fires shut down but it will start up again run for a while and cut of again

  • Tony Young
    Tony Young Jun 14, 2015

    Rough idel?


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Would that cause a rough idal?

Posted on Jun 14, 2015

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Classic valve train issues. Sounds like the valves are tight. One thing that concerns me is the "sudden onset". Valves usually tighten over time.
Make sure you also tighten the cam chain as well.

Posted on Dec 27, 2008

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Yamaha warrior bogs when i go over rough terrain and back fires

When the bike is on rough ground the engine is under more strain so this may be a sign that the spark plug, lead or coil is failing.

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2002 Suzuki Marauder VZ800 Front cylinder does not fire till bike warms up a bit?

Definately try a spark plug first. What does the old spark plug look like? ( white, oil fouled, melted, metallic?). Usually a fuel issue will make the inoperable cylinder very hot. Might have a loose valve guide in the head, or a bent valve.

Oct 18, 2012 | 2004 Suzuki VZ 800 Marauder

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This is a 1984 1200 that will not start and back fires thru the exhaust and carbs

Back fire is an indication that the bike is firing incorrectly.
Your timing chain is probably stretched, due to the year.
inproper valve timing due to stretched timing chain will make the bike backfire.

I have other thoughts like stuck valves or inproper sparkplug wires on wrong plug,
i always start with easier and less expensive method.
1st check your sparkplug wires to make sure they are on the right plug.
2nd pull sparkplugs and do compression and leakdown test.
3rd pull componets to see if valves are opening and closing, (valve clearance check)
4th if valves are good, then timing chain is probably stretched.
5th if timing chain and timing marks are good, and valves are good, then proceed to
testing the signal generator to make sure your getting a signal to the cdi,
6th if you have a signal to cdi, the cdi tells which coil to fire. either # 1&4 or # 2&3.
if signal generator is working, but coils aren't firing right then its the cdi.
obviously your coils work because its firing, just back firing.

Thats all it could be from easiest to hardest.
Good luck and have a great weekend.
Big Al

May 21, 2011 | 1987 Honda GL 1200 Aspencade Gold Wing

2 Answers

Honda crf450 no spark atall plenty of power out of stator changed cdi nd had coil checked all ok tried dissconecting kill switch to.

maybe get a new spark plug.make sure your grounded(earthed). did you take the plug out and check for spark against the motor while you cranked the bike over?

Oct 17, 2010 | 2002 Honda CRF 450 R

1 Answer

1981 yamaha 400 twin was running o.k. now it back fires and hard to start .spark is white. it seems like its not getting gas ,i dont smell gas that strong when having to kick start.when it does run its...

You may have issues with;
Fuel flow, check filter for blockage, line for obstructions and floatbowl needle and seat for dirt.
Air/fuel mix. Clean carby with a aerosol carby cleaner and check operation of slide needles (rise/fall in unison)
Sparkplug; Reset gaps or replace if wary.
Top End, is camchain tensioner working, any undue valve train noise, has it been serviced at all.
Electrical. Check wiring connections and plugcaps, coil earthed and pluglead free of other wiring.


May 29, 2010 | 1982 Yamaha XJ 400

1 Answer

04 crf450.hard start when cold(25deg).kick for 10min.once it

1. First thing is when was the last time you had your valves adjusted
2. On cold start up twist about 15 times on your throttle, as you do that the accelerator pump in carb will shot gas in cylinder, I have a 2003 yx426 & 2005 yz450 have to do to both of them when cold out to get started

Feb 07, 2010 | 2005 Honda CRF 450 R

1 Answer

Suddenly became exremely difficult to start. Fuel ok. Battery fully charged. engine turns over like normal on the starter but just wont fire.

try to perform these :
1. Check the sparkplug if it is good or not,.if it will
ignite when you are going to start.if it doesnt ignite,replace with new one.but when after replacing it is still does not ignite,then its time to check the primary coil.You can check it by looking the wire coming from the said coil through the CDI..(mostly it is a black color with a little stripe of any color.) if you already found the said wire,start the motor and ground the said wire to the body with on & off motion.If while doing this you can notice a spark coming from it,then your primary coil is good.,Thus,its time to check your CDI or need to replace it.
But,if there is a fire in the sparkplug when you start the motorcycle but it doesnt work or fire at all,then you must clean the carburator.
Onthe other hand,if your motorcycle is a dynamo/contact point operated,you must check the "timing" into right settings,or give an importance to the condenser if it has a leak and may cause short during the motor will start..

Dec 05, 2009 | 2006 Aprilia Sportcity 125

2 Answers

In 4th and 5th gear at full rev seems like

If it is hard to start after it stalls, it is probably getting too much fuel. Could be dirt in the float valve. Also try running a hotter spark plug

Jun 17, 2009 | 2005 Honda CRF 450 X

1 Answer

Sounds like its only firing on one cylinder. running real rough. changed plugs same thing, lots of spark

Check all your wires around your coils to see if they are tight or to see if any are broke. Check your sparkplug caps and coils with a ohms meter.

Mar 20, 2009 | 1994 Suzuki VS 1400 Intruder

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