Hard starting, and possibly a sticking throttle

[58Rag]

I've been having a real tough time getting my 07 to start. Gas on and choke out, it still takes about 15 or so cranks and alot of working the gas to get it to start. my fiances 450 starts all the time, no issues, but is also stock. Any ideas??

Also, it seems like my throttle is starting to stick..( not good!) I have to snap the throttle to get it to idle back down when im riding. Crap in the cable sleeve??

Any thoughts on either issue would be great.

[climb-101]

sounds like the valves are out of adjustment and that the cable is adjusted wrong. there should be a little slack in the cable when it isnt pushed in at all. the knob on the carb should be what sets the idle

[jjyfz]

once u get it start and it warms up does it start better? also when a carb is dirty it may idle high the slide wont close all the way because of dirt on the wheels. and also have seen a slide have a small nick or bad spot and wont close unless u tap the throttle. hope this might help some

[58Rag]

I was looking the FSM about doing valves..( this is my first quad) Do i get the valve adjustment pads from yamaha..or will i ust move them from valve to valve?? I also saw..( after searching..sorry) that it may be too big a pilot?? i have a 48 pilot right now, and have a full hmf system, and a unifilter..is 48 too big?

I will take the carb off as im also doing my clutch. Ill try cleaning it out. My airbox was pretty full of crap, and im sure my filter wasn't oiled as best as it could be( it is now) .

It used to just be a little stubborn on cold starts and fine when it got warm. just couldnt give it gas when hot, or it wouldnt want to start. Now, it just doesn't start worth a crap.

All my idle adjustments are done on the knob. I will check the slack, but im kind of banking on a dirty carb on that problem.

[alpinestars13523]

the jetting sounds like it should be ok maybe...do the throttle when off go smoothly or does it seem to be hung up or sticky at all? as far as valve adjustment goes...i just had to change the shims because the valves were out of spec...if you have any questions on it...go to youtube and search yfz valve adjustment...the one guy have a three part video on how to check and or replace shims and clearances...helped me out alot.

[58Rag]

With the top off of the thumb throttle, ad the side off to see the wheel, the cable seems to move smoothly, and everything is closing. Ive checked the clamps, and haven't found any loose ones indicating an intake leak.

As far as hard starting goes, this last weekend, i almost gave up and didn't go riding. I must have cranked it about 30 times. I finally had to drain all of the fuel from the carb, and start fresh...so maybe my jetting iss off.

Im just pretty well frusterated at this point. I just hate when my toy turns into a constant project...

[rsyfz450x]

Valves most likely out of spec, when they are it will wind and wind before it cranks. And sometimes it will flood the cylinder and not crank at all. Get them adjusted and I bet your problem goes away.

[58Rag]

so, before i adjust the valves, do i just run to yamaha and pick up an assortment of shims?? I appreciate everyones help on the matter.

[rsyfz450x]

If your going to do it yourself you will need a shim kit and a shop manual to know specs. You can find alot of shim kits online just google yfz450 shim kits.

[alpinestars13523]

dont waste your money on a shim kit...theyre like 65 bucks or more....if theyre the right size you might be able to re use some of your old shims on other valves...but get the manual or watch the videos on youtube and you should have no problem

[58Rag]

So, I'm bringing this thread back. My quad starts fine now. I had a small piece of dirt in the accel. pump squirter. Once I got it out, now it starts great.

Back to the throttle not returning. This is still an issue. It is not a misadjusted cable. I have checked that twice. The carb has been cleaned, ( to get the dirt out of the squirter) and no luck. I'm now looking at maybe an intake leak? I am also getting alot of popping out of the exhaust on both revving up and decel ( with just free revving) Could this possibly be a jetting thing?

Thanks.

[greenblazemike]

popping can deffinately come from improper jetting, but as long as it revs smooth without missing and sputtering and doesnt have a dead spot in the RPM curve, i wouldnt be worried about it. mine also crackles if im decelerating, but the quad still runs great

[sdime_guy9]

First thing, I'm gonna make a note on what alpinestars said in february, I completey disagree...BUY A SHIM KIT!!! If you buy shims from the dealership, assuming you only had to buy 5 to get it right the first time...you're gonna pay like $6 each, if you buy a kit they are under $2 each...and then we all know the dealership would have to order in at least one of them....and its not very likely that you are gonna get the shims sizes right the first time....and you said you have two machines, a shim kit is a neccesity with a four stroke...

if I was you I'd order a shim kit, a throttle cable, and an adjustable fuel screw

right around $100 and you can shim your valves, and swap cables, that will rule out 2 options, and if you still have any problems these guys can tell you exactly where to go from here