full spec carb issue

[masterblaster]

Im running 2 year old dual 48s off another ski that sat for over a yr and using a external fuel pump mounted a tad higher than carbs with a single pulse line,with the 2 returns in a T going back through a 2.0 main jet back to the tank. brand new triple stage rad valves from ed,with a r&d intake and angled spacer 1.8 n&s,jets are what ed had in them for another sim engine setup to this one.Cant get him on the phone and his email is full.
I had them dialed pretty well with no filters in prelim tuning with a 15/19 solas.but I noticed the hood had oil all over it above the carbs blowing back?and also the front carb dribbles ALOT more than the rear after a wot blip on the trailer? But the front carb had the most lean looking plug reading even with way more fuel dialed in on the main jet,but to get bottom crisp had way less dial on the low screw,less than half turn?still hit good though.then added prox & outer wears,and a low end prop 10/16 hooker after adding these to try and tune,it was a PITA,couldnt get low end to clean up and had a buncha mud in the mid range before it would clean up in the top end.
Checked the needle and seat in the carb,cleaned and put back in,same issue,still have to check popoff on both,any other ideas?

 

[2XLR8]

I would wait and talk to Ed.

 

[Flash-FX]

Im running 2 year old dual 48s off another ski that sat for over a yr and using a external fuel pump mounted a tad higher than carbs with a single pulse line,with the 2 returns in a T going back through a 2.0 main jet back to the tank. brand new triple stage rad valves from ed,with a r&d intake and angled spacer 1.8 n&s,jets are what ed had in them for another sim engine setup to this one.Cant get him on the phone and his email is full.
I had them dialed pretty well with no filters in prelim tuning with a 15/19 solas.but I noticed the hood had oil all over it above the carbs blowing back?and also the front carb dribbles ALOT more than the rear after a wot blip on the trailer? But the front carb had the most lean looking plug reading even with way more fuel dialed in on the main jet,but to get bottom crisp had way less dial on the low screw,less than half turn?still hit good though.then added prox & outer wears,and a low end prop 10/16 hooker after adding these to try and tune,it was a PITA,couldnt get low end to clean up and had a buncha mud in the mid range before it would clean up in the top end.
Checked the needle and seat in the carb,cleaned and put back in,same issue,still have to check popoff on both,any other ideas?

I had messed with a pair of the same vintage 48mm Full Specs. Never got those dialed in the way I think they should. The word "seamless metering" doesn't apply here. I tried ALL the suggested settings and experimented with even more than that...lots. :grumble: I finally set those 48's aside and decided to try a pair of 46's. The AM 46's have some of the same issues as the 48's, but less sensitive. The low speed screw does end up in the 1/2 turn out area (AM carbs have a coarser thread on the L/S screw than the OEM versions = less turns same opening).

I think the recommended return line "jet" is a #60 or 65 for those carbs, a 2.0 seat might be too large (lower fuel chamber pressure). Even though after changing that, those 48's won't be perfect. That "reversion" coming out of the carbs is normal on 2 strokes, keep the filters on. About the dribbling... vibration,low pop-off, worn N/S will contribute to that problem. The 1.8 N/S with a black 80gm spring should end up with about 23psi pop-off.

It's been awhile since I messed with the 48's but that "muddy" 1/4-3/8ths throttle will never go away. It looks like ED tried to clean up that throttle position problem by epoxying up the 2 transition holes and re-drilling them smaller. As the Mikuni manual states about problems and throttle position...that's where the problem lies.

The lower pitch impeller worked out better for me as to rev through that weak 1/4-3/8 throttle position quicker, and load up less. Just be sure that the low speed screw is set properly, if is out too much, it will compound the "over rich" problem you are trying to eliminate.


Hmmmm.....Ed, when I talked with him, he has a wealth of knowledge to share...if you can get a hold of him.

 

[Idok]

flash, you said you had a set of "vintage" full specs.....Torr is saying they are only 2 years old


am I reading that right, or not understanding something???

