Jet kit help please!

[bazwell]

I just went for a ride after putting in my Morleys jet kit.

My setup is
I used Seans needles (stage 7?)
Put in the air correctors
157.5 mains
STD springs
Idle screws 3.25 turns out
V-boost programmed to start opening just before 4000RPM
Seans airbox lid
Marks exhaust 4 into 2

The main problem is it stumbles when trying to cruise below 4000. If the needle is just past 4000 it's fine, and accepts WOT there without problem.

When it's stumbling, opening the throttle a bit more makes it pull OK. Just won't cruise or gently accelerate with minimal throttle.

On the freeway at 4000 in 5th it cruises, and WOT works good, no stumble. :biglaugh:

What do ya reckon?

 

[dmax1]

try putting the v-boost setting back to stock. Might be too rich at the lower rpms. :confused2:

 

[KJShover]

try putting the v-boost setting back to stock. Might be too rich at the lower rpms. :confused2:

+1

Backing your a/f screws to 2.25-2.5 might help as well.

 

[bazwell]

I'm wondering why the vboost coming on at 4000rpm will make it stumble below 4000rpm?

I might try the mixture screws today, see what that does.

edit : actually I tried them at 2.5 earlier and it was way worse.

 

[mattmullins]

Try putting 150 main jets in 157s r to big depending where you at unless you closer to sea level

 

[ninjaneer]

where are your needles clipped? http://www.vmaxforum.net/showthread.php?t=1024

i don't think i have to tell you that every carb rack is gonna vary from one to the next. you can look at here for good starting points: OEM Carbs? Post your setup
i followed this guide to get me where i'm at (after a month of weekends): http://vmaxoutlaw.com/tech/cv_carb_tuning.htm

 

[bazwell]

But wait, theeeeeere's more! (I did that in my gameshow host voice)

First up, I think it's important to mention that I may have had this problem before I put the jet kit in. In fact, I'm pretty sure it's the same problem, just worse now.

The needles are on 1st clip from blunt end.
I am close to sea level.

I played around with the idle screws, from 2.25 to 3.75 turns, and it was always bad, but seemed best at 3.25.
I rode for a while today, 2 up, and the problem was shocking with the extra bum on the seat. Much easier to describe. Basically, it's crap below maybe 1/4 throttle. Seems lean maybe? At the worst, at light throttle it will surge and buck like a bull.

Get it above a certain point on the throttle and it is much better. Of course this means that taking off 2 up is a bit funny.... especially when you give it too much throttle and the front wheel comes up!
WEEEEE :biglaugh:

It does it above 4000RPM when 2 up. Seems to be settled mostly by 5000.

So, I'm wondering what causes stumbling surging (lean?) at light throttle? Cruise enrichener? Springs?

Maleko89 ran the same setup (but with 147.5 mains) but he had the top 3-4 spring coils tied up, and v-boost on all the time.

All suggestions will be considered, as I'm about to go all trial and error in my method.
Oh, I will pull the plugs and take a piccy. That might help....

 

[bazwell]

Yowsers! Bit lean?
The rear bank is different from the front. :ummm:
1-4 in order.

 

[sdt354]

Try putting 150 main jets in 157s r to big depending where you at unless you closer to sea level

Sounds kind of small with all that air flowing and air correctors. How about 155's if you even need to correct main jetting? If the a/f adjustment doesn't work out I'd go another 1/2 clip on the needle-richer? IMHO
Steve-o

 

[one2dmax]

I would go richer on the needle too. Sounds like the transition needs that little extra fuel. Try a washer between the clip and retainer. Then take the washer our and 2nd clip if that washer along doesn't clear it up.

Sean

 

[bazwell]

According to this, maybe rich but too hot?
I'm confused.
http://www.vmaxforum.net/attachment.php?attachmentid=2edit5942&d=1327585189

edit : Sean and Steve have both said go richer with the needle. I should have looked before posting.
I guess I'll give that a go tomorrow. 1/2 a clip first. OK. Got it.

 

[KJShover]

What temp of spark plug are you running, looks like you might benefit from a cooler plug.
To me, according to your spark plug's ring, the jetting seems to be in the normal range, if not a little rich. But your Ground strap looks hot, as the color goes from the base ring to the tip, with very little range.
I'm also thinking hot because of the porcelain. its showing signs of pre-ignition as the hot ground strap is firing the air mixture before the spark gets a chance to.

 

[ninjaneer]

.

love your sig. caught myself almost flicking the bottom corner of the screen :rofl_200:

 

[bazwell]

What temp of spark plug are you running, looks like you might benefit from a cooler plug.
To me, according to your spark plug's ring, the jetting seems to be in the normal range, if not a little rich. But your Ground strap looks hot, as the color goes from the base ring to the tip, with very little range.
I'm also thinking hot because of the porcelain. its showing signs of pre-ignition as the hot ground strap is firing the air mixture before the spark gets a chance to.

Thanks for looking at that. Maybe preignition would explain the running problem. Another thing to look at.
They are DPR8EA-9's. I'll look for DPR9EA-9's.

 

[bazwell]

OK. Tried DPR9EA-9's. Not much different really.
Ran it for maybe 8 miles and pulled out one plug.

I will try and get back out there after dinner and try shimming up the needle.

 

[KJShover]

OK. Tried DPR9EA-9's. Not much different really.
Ran it for maybe 8 miles and pulled out one plug.

I will try and get back out there after dinner and try shimming up the needle.

that plug looks a lot better than the others. you can now see a change in the ground strap as the heat dissipates.

hopefully the needle adjustment will do the trick. :clapping:

 

[bazwell]

I tried it on the 2nd clip today. Much better. I need to try 2.5 though. :biglaugh:

 

[bazwell]

I went to work on 2.5 clips with idle screws 3 turns out.
It wasn't quite right, so I changed the idle mixture screws to 3.25 before I rode home.
The wasn't much to complain about on the ride home. unk:

This is riding in traffic about 25 minutes each way, with most of the riding below 4000RPM with the occasional squirt as I run from the lights.
I pulled out number one plug,



and number two plug.




How am I doing??? :ummm:

 

[bazwell]

Bump

 

[gamorg02]

not a good plug reader myself but if it runs right and the mileage is good i'd say let it be!