Jetting For My Mods

1376 Views 15 Replies 6 Participants Last post by Joester, May 1, 2009

licopico

Discussion Starter · Mar 24, 2009

04 yfz _I had it rebuilt a few months ago but have not road any since. I know I need to rejet it but dont know where to start, mods are as follows=
1. +3 hot rods crank
2. oil mod
3. 100 mm nmotion jug w/ 12.5:1 piston
4. mild port head(stock valves)
5. stage 3 hot cams
6. fci intake
7. lighter fly wheel
8. ricky stator
9. dynatek cdi (non programable)
10. Jsr 9" full exhaust
11. 41.5 bored stock carb

It pops on decel and just doesnt seam to run like i think it should. I dont know what its jetted at now. Any help would be much appreciated. Thanks

1 - 16 of 16 Posts

defiant

· #2 · Mar 24, 2009

Here's where I am at with my 501.

195 MJ, 48 PJ, NCVQ #3 clip, A/F screw is 1 1/2 turns.

I am in Iowa so, elevation is around 1200 ft.

Bike runs super strong but, I know I need to fine tune it. I have a very subtle decel pop. My mods are close to yours, just 98mm bore.

licopico

Discussion Starter · #3 · Mar 24, 2009

Elevation is around 3100+-

Oregon's Finest

· #4 · Mar 24, 2009

try 182/ 48

licopico

Discussion Starter · #5 · Apr 22, 2009

Well, i rejetted. Here it goes.
48 pilot it already had 48
185 main it had 182
ncvq-3clip
2- on air/fuel
zip tie mod

70+- degrees today

Now, it pulls like a freight train 1-3 gears then top of 4th it starts dying down and in 5th it falls on its face and dies. Still pops on decel 1-3 gear. WTF. Need help please.

Ps. Im new at jetting so bare with me. ALSO, i hear a ticking coming from motor???????

Pss. What cc is my motor now.

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licopico

Discussion Starter · #6 · Apr 23, 2009

I cleaned the carb today (took it apart and used non chloride carb cleaner) and now it wont start. WTF

lbyfz450

· #7 · Apr 23, 2009

QUOTE (licopico @ Apr 22 2009, 08:32 PM) index.php?act=findpost&pid=772994

I cleaned the carb today (took it apart and used non chloride carb cleaner) and now it wont start. WTF[/b]

well its still popping on dcel so try a bigger pilot jet, and you cleaned your carb and now it wont run... dick question but is the gas on? haha... open up the skrew at the bottem of the carb and make sure its flowing good, it sounds like you have a clog becuase its not even running now becuase theres not enough gas getting there, also explaining why it would cut out in 5th full throttle becuase its trying to pump ALOT of gas into that motor and a clog is stopping it. tps and carb switch plugged in?

licopico

Discussion Starter · #8 · Apr 24, 2009

Yes gas was on, lol. Yeah i thought about it and unscrewed the bleed off bolt to see how huch gas i was in the bowl and not much came out. Tps and switch were plugged in. I also found that my petcock is leaking. Thanks for the help hopefully tomorrow I will have this thing lined out. Hopefully and thanks again

dustin104

· #9 · Apr 25, 2009

I've been having the same problem with mine. it's a +3 stroker crank and a 98mm big bore stage 2 yz450f hot cams. I'm at 2500' here northern BC i finally got the bike to quit popping on desell. and i'm at 50 pilot 200 main and 4 clip setting on the needle. good luck.

dustin104

· #10 · Apr 25, 2009

also i'm at 2 turns on the fuel/air. With those stage 3 cams you might want to try a 52 / 205 / 4th clip setting. if it's bogging at the end of the 4th gear you need way more fuel. jet it up and plug test it if it's still white go higher. if your not sure about the color of the plug put a new one in then do the run test.

dustin104

· #11 · Apr 25, 2009

with all your mods. you should have went with stainless steel valves. worth there weight in gold. your engine is only as good as it's weakest part. check your valve shimming. might be out already.

lbyfz450

· #12 · Apr 25, 2009

theres another problem besides jetting though, becuase he cleaned it and now it wont run at all....
was there a clog anywhere in your fuel system?
are all your jets tight n stuff?

Oregon's Finest

· #13 · Apr 25, 2009

QUOTE (oldblue460 @ Apr 24 2009, 10:00 PM) index.php?act=findpost&pid=773659

with all your mods. you should have went with stainless steel valves. worth there weight in gold. your engine is only as good as it's weakest part. check your valve shimming. might be out already.[/b]

Considering how good the stock valves are, going to stainless should only really be considered when going oversize...

dustin104

· #14 · Apr 27, 2009

if the fuel is coming out of the fuel line then it's going to the carb. I would start by checking the diaphram under the carb.(accelerator pump). Really hard to diagnose without being there.

you've been having more then a jetting problem right from the start. If it's falling flat on it's face in 5th gear. then your float bowl is probably running dry. The flow rate out of your tank isn't enough. take the valve of of the bottom of your tank and clean it all out.

licopico

Discussion Starter · #15 · May 1, 2009

Well, i finally gat it to stay running(messed with idle screw a lot) is that norma? But I havent had a chance to go out and ride it or even ride it down the street. But as soon as i do i will update. I plan on gettn +1 valves done in the near future. At the time of build 1300 more was a little rough(builder said I needed a complete new head when my motor locked up).LOL Thanks guys

Joester

· #16 · May 1, 2009

QUOTE (licopico @ Apr 21 2009, 10:18 PM) index.php?act=findpost&pid=772634

Pss. What cc is my motor now.[/b]

i did the math and i THINK you have a YFZ 521.5043805cc, lol.

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