Author Topic: Jetting  (Read 2054 times)

aas5f6

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Jetting
« on: January 16, 2009, 10:54:17 AM »
I know my jetting is off. I have a uni air filter and a pipe similar to a DG pipe. What size do you think my main jet should be? Stock is 120. I know how to jet I'm just trying to get suggestions.

PilotHawK

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Jetting
« Reply #1 on: January 16, 2009, 07:45:06 PM »
I'm pretty sure that the stock main is a 128. I'd try a 132 and see how it goes from there.

Adnoh

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Jetting
« Reply #2 on: January 17, 2009, 07:42:45 AM »
Ah the million dollar question. Jetting can be fun or a pain in the rear. You say you know its off. What stuff did yo do to alter previous set up. Did you add pipe air ect. or was it already done and the jetting just seams off.
Just curious.

aas5f6

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Jetting
« Reply #3 on: January 17, 2009, 12:45:29 PM »
I acquired the Odyssey with a pipe. I added the uni air filter because when i bought it it lacked the air box and uni was the cheaper way to go.

I the problem originally it was stalling when throttle was wide open. If you keep the throttle open it eventually would hit full power. Pilothawk suspected it was the jetting.

The manual said the stock main jet is 120. I tried a 125, 130, 135. The problem seems the be getting better the higher I go.

The needle is in the middle.

Any help is greatly appreciated.

Adnoh

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Jetting
« Reply #4 on: January 17, 2009, 04:59:22 PM »
Ok If I follow ya

#1:You added a filter open to the air no box no lid thats it. Did you replace one that was there open with no box or lid or was it and the box gone.

#1 explain: If they box was once there and then removed and an open filter was added what happenes is the is more air bieng pulled thouhg the carb than before causing a lean condition to which the motro should respond reving very hard and possable damage may acccure. A mid ( neddle) and a main jet change will be needed.

If you just replaced a old filter with new then the jetting should be close and a main change should clean it up.

#2:Next you say stumble past 3/4 throttle or does it blubber( fourstroking)as you go to wot ( wide open throttle), as you back off the throttle to 3/4 does clean back out.

#2 explain: If it stumbles than there is not enough fuel getting thu the main jet and there may be a possible blockedge. If it fourstrokes blubbers it rich on the main jet. By going back to 3/4 throttle from wot and it cleans up your off the big part of the main jet due to neddle taper and you need to go leaner on the main if theres no blockedge.
   
Yes or No:

#3 did changing to a biger # jet help or hurt.

#3 explain: bigger main jet ( richer) smaller main jet (leaner) If you went bigger it should bog sooner and harder. If you went bigger and it helped you have other issues if you only replace old filter with new.

#4 is the plug new.

#4 expalin: if you plug is fouling it will lead you a stray on jetting. Always I mean always use a new plug first to make sure its not plug but jetting than start changing jetting. Once you get it to pull do your plug chops and learn to read plugs.

If it idols step one is done
If midrange pulls with no hesitation than step two is done
Then and only then do you do top end main jetting,final mid range setting plug reading.

Note: when you go bigger on the main it has an effect on the neddle. The bigger main jet is less restricive and allows more fuel to be pulled past the neddle to which it may cause you mid range to go fat( rich). Usally it takes a jump like 195 to a 205. This is where plug chops come into play. Once you dial in the mian with the right heat range of plug you can ajust the neddel to get you mid range back.

Note on plug chops: I recomend doing it with a fresh pulg so if yor fat on the main or breaking in new motor it does not mislead you and cause you to go lean.
 

Lets keep it simple and start with the 4 question and go rom there.

aas5f6

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That was one large post!
« Reply #5 on: January 19, 2009, 12:49:19 PM »
#1. I added a pod filter. No box no lid.
#2. When going past 3/4 throttle, it stalls then if you keep it full throttle it will eventually hit full power. idle to 3/4 plenty of power.
#3. The bigger jet has helped. Stock is 120 according to the manual. I currently have a 135 in it now.
#4. Plug is new. When reading the plug is a flat chocolate brown.

I think the top end problem is fixed. I feel that the problem has moved to the middle range. Should I drop the clip (lift the needle) to solve this problem.

Thanks for the help.

hoodlum

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Re: That was one large post!
« Reply #6 on: January 19, 2009, 02:58:41 PM »
Quote from: "aas5f6"
#1. I added a pod filter. No box no lid.
#2. When going past 3/4 throttle, it stalls then if you keep it full throttle it will eventually hit full power. idle to 3/4 plenty of power.
#3. The bigger jet has helped. Stock is 120 according to the manual. I currently have a 135 in it now.
#4. Plug is new. When reading the plug is a flat chocolate brown.

I think the top end problem is fixed. I feel that the problem has moved to the middle range. Should I drop the clip (lift the needle) to solve this problem.

Thanks for the help.



If it's rich in the mids, you need to raise the clip/drop the needle....
Have you leak tested it to make sure you don't have an air leak anywhere?That's a big jump in the main just to have an air box mod....
Have you checked to see if your pipe is plugged up or restricted?
Hoodlum

aas5f6

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Response
« Reply #7 on: January 19, 2009, 04:32:03 PM »
I have not leak teseted it.

It was not only a air box mod. It was also a pipe. I had never run the motor with the pipe prior to rebuilding the engine.

I repacked the pipe so I'm pretty sure there is no blockage.

Adnoh

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Jetting
« Reply #8 on: January 19, 2009, 04:42:42 PM »
Glad to here the fat jet helped. If its pulling on top now and the mid is not as crisp as it was than the mid is most likely fat caused by the bigger main jet. As hodlum said lowering the neddle by raising the clip will lean out the mid. If you go down with the neddle and it does not help a neddle taper change may be required. I will assume its a keihin carb. Heres a pic of how the neddle functions.

Adnoh

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Jetting
« Reply #9 on: January 19, 2009, 04:43:51 PM »
Do not know what happened try again.

aas5f6

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Thanks
« Reply #10 on: January 19, 2009, 06:50:44 PM »
I will let you know the results of the needle change in a couple weeks. I'm down at school and only get to work on the Ody when I go home on the weekends.

aas5f6

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Fat mid range
« Reply #11 on: January 31, 2009, 02:01:58 PM »
Raised the clip up one notch and fixed the mid range. Plug looks good too. Thanks for all the help. Snow pictures will be up on the website soon.