Engine Knocking

[rjvoight]

I hit Blater HQ with this question but have only gotten a couple responses so I thought I would throw it out to you guys.

 

The wifes Blaster is set up as follows:

 

2003

FMF Fatty

Power Core II Silencer

K&N Filter with Ourter-wear

Shaved Head to 19cc

 

Pilot: 35

Needle: Clip in 2nd Groove from Top

Main: 280

 

I run Premium Gasoline from Shell or Cheveron which is a 97-98 Octane

 

The plug is a nice medium tan color.

 

The bike runs great. Really responsive and plenty of power. My concern is that under a load at WOT it knocks loudly. It is specific as soon as I back off the throttle the knock goes away and I do not hear it at any other throttle position.

 

The two responses I got from Blaster HQ are :

 

1: Run better Gas.

 

If that will take care of the problem, I will gladley pay the 4-5bucks a gallon for race gas, but with my limited knowledge I don't think I should need that with the mods I have.

 

2: I am too rich with the Main at 280.

 

A lot of people are running 250-270 with my similar mods. My only concern with going down a Jet size is that my plug looks good now. Also, I do not understand why running rich would cause the bike to knock. If someone here could explain that to me I would appreciate it. (NO one at Blaster HQ could answer that one).

 

Any way, I appreciate your input. YOu guys helped me get the Banshee dialed in exactly so hopefully you can help me with this.

 

Thanks

 

RJV

[sredish]

First, have you run a compression check to see what your compression actually is with that milled head? I'd do that first and foremost so you/we know what you're/we're playing with.

 

Second, are you sure that the "premium" gas your buying is 97 / 98 or more like 91/92?

 

I believe you might be needing to run some 110 in it to keep if from "knocking". I have a feeling your compression is higher than you think.

 

I'm not a blaster guy at all, don't know the typical jetting settings so I can't help you with jet sizes. I'd try the needle a clip richer and see how that goes. What I can say is, run a plug check to see what it looks like and that will tell you how your main jet is sitting, then adjust the needle for best performance, same with the pilot.

 

Get back after you check the compression and run the plug.

 

Scott

[rjvoight]

I will get the compression checked. And yes you are right, 91/92 premium, regular is 87. typo on my part. As to the needle, I had it in the third notch and put it back to the second notch which is stock. It seems to run better in that slot.

 

I have been all over the board on this thing. I have been as high as 320 mains, I changed, pilots, clip positions and sprockets. I am as close to perfect as I have been on the set up other than this knock. If I can get it to go away, I will never touch the thing again.

 

Thanks for your input, anyone else with any ideas???

 

RJV

[Nighty]

Well if premium is 91 and you shaved your 200cc blaster head to a 19cc dome

(compared to 175cc banshee 1 cylinder with a 22cc dome stock)

 

I say fuel. the knock will be predetonition most likely,

They dont even have 91 here in europe.

its either 95 or 98.

 

I second sredish, do the compression test.

 

*i do know you cant compare a blaster to a banshee*

[sredish]

I will get the compression checked.  And yes you are right,  91/92 premium, regular is 87.  typo on my part.  As to the needle, I had it in the third notch and put it back to the second notch which is stock.  It seems to run better in that slot.

 

I have been all over the board on this thing.  I have been as high as 320 mains,  I changed, pilots, clip positions and sprockets.  I am as close to perfect as I have been on the set up other than this knock.  If I can get it to go away, I will never touch the thing again. 

 

Thanks for your input, anyone else with any ideas???

 

RJV

You can go to the dealer and get 4 or 5 gallons of race fuel and try it to see if it goes away. That's another thought. No matter what, you need to check the compression.

 

Later man.