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RMZ 450 Starting Issues

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08 with 09 motor. Just did top end with new valves. PC5, Dialed in the TPS and checked FI indicator light for any codes. Bike has been hard to start ever since I did the top end. I really like the bike but the hard starting and random stalling is killing me.

 

When cold I kick it over 4 or 5 times easily then get it to TDC and kick it hard and it runs for a second or two then dies. I have do this 3 or  4 times, and each time it runs a bit longer, then finally it runs. When it's warm it starts right up, if it's in neutral and I get a good kick kick from TDC.

 

The other really annoying thing that it does is stalling when trail riding on a really slow 1st gear section of trail. It has a rekluse Z-start pro and just parking lot testing when rolling on from a dead start or just barely coasting (even up a steep grade) it nevers stalls. When it stalls on a trail it's in the oddest places I''l just be coasting  and roll on the throttle poo it dies, only happens though after it's good and hot a half hr or more into a ride. 

 

 I am wondering if their is a way to improve the starting by replacing some specific compenents? I have done a search and several people have had similar issues but non of the threads ever have a solution. The way I understand it, is that there is a capacitor in the ignition that holds the charge untill the magneto can support the spark. I heard the newer ones start easier becasue of the ignition,

 

Anyone try the black ops igntion coil?

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I have the black ops coil. Definitely improves starting and throttle response at low rpm. I would either get a new injector or get your L's cleaned. If idle seems hard to get right at the choke,adjust the hot start tension. There should not be play at hot start. Male sure the air box air sponsor is good. They can dirty yet not throw a code. Does it have manual can chain tensioner? Either way makes sure tension is correct. Put a new spark plug in. Sometimes either adding slack or removing play from throttle can help. As for the starting,sometimes it does take a few kicks when cold,but once warm it should be one kick.

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Hmm I assumed there should be play at the Hot Start, and actually added a little because the bike was idling high like it was lean. I'll see if the manual calls out the spec for that. Thanks for the suggestions on things to troubleshoot, hopefully I can get it dialed in.

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Hot start is tied to the enrichener circuit,which is part of the idle.. more of a mechanical adjustment. Not sure if it effects TPS. Basically if your idle knob is out far adjusting play/tension on the hot start will adjust idle and get the choke idle setting more tunable. Wish I could find more info on setting it up. I do a lot of dead engine start races and by adjusting all of these and keeping injector clean my bike will fire up in first gear in 1 kick. It took a lot of fiddling to get it to do this consistently. I do not use a Programmer on my 450. I have an 11 and with the stock mapping and couplers I feel it is mapped pretty good. the ignition could use some help,and that is where the black ops coil pack helps out. I run a rekluse exp. The basket/hub of the clutch needs to be torqued lighter than factor recommendation or get an aftermarket basket. Stock basket and hub flex. The push rod and edges of the basket I polish. Having tps set to correct values definitely makes a difference.

Edited by ac717

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Still a little confused on how it's tied into starting and the idle adjust but I get that it's more of a feel thing so basically just start fidling with it? 

 

Have to check on the cleaning or replacing the injector too.

 

Looks like Tokyo Mods stopped making the RMZ manual cam chain tensioner. They are sold out everywhere and not listed on their website. I ended up going with a rather crude looking tensioner off of ebay.

 

The bike still has the stock basket as well so I'll get a nice hard anodized number from Rekluse, Barnett, or Hinson. I like the Barnett's becasue of the replaceable SS inserts, any thoughts there?

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I would have to look closer at the hot start/idle to understand how it exactly works. But,to understand relation between the 2-just by putting a little pressure on hot start while bike is running, the RPM will increase. Not sure what tensioner you got,but they are all pretty good as long as they function and tension is set properly. A loose or tight tensioner can effect timing. Its definitely something you got to have a feel for. Any good aftermarket basket will be an improvement to the clutch. If the stocker is in good shape,just torquing properly can make a big difference. The Barnett basket is very good. I just buy what I can get a good deal on.

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I have the exact same bike with the exact same issue. I thought it was the valves out of adjustment so I ajus ted the clearances which it did need. After getting it all back together I broke into a sweat before I  finally it started but won't idle at all. It seems like it is harder to start now than before I adjusted the valves. It does seems like its somthing to do with either the air/fuel but with FI its hard to diagnose without some kind of tool I guess. The interesting thing I've noted in this post is the mention of the Hot start.  A while back the hot start got stuck and I broke it tryng to get it out. I ended up having to drill a small hole in the hot start piston and use a screw and pliers to get  it out of the throttle body.  It is located just above the choke/idle knob and basically is the same kind of mechanism. I guess it is possible that went I replaced it I didn't get the right amount of tension back in the hot start cable because I have to turn the idle up all the way to get the darn bike to idle.

