Redhead 700 Tuning Questions for Newbie

[MNMead]

The sled has a Holtzman Vari Flow, so the carb vent tubes are fed back to the adjustment knob and then the intake hose is just sitting on the bulkhead under the air box. I have the vari flow set to full rich. I do not have pics, but it is following the standard air box mod. 6 or 7 one inch holes drilled in the top, air box empty except for the center shelf, which also has the 1" holes drilled in line with the top cover's holes. I will check the needle jets. Where is sizing listed on them? I have not noticed it before. Do they just pull out with a soft pliers?
Floats I am unsure of proper adjustment. How do I measure? I assume I just carefully bend the tab the little needle sits on?

 

[MNMead]

Follow up - What do the little air jets at the mouth of the carb do? Should I verify sizing on those?

 

[sideshowBob]

I wondered if the sled had an altitude compensation system like Holtzman.
Before you do anything, disconnect the Holtzman and let the carb vents just hang down beside the carbs. I suspect this is your lean issue.
Run it again and see if it is still lean
I doubt they changed the little air jets in the carb bells and they wouldn't have a huge effect at full throttle.
The needle jets have the numbers engraved on their sides just like main jets.

 

[74Nitro]

Again, it takes quite a bit of run time for your plugs to develop a colour. Putting a new plug and running full throttle a few times won't tell you anything about your jetting.....except fool you to think its lean. Jet it on the very safe side, then go out and burn through at least a half a tank of fuel of hard fast riding.
Also, if you're fouling plugs on a regular basis, the needle jets may be worn out at the top. This is something that is overlooked VERY often.
How many miles on the machine?

 

[MNMead]

Bob so I should disconnect the hose that connects to the left side of this black T? Nitro, that has really been my hold up. Fear of burning down while determining what is safe vs lean. I’ve read so much about running a quarter mile wfo on new plugs, vs always using old plugs, etc etc I just don’t have the experience where I trust I will be “safe enough” to actually get on the sled and go on that first tank of rides. I honestly don’t know how many miles because it doesn’t have an active odometer. I do have the original hood which says 1226km, I would assume my old man put less than a thousand miles on it in the mountains over the 4 years he hit it hard.

 

[MNMead]

This is that plug I pulled.

 

[sideshowBob]

Bob so I should disconnect the hose that connects to the left side of this black T? Nitro, that has really been my hold up. Fear of burning down while determining what is safe vs lean. I’ve read so much about running a quarter mile wfo on new plugs, vs always using old plugs, etc etc I just don’t have the experience where I trust I will be “safe enough” to actually get on the sled and go on that first tank of rides. I honestly don’t know how many miles because it doesn’t have an active odometer. I do have the original hood which says 1226km, I would assume my old man put less than a thousand miles on it in the mountains over the 4 years he hit it hard.

Take that line in your hand off the hotlzman unit and let it hang down free so it is an open vent to the other carb vent lines.

 

[MNMead]

Is there anything I need to do with the black vacuum source hose? I've been doing some reading on the vari flow units and I'm not sure I understand why having it hooked up to the controller that is set to rich would still cause a lean condition.

Feeling like I am finally getting somewhere and am hopeful I'll actually be able to take it on a legitimate ride over the new year.

 

[sideshowBob]

Plug the vacuum source hose.
Without having the sled its hard to know if the holtzman is causing an issue but by eliminating it ensures its not an issue.

 

[MNMead]

Well I had the day off work and headed north early. I unplugged the two lines going to the holtzman and plugged the vacuum line fitting. Bowls came back off to swap in 157.5 jets for safety. Adjusted the fuel screws down to 1.5 with the 55 pilots. I think it’s got a lean bog when you mash the throttle as it gives a bit of a Brrrrr before roaring into a full throttle scream. I decided to wait till tomorrow to run it for a long ride on trails just in case I have an issue. I’d rather be stranded in daylight. I wish I could get this avenger to stay on, it would be great to have egt readings during this. I just cannot figure out why the sled won’t charge it. Thanks all for your help. This has been a humbling yet rewarding project.

 

[MNMead]

Well I successfully rode about 12 miles. Snow conditions were marginal so I cut it short since it’s got a 2.25” paddle and my gauges aren’t working. Didn’t want to overheat. Finished my ride with a measured 350 yard wide open pull on the lake and shut down. These are the 3 plugs. Still wondering if PTO is lean but the other two look good to me. 23 degrees Fahrenheit today. Now I need to look into clutching and this gauge.

 

[MNMead]

Forgot to mention piston wash looked similar on all three. Black but with speckles of metal showing. Not sure how to take that myself.