Needle setting/cruising

[Coffinator]

My bike runs like crap while cruising, when I have the clip in the fourth slot from the blunt side of the needle. If I move it to the fifth, it's almost good, but I still get annoying stumbling when going slightly downhill/cruising. I have 165 DJ mains installed, and a stage 7 kit.

Is it not a bit much to have to use the fifth slot for achiveing a somewhat smooth operation? I feel like I'm running it too rich that way..

I've taken the carbs apart, and the pilot jets are not clogged. What else can I look at to achieve a smooth cruising engine? Does the float setting affect cruising much?

The bike runs fine under acceleration, and if I whack the throttle in first gear, it does leave a nice black stripe on the road..

I've synced it, and played around with the a/f screws without much luck..

 

[sdt354]

How are the deceleration valve circuits and diaphrams?

 

[tugla]

gonna need little more info on your bikes hole set yup. and exhaust ......

 

[Coffinator]

I've got a full UFO exhaust, individual filters, Vboost eliminated. I've got new slides, springs and diapraghms. The Pilot air jets are 90 and 170.
I feel like I always have to be accelerating slightly to make the engine run evenly. It can't handle small throttle angles without stumbles.
Randomly it will be running fine, but 95% of the time it's not. So I'm thinking dirt in the circuits, but i just can't find it.

 

[Coffinator]

The deceleration diapraghms are not excactly new, but they look whole..

 

[srk468]

Pilot is lean and that's where your stumbling, your needle is way fat though.. try moving to the second or third from blunt end and open up your idle mixture screws some.. my bike also stumbles around as you are stating but it still makes great power wot and gets over 40mpg.. that's roughly my setup but I have vboost and a Morley's jet kit..

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[maleko89]

What are your floats set at? Pilot screws?

 

[tugla]

Agreed try clip 3 and about 2.75-3.25 turns on the a/f screws.....but one take less turns I find with the stg 7 . I'd try the stock springs also.
Check your throttle end play....don't have too much slack in it.
If ou took out vboost are you using a weber to sync carbs.....might wanna try it with vboost and or leave then in,you can close to sync then leave them wide open afterwards but won't be able to sync correctly with out something like the weber or isolating the carbs.

 

[Coffinator]

Yeah I'm using a weber to sync the carbs.
I'm having them ultrasound cleaned tomorrow.

The plastic part where the throttle cable goes into the throttle handle, is broken, so it does have a lot more play then it is supposed to have.. Do you think that messes up the syncing?

I've adjusted the A/F screws, and left them all at 2,5 to 3 turs out.

I've run the bike at the 5th slot for months, getting 120-130 miles before the red lights comes on, when cruising long distance. City driving, or messing around, I get around 90 miles before the light comes on.
So it has worked quite well with the needle on fifth, but I don't understand quite why. I just gave up and left it there. it did not mess up the plugs either..

But I want to be able to ride more comfortably at low throttle angles, so thats why I've started working on them again.

I'll fix the throttle cable plastic thingy that allows you to adjust the wire near the handle, and reassemble after ultrasound cleaning, and we will se how it goes.

 

[tugla]

Mmm....interesting. So it's on 5th so closer to the pointed end right......and that kind I'm mileage with dj165,cool cool

If you got her dialed and its good.....maybe that throttle cable issue is messing it up...
I like to be accurate with the a/f screws as that half turns makes a I'd reference unless that's how you need it to be to run best....

 

[Coffinator]

Got the carbs back from ultrasonic cleaning. Put it all back together. The idle is a lot better.
I checked the wet float levels, with a clear tube and tape marks as described in a sticky in the forum. The wet float levels are within spec.
I moved the clip on the needle to the second slot from the blunt end, and the bike was practically unrideable.. It would just die if i gave it some throttle. It would only run at very small throttle angles.. Is that normal, ever? I'm suspecting an air leak since i need to run the needles so fat for a smooth ride..

 

[dannymax]

With the bike standing still and revving the motor, does it return to idle normally or seem to hang up around 2500 - 3000rpm?

I use unlit propane to test for vacuum leaks.

 

[Coffinator]

Yeah, they drop alot slower from 3k to 1k5 than they do in the rest of the range. I'm waiting for new rubber joints now. The old ones had alot of cracking on the inside, especially the vboost ones. No wonder, since they might have been on there since 1988..

 

[jwood]

Let us know what you find, i am having the same problem since my stage 7 install over last weekend...

Did you pull the float bowl air hoses off of all 4 bowls? This is a must for stage 7..

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[Coffinator]

I won't have the parts until next weekend. But I'll let you know how it turns out.
Why pull the vent lines off? I think that could very dangerous. Fuel would end up all over the engine if the float bowls are accidentally flooded..

 

[dannymax]

Yeah, they drop alot slower from 3k to 1k5 than they do in the rest of the range. I'm waiting for new rubber joints now. The old ones had alot of cracking on the inside, especially the vboost ones. No wonder, since they might have been on there since 1988..

Might be worth replacing the o-rings under the intaker runners also, they rarely go bad but I had one on my '99 that was installed improperly at the factory....took over 10 yrs. to finally show up.

 

[Coffinator]

Might be worth replacing the o-rings under the intaker runners also, they rarely go bad but I had one on my '99 that was installed improperly at the factory....took over 10 yrs. to finally show up.

They look ok. But I want to change them anyways. My bike is in a garage in a different town atm. Anyone know the o-ring size? The dealer wants 9.50 euro pr O-ring.. I don't want to pay that much..

 

[sdt354]

Might be worth replacing the o-rings under the intaker runners also, they rarely go bad but I had one on my '99 that was installed improperly at the factory....took over 10 yrs. to finally show up.

Prob. over kill, but I put new o-rings on the intake manifolds whenever I take them off. I run a bead of high temp silicone one the o-ring too.
V-boost, and carb rubbers do go bad. It's hard to see the cracks till they're removed.

 

[Coffinator]

So I've changed all the rubber. Installed DJ175 mains, and ran the needles at the fifth slot. Bike behaves the same. Did 120 miles before the fuel light came on. Then I changed the PAJ from a mikuni 170 to a DJ190. That did smooth things out a bit, and has made the most noticeable difference yet.. How does the pilot air jet work in the carbs on the vmax? Does it lean out the idle circuit? Or does it increase airflow past the pilot fuel jet, and make more fuel/air mixture come out of the idle circuit and into the engine?

 

[tugla]

With the bike standing still and revving the motor, does it return to idle normally or seem to hang up around 2500 - 3000rpm?

I use unlit propane to test for vacuum leaks.

You thinking also out of sync and or sticking slides......think we seen that before....actually combo of both.......

Unlite propane right Dan-o....hahahah