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4mil dune port jetting help ASAP plea


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Hey guys I need some advise on jetting my mains

 

02 shee

Fresh build by Jeff at FAST

Welded 4 mil crank

65.5 mil wiseco slugs

Dune port by the man

FAST/NOSS head with 23cc stroker domes

Dynatek CDI set on stock curve

4* on timing plate

T-5 pipes

Vforce 4 reeds and billet intake with internal crossover

33mm keihin carbs

K&n pods

Pingel dual valve

Gutted fuel cap with open vent hose

15-38 sprockets with 20" tires

45:1 amsoil dominator oil and 91 pump

1500ft elevation

 

Ok my current jetting is 35 pilot cel needle in middle and 165 main

 

My issue is riding in town occasional wot is fine. out of town up to 45 mph is fine cruising part throttle just under powerband. Rolling into the throttle to wot from 45 to 50ish the pipes just start smoking white colored real bad and you get a oil on fire smell not just occasional 2 stroke smoke. Last summer I torched the pistons because I sucked a carb dry and it did the same thing, smoking like this on long pulls (could get it to pull past 65 before smoking though). I talked with Jeff last fall about jetting and did a ton of chops last fall and sent him pictures and he thought 165 mains were a bit much for me and questioned why my smoke rings did not go all the way around the porcelain. They are about 1.5mm high.

 

I have not chopped this week because I am thinking I'm severely lean. This week temps here have been high 80's and humid about 80%. I had my stock fuel valve (molded with 2 outlets) in last week when this started and I drained the tank and found some small debris partially blocking the screen maybe about 20%. I decided to put on the pingel and pull the head to verify I didn't do damage yet and all is good so far. I rode it tonite and it still smokes only from about half to wot throttle. I assembled the whole engine using a bit of Yamaha 3 bond on all gaskets and it passes the leak down test.

 

Do you think I need bigger mains? Also comparing to everyone else's jetting specs it seems I'm way under most comparable builds on pilots but a bit above on mains and Jeff thinks the mains were a bit big too. This is making me sick I'm going to burn it up again. I'm going to meet some buddies for the weekend and can work on it there but don't wanna wrench all weekend so can whoever so still up please help out before I leave for the weekend?? Thanks!

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With the white smoke and oil stench you speak of I think you may be talking about a pto side air leak. Is it just the right side pipe doing the weird smoke? Could be getting a little case oil in the crank area.

 

My thoughts on the jets is that you are all over. This could also cause the excess smoke but your description sounds like your are saying crank case oil smell not premix smell. I think at most that bike would be a 50-55 pilot and 158ish main. Needle will probably be 2nd from the bottom clip or even the middle clip with the toomeys.

Edited by trickedcarbine
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I have been running between 40 & 50:1 in all my dune motors with no issues. I agree with tricked, sounds like your tranny oil might be getting some where it isnt supposed to be. check your tranny oil leve and do a leak down test maybe? :cheers:

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  • 1 year later...

hey i have a stage 3 port job with a cool head and 21 cc domes 65mm wiseco 795 pistons vf4 reeds uni pod filters fmf gnarly pipes with power core 2 silencers runnin a hotrods 4mil long rod crank and stock carbs my areas temperature is imbetween 75 and 95 degrees my elevation is between 600 and 850 ft what main jet and pilot jet size should i use and what should my needle jet be set on thanks

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hey i have a stage 3 port job with a cool head and 21 cc domes 65mm wiseco 795 pistons vf4 reeds uni pod filters fmf gnarly pipes with power core 2 silencers runnin a hotrods 4mil long rod crank and stock carbs my areas temperature is imbetween 75 and 95 degrees my elevation is between 600 and 850 ft what main jet and pilot jet size should i use and what should my needle jet be set on thanks

Start your own thread Haas.

 

To the OP, check your floats and make sure the height is set properly.

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Op I have stated in another thread most jetting I've done on 33 s tend to like a bigger main then there 35 mil counterparts . I know jeffs motors well give it what it wants if I were you I would add fuel till it doesn't like it then back down one size. Once you get the main figured out then play with the needle positions till your happy, if you can't finda position that works time to look for a diffrent needle . I found I like dek needles in 33 with my Porting style also last duneport of mine dialed in at 172 main 50 pilot dek 2 nd clip and a perfect 2-3 mm ghost ring any questions hit me up

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