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Discussion Starter #1 (Edited)
Hey Guys I am new to the forum, looking thru some of the jetting info have not found the info I am looking for yet. I am trying to find proper or close jetting for my sons raptor. Ran fine before rebuild-had to add rings so I just put in a 10.1 Big Bore 686 Kit. Starts fine and about 1/2 throttle it cuts up like a imiter, I have since went thru all of the limiters and they are good. I then pulled the carbs apart had stock 140/145 jets in them. I had some jets from a kit I bought for a 350 warrior so I stuck in the biggest 2 it had 148/150 and it is a TON better still needing fuel up top. I would assume from what I have read I need somewhere around 160-170 jets? I did move the needle to the 3rd position.
Any help would be great!
Stock Needles By the way. 3rd Position as stated above
 

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Discussion Starter #2
So I drilled out some small jets to see how close I could get it.
So first I drilled out both to dynojet 146 both needles at 3rd position. Ran pretty good seemed to have a powerband kick in in high gear after holding it there for a bit. So I decided to add jet because it was still dead clean out the exhaust. So,
Right now I have dynojet size 146 primary with needle at position 3 and the 2nd carb at 178 dynojet size and needle at 4th position. Seems pretty good zero smoking under acceleration or letting off.
I would have went ahead and drilled out the primary side to match the 2nd carb but the carb boot split.
Now have to order that.
 

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So I drilled out some small jets to see how close I could get it.
So first I drilled out both to dynojet 146 both needles at 3rd position. Ran pretty good seemed to have a powerband kick in in high gear after holding it there for a bit. So I decided to add jet because it was still dead clean out the exhaust. So,
Right now I have dynojet size 146 primary with needle at position 3 and the 2nd carb at 178 dynojet size and needle at 4th position. Seems pretty good zero smoking under acceleration or letting off.
I would have went ahead and drilled out the primary side to match the 2nd carb but the carb boot split.
Now have to order that.
What is your intake and exhaust setup?

Dynojet jets and OEM jets use a different numbering system. 178 dynojet would be WAY too big.

The 660 in my signature has a dynojet 146 in the left carb and a dynojet 148 in the right carb if that helps at all

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Discussion Starter #4
Stock intake with no air cleaner top, and K&N Filter.
What jetting would you recommend? I assume the 146 / 148.
What about needle position with the stock needles?
 

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Stock exhaust?

If i remember right, my needles are 1 notch richer than center. But im using the Dynojet needles. Ive heard its extremely difficult to tune one on the stock needles after the airbox is opened up.

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With an open air box your going to need #25 pilots and a set of aftermarket needles.

Aftermarket carb needles will richen up the mixture in the 1/2 to 3/4 throttle area. If you get it to run properly in the 3/4 throttle area with out doing carb needles you usually end up with an excessively rich main jet that will cost you power at Wide Open Throttle.

A dynojet stage 2 kit is the only way to get a pair of aftermarket carb needles now days. It will come with the proper size mains as well. You really shouldn't need to jet specifically for doing a 101mm bore. You do need to jet for the slip on exhaust pipe and running no air box lid though.

You could have also been trying to jet with air leaks due to cracked intake boot. The cracks cold have e already been present and finally split open the last time you went to put the carbs back on.
 

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Discussion Starter #8
With an open air box your going to need #25 pilots and a set of aftermarket needles.

Aftermarket carb needles will richen up the mixture in the 1/2 to 3/4 throttle area. If you get it to run properly in the 3/4 throttle area with out doing carb needles you usually end up with an excessively rich main jet that will cost you power at Wide Open Throttle.

A dynojet stage 2 kit is the only way to get a pair of aftermarket carb needles now days. It will come with the proper size mains as well. You really shouldn't need to jet specifically for doing a 101mm bore. You do need to jet for the slip on exhaust pipe and running no air box lid though.

You could have also been trying to jet with air leaks due to cracked intake boot. The cracks cold have e already been present and finally split open the last time you went to put the carbs back on.
New Boots ordered, Stage 2 Jet Kit ordered and the #25 Pilots ordered. Which jets do you guys think would work best for my Raptor? Aftermarket needles in the #3 position? I appreciate all of the help.
 

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Master of the Electron
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DJ 146 left, 148 right would be my 1st choice, with needles 1 notch rich of center, 25 pilots with screws about 2 1/2 to 3 turns out.
 

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Master of the Electron
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I don't remember how many notches DJ jets have, which is why I say 1 notch rich of center (so needle is a bit further away from the jet opening).
 

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Discussion Starter #12 (Edited)
Have the new jet installed. I went with 144/146 and it seems good. I also put the #25 pilot jets in. I can rev it at idle to full throttle with no hesitation. If there is an issue left it may be lifting with a little popping out the exhaust. Not Horrible but it is there. Any idea on a fix for that? Are the pilots a little small or can I adjust the mixture screws a bit? They are currently both at 3 turns out. Also I did put the breather box lid back on after modifying it like the dynojet kit said.
 

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A little popping out the exhaust on deceleration is normal. If you richen it up to the point it goes away then its going to be to rich. You have a motor at High RPMs and the throttle shuts it creates a lean condition. The motor doesn't operate under power in these conditions so why tune it like it does?
 

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Master of the Electron
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Just turn out (ccw) your fuel screws no more than 1/4 turn each - you're a tiny bit lean in the pilot (idle) circuit,

It won't hurt for the pilot circuit to be a bit richer UNLESS you start to feel a burble, stumble or hesitation when you slam from fully closed to wide open throttle - then you've gone too far.

You can simulate this by turning the choke on, incrementally, until the decel popping stops... do you feel a change in hard onto throttle performance? If not you won't feel it by opening up the fuel screws a bit either.
 

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Discussion Starter #15
Ok. I will mess with the mixture screws a bit. Also I played with it a bit and seemed rich in the higher gears. So I jetted it down to 142/144 made a couple pulls up the road and seemed better but was getting too late. Going to mess with it some more over weekend.
 

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Ok. I will mess with the mixture screws a bit. Also I played with it a bit and seemed rich in the higher gears. So I jetted it down to 142/144 made a couple pulls up the road and seemed better but was getting too late. Going to mess with it some more over weekend.
Don't do mulitiple adjustments at the same time. One might make it better while the other makes it worse. Then you don't know which one did what. Also when you jet start at the top and work down. Dial the mains in 100% for the best WOT performance. Then adjust the needle clip position for the best midrange performance. Followed up with the pilot circuit and fuel screws.

That way you don't end up with a jacked up needle setting to compensate for having the wrong main jet in. Or have an extreme pilot / fuel screw setting trying to compensate for wrong needle setting.
 

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Discussion Starter #18
I installed a bigger piston because it needed a piston and jug anyway. So why not go a little bigger? I want to do a cam but wanted to get it up and running then do my research and decide which cam is best for our application.

Bike seems to run well at this point, no issue's. Have the needle at the 3rd position and the 142/144 jets left the fuel screws out at 3 turns. I also put the air box lid on. Went to the shop today and they chip and sealed the road up there now it sucks! Not sure why they done that been on that road for years. Never been done before.
 

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Master of the Electron
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You lose power with the lid on... If you take it back off, you'll need to move to larger DJ jets - 2 to 4 larger each
 
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