Hey guys, despite the very old user name, I have a 2009 rmz 450 that I've been super happy with now since last summer. last ride out last season my bike died on me a couple times on the track...i thought it was a loose CDI connection as if I fiddled with it it would usually start again...

First ride of the season today, went out for maybe 5 laps..she ran great, went to the truck...went out another 5 or so laps, ran great..then my third time out..it died on me half a lap in... i got it running, got another half lap in then died and wouldn't start...walked it back to the truck, and she started ok.
So I let it sit an hour..started up first kick..then same thing, half a lap in it died on me in a corner.. wouldn't start for nothing so had to walk it back in again. at that point i gave up and went home as it'd probably do the same thing again.

These bikes are so complicated. Any ideas? I was thinking maybe a bad fuel injector? or valves changing spec when it gets hot?(but the last time out it stayed cold during that half lap so i dont think that's the case) maybe a wiring issue with the cdi? (I don't have the cdi bracket so it's tied up with a shoelace to the frame but it's pretty secure.) I really have no idea here..it's so annoying I just want it to run!

Thanks.
Mike

i'm afraid if i take it to a shop, it'll start up no problem for them and they'll tell me its fine when it's really not.. it starts and idles fine but like i said, half a lap in it just dies..

were the 09's the year full pumps were starting to go bad? I heard there was a problem with suzuki fuel pumps but have no idea what year or 250 or 450. an electrical connection is a possible cause too. does the cdi need to be grounded to function properly? maybe the shoe lace isnt holding in place where it should be. id say buy a bracket, check up on the fuel pump and wait to read other answers from other members.

Ya I'm really not sure what the problem is. you cannot buy the cdi bracket..it's not on any part diagram and not listed in any dealers diagrams or even shown.. so that's why i used a shoelace and zip ties.

I would bet money its the fuel pump.go over every connection.it may be the filterbut i dont think it is easily replaced on the earlier ones.another simple thing woul be the fuel brather clogged

There are two filters on the earlier injected bikes, one is in the fuel pump and is a bit harder to get at and the other is on the throttle body just before the injector, give them a clean and try running her again. I sold my 08 450 last year and the guy i sold it to told me of a similar problem after he had the bike little more than a month, he tried lots of things to rectify the problem but in the end he went back to the basics of fuel air and spark, put in a new plug and it cured the problem, maybe worth a try!

awesome. thanks guys. I don't have a owners manual with it so I'll have to try and figure it out myself!
Is the fuel filter at the pump inside the gas tank? do i have to remove the whole fuel pump to find the filter?

Edited by yamaha_yz250f, 02 May 2012 - 12:32 PM.

anyone? I just checked the spark plug and there was some oil on it..could it be my piston rings?  I can't find these 2 fuel filters

Sure it was oil? Try a new spark plug? Pretty much just gotta start tearing it a apart. Verify you are getting fuel,spark,compression  and air. It could be a whole list of things. What makes it difficault it is intermittent. Check the breather hose for the crankcase.Check the breather for the fuel tank. Do you have a manual? It will help alot to check parts. For it to run for 15min and then die-sounds like a fuel or electrical issue. If you take the gas cap off and kick the bike-should here fuel pump run-twist throttle,etc to make sure it is running. If the plug is wet-it is probably fuel. Check for spark-take plug out and look for a spark when kicking bike over with plug in cap and touch the elctrode against the frame. If you find a parts micrfiche-the filters,wires etc will be layed out to help diagnostic.Sny place that sells oem parts online should have small diagrams.Either that or find someone else with an RMZ450 near you and try swapping parts until you find the culprit.

update- brought it to the dealer...they checked everything, valves, stator, etc. they noticed my cdi was cracked pretty badly. they said that everythign led them to believe my cdi was bad. so i spent 400 bucks on a new one and still no spark!! just bought a new sparkplug too. so far i'm into this for like 700 bucks with the dealers labour and I'm no farther ahead! what could cause my bike to be getting no spark???!?! I haven't rode all summer because of this stupid thing!

Only a couple items involved in the ignition. The stator-located inside the left engine cover by shifter.Take it off and make sure the pickup,wires and the stator are ok. Sometimes its just a piece of dirt. Wiggle crank see if there is play. The coil,right above the valve cover-this gives you spark-make sure its connected properly. All the wires (including kill switch) make sure they are not broken or shorting out. Capacitor-big round black tube by throttle body. Find someone good at testing electrical problems-like an electrician,auto tech,etc if you cannot find a good motorcycle mechanice. The manual is going to be your guide to go through the bike and troubleshoot the problem.

Thanks, I'll take a look tomorrow.. the dealer said that my stator was fine, they were getting good readings from it.. so I''ll try the other things you mentioned.. I've been losing alot of sleep thinking about all the money I've spent on this and still haven't fixed the problem . I'm not used to not being able to fix something!! Oh, and I don't have the manual..I never got one with the bike. someone said it could be a bad crank position sensor not allowing spark...I don't know how to test it..or where it is..I really don't know!

Wow a good used cdi box on eBay is 50 bucks. That dealer saw you coming. " if the bike is quitting after a short run time " then it's 1 of 3 issues. Cdi or primary coil or secondary coil (stator). I wouldn't trust the dealer if they sold you a 400 dollar cdi box. Get V meter and test for resistance through both coils as per manual or YouTube instruction. Chances are the coil is heating up and producing a very weak spark when motor is hot. Thus the bike quitting. Let us no.

Ive just gone through the same kind of problem with my 2010 Rmz 450. It might not be the exact problem u have but i spent about $2000 on rebuild cam chain and labour and was none of them
It ended up being a few worn wires that earthed out on my frame..that's why it would start and run fine until i hit a rough ground and would earth out, so id check all your wires before you spend any more cash mate..

Hope you get it fixed

ratrodster, on 23 July 2012 - 04:25 AM, said:

I checked ebay..all those for 50 bucks are for 2005-2007 models. not one used one for 08 and above...400 bucks was a "deal" the guy gave me, basically saved me the tax.. theýre 359 on all the american oem websites so that's just what they cost new, I didn't have any other choice..

anyways, its not getting ANY spark at all, therefore wont even run for a few minutes now. I looked at all the wires under the gas tank and there are no obvious worn or grounded out wires. I guess back to the dealer it goes   i'll check the primary coil myself first

Its my personal opinion that if you cant strip down, repair and re assemble your motocross bike then you shouldn't be allowed to own and ride one. On a lighter side, im sure if you keep throwing money to the dealer they will keep giving you free stickers. lol good luck chuck

Not sure if that is a fair statement. These bikes arent tinker toys anymore. Intermittent problems are very hard to troubleshoot. Now that there is no spark-it should be much easier to find what is wrong. Not everyone is mechanically or electrically inclined. Even the people with such title as mechanic or 'technician'. Yamaha yz250f-pm me and i will help you out. You will need a volt meter

ratrodster, on 26 July 2012 - 03:46 AM, said:

Who said I couldn't strip the bike down the the frame or the motor and reassemble it?
ac717 is right..this isn't a CR 250... the electrical on these new bikes is the only thing that stumps me...and apparently my local suzuki dealer as well.

Check your tip sensor, little black box underneath the gas tank in front of the cam cover, sometimes they fail. this is used to turn off the spark in case the bike was tipped over while running so that it doesnt idle on its side for more than 30 seconds

part numer:33960-06G10

I think it might be the tip sensor. Some guys replace it with a resistor so the bike doesnt shut off on them.