Jetting RX-1 MCXpress turbo - HURRICANE's turbo springs

[rxrider]

Tried her at 16 lbs once but she went lean popping within 5 sec after hitting WOT. This was with the stock 135 mains in so I didn't dare to make another pass.

Anyone with a AFR meter riding at 500-1000 ft with the MCXpress 16T rear turbo know what jetting to run at 16 lbs????

I got 140 mains in today, will testride it tomorrow. Hope she's getting enough fuel. I will also try to seal the carb caps.

 

[rxrider]

ttt

140 mains works great, have been at 18 lbs STM caps are on, all T's are sealed with epoxy.
Sled is running great except down low, throttle response could be better, seems a little fat??? I don't have an AFR gauge. Currently running 140 mains, needles in 3 position, stock carb springs, 17.5 pilots, pilot screws 2 turns out, boost at 16 lbs.

Any suggestions on pilot jets and pilot screw settings are much appreciated. Thanks.

 

[jornab]

Have you installed wiseco low comp. pistons??

 

[rxrider]

Yes, and thicker head gasket. I know that the compression drop will reduce low end power.

What I need is information on low end jetting

 

[rxrider]

Innovate installed. Low end jetting was rich as I assumed, when giving it wot from 4500 rpms it went 9.8 AFR. Steady cruise at 5 lbs was 12.5 AFR. WOT from steady cruise 5 lbs was 12.5 until about 10 lbs where it went rich 10+ AFR up to max boost of 16 lbs where AFR was 10.2

My jetting was:
Main jets = 140
Pilot jets = 17.5
Pilot screws = 2 turns out
Needle = 3 position (stock)
Stock carb springs
STM Billet Carb Caps

Installed stock 135 main jets and green Holtzman springs yesterday, will take her out for a test ride asap.

 

[rxrider]

Update on jetting, AFR. Temps was 40+ F or +5 C.

Idle hot: dropping from 14.7 to 15.5
Driving slow: 14.5
Cruising 0 lbs of boost: 12.0
Cruising 5 lbs of boost: 12.5
WOT 10 lbs: 11.2
WOT 16 lbs: 10.9 (I don't mind this AFR with temps that day, my guess it will be close when temps drops below 0 F)

Jetting:
Main jets = 135
Pilot jets = 17.5
Pilot screws = 2 turns out
Needle = 3 position (stock)
Holtzman Green carb springs
STM Billet Carb Caps

When going WOT on the lake (16 lbs boost) to 120 mph and letting off the throttle to maintain that speed AFR goes 14-14.5 and boost slowly come down towards 10 lbs where AFR goes back to normal AFR 13.0 at 5/8 throttle.

Will this lean spot hurt my motor?

How do I fix the lean spot, if it's needed that is?
Current springs and raising needles? but that may make low end even richer than it is now.
Softer springs without raising needles?
Stock springs and raising needles?

We are still riding on spring snow. I may try a few different springs, will post results if so...

 

[Ted Jannetty]

Update on jetting, AFR. Temps was 40+ F or +5 C.

Idle hot: dropping from 14.7 to 15.5
Driving slow: 14.5
Cruising 0 lbs of boost: 12.0
Cruising 5 lbs of boost: 12.5
WOT 10 lbs: 11.2
WOT 16 lbs: 10.9 (I don't mind this AFR with temps that day, my guess it will be close when temps drops below 0 F)

Jetting:
Main jets = 135
Pilot jets = 17.5
Pilot screws = 2 turns out
Needle = 3 position (stock)
Holtzman Green carb springs

When going WOT on the lake (16 lbs boost) to 120 mph and letting off the throttle to maintain that speed AFR goes 14-14.5 and boost slowly come down towards 10 lbs where AFR goes back to normal AFR 13.0 at 5/8 throttle.

Will this lean spot hurt my motor?

How do I fix the lean spot, if it's needed that is?
Current springs and raising needles? but that may make low end even richer than it is now.
Softer springs without raising needles?
Stock springs and raising needles?

We are still riding on spring snow. I may try a few different springs, will post results if so...

You can drop the needles 1 position.
Lean out on Decel is never going to hurt anything so no worries.

 

[rxrider]

Thank you Ted - BTW I love the Vortech BOV it made a big difference

 

[Skydog]

TTT

 

[rxrider]

Update on jetting, AFR. On the same lake in late April 2007.

Idle hot: dropping from 14.7 to 15.5
Driving slow: 14.5
Cruising 0 lbs of boost: 12.0
Cruising 5 lbs of boost: 12.5
Cruising 10 lbs of boost: 13.5
WOT 0 lbs: 10.5
WOT 5 lbs: 10.9
WOT 10 lbs: 11.2
WOT 16 lbs: 11.4

Temps that day were -4C or 25F

Jetting:
Main jets = 135
Pilot jets = 17.5
Pilot screws = 2 turns out
Needle = 3 position (stock)
Holtzman Green carb springs
STM Billet Carb Caps

This data was from my notes from last season.


Update for 2008 season:
I have now changed to stock carb springs and needles in #2 position, 22.5 pilot jets and 2 turns out from seated, seems a little fat down low, have not been testing it yet, but will do this coming weekend.

 

[Skydog]

How do you have your lines to you slides set up? Did you added a 2nd one?

Thank you Skydog

 

[lakercr]

How do you have your lines to you slides set up? Did you added a 2nd one?

Thank you Skydog

MC comes with two lines from the 'factory'.

 

[rxrider]

Yes they do

Here's what it looks like

 

[Skydog]

WOW yea Thank you You guys are the best!!

 

[rxrider]

My idle AFR is a bit low, like in the 12s at idle on a warm engine.

I have 22.5 pilots in and pilot screws at 2 turns out. How much should I turn the pilots in to get the AFRs closer?

No snow to ride on so I have not been able to test properly. Will try to get out on the lake this weekend to test jetting and clutching.