Raptor Forum banner

1 - 20 of 20 Posts

·
Registered
Joined
·
10 Posts
Discussion Starter #1
Just bought a raptor that needed an engine rebuild. It had a 686 bore kit in it but when I took it all apart the cylinder was whooped as well as the cam journals. Figured I’d start from scratch with this thing so I bought a new 100 mm std bore cyl jug, std bore 9.9:1 piston top end kit, new head, valves, valve springs, cam, rocker arms, valve seals an all that jazz. When I put it all together and fired her up she was running rough/misfiring and rich. I double checked my timing, valve lash, compression and also checked my spark, that was all good still. I did some research and started playing around with the pilot screw. Didn’t make any difference (adjusted a 1/4 at a time all the way to 3 turns out). I went ahead and took the carb apart and cleaned and inspected eveything. I couldn’t read the jet sizes it wasn’t legible.
Was wondering if anyone had any ideas of what size jets to put in this thing also if anyone knows of something else I should check. For the jets I’m at sea level, has a stage 4 exhaust and k&n filter.
 

·
Master of the Electron
Joined
·
15,180 Posts
Welcome to the forum!

Is the airbox stock or is it lid off or holed, is snorkel intact or modified?
 

·
Master of the Electron
Joined
·
15,180 Posts
What's in there right now?

With lid off you need (Mikuni mains) 160 in the left carb and 165 in the right. You also need aftermarket needles (made by DynoJet) and 25 pilot jets.

If you don't already have the needles, DynoJet sells a 660 kit that comes with the needles and jets you need - but from DJ the mains would be 146 for left and 148 for right - they use a different measurement scheme.

So, Mikuni - 160 L / 165 R, OR Dynojet - 146 L / 148 R. main jets
Dynojet needles at 1 step rich of center.
25 pilots with fuel screws around 2.5 turns out.

You may need to tweak these numbers a bit but you'll be close - good luck!
 

·
Registered
Joined
·
10 Posts
Discussion Starter #6
What's in there right now?

With lid off you need (Mikuni mains) 160 in the left carb and 165 in the right. You also need aftermarket needles (made by DynoJet) and 25 pilot jets.

If you don't already have the needles, DynoJet sells a 660 kit that comes with the needles and jets you need - but from DJ the mains would be 146 for left and 148 for right - they use a different measurement scheme.

So, Mikuni - 160 L / 165 R, OR Dynojet - 146 L / 148 R. main jets
Dynojet needles at 1 step rich of center.
25 pilots with fuel screws around 2.5 turns out.

You may need to tweak these numbers a bit but you'll be close - good luck!
I appreciate all that. Thanks for taking the time to reach out and respond back!
 

·
Master of the Electron
Joined
·
15,180 Posts
What are your present jet numbers and needles?
 

·
Registered
Joined
·
10 Posts
Discussion Starter #8
The jets are hard to read but from what I can make out L-167.5 R-172.5
The needles do not have any numbers on them. The clips are in the 4th slot counting from top to bottom.
 

·
Master of the Electron
Joined
·
15,180 Posts
5 slots or 6 on the needles
 

·
Master of the Electron
Joined
·
15,180 Posts
So, you already have the main jets and needles you need - I think you may be a bit rich on the mains but Sixpack is running close to your's with excellent results.

You really do need at least the 25 pilots (I suspect they're already there) so just try to clean and verify their numbers.
 
  • Like
Reactions: Sixpack577

·
Master of the Electron
Joined
·
15,180 Posts
Great! What numbers are you finally using?
 

·
Registered
Joined
·
10 Posts
Discussion Starter #19
I bought the dyno jet kit and put in the 146 mains on the left and 148 on the right. For the pilots I got the 25’s to replace the 22.5’s that were in there and have the screws at 2.5 turns out. The needles I left the same with the clips on the 4th slot
 

·
Master of the Electron
Joined
·
15,180 Posts
Fantastic - you fit the normal numbers for your mods. have fun with it!
 
  • Like
Reactions: Ryan238
1 - 20 of 20 Posts
Top