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06 yamaha yz450f throttle and idle

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This dirtbike is awesome. A lot of power, sometimes you dont know where the hell it comes from. Anyway when riding, if im just putting in 1st or second gear and blip the throttle or just accelerate really slow and then close the throttle the bike still holds the momentum i had when i was accelerating and is in a sense still pulling me but at a constant speed. Also it does backfire on decel in 4th or 5th and if im cruising in 5th like 90% throttle and go to slow down quickly and pull the clutch im, my rpms will stay pretty high untill i slow down to a near stop and feather the clutch into like 1st or 2nd then it will go back to normal but then a little throttle and then closing it again completely will like speed the bike up to a constant speed and then if im rolling and pull the clutch the rpms dont die down

 

Does this sound normal?

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That is called hanging idle. 
It happens from worn out parts or a carb that has not been serviced often enough, or properly.
You need to service the carb for WEAR and for CORROSION AND DEBRIS.
 
http://www.dirtrider.com/features/protips/141_0707_keihin_fcr_carb_rebuild/


Forgot to add i live in Lancaster pa. Im in Clearfield pa right now just started havung problems in the mountains. The bike was bought in nc where my bestfriends older brother bought it and had it for several years when he was in the army for several years and was originally tuned for nc weather. No problem for the last year since ive owned it in pa

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Ill keep this active..but im leaving tomorrow to go back home. Ill ride it around see if im having the same issue when im back when i didnt really have those problems. Any advice on what to hear for getting my a/f mixture right? I dont have a screw out the bottom so i would have to (i guess turn it sideways and take the cap off and use a small flat head). Also my hot start was stuck yesterday or friday and i couldn't pull it back but when i finally got it to "engage" it didnt return to it normal position. Dont know if that has anything to do with it but i tried to keep it closed but its like not returning to its original position on its own like the clutch or brake lever operates. kinda just hangs there. But like the whole grey cable AND the protective plastic housing moves together not the actual grey cable itself.

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I guess i have to turn my carb sideways to adjust the screw so im just going to try and clean it tonight see what happens. going to purchase a new fuel screw thing lol that comes out the bottom of the carb tonight. Any ideas as to why my hot start got stuck and then by me using excessive force to pull it back did i screw up a spring or something so it wont return to its closed position

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There isn't enough room to turn the carb sideways, or remove it without pulling the shock, for that matter.  A very short stubby screwdriver is required, but a better solution is an extended fuel screw that has a knob accessible to your fingers. 

Hanging idle can also be caused by tight intake valves, which cause compression/combustion to leak back into the intake tract and dilute the incoming F/A charge.  Check your clearances if you haven't done so in a while. 

Check for an external air leak at the mounting sleeve, too.

The problem with the high altitude jetting theory is that an increase in altitude makes the jetting richer, not leaner.

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I will look into that before i mess with the carb because i have owned the bike for a little less than a year and havent had to do maintenance other than oil changes. After i get this squared away I need to do fork seals. Would anybody have a idea on labor costs to have them done i have the seals and fork oil already... hopefully i just need to reshim and not need to get head or valve work done as far as adjusting the carb later with the stubby flathead which way richens or leans ?

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Right/in/tighter leans the idle, left/out/looser richens it.  Base line it first by running it in until it just stops, counting the turns to see where it is now.  It should normally be about right somewhere around 1 3/4 -2 turns out.  If you have to go farther out than that, it means there's a problem somewhere.

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At the shop I work at we charge $300-$350 for fork seals if it only needs seals.  If it needs a complete rebuild kit, we charge $350-$400.

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At the shop I work at we charge $300-$350 for fork seals if it only needs seals.  If it needs a complete rebuild kit, we charge $350-$400.


Thanks for that. My buddys brother who i bought the bike off of changed them out but i dont think he had a seal buddy thus causing them not to seal completely and causing them to leak but im not sure. We will find out soon enough.

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Right/in/tighter leans the idle, left/out/looser richens it.  Base line it first by running it in until it just stops, counting the turns to see where it is now.  It should normally be about right somewhere around 1 3/4 -2 turns out.  If you have to go farther out than that, it means there's a problem somewhere.


Correct me if im getting ahead of myself or i shouldnt go about doing this the way im thinking i will

So as for starting to fix the problems im having (best case scenario) should i start by making sure my timing is on point, the valve clearances are in spec and if not ill shim them so they are within spec. I guess at this point taking the carb out isnt necessary but ill make sure the fuel screw is within 1 3/4 - 2 turns out. Start it up adjust the screw if necessary.

What would be the effect of my hot start being stuck open?? Im not 100% sure that it is but there was a point last weekend where i couldnt pull the lever but when i finally used enough force which i shouldnt have done. the lever wont return flush and the cable and the cable housing just moves together. Its connected with a aluminum peice on the top of the carb. Could the cable just need a good lube ?

I just want to be able to either single out the hot start being apart of the problem as well as out of spec valves/ dirty clogged carb or it having nothing to do with it so im not making it more complicated like ive made this post haha

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It all matters, so you can't single anything out till you inspect it.  To run will it has to all spec well. 

I can tell you right now you hot start cable is rusted, and now it is probably holding the hotstart partly open.

Just service it and be done with it.  

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If the hot start is open, it will be very lean. It's basic function is to cause an air leak, essentially, by opening a passage for air from the intake bell of the carb to flow over the slide and into the intake port so as to offset the tendency toward "flooding" when the engine stalls at full temperature. 

Usually, this happens because the brass plunger valve in the carb body gets seized by aluminum corrosion, in which case you'll need to remove it and brush it out with something on the order of a pistol bore brush until it works smoothly again.  You may also have the cable jammed at the carb because of a broken plastic nut the holds the cable in place. 

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My guess is this should just come right out? And if im using the terms right thats the plunger thats stuck in the carb?

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Okay so that didnt take long tje cable broke off so is it safe to pb blast and then how should I go about removing this with out drilling if not necessary 1492888024196.jpeg

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If the hot start is open, it will be very lean.....


Took the shock off which made taking the carb off so much easier.. gonna find out what jets are in it and all that but was wondering what this screw is. I know its not the fuel screw because of the large nut i have to take off to get to that...which at least ive always thought it was under the spiderweb looking nut lol one1492892933701.jpeg

20170422_162328.jpg

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