Tuning duals after choke removal- Help

[Shifty]

I need some tuning help,

I pulled the carburetors off of my all stock ‘08 SJ to remove the tamper caps and install the primer fittings. After I removed the chokes, I cut off the extra castings that now serve no purpose. I didn’t cover any of the carb nipples or throat while using the cut-off wheel to hack off the castings. Since there was aluminum dust everywhere afterwards I decided to rinse them under hot water with a soapy brush. Before I rinsed them I cleaned out the inside each nipple with a Q-tip, careful not to push any contaminants back into the carb, then capped the throat and nipples with duct tape. There wasn’t any considerable debris in any of the nipples thankfully. I blew the carbs off with compressed air and did not direct any into the nipples. I sprayed each carb down with silicone spray and installed with a new gasket.

Sorry for the essay, but it continues…

After bolting it all up with a new OEM Gasket my ski is running like hell. I have read to open up the low a tad after primer install but this didn’t help. I played with the low and at one point it would gurgle when I punched it off idle, if I feathered it up to full throttle it would top out. Is this the “too rich” gurgle I have read about? I have it at 1 turn out (stock 7/8) on the low now and it runs well when I hammer it in a straight line but when I come up to a wake and want to launch off of it, it seems as if there is no power.

Why would a choke removal make such a difference?

I have read the tuning guides of both Mikuni and Group K but can not hear a difference in smoothness when tuning the low speed at high idle. How are you supposed to get this right without a tach? And how can you tell with dual carbs?

Sorry for the long post but I need to get this one figured out,

Thanks in advance

 

[RMBC Freeride]

read this thread: http://www.x-h2o.com/threads/30989/post-434676&highlight=choke#post434676


specifically what SUPERTUNE has to say about choke plates on 38's. He knows his stuff!

 

[Shifty]

I have a wave blaster with the 62T and when I removed the chokes it also has run like crap since. Too late for my SJ now, why does everyone say to do this? How in the hell do I fix this, becasue this ski isn't even a month old and I cant deal with a poor running ski.

 

[RMBC Freeride]

Rejet... thats all there is to it. You probably need to lower the popoff pressure and possibly go to a larger pilot jet. By removing the choke plate and shaft, you have lessened the restriction in the carb which lessens the signal (suction pressure) on the jets. So you need bigger jets to achieve the same air/fuel mixture that worked well before.

 

[Shifty]

I figured that, I tried lowering pop off on my blaster but that did not work. I just dont get why everyone says to run primer kit when it clearly jacks up your tunning. I fugured the stock F/A would keep the vacuum up high enough to keep things in order. I will be getting a limited factory pipe soon, and was planning on rejetting then. Will the stock jetting not allow a stock boat to run a without chokes? I have not tried tunning the highs at all.

 

[augustaf]

Rejet... thats all there is to it. You probably need to lower the popoff pressure and possibly go to a larger pilot jet. By removing the choke plate and shaft, you have lessened the restriction in the carb which lessens the signal (suction pressure) on the jets. So you need bigger jets to achieve the same air/fuel mixture that worked well before.

I agree! Since the low speed needle doesn't have much effect after 1 turn out, you need larger lowspeed jets (the smaller ones towards the bottom of carbs).Lowering the pop off pressure by going to weaker springs would also help. If you plan to go big bore you would need to install 2.0 needle/seats - that also lowers pop off!

 

[augustaf]

I figured that, I tried lowering pop off on my blaster but that did not work. I just dont get why everyone says to run primer kit when it clearly jacks up your tunning. I fugured the stock F/A would keep the vacuum up high enough to keep things in order. I will be getting a limited factory pipe soon, and was planning on rejetting then. Will the stock jetting not allow a stock boat to run a without chokes? I have not tried tunning the highs at all.

If you ever run your ski out of fuel, sank it or stored it for a long time you will find the primer an absolute necessity! Even lowly weedwackers have them, 2 cycle engines are easier to start that way. Keep in mind, new skis are set up to be lean to satisfy EPA, so if you delete choke plates, install a pipe or make other changes which increase power or increase fuel consumption, you have to make jetting, pop off and or fuel valve (needle & seat) changes

 

[Shifty]

Does anyone know what the stock high and low jets are and what the recomended replacements would be? The top end seems fine, would just the low speed jets need changing? Might sound cheezy, but what about some additional screens in my F/A so I can get throught the weekend?

