high fuel consumption??????

[hillbilly550]

Sorry for the long post,,,

So here is my problem, my buddies 06 SXR (with an 07 top end & carbs) started to have a hesitation on set up for wake jumps. Then he landed a jump hard & developed a vibration. We towed in the ski at that point and put it on the trailer. We inspected it & couldn’t find any thing out of place, (no broken mounts or things amiss).

So I had him pull the carbs off & I rebuilt them with new WSM kits while I was at work. Right after he reinstalled them I learned I forgot to install the diaphragm for the fuel pump, Yea, I know, stupid mistake, severe over fueling and filled the front cylinder with gas but it was found before ski was rode…… So he was at my parents place at the lake & I robbed my sbn 44 diaphragm from my 550 & installed it in his pump. We cleared his ski & rode a tank out. Problem was he ran out of gas before me, I have a group k big bore sleeper Sxr and his is bone stock,,, I wasn’t on reserve yet and he was out when we got to the house.

He rode last weekend, we noted sluggish starts and he still consumed way to much gas. So I had him pull the carbs back off & I put new kits in again (wsm) he put them on and it still seems to have lots of fuel in the exhaust water (running on the hose). I may need to ride it & see if it is just residual in the exhaust from before but that will happen this weekend.

I don’t think the reeds are bad because we are not seeing fuel coming back up out of the cards when we rev it.

Also we never experienced the abnormal vibration again as of yet, but skis get mad at you when you land sideways.

It seems to pool fuel on top of the plates when he shuts in down (with the air cleaner off)

So what tips do you have for me to look for. I have rough days and all but I find it hard to believe I effed up a carb rebuild twice in a row. Or should I order kits from Mikuni and see if the problem is fixed?

 

[djkorn1]

Get the mikuni kits....

 

[hillbilly550]

thats what I 've been thinking,, with all the issues Ive had with aftermarket parts on cars I am putting alot of OE parts cust cars on due to poor quality.

hey DJ, Thanks for the quick post.

 

[kawi--rider]

What kind of a story do the spark plugs tell?

 

[hillbilly550]

they were both reading rich but they were not dripping wet. I am going to ride it tomorrow & see where we sit. At least they are even, its not like aI have a blown base gasket & i already check comp and it was good.
I need to ride it since i redid the carbs the second time to make sure it wasn't just residual fuel in the exhaust from before. Also I will put my tiny tac on it to get base idle correct on the water. I'll let you know what I find.

I am still going to order up mikuni kits for this ski & all others i do in the future just to eliminate that as a problem

 

[hillbilly550]

so,,, It would appear that the button on the diaphram that pushes the pivot lever is larger in the WSM kits than stock Mikuni Diaphrams. I put one of the WSM diaphrams in my 550 sbn 44 and had the same overfueling problem,,, to the point that it would not restart do to flooding. So I adjusted the lever & problem solved.

I have new mikuni parts on the way but it is just proof that a pop off gauge would have caught the issue before it was on the water. the needle was not being held to the seat causing overfueling issue in the idle/low rpm range. I am actually supprised the SXR ran as well as it did.

I am also ordering a pop off gauge to prevent this from happening again.

BTW, after I shut down the engine you could see fuel pooling onto the butterflies from the bomb sights.

 

[blaster800]

did you replace needle and seats ! since you say pooling after shut off ?

 

[cattledog]

Get the mikuni kits....

x2, dont use wsm or wonderosa just asking for trouble

 

[hillbilly550]

so the fuel consumtion issue is fixed with the new Mikuni carb kits. I'll tell all about the parts differances later.

I unfortunatly still have a bog on set up for jumps. I think Im going to take a look at the crank seals but i dont think that is the problem

hard run, let off gas, back on gas (hesitation) then it rips again
most often happens when setting up for jumps

any ideas? mabee needle & seats but has good pop off. The plugs look great (mabee a little fat) but i need to put in fresh plugs after all the gas it passed through it.

thanks for any help

 

[X2Pilot]

Either you need to jet down your main one size at least or add 1 check valve on top of the existing one. I would bet you are just fat due to temperature rise.

And I second the comment about using only genuine Mikuni rebuild kits! It is WELL worth it to have the exact replacements...

 

[hillbilly550]

the Mikuni diaphram is thinner material. (faster responce to the fuel leaving the bowl)
the button on the diaghram on the aftermarket kits is to thick (in this case holding the spring arm open)
the Mikuni gaskets fit better. Im sure there are irregularities in the jets form the aftermarket.

its not worth the headace to me for the $15 differance in price