Question about 2005 Honda CRF 450 R

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Bike keeps back fireing when first starting

I just got a crf 450r and every time i go to start the bike it always back fires for ages then it mite go or not is it stale gas or is av gas the bike shop ffilled it up when i got it what would be a good gas to run plz

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  • b_cfalcon Dec 25, 2008

    Awesome, cheers for that!!! It is very much appreciated. And thanks for getting back to me so quickly

  • Anonymous Mar 28, 2014

    back fires ran bike without led substude forgot to put in the gas did i burn my vales

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Hi and welcome to FixYa,

Initially, backfiring is a spark/timing issue or contaminated fuel (water) or as you stated stale fuel. AVGas would not result to backfiring but rather a stronger pull though would heat up easily.

Good luck and Thank you for using FixYa. Happy Holidays.

Pls be informed that due to my current rank and rating, even a Helpful would be detrimental to my status. Should this solution not address your concern, it would be appreciated if you could just not rate it at all. Cheers.

Posted on Dec 25, 2008

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1 Answer

I have a Yamaha yfz 450r it don't wanna start up it turn's over and just back fire's


Hi nice ATV, Usually a single cylinder motor that back fires is either the timing Or a dirty spark plug. Check out this youtube video, This guy shows the right colour spark and I didn't know this but it should spark over the top of the centre electrode, Hope the is helpful.. CHEERS...
https://www.youtube.com/watch?v=mUOmsGiirTU

Mar 15, 2016 | Yamaha Motorcycles

1 Answer

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


hello
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

1 Answer

It back fires when i let off the gas and will run for about ten mins then just quite and it will start i thought it mite be that i have bad gas or the spark plug faled or my valves need adjusted do you now...


the back firing is normal on a fourstroke and try cleaning your carb the carbs on those bike are a regular maintenance item if they set for any period of time they need to be cleaned

Mar 27, 2011 | 2004 Yamaha YZ 250

1 Answer

2007 honda crf 250. Sat for 1 1/2 yrs. won't start by cranking, or pushing.


Try a small shot (about a 2 second spray) of starting fluid in the air intake then cranking....
WARNING- DO NOT TRY AND KEEP IT RUNNING BY USING THE STARTING FLUID! It can damage your engine.

If your bike fires and runs for a bit, the most likely problem is your gas has gone "sour". You need to drain all the old gas out and properly dispose of it.

Over time, gas will cause a varnish buildup in your carb if it sits too long. You can try adding some carb cleaner to fresh gas, but the results will not be immediate. You may have to have the carb rebuilt.

When you store anything gas powered, there is an additive called Sta-bil that will act as a gasoline preservative for about a year.

Feb 13, 2011 | 2005 Honda CRF 250 R

1 Answer

Engine back fires


It may still have some water in the tank/system or the spark plug is no good.With a full tank of fuel,add 200ml of methilated spirits.It breaks up any moisture and lets it burn away.Also,with the motor out of gear,run the bike at higher revs and close the choke fully on and give full throttle at the same time.When the motor starts to die,flick the choke off.This can sometimes unclog a carby jet that may be slightly blocked because with the air choked,it gives a sudden **** off fuel.This may/maynot fix the bike but it the 1st thing to try before paying a dealer and it can't hurt anything.Hope this helps you

May 29, 2010 | 2003 Honda CRF 230 F

2 Answers

2005 Honda TRX 450r is blowing out antifreeze from the overflow.


hi,without seeing the bike i would guess that the head gasket has failed,when this happens the compressed gasses inside the combustion chamber escape into the coolant system and presurize the coolant,the end result being coolant escaping out through the overflow as the pressure increases,i would recommend getting it looked at fairly promptly as the engine will start running poorly and possibly fail...cheers

Sep 12, 2009 | 2005 Honda CRF 450 R

3 Answers

Hard to start back fires


i think there is problem in ur fuel pump or the pipe check it out 1st

Jun 19, 2009 | 2002 Honda CRF 450 R

1 Answer

Crf 450 running hot


Back firing usually indicates a timing problem.

Apr 30, 2009 | 2002 Honda CRF 450 R

2 Answers

Problem starting


sounds more like a slipped timing chain to me, big problem area on the big power 4-strokes, tokyo mods makes a manual timing adjuster, will make a big difference in longevity of your next timing chain, i wound also check the vaves to make sure the piston hasn't shaken hands with the valves

Dec 25, 2008 | 2005 Honda CRF 450 R

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