 

[masterblaster]

Idok I think he means pre 49 mil,I think that happened a little less than 2 years ago?I wonder what the diff is other than just 1mill bigger?
with the dribbling I have plenty of vibration on the motor at that rpm when it does it,but the back carb doesnt,the n&s look fine,I may have to remove both carbs and test pop off on both. the return is a 60,I was thinking about something else.
If your jamming on the throttle you always felt that muddy transition in the mid with ful specs,For this kinda $ id expect perfection
I spoke with ed once months back when I first got these,he is very helpfull,hard to comprehend it all,should have recorded it.he was a pain to get though,like 10 tries to luck out once.

 

[Flash-FX]

flash, you said you had a set of "vintage" full specs.....Torr is saying they are only 2 years old
am I reading that right, or not understanding something???

Yep...about 3 years old.

Idok I think he means pre 49 mil,I think that happened a little less than 2 years ago?I wonder what the diff is other than just 1mill bigger?
with the dribbling I have plenty of vibration on the motor at that rpm when it does it,but the back carb doesnt,the n&s look fine,I may have to remove both carbs and test pop off on both. the return is a 60,I was thinking about something else.
If your jamming on the throttle you always felt that muddy transition in the mid with ful specs,For this kinda $ id expect perfection
I spoke with ed once months back when I first got these,he is very helpfull,hard to comprehend it all,should have recorded it.he was a pain to get though,like 10 tries to luck out once.

Check the pop-off again to confirm good sealing with the N&S.

I agree, with all the $$ that those 48's cost, they should be close in performance to fuel injection.

 

[750SX]

I'd probably replace the needle and seats. Also make sure your first fiberglass reed is installed correctly. They have a little rubber lip that is supposed to aide in sealing against the reed cage. If you flipped that the wrong way it could be part of your spit back problem. Also from your post it looks like you were running it without filters on, if I did the same thing mine would probably blow fuel all over the hood too.

I got a set of 49's this year from ed and have been very pleased with them. They are like fuel injection imo. I have also heard rumors that the 48's have better response and have ridden friend's skis that had them and they have ran super smooth as well. It's all in the tuning and total package. Keep trying to dial it in. Give Ed a call and tell him your setup just to make sure you are on the right track with jetting.

I was actually having an issue with my plug readings being different on my 49's. It turned out my rear low speed adjuster was backing out due to vibration. A little more tension on the spring fixed it up.

Good luck!

 

[masterblaster]

hmm good to know,I got these reed cages from ed already put together so i didnt even look at them. hopefully it will be a worn spring or something causing pop off to be diff between the 2 of them

 

[masterblaster]

got in touch with Ed, he told me to replace the tiny little clear reed on the back of the jet cover plate.also that the highs cant be turned more than 1/2 turn open,this causes a better transition from low to high,so did both of these things and checked pop off,front carb was 24 back was 27 even with the same springs? anyway most of the dribbling stopped and it really ripped hard,much easier to just tune the low end leaving the highes at 1/2 turn open.
something happened towards the end of the tune session and the ski just started bogging out so bad it would die at odd rpms,then it wouldnt start at all.had spark,then started again on the trailer,ill give it a go fri and see whats up

 

[2XLR8]

Have you checked compression yet ?

 

[masterblaster]

brand new motor dont even say that

 

[masterblaster]

lmao,of so the prob looked like it was coming from the fuel pump,random air bubbles in the line.follow it back and guess whats stuck in the front of the fuel filter,A big freakin green fly has his head stuck in the fuel filter,I guess his ass wasnt jetted large enough for constant fuel flow. she ripps so hard it hurts less the flys ass in the way.
One more plus for semi clear fuel line.

On another note,checked popoff it was 24 in the front and 27 in the back,didnt seem to make much diff though once the highs were set back to little more than 1/2 open,might need to go up a jet size in the main,from a 135 to a 140