With lid off you either have to have your slide spring cut to 3 inches or install a weaker spring.
If spring is old style - longer than 3 1/2 inches you may be having alittle slide flutter that will richen the top end and not pull well. With your mods and you saying the 170 felt best is a good indication that you are having alittle slide flutter.

 

I did the slide spring trick a long time back, I think I cut 3 or 4 coils off of it. Could it have to light of spring pressure and cause slide flutter, what year DS has a better spring.

 

The new 05 spring is the best to date.
Here is the difference between an 01 cut 5 coils - This made the spring overall length between 2 7/8 and 3 inches. This is the minimum length.

These measurements are in grams.
01 05

2 7/8 25 35
2 1/2 105 125
2 220 215
1 5/8 310 300

The 01 has a pitch of .140P
The 05 has a pitch of .120P

You may have an extra 1 1/2 coils more than the 01 above. This would put you at around
340-350 grams of force.

I have not cut the length of the 05 spring, but if I did , I would just cut 1 coil.

Then the difference between the 01 and 05 would be roughly 345(01) to 285(05)

I would also drill out your 2 vacuum ports in the slide to 1/8 inch. This also helps.

I am presently using a spring with only 145 grams of force. I have tried 290 and 230 also.
To use such a light spring you have to change your jet needle. Otherwise midrange leanout.
I am still testing.
When done I will post in a new thread.

 

grams of force?[img]i/expressions/face-icon-small-confused.gif[/img] wtf?

 

I'll have it on the dyno this week, what should I look for in the curve to indicate slide flutter?

 

Your horsepower curve will drop off like a 2 stroke.
From 6 to 8k your curve should be relatively flat. Within 10hp

When you run with lid off, you do remove the gasket?
Plug snorkel tube holes to help reduce air turbulence.

 

I've got hte lid off, snorkel tubes out, gasket is still on sealed it with silicone a while back when I was doing a bunch of creek riding with the lid on. I measured the slide spring today and it was a fuzz under 3 inches, I can't remember how many coils I cut off. I'll have it on the dyno thursday afternoon, hopefully I can get it fine tuned with the stock carb, but it really is screaming for more air flow, I sure do wish I could get a bigger carb now!!!

 

The distance between the seat and lid gasket is very close. Alba did alot of testing and had their best results with lid gasket off. In Wisconsin we are not allowed to use a direct mount filter in stock class. When we were allowed, I connected a Unifilter to a velocity stack and then to a rubber boot to the carb. No air tumbling turbulence to cause the slide to flutter and it screamed. Getting air into the box without causing slide flutter at high rpm's is a problem.
Having the lid on reduces turbulence and the extra negative pressure at high rpm's, stops slide flutter. Great for mid-range torque, but restricts air for top end.
You notice that when MrHorsepower uses a Lectron carb, he removes most of the airbox to maximize air flow. For any carb changes to be really effective, the need for someone to come up with a way to get more air through the stock airbox. You wanting a bigger carb will still have an old problem. We all like to trail ride and need to keep water out of the airbox.
Snow just got off the ground and dried up enough to start testing the new springs I had made. I just finished putting a few mods to a wolverine for one of my son's. I have 2 DS's and my older son has one. With 3 DS's in the family I will figure this problem out.
Let me know how your dyno test's turns out.

 

well I'm back from a 1 hr. dyno session and hears whats going on. 1st pull with 175 main made 46.5 hp, this is with razr 2 tires, my air fuel was around 14.5:1, 2nd pull with 180 main made 44.8 hp air fuel was around 14:1, 3rd pull with 185 main made 42 hp with air fuel at 13:1, this is what the tech said is ideal but I was loosing power. 4th pull with a 170 main made 48.6 hp air fuel at 15:1, what is the cut off for to lean on the air fuel, it runs so much better on the lean side, I'm thinking of trying a 165 main to see how it reacts, what signs will it give me if its to lean??

 

I forgot to ask about jet needle.
Are you in the 4 or 5 groove from top of needle?
The tip on the needle is .025 and this is a fast taper.
I have found that when in the 5th groove I would have to run leaner than when in the 4th.
I am thinking that the diameter of jet needle and opening of needle jet have a relationship
because of the aggressive taper. If you are in the 5th at 170, you may find being in the 4th with a 175/180 may give the same results.
222 had some logic when he said to tune to the O2 sensor. But your testing earlier in the week matched what you found on the dyno. So logic losses to the seat of your pants tests.

Let your motor tell you what you need to know.

Sparkplug Reading - After a good run - pull a plug. If you haave a small eye lope this will help.
End of plug should be mostly grey and alittle black.
IMPORTANT - Carbon on the electrode should be in the middle of turn.
If end black and carbon past curve heading for end of electrode - rich. Jet down.
If end clear and carbon heading for end of plug - lean. Jet up.
If carbon is in the middle of electrode curve - everything if fine.