Boggy midrange - needle questions

[MOC]

GS450L
Stock exhaust
Pods
floats are at 26mm

Carbs have been completely torn down, dipped, and rebuilt using new rubber (thanks cycle-orings.com) including manifold boot gaskets. they are clean as a whistle.

I obviously needed a rejet after the pods. the bike would bog at anything above around 1/4 throttle.

I upped the mains to 130 from 115 and then raised the needle by about 1.5mm

now the bike pulls nicely through 1/4, then stumbles through the midrange, then transitions onto 100% and pulls fine.

I would continue to raise the needle but it's the kind that only has one groove, and it's not set up where i can just add shims beneath it, it's got shims above that have to be removed to raise the needle.

i'm out of shims to remove.

what do i do to richen it up in the midrange in this situation? I really don't want to play games with new needles if i can avoid it. anybody have experience with this problem?

[Agemax]

you need to do some mid range plug chops to see if it is actually running too lean or too rich before you go any further.
a stock exhaust may be too restrictive with the pod filters to get them to run right throughout the rev range

[MOC]

that's an excellent point. i hadn't thought about that.

[BassCliff]

Hi,

Sometimes it's worth it to buy the jet kit just for the slotted needles.



Thank you for your indulgence,

BassCliff

[MOC]

i've looked for jetkits for my bike, but alas, they make none. if i knew the taper on the existing needle i'd just buy replacements with slots, but again, i'd like to avoid that.

ive also discovered a slow leak in my petcock which has hampered any tuning attempts. parts in the mail currently.

once that's sorted, it's off to the stadium parking lot to blast around doing chops and hopefully that will sort things out.

[Guest]

Stumbling in the mid range could also be too rich. You might try dropping the needles slightly to see if it smooths the mid range stumble out, and then do plug chops to insure it's not too lean.

[MOC]

Preliminary plug chops indicate a lean condition. I rode at half throttle up a long hill in fourth and chopped twice just to be sure. Plugs were not white but definitely light gray and ashy.

My petcock parts arrive tomorrow. After I install that I'm thinking maybe increase the float heights slightly? I would like to avoid modifying the plastic retaining clip that holds the needle down but I can't think of many other options besides playing musical needless.

Thoughts? As always your expertise is greatly appreciated.

[Guest]

You are not going to gain anything except ease of accessibility from pods. Going back to the stock air box would make your life a lot easier.

[Agemax]

send a PM to Pete, he is the resident expert on the 450's on here. he has modified his carbs for pods and an exhaust with good results. he will help you out

[Steve]

My petcock parts arrive tomorrow. After I install that I'm thinking maybe increase the float heights slightly?

If you adjust the float height, you will affect all the circuits. Yes, you will richen up the mid-range, but you will also richen up the pilot and main circuits, and you will likely be chasing your tail trying to get them all in sync. Just keep the float height at the proper level and tune each circuit as needed.

I would like to avoid modifying the plastic retaining clip that holds the needle down but I can't think of many other options besides playing musical needless.

One option would be the one that most of us choose. Don't modify your retaining clip. In normal assembly, there is a nylon spacer above the clip. Its thickness determines the position of the needle. If you replace that spacer with a short stack of washers that is about half the thickness of the spacer, you will effectively raise the needle about one notch. If you were to swap the positions of the nylon spacer and the metal washer on the other side of the clip, you will raise the needle the equivalent of two notches.

.

[MOC]

that nylon spacer is already gone. i'm down to only the clip. as for going back to the stock airbox, it was cut in half by the PO and is a nice oily paperweight now.

[jeffasaurus2]

So I've just gone to K&N pods and a much free-er set of mufflers on my 450. I've got a 140 main and had to up the pilot jet one size, haven't touched the needle. It seems to be pretty close to where it should be, I have no stumbles in any range.

Without proper chops the plugs look a little grey, I plan on going through the carbs properly Friday if the weather stays nice. We'll see where they are really at.

[MOC]

thats surprising to me, given your altitude in denver. do you just have slip on mufflers? or did you ream out the stock units?

[jeffasaurus2]

They're the shorty reverse cones from Dime City Cycles. Slip-ons. They seem to be only slightly more restrictive than running open headers.

[MOC]

petcock parts have just walked through the door. thanks to daylight saving time i have the chance to fiddle with the carbs for an hour or so after work too. i will try to get a test run in this evening and report back.

cheers