 

I also have flame out and stalling issues.

 

I'll mess with the hot start tomorrow to see if it helps.

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Ok, I checked ECM for codes and found none. Next I checked the TP voltage and made the ajustments needed. The bike ran a little better but would not idle. I added some tension to the Hot Start cable until the bike would idle. I then adjusted the hot start cable as recommended to give more range of adjustment to the idle knob.  The service manual indicates that there shoud be no tension in the hot start cable in the closed position, so while this method seems to fix the idle issue I think there must be something else going on with the FI system.  In order to start the bike I have to roll on the throttle as I kick. Anyone have any other ideas?

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I adjusted the TPS to within the specified voltage so I don't understand how it could be the TPS.  At 180 dollars that's an expensive item to replace if it doesn't fix the problem. Is there a way to adjust the throttle cables to a more open position? Just got back from riding today and this bike flamed out on me a dozen plus times.

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im having the same issue with my 2008 450 it wont idle even when the knob is turned all the way out and it will randomly shut off and start back up im at a loss 

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Well. I just had this happen on my 13 rmz250 this weekend. Thought the fuel pump was clogged or worn+took it off and hooked to 12v battery-it did have some junk,but it worked and pumped fine. So then I cleaned injector. It now runs fine. The symptoms were it was hard to start,wouldn't idle,any throttle past 1/4 it would break up or shut off. If you can confirm that the fuel pump is pumping and clean or replace the injector-that will rule out a fueling issue. Still have throttle position sensor as a possible culprit.another member had issues and it was the TPS.

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I cleaned my injector and replaced a bad spark plug and now she runs great!  :thumbsup: Never rule out the simple stuff 

Edited by Ericyzf359

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I cleaned my injector and replaced a bad spark plug and now she runs great!  :thumbsup: Never rule out the simple stuff 

Are you cleaing the injector using the KTM method with a 9 volt battery?

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Awesome! Yes,the KTM 9 volt cleaning method applies to the Rmz injector. Actually,an ultrasonic jewelry cleaner or a shop that specializes in injector cleaning can also do it. Tue injector holes are big on the rmzand I never saw one clogged until mine. It sucks. I will now be cleaning it periodically. Its easy to do and is cheap insurance that bike is running right. I use the 9v cleaning method with carb cleaner and compressed air. That is what fixed mine.

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yes i used the 9 volt method like you would a ktm this method applies to any fuel injector 

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Hi all, i have a similar problem with my rmz 450 2006, the idle thing is driving me crazy, have been through everything and have now found that the primary coil OHM resistance is a bit low, according to the book it should be 0.17Ohm to 0.70ohm i am getting a resistance of 0.6ohm could this be a problem, the book says if found to be out of the allowable then replace the coil???

When i initialy put the probes on the reading drops from 0.13 slowly down and settles on 0.6ohm.

Edited by Brett Ralph

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Hi all, i have a similar problem with my rmz 450 2006, the idle thing is driving me crazy, have been through everything and have now found that the primary coil OHM resistance is a bit low, according to the book it should be 0.17Ohm to 0.70ohm i am getting a resistance of 0.6ohm could this be a problem, the book says if found to be out of the allowable then replace the coil???

When i initialy put the probes on the reading drops from 0.13 slowly down and settles on 0.6ohm.

Have you tested it when warm? Resistance will typically rise alongside everything else as it heats up. 

 

Cold readings don't mean much unless you are not getting spark. 

Edited by BDubb106

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Have you tested it when warm? Resistance will typically rise alongside everything else as it heats up. 

 

Cold readings don't mean much unless you are not getting spark. 

Thanks, i will have to check that out, yes it was tested when cold, this thing is starting to drive me mad, yesterday i spent a few hours setting the air/fuel screw, got it to to where it was idling nicely then took it for a run and coming just off idle say quarter throttle it would jerk and splutter, figured it was to rich so turned the screw in half a turn then it stared popping and backfiring badly, but still idled ok, let it sit for 10 min and she wouldn't idle again, tearing my hair out now as when i get her to idle she seems sluggish and when cruising along she surges forward then almost beaks down and jerks a bit, thinking maybe my plug is getting tires or its just crappy fuel, problem is its been doing this for a few months now. book says 1 3/4 turns out but it is way to lean at this setting at 1 turn out she wants to die and 2.5 turns out she wants to die so happy place would be about 2 turns out, yet plug is burning black, any suggestions!!!!

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