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Message started by oram on 04/11/16 at 17:04:20

Title: Punched Baffle Plate Causing Excessive Afterfire
Post by oram on 04/11/16 at 17:04:20

Hi Guys,

nutshell: I poked a long drill bit into my stock muffler and whacked it with a hammer. Now after firing has gone from normal to straight out of compton (NOT normal).

So, I pulled the idle mix plug. It was at around 2 turns stock. I turned it CCW 1 whole turn to have it set at 3 turns out; the max as I understand it. Not much change, if any. I need to fix this situation.

Should I need to adjust the main jet to 150? 152.5? and/or go 1/2 white spacer? Currently I am completely 2006 stock at sea level in the great white north.

Any comments would be appreciated. I hate to have to park this beast just as the season is getting started.

Title: Re: Punched Baffle Plate Causing Excessive Afterfi
Post by verslagen1 on 04/11/16 at 17:20:54

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1244217127

Title: Re: Punched Baffle Plate Causing Excessive Afterfi
Post by oram on 04/11/16 at 17:36:03

Thanks - I have read that thread countless times. I was actually reading it again when you posted the above message. My question is - which step in the progressive guide would a punched out baffle plate match? 3, 4, 5?

I have a jet set on the way so hopefully, I'll be able to tinker with it soon.

Title: Re: Punched Baffle Plate Causing Excessive Afterfi
Post by justin_o_guy2 on 04/11/16 at 20:05:19

Spend some money.Get a Dyna muffler, UNMOLESTED.

Title: Re: Punched Baffle Plate Causing Excessive Afterfi
Post by Kris01 on 04/11/16 at 20:12:21

I agree with JOG. ;)

You'll probably have to play with the jets to find the right ones. It's not as simple as saying "you need a 'xxx.x' jet and x/x spacer".

Title: Re: Punched Baffle Plate Causing Excessive Afterfi
Post by Dave on 04/12/16 at 04:31:53

The main jet has nothing to do with backfires or after fires - they all occur when you are closing the throttle. The main jet controls the fuel flow at high throttle settings only.

The pilot jet controls fuel mix at low throttle settings - but you will never be able to find a jet that will control a muffler that is allowing the exhaust to go straight through.....it will belch constantly.

You should get a proper muffler, and then jet the carb so the engine runs well the throttle is open and you are riding.....then learn how to use the throttle gently to limit the noise. If you hold the throttle slightly open between shifts and while slowing down - you can reduce the amount of backfiring. The throttle should never be opened or closed quickly........a big single with a carb just isn't sophisticated enough to know what to do with that kind of treatment.....and it will protest loudly.

Title: Re: Punched Baffle Plate Causing Excessive Afterfi
Post by oram on 04/12/16 at 05:47:30

Thanks Dave et al,

I suppose I should have mentioned that I recently purchased an HD slip on from SuperThumper. Although I won't be able to get my hands on it for another month or so for unrelated reasons. The muff has a cat and it's my thought that I will go with 1/4 white spacer and 152.5 main; jetset is on the way from Lancer. So I guess I'll then dance between 2.5 to 3 turns on the idle mix to achieve step 9 to 10 of the progressive guide. If you pros think that is a bad plan - please chime in.

For the bike I currently have parked in the driveway, as is. Would performing the white spacer mod help the afterfire problem a little bit? My understanding is that this would add more fuel to the low-range circuit. Any concerns about doing this while keeping the stock jets? (52.5 / 145 I think).

Thanks guys - this community is a wealth of knowledge.

Title: Re: Punched Baffle Plate Causing Excessive Afterfi
Post by Dave on 04/12/16 at 06:02:56

The spacer mod riches the mixture from 1/8th throttle and up to about 1/2 throttle when the main jet starts to take over. The spacer mod resolves the lean surging that occurs when you accelerate slowly using light throttle (like when you are following a school bus or the cops/your mom is watching you ride). The spacer mod will likely do nothing to the backfire issues.

You need to adjust the idle fuel mix.....you just don't turn it to 2.5 or 3 turns - without adjusting it. When you turn the screw out to a prescribed number of turns - it is a starting point for making an adjustment based on the sound/smoothness of the engine. Once you have fully warmed up the bike and made the adjustment properly - you can open the mixture screw an additional 1/8 - 1/4 turn to see if it helps reduce bacfires - but opening it up more than that is just wasting fuel as the engine will run too rich. If you can turn the idle mix screw all the way in and the engine continues to run - your pilot jet is too big. If you have to open the idle mix screw more than 2.5 turns - your pilot jet is too small.

This is how you set the idle mixture screw (with a fully warm engine). You set the idle speed a bit low for the adjustment - but then you must increase the idle speed to about 1,100 rpm to keep your cam healthy....and a higher idle speed also helps reduce the backfires as it provides more fuel to the engine when the throttle is closed.

https://www.youtube.com/watch?v=YxpQjDQzX7g

https://www.youtube.com/watch?v=zm5mB3R8Ucw