Cylinder porting..How much does your tuning change?

[Roseand]

Currently I'm running a 44mm carb, 61x/61x setup with a limited b pipe, 180 compression(yes I know it doesn't effect tuning but it does make it run hotter, correct?), dual cooling, etc.
Right now I'm sending my cylinders off to HPE for exhaust porting and the transfers to be cleaned up/matched. Yes, I have talked to him about tuning changes but he said he rarely does anything with 44mm carb setups and said if anything, I'd maybe have to go up a size on the main jet.
With my current setup, I'd say if anything it's a tad rich but rips pretty hard. 145 main 120 pilot stock n&s and 95g spring and only one screen on the spark arrestor.
On my new hull, I'll be swapping out to 33 domes and my hull will be 30-40 pounds lighter than my current hull and my new hull probably won't endup seeing a ton of WOT.
Where should I start? Does porting change your tuning drastically compared to the typical b pipe setup? Because from what I understand, the standard b pipe jets are actually a little rich to begin with. IDK how many turns my screws are out right now but if absolutely necessary I can check that later. I don't hear of alot of people running a 61x/61x single carb 44mm with freestyle porting so I thought i might as well ask around..

Thanks aheada time!

 

[eastcoastjumper]

61x/61x motor is all I have been running.
Ported maniac motor
35cc domes Ada head
B pipe

I ran both a stock manifold and reeds with a 44sbn & a wetjet manifold with boysen reeds and a wetjet 46mm carb.

With the stock manifold and sbn 44 I run a stock 61x flame arrestor box with 1 screen in it. 125 low jet, 147.5 main jet and 18psi pop off.

With the wetjet I used a 135 low and a 160-165 main jet. I also had to dabble with the pop off to crisp things up. If I remember correctly I went closer to 20psi pop off using the same flame arrestor. Throttle response was crisp and I had absolutely no bog off idle and could hold this motor WOT as long as I wanted to.


Important note - I'm also at sea level with water temps from 50-80 degrees across the season, and air temps from 35-90. I only have to adjust my low and high speed screws a tiny bit as temps change.

Your jetting will be different from mine if you are at different elevation and temps.

 

[eastcoastjumper]

Condition of your throttle plate and the bushing seal is important. I had to rebuild mine a few times. Also the low and high speed adjuster o rings need to be new soft rubber so they don't leak.

Small turns of these needles make big changes. It is important not to change too many variables at once. Keep all tests consistent

 

[Roseand]

Good to know! I ride like 800 feet above sea level, and your water temps and air temps are seriously the same as what I ride in.
I've never touched any of the butterflies,etc. But every single other diaphragm, check valve, rubber part. etc in the carb was freshly rebuilt with genuine mikuni last season.

 

[Big Kahuna]

Best thing to do is get jets for the few steps up and down on highs and lows. Go out and test.......... Reference the carb setup thread in the Tech Fa

 

[eastcoastjumper]

Just make sure your butterfly valve is a perfect circle. When the sides start to get worn out air leaks past at idle. You will be able to visibly see the wear. This will cause you to compensate with the low speed & idle adjuster more than you have to. Same with the leaking throttle shaft bushings and seals. If you have excessive play in the shaft you will feel it. And it will wear the brass butterfly faster.

 

[Quinc]

Wow who talked you into finally adding some compression?!

130/132.5 low
155/160 high
15-20 pop off pressure. (with a/m arrestor)

 

[Roseand]

Wow who talked you into finally adding some compression?!

130/132.5 low
155/160 high
15-20 pop off pressure. (with a/m arrestor)

Once I went from 150 to 180 psi I've become a firm believer that high compression is freeken awesome.

 

[txsuperjetfreak96]

Stock compression to 180 with b pipe and enhancer was sweet

 

[Quinc]

Stock compression to 180 with b pipe and enhancer was sweet

Add some boyseen reeds and it gets even sweeter.

 

[Roseand]

Pfffft, when I put on a 9/15 hooker from the stock aluminum prop i had such a smile ear to ear it was crazy. I was mind blown honestly lol

 

[txsuperjetfreak96]

Add some boyseen reeds and it gets even sweeter.

Lol yeah i had carbon tech reeds, 12-20 skat prop it would get it

 

[eastcoastjumper]

@Quinc what size carb were you using that jetting in?

 

[VXSXH20]

James/eastcoastjumper, what needle and seat where you using in your wetjet setup? I just acquired one for my maniac/blue ported 61x setup...I also got a set of pro35 boyesens thanks to Quinc

 

[Quinc]

@Quinc what size carb were you using that jetting in?

46mm. Originally had it in a 44 then switched it over to a 46. Cant say I noticed much change between the two even after playing with the adjusters.

 

[eastcoastjumper]

James/eastcoastjumper, what needle and seat where you using in your wetjet setup? I just acquired one for my maniac/blue ported 61x setup...I also got a set of pro35 boyesens thanks to Quinc

2.3ns at about 20psi. I had a lower pop off at first and raised it up to clean up the rich condition off idle. All tested with mikuni pop off gauge. The 4 spring colors were all consistently a few psi off so don't go by that chart. Best to test and exactly know.

 

[eastcoastjumper]

46mm. Originally had it in a 44 then switched it over to a 46. Cant say I noticed much change between the two even after playing with the adjusters.

I had changed my reeds to the Boysen 2 stage at the same time as the carb and manifold. I didn't notice any bit of a gain with my butt dyno, but it tuned in perfect and I didn't have any increase in fuel consumption. That maniac/blue 735 motor ran without a hiccup for over 500 gallons of fuel last season so I was satisfied.

 

[Quinc]

When I added the reeds to my blaster it was the only change I made and noticed it right away. Then again my stock reeds could have been worn out...

 

[BruceSki]

I had changed my reeds to the Boysen 2 stage at the same time as the carb and manifold. I didn't notice any bit of a gain with my butt dyno, but it tuned in perfect and I didn't have any increase in fuel consumption. That maniac/blue 735 motor ran without a hiccup for over 500 gallons of fuel last season so I was satisfied.

That thing ran good for a single carb!

 

[Roseand]

Any other insight on this carb setup? Other people with similar setups?