2012 Txc 310 Won't Start!!

My dad bought a nice very low hours txc310 2 weeks ago. It started up and ran fantastic on Sunday and Monday. On Tuesday it was a cold day he said it was hard starting for 20 or seconds and then he gave it some gas at the same time and it fired right up. I told him to try the red lever on the bars since it was supposed to act like a choke for EFI so the next day he did and it fired up immediately. He ended up holding the lever in for about 2 minutes while the bike ran and then it died and has not started back up since. It turns over fine and you can hear the fuel pump cycling but acts like it is either not getting fuel or not getting spark. I was told to replace the temp sensor because they are known to cause problems but that did nothing. Any suggestions? I don't want to start randomly replacing things to find out what's wrong with it. thanks!

You can test for spark by pulling the plug testing it against the engine. With the plug wire attached, kick push the starter button for 5 secs with the plug grounded to the engine. Take pictures of the plug, it may offer clues.

You can also do the same thing with the injector to test for fuel flow.

I'm swinging in the dark here, you may want to sample the gas in a clear container. If it is amber yellow, the gas could be really old. People often sell bikes after they sit for a couple years of non-use. Fresh gas is important. If the gas is bad, you may need a new fuel filter and your injector may need a good clean.

Why did your dad hold the decompression lever for 2 mins? Did he need to do that to keep it running?

Good comments.

Yes smell the gas.

That "decompression lever" is actually a air bypass valve to increase the idle RPM when cold.

I suspected maybe the injector or fuel filter maybe clogged but it ran good for quite a while then all of sudden it quit. The gas checked out ok. As for the lever I read here that it was used to aid in cold starting because we were not sure what it was for, I think he assumed it worked like a choke and needed to be held on until the bike warmed. We will check for spark, thanks for suggestions.

My appologies. I'm not very familiar with the 2012 Mikuni EFI model. If this is an air bypass (increases air flow) and it worked, I believe this would suggest it's running rich or the fuel is poorly atomized. I would clean or swap the injector.

You can tell if the temp sensor has been updated by inspecting it. If it is white, it's the new style. I think the original ones were colored. You can also check the part number. The old one was 8000a6736 and the new one is 8000h3649.

We did replace the temp sensor already but that did nothing. I'm suspecting fuel injector and or filter. thanks

You may have to hook it up to iBeat. Only way to set TPS and adjust CO1,2,3

I hold the cold start lever on for a minute or two but I'm at 8000 ft. Is there a significant altitude difference from where it was owned previously to now? It kind of reminds me of a small engine that will start and run on choke but is too lean otherwise. So fuel flow could be it.

No the elevation is the same. When it was running it ran great. The first issue was starting it on a cold day. It was reluctant to start for about 20 seconds or so but once we gave it gas it fired and ran fine without ever touching the lever. The next day the lever was used and held on to warm up. It ran about 2 minutes, backfired, the died and hasn't started since.

You might've sheared the flywheel key during the backfire.

Ok is that something that is easy to check?

No. Plenty of threads though.
You have to take the left side cover off, and the flywheel nut too- at the very least.

Ok thanks Trenchcoat I'll look around the forum.

Trenchcoat I have one question about the sheared key. If the key is sheared will the bike still crank? Sorry I don't really know much about electric starters.

yes. and it may (probably) still spark, and it's a very slight possibility it'll run- poorly. But also there's a bigger chance that the bike will "backfire" more possibly causing damage.

but you can safely check for spark if you want, if the spark plug is removed (and grounded); as long as there is no broken "stuff" on the flywheel side I guess.

lay the bike on the right side to drain the oil to the other side, remove the left side cover, and remove the flywheel nut (19mm? in gear- jam some spare chain in the sprocket to keep the motor from turning).

you *may* be able to see the keyway(s)- and any perceptible misalignment means it's sheared... it's gonna be small. disclosure: i've recommended this technique a few times before and no one has come back to say it was successful. OTOH- no one has disputed it either.

if you do this or anything else, take pictures along the way. helps you; help us.

good luck.

Sometimes there is minor damage to the worm/ring gear set during "backfire", and then these have to be replaced. If not, the starter is unable to turn the motor over. This damage can happen without the key shearing- in fact, I'm guessing it is probably more likely to happen when the key does not shear.

BTW, this "backfire" can also happen during kickstarting (where it's better known as "kickback"); and it can still cause damage to your electric start drive train.

here are a few threads on sheared keys/starter drive:

http://www.cafehusky.com/threads/2011-te-310-sheared-keys-non-start.86537/
http://www.cafehusky.com/threads/2012-te310-dreaded-starter.87560/
http://www.cafehusky.com/threads/sh...arting-a-few-long-thoughts.87927/#post-630074
http://www.cafehusky.com/threads/sprag-clutch-part-numbers.41148/#post-579629

I am thinking sheared key too from description of symtoms. I remember seing George (UptiteRacing) fix one.

Quick update. Took out the spark plug and cleaned it, fired right up and running perfect!!

Nice. How bad did the plug look?

Thanks for the final report.

I didn't do the work so I don't know what the plug looked like, just hearing feedback from my Dad. They checked and made sure it had spark to the plug but when they checked the plug it barely had any. They put in a new plug and it fired up and has been running great.

Sounds like a miracle. We'll take it.