Sbn pop off

[SnAdam]

Putting together my sbn 44. While pop off testing air starts leaking from around the needle before pop off. From my understanding no air should pass by until pop off. Correct?

2.0 needle & seat
115g spring
Starts to leak at around 30lb
Pops at just over 50lb

Brand new mikuni rebuild kit. New mikuni brand needle, seat & spring from sbt.

 

[Quinc]

Is it the needle or the oring around the seat? Also are you adding wd40 or gas between each test?

 

[wmazz]

As I understand it, aftermarket Mikuni carb kits do not include that o-ring?

Is it the needle or the oring around the seat? Also are you adding wd40 or gas between each test?

I like testing pop-off inside Zip-Loc gallon size freezer bags. The pop-off should
closely match the Mikuni pop-off table.

You should test two different ways: normal way, unassembled. The 2nd test
is fully assembled, and the pop-off should match the earlier unassembled
results.



Bill M.

 

[SnAdam]

Needle....
Tried wd-40 and 2stroke oil. Leaking by needle at about 30lbs then increases as psi goes up. I can apply slight pressure with finger and it stops. I even tried/ ordered a second spring incase one was not giving me correct pop off.

I have taken it apart and made sure it is clean. I dont know what else to try..

Sounds like I will be ordering a 2nd new needle and seat but was hoping to get it back together and ride this weekend. Just wanted to ask if I may be missing something.

I guess

 

[wmazz]

Looking at SBT's web site, they only show SBT Brand (Chinese) needle and seats.

It looks like they sell Genuine Mikuni rebuild kits for ~$58.00 each.

Since you ride Yamaha, Try Protec. Not very good prices, but they have a lot of
experience.


Bill M.

@Admin: Sorry for the link.

 

[SnAdam]

Nice. I must have not looked at it very closely... I did get the mikuni brand rebuild kit. Knew better than the knock off, just never paid attention I guess

 

[Quinc]

You probably just need a new needle. But you have to buy a needle/seat combo to get it. @JetManiac sells them. Or sometimes you can get them cheap on ebay.

The orings you can get in the harborfrieght oring kits for 5$

 

[SnAdam]

Wmazz and Quinc called it. I thought I was getting a genuine mikuni needle and seat. Nope, the SBT is not a mikuni N&S. Never worked out of the package, money down the drain.

The genuine mikuni came in today and worked like a champ, no leaks. 31 pop off with a 115g spring and 2.0 N&S.

I knew better from reading on here so many post before. I was rushing and ordered so I could get on the water while at home. Wasted a weekend I could have been riding waiting on new parts. Now I am stuck at work 200miles from any body of water. I will try again when I get home in a few weeks. Lesson learned.

 

[smoofers]

I was going to say, I've never had good luck with SBT N&S sets. Mikuni is the only way to go.

 

[mikidymac]

SBT fails again.....