Introduction: 7 Things to Do When Your Dirt Bike Won't Start

Picture of 7 Things to Do When Your Dirt Bike Won't Start

Sometimes when your dirt bike does not get used, it won't start.

Here are some ways to start a "mad motor."

Step 1: Follow These Steps to Get Your "Mad Motor" Running

Picture of Follow These Steps to Get Your "Mad Motor" Running

1. Make sure the gas line is ON.

2. Make sure you have gas in the dirt bike.

3. Make sure the spark plug boot is pushed in.

4. Make sure you have spark. To test for spark, take the spark plug out from the head, but not out of the boot. Put it against some metal on the bike and turn it over while kicking the kick start (or if you have an electric start, use that). You should see spark. If you see no spark, then put a new spark plug in. Make sure to put the right size spark plug in and do not over-tighten the spark plug.

5. Use choke.

6. If the motor has not run in a long time (i.e. more than 1 year), you should put new gas in it.

7. Once you have done all of these steps and it still won't start, then clean the carbs.

8. Clean the air filter.


RobertJ205 (author)2017-11-07

I just bought a yz250 for a project. Rebuilt the top end put brand ne carb and spark plug. It get a lil spark but not a lot. It just wont crank i even tried to roll down hill. She want to crank but just wouldnt crank

nicoa28 (author)RobertJ2052017-12-09

What colour is the spark? Must be a nice blue spark. Is the air filter clean? I'm guessing you need a new coil

m4xrusso (author)2017-09-07


I tune up my kid Dirt B. more than a year ago, we used for a
month and leave it untouched for a year. We are in Florida and we need it NOW
to use it after #hurricaneirma, I change the gas and fill it with new gas. Check everything
I check like when I had my Honda XL125S 30 years ago. But nothing works… any advice?
Hurricane is coming


HunterD29 (author)m4xrusso2017-09-29

1. check and clean/replace the fuel valve Filter or replace the fuel valve all together (repair cost $10), in my case i had let the bikes sit for 2 years with the fuel valve turned ON and the dried up ethanol created blockage that couldn't be cleaned.

2. Replace the air box filter and make sure its cleaned out real nice, a new freshly oiled air filter will make sure your carburetor doesn't suffocate (repair cost $20).

3a. Try to get the engine going using the methods in this article. If it starts up fine but still struggles to keep running, buy some seafoam engine cleaner ($10) and create a 50% gas 50% cleaner mixture and inject it directly into the carb. Let it run on that for an hour, then directly inject 100% cleaner until the carb dies out, let it sit overnight. The next step is to connect the gas line back to the carb and run the bike until all the cleaner is pushed out of the exhaust. This is the method i used to get all 3 of my families bikes going after letting them sit for 2-3 years.

3b. If the engine does not start after steps 1 & 2, buy a new carburetor. (Repair cost $80-$120)

JohnH664 (author)2016-09-17

look i have a 2003 honda cr85 that wont start I've changed a Magneto change the spark plug to the carburetor rebuild kit and check the reeds I know it needs a new stator I push started it once and got it to crank up but after that it won't do nothing but bog out trys tp start but wont it doesn't seem to be getting gas it had a little bit of nasty milky water in the head I checked the head-to-head seems fun and it seems like it has good compression but I can't get it to crank up even if I push start it again I don't know what to do please help

JohnH664 (author)JohnH6642016-09-17

I've even checked the kill switch the one time it started it took off on me but the throttle wouldn't give it gas or slow down it just took off as fast as I can go and I had to hit the kill switch I really don't know what to do i mean the head and the piston looks fine it's got compression I clean the exhaust pipe and change the oil too

chantimm04 (author)JohnH6642017-05-17

i think your problem is its idled to high

JonH129 (author)2016-09-26

my bike started up and i let it run for a minute and when i went to leave it staled, ive checked the plug and my magneto and it still wont start, if you think you know the issue text me at 810-341-2351 thanks

hflorman (author)JonH1292017-05-07

You might wanna try turning UP the idle

Wywon1 (author)2017-03-18

I tried all of these things, still won't start it wants to start but it doesn't I have a 1990 kx80 text me to help me out 720-618-5970

JohnH664 (author)2016-09-17

if u can think of anything text me 5042566965

JanD100 (author)2016-09-16

I did all these steps put a new carb new spark plug for my 125cc sdg mini speed pit bike still wont start sound like backfiring in the engine like a cough

DylonW (author)2016-06-02

Hey guys i have a 2001 rm 80 and i took it down the street for a little to long and it shut off i put a new piston in it but still wont start. Ive tried roll starting it and itll run for a sec and then shut right back off. Ive changed out all the oil and not sure else what to do what do you think?

hflorman (author)DylonW2016-06-04

Might have been the spark plug or the spark plug boot.

hflorman (author)hflorman2016-06-29


hflorman (author)DylonW2016-06-04

It might have overheated.

JacobA31 (author)2016-03-29

Mine keeped bogging down in first after I cleaned the carb and the air filter and all of the sudden it was hard to start and once I got it started and i had it at full throtal in 3rd gear and it bogged down and died and it wont start and it has plenty of gas and is getting spark. any help?

TerrellB3 (author)JacobA312016-06-28

Could use a tune

JacobA31 (author)TerrellB32016-06-28

I think there is something wrong with the rings or there is a hole in the piston soon i will take it apart

TrevorK18 (author)2016-05-17

What would you guys think the problem is...i went to go ride my bike after riding it a few hours rhat day and then it just souldnt start...its a yz250...i changed the plug and all partially turns over and i smell gas...any thoughts?

mykiscool (author)2015-08-09

Easy starting technique (won't fix hardware issues except the kickstarter)

1. Walk to the side of a steep hill

2. Shift into 1st and pull in clutch

3. Push of the side of the hill

4. When you get going fast let the clutch out and give a small ammount of throttle

mattydeee93 (author)mykiscool2015-08-17

Personally i find doing it in 2nd gear is more effective as there is more chance of you being able to turn the engine over, i also jump down off the pegs onto the seat just as i let the clutch out

mrandle (author)mykiscool2015-08-16

I find second works a bit better depending on the situation. Especially on flat ground.

hflorman (author)mykiscool2015-08-10

Always works.

DoStuffRight (author)2015-08-06

if it has been sitting with gas for a little bit, the pilot jet is most likely clogged. this could also be the problem if the bike sounds like it isn't getting enough gas.

dgodwin3 (author)2015-08-06

Another good trick is to take out the spark plug and put a little gas down the hole to get it fired if it sat all winter.

rottnjeep (author)2015-08-06

Good ideas for just about any small engine that people sometimes forget about

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