Do all carbs use same needle and seat?

[mikidymac]

Paging Dr. Honda

So a the title goes I know all the Mikuni carbs use the same needle and seat except for size but what about the 46i carbs?
If you go by the Mikuni part numbers the carbs for the 580-787 engines use the Mikuni number 786-35015-size e.g. 1.2-2.0
They list the 46I as using # 786-35018-size e.g. 1.2-2.0

If you go by seadoo numbers they list the same part number.

Does anybody know if there is actually a difference? These are the first 46i's I have worked on and want to make sure I use the correct needle and seats.

 

[Strizzo]

I know that some of the 720 motors used a 1.2 instead of a 1.5 N/S but i think you're supposed to use the combination of N/S, spring and bending the arm to acheive the popoff desired.

 

[Sportster-2001-951C-Stock]

For the 2001 951 46I carbs.....

Needle valve seat: 2.0 p/n 78635015-2.0 is the one I use for the 951 carbs, the factory spec 95 gram spring works well with the factory air box. Mine currently has the 80gr spring and is just a touch richer than necessary off idle. But I also went up two sizes on the pilot jet as well, one size would have been sufficient, in my case. Still has great throttle response and doesn't load up using this calibration.

Arm Spring: 95gr p/n 73003027-T, silver wound backwards
80gr p/n 73003033
Needle valve: 2.0 p/n 78635015-2.0
Low Jet: 75 p/n N100.606-75
77.5 p/n N100.606-77.5
80 p/n N100.606-80

The factory calibration works well most of the time according to everything I hear but it was too lean for my taste so I fattened this up a bit as you can tell from my choice of parts. Much better, but I think next time the carbs come off I'll use the 95gr spring with 77.5 jets in there for my last tweak, it's maybe a hair fatter then need be down low with an acceptable amount of 4-stroking.

The heat-soaked restart is fantastic.

 

[mikidymac]

Thanks, for taking the time to respond. I know the size and pop off like 1.2-1.5-2.0 and springs but I just found it strange that the part number for the actual seat from Mikuni was a different number for the 46i series carbs than the smaller ones 786-35018 vs. 786-35015 so I was just wondering if there was a difference and if there is then Speedster you used the wrong ones. I still have no clue, I know some of the yamaha ones look the same but are silver instead of brass and have not seen an answer if they are functionally different too.

 

[Strizzo]

it may be that the 46i just has a different shape to the needle/seat body than the smaller carbs. i haven't held one in my hand so i don't know.

 

[Sportster-2001-951C-Stock]

Yeah, aside from the pump diaphragms and pump side gaskets the SBN and SBNI(improved) use the same press-in jets and n/s, diaphragm, etc. as far as I know. Chose the appropriate sizes for your particular tune, of course. The SBNI uses the new style fuel pump, so those parts aren't interchangeable.

As far as silver finish goes, I would stick with brass as opposed to some kind of questionably plated pot metal that might corrode.

For my application, I did cross the 78635015 over to WSM's 006-361, which is what actually went in, and by my careful inspection (always scrutinize aftermarket parts carefully) they were identical to the OEM parts they replaced.

The only difference between the 78635018 and 78635015 I'm aware of is, the 35018 uses an alcohol-proof (silicone, I believe) tip on the needle. I've noticed before these silicone tips tend to be red colored under the black impregnated lubricating film and so it's easy to see when the lubricant layer has worn off and the needle should be replaced, ie: easier to see than the Viton version.

Come to think of it, I'm not sure it's actually silicone, it just feels like it. It must be some other elastomer such as Kalrez.

 

[Sportster-2001-951C-Stock]

it may be that the 46i just has a different shape to the needle/seat body than the smaller carbs. i haven't held one in my hand so i don't know.

They're the same exact n/s, the part number the OP is asking about is the alcohol-resistant version.

Edit: But if you guys some across a silver-tipped version let me know b/c that's the one I'd prefer to use.

 

[Sportster-2001-951C-Stock]

This guy on fleabay has a good price on the WSM version, that's the one I have in my carbs now and it works fine.

http://www.ebay.com/itm/006-361-Mik...Parts_Accessories&hash=item1e89e6e703&vxp=mtr

 

[mikidymac]

Thanks everybody looks like sporster wins. I dug a little deeper and found this page in the 2014 Hot Products Catalog. Looks like we should all be using the 18 number for ethanol fuel.

 

[Sportster-2001-951C-Stock]

Maybe we should, except I still use the viton out of force of habit, LOL!

Or, you could pay up for brand new carbs, some guys go that route but I enjoy tweaking.

 

[Sportster-2001-951C-Stock]

Thanks everybody looks like sporster wins. I dug a little deeper and found this page in the 2014 Hot Products Catalog. Looks like we should all be using the 18 number for ethanol fuel.
View attachment 26007

Hey man, when you get those let me know if they have silver-colored tips, would ya? Thanks!

 

[mikidymac]

Will do, should have them in a few days. Funny Amazon had the 1.2 in the new design but not the 2.0. Ordered the 1.2 for a SPX. Having a hard time time finding the 35018-2.0

 

[racerxxx]

Are you talking about the Viton tips? If so I'll post a pic in a few hours, got them sitting on my bench for my XP

Sent from my SGH-T889 using Tapatalk

 

[racerxxx]

Here you go Genuine Mikuni Viton tip. Just got these the other day, unless they bagged them wrong this is what they should look like. Look just like the ones I put in my XP which were from atlanticjetsports.com, which I asked numerous times for genuine mikuni and got WSM or some aftermarket and they were NOT viton. Thankfully they worked and I've had no issues. You can see where I bought them, they were $20 a pop, but their jets are genuine Mik as well and they are like $3.95 a jet but the full rebuild kit was $50.95 ea. So I did the math and after I paid to have kits shipped for as low as $42 per kit the shipping put them close to $50 a kit. This place was a one stop shop and they shipped the same day, I bought from their Ebay store and if they don't have what you're looking for they will list it if it's in stock.

 

[mikidymac]

Those are the Viton Tipped 35015 but there is a new one out that is ethanol resistant and is number 35018. Amazon has the BN-38/44 kits for $47.95 shipped and the BN-46i kits for $37.23 shipped. They have the standard viton 35015 needle and seats for $16.38 shipped but I can only find the new 35018 in a 1.2 and it is $14.78 shipped.

 

[Sportster-2001-951C-Stock]

Did you ever locate a set of 35018-2.0 needle/seats? I wanted to know if they have the silver colored tips.

 

[mikidymac]

I never did. I could only find the 1.2 in the ethanol resistant ones. Damn, I wish I still had a Hot Products account. They have some great stuff.

 

[Sportster-2001-951C-Stock]

I'm pretty sure the silver tips are graphite impregnated Viton. Not really sure of the elastomer though, could be Kalrez... Anyway, I'm still keeping an eye out for the silver tips b/c I'd like to try them in my carbs despite the plain-janes are working fine so far, oh well LOL......