 

[Big Kahuna]

never had to rejet, but I had a pipe, rejetted for that.

 

[surferdude345]

Since there was aluminum dust everywhere afterwards I decided to rinse them under hot water with a soapy brush.

Water is a huge problem you need to clean those carbs out now with carb cleaner-- Water plus ethonal gas does not do well and can ruin internals.

 

[yamanube]

I pulled my chokes on my stock 38s and rejetted for a new pipe and never had a problem. I find it hard to believe that just the removal of the chokes is your problem. You should be able to pull your choke plates, install the primer and ride, I cant imagine having to rejet or re tune just because you pulled your chokes out.

 

[Shifty]

No doubt, the only reason I think it is the choke removal is becasue when I did this to my waveblaster (62T) I remember it sucking as well. I dont think water could be an issue, as I have run almost a full tank through them at this point. It seems to run ok at the stock 7/8 to one turn out on the low but if I hammer the throttle up the face of a wake it suffers and seems underpowered to me. The top end feels good to me. The ramped casting in the carb throat is there to angle the air under the choke shaft as it is an obstruction to the venturi, I wonder if removal of this shaft is causing a disruption of the air that only larger jets could correct?

I still dont understant the low speed tuning by idle smoothness, how to you detect that?

Again, Thanks for the advice

 

[sflsurfrider]

adding additional screens, or somehow restricting the air intake, would probably work as a temp fix in compensating for where the popoff should be.

i used to remove all of my choke plates and add primers, but i found that it does cause other issues.

it is possible to run a primer and a choke. just drill and tap your F/A for some brass fittings for the primer line to attach to, and leave the choke installed, as is.

 

[Shifty]

I think I may add some extras, I dont want to mess with jets untill I get my pipe, and can use known specs. How about this low speed tuning thing on twins, I just cant see how you can hear the difference, I notice no change...

 

[Shrivel]

it is possible to run a primer and a choke. just drill and tap your F/A for some brass fittings for the primer line to attach to, and leave the choke installed, as is.

That's a great idea. I've put off running a primer because I did not want to get rid of the choke plate. I like the extra insurance offered by a choke.

 

[yamanube]

That's a great idea. I've put off running a primer because I did not want to get rid of the choke plate. I like the extra insurance offered by a choke.

What extra insurance could a choke plate possibly add?

Shifty- why do you have girdled studs with a stock head?

 

[waxhead]

I would like to help you but to be honest if you have done this to the carbs and cleaned them the way you have talked about
I suggest you take them to a shop and get them sorted
I dont think your knowlodge lvl is enough to rejet these carbs and you will more thna likely end up with an expensive problem

 

[ski4]

i've been told a water bubble can get stuck in the screen/filter and stay there
and mess up our fuel mixture:banghead:

 

[Shrivel]

What extra insurance could a choke plate possibly add?

A couple seasons back I got some water in my gas tank and got stuck in the middle of the lake. The ski would crank, but wouldn't stay running for more than a few seconds. The only way I could get back to shore was by engaging the choke about 1/4 of the way, which allowed the ski to stay running (albeit not too well). I don't think a primer would have helped in that situation.

I'm not saying a choke is better than a primer by any means, but I do think there are certain cases where a choke can get the motor going when a primer would not.

 

[sflsurfrider]

A couple seasons back I got some water in my gas tank and got stuck in the middle of the lake. The ski would crank, but wouldn't stay running for more than a few seconds. The only way I could get back to shore was by engaging the choke about 1/4 of the way, which allowed the ski to stay running (albeit not too well). I don't think a primer would have helped in that situation.

I'm not saying a choke is better than a primer by any means, but I do think there are certain cases where a choke can get the motor going when a primer would not.

agreed.

kawis need primers.

yamis barely even NEED chokes.