I have to do this....JETTING

[Castor-426ex]

ok all was good with the big gun...but i got rid of it and got an hmf full system

well now the son of a ***** will not run right

it had a dj165 and it still would pop on decel but would run fine
No i have not pulled the plug because i dont have a wrench to fit it......well i pulled the fricken dyno kit out...and worked my way from a 170 all the way up to a 180 that is in it now....

I am 3.5 full turns out on the mixture screw

now when i let off the throttle it will shoot a small flame out of the muffler....and it has a rapid pop on decel

needle is on second groove as most are...i pulled the airbox lid off and it made a difference it ran better but still

I dont like the pop and i want it to run good......help me

[Castor-426ex]

:( :( :( :( :( :(

[the yella yeti]

Sounds to me like your runnin rich.
Try downsizing the main jet.

[Castor-426ex]

good lord it had a dj 165 main in it with the big gun....and then with the hmf it popped on decel with that jet so i junked it and went with keihens.....i figured the 180 would be too much....but ill give it a shot

what about the screw??

[Castor-426ex]

Originally posted by Castor-426ex
good lord it had a dj 165 main in it with the big gun....and then with the hmf it popped on decel with that jet so i junked it and went with keihens.....i figured the 180 would be too much....but ill give it a shot

what about the screw??


also ive tried a 175, 178, 180,

i thought the pop meant lean....ill bring it down


you think a 170 should be close?

[airheadedduner]

Pop is lean. You said needle in second grove, from the top or bottom? The lower the clip is on the needle the richer. I don't think the screw should be more then 2 turns out but thats for 2 strokes, I am new to thumpers so it could be a little different. Dynojets sizing is different then kiehins, to save some headaches maybe it would be better to go get kiehin jets.

[JOEX]

Someone posted recently that the pop on decel was normal. I'll try to find the thread.

Anyone else read that one?

Joe

[Castor-426ex]

my big gun never did it

[airheadedduner]

Originally posted by JOEX
Someone posted recently that the pop on decel was normal. I'll try to find the thread.

Anyone else read that one?

Joe
Never heard that but mine does it too. Only like a couple though on a long decel so I am not worried about it.

[Castor-426ex]

i pulled the dyno kit


the pop isnt bad but it is rapid....it ran perfect with the big gun....how much of a difference is there? i know this hmf headpipe is massive

but dayum

how many turns should i go on the fuel screw?

Oh boy isnt jetting fun. I think you may just have another problem there castor. The decel pop could also be from the slow/pilot jet or?

Check around for possible air leaks. Around the carb inlet and all around the pipe connections a leak in the exhaust could cause the pop also.

I do think the HMF would need a little larger jet but this is sounding like too much of a change just for swapping silencers.

One very important thing you forgot to tell us or test etc is how it actually runs at different throttle positions. Will it idle?

I would think you should need someware between a 162-172 keihin mj (but as you know its impossible even for the pros to guess) with your mods so I am seriously thinking since you still thought it was lean at 180 there may be other things wrong.

[Castor-426ex]

it will start and idle with the 180 and 175...and it revs perfect...but pops on decel....this is the hmf full system

tomorrow ill try a 172...and the 170...i dont have anything below that


however with the 180 if i crammed it wot under load it would just not respond...almost like it cut off...but if i let off of it it was ok

its prob too rich


no air leaks either...

[JOEX]

After a brief search, I haven't found the post I was looking for.
From what I remember, which can be questionable, ... when the motor is decelerating off the throttle it is sucking in more air than usual which causes a lean situation and the pop.

I'm sure the post was from a more knowledgable member here, IMO, that is why I remember it. I just can't remember who:rolleyes:

Joe

[Ketch]

Castor, I had a set up just like you at one time. This is what worked for me. 40pj needle in the middle 165mj 3 turns on the screw. This should do it.:cool:

[MIKE400EX]

Make sure you don't have a leak at the exhaust flanges.

[dhines]

Yeah, pop on decel indicates a lean condition - usually on the pilot jet. Bump that up a size or two and bring that main back down.

Castor..just AIM me and we'll get it figured out...:cool:

[thejeepdude]

Originally posted by dhines
Yeah, pop on decel indicates a lean condition - usually on the pilot jet. Bump that up a size or two and bring that main back down.

Exactly... I'd say you should be closer to a K 158-160 main with the HMF... K 180 <!> is way too big unless you're running some major motor mods... I'm running a 160 on mine (runs strong) and I'm waiting for the K 158 & 155 to show up so I can try those.

[Castor-426ex]

i have minor mods hotcam stage 2 je 426 piston kit ect

[knighttime]

castor, in not sure what your setup is, but my sig below may give you a good reference point :eek2:

[Castor-426ex]

i called hmf they told me to use the settings on their website


they call for a 200 main!!!! wtgdf

[brokeitin3]

still have the big gun system?

[Castor-426ex]

nope


also i notice the headpipe on this hmf is massive

especially where it connects to the muffler

I mean my ole lady took one look at it and was like:eek2: :eek2:

kinda made me jealous:D

i think the big difference between the two exhausts is that the hmf is a no backpressure exhaust

plus its way better looking

Well from what I have seen in this thread I am looking directly at the pilot/slow jet and the adjustment screw.

What pilot/slow jet are you running?

If there are not any leaks either intake or exhaust then pick one of the Main jets you tried allready that didnt bogg at WOT and put that one back in and work on the slow jet circuit and then after the pop is gone go back and fine tune the main, I know its not as easy as it sound because I rejet every couple months at min.