2011 yz250f hard to start

Check your valves. They need adjusting i'm sure.

bmach wrote: I bought my bike less then a month ago and have been haveing problems getting it to start. Its easy to kick and sometimes you can hear it wanting to start but it takes along time to get it started. Im talking 50-100 kicks is there anything i can do to get it to start easier or anything you think i may be doing wrong to cause this?

How many hrs on the bike? Make sure you have spark, fuel, clean air filter! choke on when cold, hot start when warm? make sure when your kicking it over, NO throttle!

In total there is maybe 6 hrs on the bike. I changed the oil and everything after the break in, didnt think to check the spark, but the air filter is clean, use the choke when its cold and when the bike is warm i have no problem getting it started its just the initial start that is a problem.

If you still have a 30 day yamaha warranty on it, take it up to the shop or any yamaha place if they still offer the 30 day plan? Try a new plug and some fresh quality fuel! If its starting i guess your getting spark LOL, Most new bikes take some break in time and will start easier, but it should nt take that much to start it! Try the plug and fuel! If its within 30 days call the shop.

your symptoms sound like tight valves which is part of routine maintenance and probably will be covered by warranty.

lumpy790 wrote: your symptoms sound like tight valves which is part of routine maintenance and probably will be covered by warranty.

? routine at 6 hrs, dam.

Another four stroke not starting? That's a shame.



Your best bet is to trade that heap in while you can and get a two stroke.

If you are using pump gas (with ethanol) check your slow speed jet and see if it is blocked.

im useing 110 octane race fuel

bmach wrote: im useing 110 octane race fuel

Leaded fuel? Leaded fuel is not good for valves..Modern 4 strokes are meant to run off of pump gas unless the engine is modified then 100-105 octane.

u4. 4 is great if you got the cash.

lumpy790 wrote: your symptoms sound like tight valves which is part of routine maintenance and probably will be covered by warranty.

mxb2 wrote: ? routine at 6 hrs, dam.

I am used to street 4 strokes but they get valve inspection at the 1st service...... I know I check them after break in along with stripping the bike down and greasing.

bmach wrote: im useing 110 octane race fuel

mx295 wrote: Leaded fuel? Leaded fuel is not good for valves..Modern 4 strokes are meant to run off of pump gas unless the engine is modified then 100-105 octane.

the manual says to use 96 octane or higher and premiume is only 92

I know you're the one with the manual, but I call BS.

bmach wrote: the manual says to use 96 octane or higher and premiume is only 92

There's a difference in octane rating systems. The manual is specifying RON octane ratings. In the US octane rating is displayed in AKI. In some east coast states, up to 94 AKI (98 RON) is available [4]. In Colorado as well as parts of the Midwest (primarily Minnesota, Iowa, Illinois and Missouri) ethanol-based E-85 fuel with 105 AKI is available [5]. Often, filling stations near US racing tracks will offer higher octane levels such as 100 AKI[citation needed] . California fuel stations will offer 87, 89, and 91 AKI (91, 93 and 95 RON) octane fuels, and at some stations, 100 AKI or higher octane, sold as racing fuel.

For us in central Missouri, the best pump fuel to use in four stroke race bikes with stock engines is Conoco/Phillips 93 octane that is labeled as "No Ethanol". Some other brands will have an identical fuel as well, but I have found that BP's 93 octane (if the station has it) does contain ethanol.

Gas mixtures vary greatly from region to region and distributor to distributor, so you can't even count on a particular brand in one area to be identical in another.

Yamaha valves normally seem to last longer than the others, but it wont hurt to check the clearance.

When you bought the bike did it have gas in the tank? Even though it was new (I assume it was new?) if the dealer had put in some regular gas in it to start it after assembly and then it sat there for sale for awhile before you bought it then its very likely the pilot jet is plugged or partially plugged.

Most of the 250f"s around here that I have dealt with run better if you go one size bigger on the pilot jet. If you are not good on jetting, one sign of a lean pilot circuit is popping/backfiring on de-celeration. When you have your carb off its a good idea to replace the stock fuel screw with a good aftermarket screw with the knob that you can easily reach to adjust.

Have you put a new spark plug in? With a fouled plug, it will never start. Did you jet the bike for 110 fuel? Probably running rich. Check the pilot jet, make sure it's not clogged.

Thanks for all your input guys. I went and cleaned the carb changed the spark and changed the fuel. Since then the bike has started alot easier and usually within a few kicks.

bmach wrote: Thanks for all your input guys. I went and cleaned the carb changed the spark and changed the fuel. Since then the bike has started alot easier and usually within a few kicks.

cool, make sure you use good fuel.

bmach wrote: Thanks for all your input guys. I went and cleaned the carb changed the spark and changed the fuel. Since then the bike has started alot easier and usually within a few kicks.

mxb2 wrote: cool, make sure you use good fuel.

Yes SIr! I plan on it... I thought i was until i started this thread.

bmach wrote: Thanks for all your input guys. I went and cleaned the carb changed the spark and changed the fuel. Since then the bike has started alot easier and usually within a few kicks.

mxb2 wrote: cool, make sure you use good fuel.

bmach wrote: Yes SIr! I plan on it... I thought i was until i started this thread.

lol, if you got the cash VP u4, 4 is good, renegade, dragon make good products, not cheap! but you get what you pay for!

I have had an 09, 10, and now 11 yz250f's. My 09 and 10 started flawlessly so when I went through the same thing on my 11 as you are doing, I was really bummed out. I was explained by a dealer that sometimes there is a "coating" from the factory on the jets and it causes hard starting. I cleaned out the carb and jets and got out a small amount of varnish type stuff. It starts just as good as my previous bikes now.