Here's how my carb rebuild is going

[lakeeriejoe]

Some background:

I am handy with home projects (remodeled a bathroom down to the studs among other smaller projects) but when it comes to cars/engines/mechanical things like that, I am very green. Purchased some late 90's skis two years ago and one had continuing problems which most people seemed to think pointed to carbs needing rebuilt (787 engine). So alas, I finally pulled them a few weeks ago and just this week had time to start tearing them down. I have all of the internal parts removed and this is what I have encountered so far:

• Stripped screw hole for cover plate on PTO side carb (the plate housing the fuel filter)..and no, I didn't do it.
• Speaking of fuel filters, NEITHER carb had one
• Stripped pilot jet on PTO carb (this WAS probably me...think my screwdriver had too much wiggle room/movement, but I was impatient on finding something better. I had to use the torx screw (T10) trick, worked like a charm (had to drill as well)
• Stripped metering block check valve screw on PTO side (this may have been me, not sure), I found a better screwdriver (this one isn't JIS is it?) for the MAG side. I again used the torx trick to remove it.
• I must say, other than the issues with stripping and such, the inside of the carbs appear pretty clean, no gunk, no blocked seats or jets, etc.

So, I am waiting on proper tools/supplies to fix stripped screw hole, a new pilot jet, and a new screw for metering block check valve. In the meantime, I am going to start cleaning all of the parts and the carbs themselves. I have mostly been using the guide pinned in this thread for the re-build, but have a few questions that aren't totally covered there (or I have missed it):

1. Best chemical(s) to clean the parts that I have removed?
2. MAG side adjustment screw with the "T" handle...it doesn't have a "point" end, is that correct? Basically just a screw that manually pushes on the butterfly?
3. As I understand it, the PTO side uses NONE of the diaphrams/gaskets (save for the circular one w/ the red thing in middle) from the kit, correct?
4. For the MAG side, does it use ALL diaphrams/gaskets? There are three cardboard-like gaskets, I know I use the one that is tan/brown as it is the one I had to spend an hour scraping/sanding off the block. I know I use the two thin black gaskets as well as the clear one (and the small circular ones). The kit also has two grey-ish looking gaskets, do these get used? Pics attached for reference

 

[mikidymac]

Sorry for the bad news but that Titan kit is not OEM Mikuni so you are going to have the reorder all the parts and they have to be Genuine Mikuni.

Then all your questions will be answered here in the Carb Rebuild Thread. The Seadoo Carb Rebuild Thread

Also make sure you get the new correct pop-off spring and new needles and seats.

 

[lakeeriejoe]

Sorry for the bad news but that Titan kit is not OEM Mikuni so you are going to have the reorder all the parts and they have to be Genuine Mikuni.

Then all your questions will be answered here in the Carb Rebuild Thread. The Seadoo Carb Rebuild Thread

Also make sure you get the new correct pop-off spring and new needles and seats.

The kit itself IS Mikuni (one for each carb). The Titan bag is supposed to have Mikuni Needle/Seat in it....but I will double check to be sure it really is.

Edit: The Titan bag does NOT contain the Mikuni brand needle/seat, so I will be returning.

 

[lakeeriejoe]

 

[lakeeriejoe]

My goodness it was hard finding the Mikuni brand needle/seats. Everyone tries to trick you by throwing their name around....this is why I ended up w/ the Titan brand. In any event, the Mukini brand is on the way.

 

[mikidymac]

Nice! You had me worried there.

 

[JC-SUPERJET]

Either use a Japanese Industry Standard JIS Screwdriver or an American Impact Driver Phillips Bit for the Mikuni Carb Screws. Anything else will strip the Screw Heads.

American Phillips Screw Tips are designed to cam-out at a certain torque. The JIS are designed to seat deep and tight. Has to do with different mass assembly philosophies. So the Screw Slot angles and depth are different.

The American way, the Assembler would just torque the Screws till the Driver slipped; that's how they knew the screw was set.

The Japanese relied on the Assembler or a Torque Limiter. Once the correct tightness or torque was reached, the screw was set.

Vessel makes good JIS Drivers. Buy yourself a Set. You can buy a new Carb Stainless Screw Kit on Ebay

Mikuni Carb Stainless Screw Kit Super BN SBN 38 44 46 Seadoo Sea doo XP SPX GTX | eBay

 

[lakeeriejoe]

Either use a Japanese Industry Standard JIS Screwdriver or an American Impact Driver Phillips Bit for the Mikuni Carb Screws. Anything else will strip the Screw Heads.

American Phillips Screw Tips are designed to cam-out at a certain torque. The JIS are designed to seat deep and tight. Has to do with different mass assembly philosophies. So the Screw Slot angles and depth are different.

The American way, the Assembler would just torque the Screws till the Driver slipped; that's how they knew the screw was set.

The Japanese relied on the Assembler or a Torque Limiter. Once the correct tightness or torque was reached, the screw was set.

Vessel makes good JIS Drivers. Buy yourself a Set. You can buy a new Carb Stainless Screw Kit on Ebay

Mikuni Carb Stainless Screw Kit Super BN SBN 38 44 46 Seadoo Sea doo XP SPX GTX | eBay

View attachment 62509

I have a JIS screwdriver. The screw hole in question I came to find out had the remnants of an old screw in it (from whoever messed w/ these last)...popped out when I was drilling it to re-tap. I went the next size up and I think I am good to go. As for the small screw on the check valve, if I was the one who did it, it was because my JIS screwdriver was too big, but I didn't see a dimple so not sure if it even is JIS? regardless, on the other one I found a small screwdriver that fit better and came right out. What do you use for the jets?? For most of my flat screwdrivers there was some play which led to me stripping the idle jet (and with such a small hole I didn't have many to choose from)...and they were in there pretty damn tight.

 

[mikidymac]

I use some Craftsman flat ones that I ground down for a perfect fit 25 years ago, they are stored in the "Carb Drawer" with the JIS Philips, LOL.

 

[lakeeriejoe]

I use some Craftsman flat ones that I ground down for a perfect fit 25 years ago, they are stored in the "Carb Drawer" with the JIS Philips, LOL.

My issue isn't necessarily finding one that will fit down in there, but one that will fit AND is "thick" enough so there isn't a lot of wiggling which is what contributed to me stripping it....and the fact it was in there very tight.

 

[mikidymac]

Oversized screwdriver then file and grind to fit.

 

[JC-SUPERJET]

Yep, customizing a Flat Head Screwdriver is the simplest way.

I actually do have a couple of unmodified Flat Head Screwdrivers that fit the Width, Length and Depth of the Brass Jet Slots perfectly.

No mushing Brass Jets...

Unfortunately, one Screwdriver has no size markings and the other one's are illegible.