Brand new YFZ450 ?'s

[blown331]

Hey guys

My neighbor just bought a brand new 06' YFZ450... I was out riding all morning in the dunes came back and he finally had it picked up from the dealer

we went out to some hardpack stuff to break it in

he rode it for awhile, in my opinion maybe a little harder than I personally would have for break-in but I guess thats a matter of opinion. He wasn't on it fully but maybe 1-2 times so who knows

anyway, when i went for a test ride i noticed he had a pretty major exhaust leak where the canister meets with the head pipe

so we went and heat cycled it again, loosened the bolt, re tightened and the leak went away for now

also... i noticed when it was hot after a short ride and you give it a decent rev it sounds to crackle a little bit

also, after a brief warm up if you get on it about 1/2 throttle it seems to stumble... I'm assuming the dealer has jetted the bike according to where we live (about 3,100 ft)

So, I'm assuming the best thing to do is just watch the exhaust leak maybe re-tighten as needed but what about the crackle? and just check the plug here shortly and check jetting?

I'd appreciate some input thanks a bunch

[blown331]

Also, forgot to mention this the SE "Special edition" titanium 5 valve?

Just incase that helps diagnose

[bsjoe]

I had thatt problem, my gasket was screwed up so i bought a new one, and tightened down the bolts securing the pipe to the head, and then put heat loctite on it (the loctite that is made to get hot)


I lost my headbolts maybe 3 times because after I tightned them it would heat up and the bolts would become loose. I didnt want to tightn it up after it got hot again like the dealer said because I was afraid of it stripping the head out when it cooled down. The amount of expansion was so much the bolts were so lose to just viberate out... so that was alot of expansion, which i feel when it cooled would strip my head .


sorry kept talking...


i have an aftermarket exaust though so i dont know if it applies to you.


Also, I'm not going to say its true, but i doubt the dealer would jet it for your area, around here they were so lazy they tried to sell me the bike when it was still in the crate, they didnt even want to have to unpack it, so i doubt they would go through the trouble to jet it for you, plus i belive its all the same jetting... I belive its 38 pilot, and like 142 main, somewhere around there..


I'm running 178 (its too lean still) and 48 pilot (pilot is very very very very very lean for me



re-read your post


does the crackle happen on decel?

if so pilot is too lean


The bike sounds like its jetted lean.


To the best of my knowledge, they jet it for 1,500 feet, so you are going to have to richen the jets up.


you can buy a kit for like 45-60 bucks or buy single jets for about 2.50 to 5 dollars eacjh

[250r4life]

Originally posted by bsjoe


To the best of my knowledge, they jet it for 1,500 feet, so you are going to have to richen the jets up.




if they jet if for 1500, and he is at 3100, you dont richen the jets up... you need to go leaner as you increase in elevation

[250r4life]

when you stab at the throttle, that stumble and bog is normal. taking the baffle out, and the lid off will help... rejetting it and/or the boyesen accelerator pump with help even more...

[250r4life]

Originally posted by blown331
Also, forgot to mention this the SE "Special edition" titanium 5 valve?

Just incase that helps diagnose

theyre all titanium 5 valve

[bsjoe]

my bad, wasnt thinking right :ermm:

[blown331]

I think for our elevation they have run it too lean

the only reason i'm assuming this now is because we went riding again yesterday and on hard decel or a decent rev it is still crackling/popping so i'm assuming this is a lean pop

Going to pull the plug today check it, and re-jet accordingly and make sure everything is good to go.

I'm just glad he bought the extended warranty on this thing :)

[oldskoolex400]

is the boysen accel pump worth it?

[toomeyshee87]

Originally posted by oldskoolex400
is the boysen accel pump worth it?

you bet your ***** it is haha

[oldskoolex400]

any other tips/tricks to do to a yfz?

im looking at the boysen accel cover and a zip ty f/s

[infantry317]

Put in a smaller leak jet, it really helps.
$10 versus $100. :chinese:

[toomeyshee87]

Originally posted by infantry317
Put in a smaller leak jet, it really helps.
$10 versus $100. :chinese:

what is a leak jet? (dumb question):ermm:

[SandShark400]

what does the boyeson pump do? They are only like 100 from rockymountainatv.com. so what does it do?

[Bill Fuller]

I don't think this is the best site to ask YFZ questions. Change the leak jet as suggested. If you don't know what one is the research and learn.I have never lost a head bolt so I don't know what bsjoe is talking about.There are some very good YFZ sites out there,check around.

[quadgeek631]

Originally posted by oldskoolex400
is the boysen accel pump worth it?

I wouldn't spend the money if I were you. It's obviosly a rip off for $100 or so for a stupid accelerator pump cover. Wire-ty the fuel screw and maybe get a new leak jet, but from my experiance the quick shot is a ripoff.