To add a BOV or not, a bit of boost run-on

[Danbot]

Installed a Silber kit on my 2019 Axys 850 @7psi. Running great, loving my first turbo sled!

There's a moment of "run-on" coming off boost. Not an issue at all in deep snow, but can be annoying from time to time on higher traction.
The held rpm seems to be linked to boost left in the system, as soon as the turbo flutter gets quiet it returns to normal idle.
Running 100%LL, new top end, new reeds, no leaks, seems to run perfect otherwise.

Will a BOV help with this? Am I getting into a tuning nightmare adding a BOV? Looking for some experienced advice in this area especially Silber/850 info.
Such a small issue, would love to nail it down though.

 

[Bnorth]

What about a stiffer spring to close the throttle bodies if the boost is holding them open for a moment.

 

[ABMax24]

No BOV? That's odd to say the least.

A BOV should get rid of your issue, i just don't know how you'd attach it to their silicone hoses, may tee off the MAP sensor location?

You'd also need a boost/vacuum reference signal downstream of the throttle bodies to the BOV to allow it to open.

Depending on how it's tuned you should be okay, when the ECU senses the loss of boost it should cut fuel and not flood the engine, however maybe phone Silber and see what they say.

 

[Danbot]

What about a stiffer spring to close the throttle bodies if the boost is holding them open for a moment.

I don't think thats whats happening but I could be wrong. Is this a thing with turbo kits? I would expect the spring in the TB's to be plenty

 

[Danbot]

No BOV? That's odd to say the least.

A BOV should get rid of your issue, i just don't know how you'd attach it to their silicone hoses, may tee off the MAP sensor location?

You'd also need a boost/vacuum reference signal downstream of the throttle bodies to the BOV to allow it to open.

Depending on how it's tuned you should be okay, when the ECU senses the loss of boost it should cut fuel and not flood the engine, however maybe phone Silber and see what they say.

Yeah I'll talk to Silber, but they don't use or sell bov's for 2 stroke kits. Someone somewhere has bov'd a silber polaris I figure lol.
I'm capable of drilling / tapping for the vac nipple, hoping someone has a setup to share for the rest.

 

[06 Dragon]

I believe it is a recirculating BOV on a Silber Kit

 

[Bnorth]

I believe it is a recirculating BOV on a Silber Kit

In those pics the bov is on the compressor housing.

 

[Danbot]

Well, my Silber kit certainly does not have a BOV. Does not look like those pics. Must be an older kit?

 

[Danbot]

So, I've been doing some tweaking with the idle speed.
-idle speed was low on cold startup when I installed the turbo, so I had adjusted it up a little.
-now I lowered it back down, which seems to have helped a lot with the run-on. Idle is @ about 1100 - 1200 cold, once warmed up it's @ 1650.

I'm happy with how it's running now, just have to use the throttle adjustment on the cable @ the bars to keep it from stalling when cold starting. No big deal.

 

[Dragonalain]

Well, my Silber kit certainly does not have a BOV. Does not look like those pics. Must be an older kit?
View attachment 264996

I think some sellers pulled fast ones on there customers. Buddy has a silber that also does not look like the one in the photo and it’s not that great. The pictures on the website of the company were the same as picture. It was a us reseller.


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[Danbot]

I think some sellers pulled fast ones on there customers. Buddy has a silber that also does not look like the one in the photo and it’s not that great. The pictures on the website of the company were the same as picture. It was a us reseller.


Sent from my iPhone using Tapatalk

I bought my kit directly from Silber, and I'll confirm that it runs like a raped ape.

 

[Modman]

I bought my kit directly from Silber, and I'll confirm that it runs like a raped ape.

Just add one in-line. This is the BOV on my sled, base kit was from Silber.