Magoo Ported 62T jetting questions

[SkiDaddy]

Looks like Pauls away till Saturday, so maybe someone here can help in the meantime. I wanna break it in tomorrow!

I had Paul turn my RIVA pump gas ported cylinders into freestyle ported cylinders, & he recommended different jetting. I've only run it on the trailer for 10 minutes today (just got done reassembling the ski) to check for anything loose & I noticed it hesitates when whacking the throttle open, from anywhere in the range of off idle to maybe 1/16 throttle; once past the hesitation it's strong & crisp. If you whack it from above 1/16 throttle it's fine. I opened up the low speed adjusters up to 1.5 turns out, which helped some.

It's a 62T, 82mm, 33cc domes, B-Limited, OEM carbs/FA w/one screen each. Paul's recommended starting point was:

137.5 Mains
75 Pilots
95 gram springs
1.5 N&S
1.5 turns out HS adjusters
1/2 turn out LS adjusters

I'm thinking about going to 77.5 pilots & 1 turn out; should I lean out the mains to 135 to compensate? What's the combined jetting for a freestle ported 62T w/my setup?

 

[Mile9c1]

I'm thinking about going to 77.5 pilots & 1 turn out; should I lean out the mains to 135 to compensate?

Sounds good. That's with dual 38's right?

 

[SkiDaddy]

Yeppers.

 

[SkiDaddy]

Anyone else? SuperJett, Waxhead maybe?:sneaky:

 

[SuperJETT]

I don't have any experience with the stock 38's, but from what you described I'd say drop the popoff with 80 gram springs and/or adjust the low speed screws for idle.

Really though, you'll need more time testing/running it to see what it really needs.

One thing to do is run it, get it warm, etc., then put it on the trailer and let it idle. It should idle forever, and when you blip the throttle it should yank. If not, you need to start there and tune your way up the circuits.

 

[SkiDaddy]

I don't have any experience with the stock 38's, but from what you described I'd say drop the popoff with 80 gram springs and/or adjust the low speed screws for idle.

Really though, you'll need more time testing/running it to see what it really needs.

One thing to do is run it, get it warm, etc., then put it on the trailer and let it idle. It should idle forever, and when you blip the throttle it should yank. If not, you need to start there and tune your way up the circuits.

I agree with more time, I just want to get some input on where I should go if it still hesitates after some actual riding.

I thought about the pop-off, but it was hesitating w/just a small blip of the throttle as well as grabbing a handful. I would think this would be the pilot, not the pop-off?

 

[SuperJETT]

To test the low jet size, you ride at 1/4 throttle for a while, like 45-60 seconds then nail it. If it hesitates, it's too small or if it's loaded up and takes a second to really pull, it's too big. The low jet has almost nothing to do with idle performance.

 

[SkiDaddy]

I'll try that tomorrow. Hope it's warm. It was 50 degrees this morning.:bigeyes:

 

[#ZERO]

Your jetting sounds about right, I would open your low speed screws 7/8 to 1-Turn open. The low speed screws work from idle to about 1/16th throttle opening and the pop-off pressure works from 1/16 to 1/4 throttle opening. The low speed jet works from 1/4 to 3/8 throttle opening and you may create a surging problem when slowing down, if the low jets to large.

Be sure to use a 25:1 premix fuel ratio for the first 5 hours or first 2 tanks of fuel on your new Wiseco’s. :wink:

 

[SkiDaddy]

I dunno about the 25:1, that's pretty rich. I run Maxima 927 at 40:1, and I had Paul set up the clearance for Wisecos (around .0055) so I should be OK. My last Wisecos looked new after 4 months hard use (skirts), except for the hole melted in one. I warm up & break in carefully.:sneaky:

 

[Sanford]

I dunno about the 25:1, that's pretty rich.

It is but not for breaking in the motor. Run 40:1 after the initial break in period.

 

[kingnothing3]

I'll try that tomorrow. Hope it's warm. It was 50 degrees this morning.:bigeyes:

50!!!! im praying for 50degree weather! its been cold for so long here. just starting to warm up.

im looking forward to having my own jetting situation when i get my magoo ported cyl. back.

 

[SkiDaddy]

50!!!! im praying for 50degree weather! its been cold for so long here. just starting to warm up.

im looking forward to having my own jetting situation when i get my magoo ported cyl. back.

Yeah, we had a cold snap. I'd gotten used to wearing shorts in the morning. Long pants, Ugh.

As to the extra oil, I'm straining my memory, I ~think~ I had asked Paul his opinion on that & he was more in favor of richening the jetting a bit for break-in (new top end only). I could be thinking of someone else though.

Supposedly memory is the first thing to go....... Maybe it's time for the red Corvette?:Banane01:

 

[Idok]

Yeah, we had a cold snap. I'd gotten used to wearing shorts in the morning. Long pants, Ugh.

As to the extra oil, I'm straining my memory, I ~think~ I had asked Paul his opinion on that & he was more in favor of richening the jetting a bit for break-in (new top end only). I could be thinking of someone else though.

Supposedly memory is the first thing to go....... Maybe it's time for the red Corvette?:Banane01:

too easy

:sneaky:

 

[SkiDaddy]

???????

 

[butti]

???????

ya i dont get it either

 

[SkiDaddy]

BTW I richened up the pilots to #80, richened up the pop-off to 80 grams & currently have the LS adjuster at 3/4 turns out. It rips!:Banane01: :Banane01: :Banane01: :Banane01: :Banane01: :Banane01: :Banane01: :Banane01: :Banane01: :Banane01: :Banane01: :Banane01: :Banane01:

Still not ~perfect~ but way better.:biggrin: