SuzukiSavage.com - What else causes surging?

IslandRoad

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Re: What else causes surging?
Reply #45 - 02/06/17 at 23:24:15

I was wondering if you had had the Dyna installed yet. Let us know how it goes.

eau de sauvage wrote on 02/06/17 at 20:01:46:

I'll be hopefully fitting the dyna next week, (as well as a k&n) and I will have the carb apart. I'm also curious to see what tube is about. My guess is that it will be there. FFIW, our S40 had bad surging when we got it (almost new 800kms), but a bit of pilot screw fiddling sorted it out that was with the standard pilot jet and three turns out; the bigger pilot allowed 1 3/4 turns out but the surging stopped either way. That's all it may be just a bit of fiddling with the pilot screw! I don't know how many turns out it is at the moment, but maybe turn it out another 1/2 turn and see what that does, easy and fast to do.

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S40, 2014, Dyna, Raptor, 52.5/152.5, spacer mod, sea level, cat-eye LED tail light, bullet style halogen turn signals, 'Superbars' with custom 40mm risers, modified stock seat, Metzeler tyres.

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IslandRoad

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Re: What else causes surging?
Reply #46 - 02/06/17 at 23:33:53

Thanks for the advice Justin.

I tried a larger pilot jet amongst all the 'plastic tube drama'. I had the idle mix screw opened up quite a bit and I think it vibrated itself substantially CCW. Then I was also adjusting the idle speed screw with gloves on, at an intersection. Pretty sure I put it all out of whack. The bike ran like crap (The exhaust sounded aweful) and when I got back home the idling was drastically horrible .. the bike was blowing smoke and sounded awful. It scared the hell out of me. I had been testing the top speed and thought I had blown something.

I had a cup of coffee, reset the idle mix screw and the idle speed. Everything went back to a recognisable state. Absolutely scared the hell out of me.

I take your point about writing down the turns and doing it properly.

Also, I think I have somewhat overlooked the effect of the idle mix screw, while doing all this tuning (I was just thinking that last night). I have some time to tinker tomorrow, so I'll do some experimenting.

justin_o_guy2 wrote on 02/06/17 at 20:09:00:

Before fiddling, gently close it, count turns, write it down. That way you will always be able to get back to Square One, and you will know if you're getting it out far enough to
A: risk vibrating loose
Or
2: require a jetting change.

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S40, 2014, Dyna, Raptor, 52.5/152.5, spacer mod, sea level, cat-eye LED tail light, bullet style halogen turn signals, 'Superbars' with custom 40mm risers, modified stock seat, Metzeler tyres.

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justin_o_guy2

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Re: What else causes surging?
Reply #47 - 02/07/17 at 06:25:17

If the idle speed is set properly it's hard to hear what the idle air mix screw is doing. Drop your idle speed to get that adjusted. I took a ride with a screwdriver in my shirt pocket and adjusted at the lights. That way it was only parked,idling every now and then and only for a couple of minutes, AND I was riding.. And it w a s not on the sidestand.

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IslandRoad Serious Thumper Offline It doesn't vibrate, it purrs! Posts: 1147 The Kiewa Valley, Australia Gender:	Re: What else causes surging? Reply #48 - 02/08/17 at 00:38:28 I had some time to work on the bike today so I pulled the carb to check out that plastic tube. And to see if it is actually a limiter. This is the tube as it sits in the carb:
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IslandRoad Serious Thumper Offline It doesn't vibrate, it purrs! Posts: 1147 The Kiewa Valley, Australia Gender:	Re: What else causes surging? Reply #49 - 02/08/17 at 00:39:10 Here's a closer look:
Back to top	Tube_Removed.jpg S40, 2014, Dyna, Raptor, 52.5/152.5, spacer mod, sea level, cat-eye LED tail light, bullet style halogen turn signals, 'Superbars' with custom 40mm risers, modified stock seat, Metzeler tyres. IP Logged

IslandRoad Serious Thumper Offline It doesn't vibrate, it purrs! Posts: 1147 The Kiewa Valley, Australia Gender:	Re: What else causes surging? Reply #50 - 02/08/17 at 00:40:17 The image on the left shows how high the lifter can rise with the tube in place. The image on the right shows the same with the tube removed:
Back to top	Lifter_Comparison.jpg S40, 2014, Dyna, Raptor, 52.5/152.5, spacer mod, sea level, cat-eye LED tail light, bullet style halogen turn signals, 'Superbars' with custom 40mm risers, modified stock seat, Metzeler tyres. IP Logged

IslandRoad

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Re: What else causes surging?
Reply #51 - 02/08/17 at 00:58:25

I'm gonna go ahead and say yeah, it's a rev limiter.

I did two solid test rides on a warmed up bike, with a newly-cleaned and tuned carb:

1. with the tube in, and
2. with the tube out

(no other changes).

Today's test confirmed my initial test from the other day (when I had other things going on, so I wasn't confident about the accuracy of the test).

The difference is significant. With the tube removed I can feel an increase in 'pull' while accelerating hard up through the gears. I could feel it in the suspension as the bike leaned back at full throttle. The bike was able to rev a bit higher (by about 500 - 700 rpm) and the top speed increased by somewhere around 12 - 15 km/h (7.5 - 9 mph). It also reached top speed more easily.

I think the bike probably had a bit more to give if I wound it out further, but I'd pushed it hard enough to confirm my earlier conclusions, and then backed it off and enjoyed a casual ride home ... with a big smile on my face Grin

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S40, 2014, Dyna, Raptor, 52.5/152.5, spacer mod, sea level, cat-eye LED tail light, bullet style halogen turn signals, 'Superbars' with custom 40mm risers, modified stock seat, Metzeler tyres.

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eau de sauvage Serious Thumper Offline Posts: 2565 Queensland Gender:	Re: What else causes surging? Reply #52 - 02/08/17 at 05:23:39 @IslandRoad, thanks for the photos, I'll definitely be removing the tube if I find one. I assumed that you would already be aware of the pilot mix screw turnout. Anyhoo, are you saying the surging is now solved? And what pilot jet size and how many turns out have you settled on. I'll have the dyna in mid next week.
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IslandRoad

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Re: What else causes surging?
Reply #53 - 02/08/17 at 05:56:36

Yeah, the surging is resolved

. I still have pretty regular backfiring, nothing serious though.

I knew about the idle mix screw but kind of forgot about it once I got onto the spacer and main jet.

At the minute I'm on 52.5/152.5 with a 50% spacer. I finally found some stainless steel washers that fit nicely - 6 of them equal the height of the spacer. I'm using 3. I've turned the idle mix screw out close to 2 turns.

I had a hell of a time troubleshooting the tuning due to a leaking vac line on the petcock, and admittedly I didn't realise how important it was to wear gloves and clean up really carefully with carb cleaner when handling the inner parts of the carb (newbie mistake).

I only ditched that white tube today and all went well. It really does open up the top end of the throttle, as you can imagine. Puts a smile on your face.

Once I cleaned the carb (I flushed whatever I could reach with spray carb cleaner) and replaced the petcock, the tuning came together in line with what I've been reading on this forum.

In a couple of days I may try out a 55 pilot just to see if it stops the backfiring, but I'm not too concerned about it. The bike is running great.

Keep in mind I'm also using this as a learning exercise so I'm happy to keep going until I prove to myself there's no further to go

eau de sauvage wrote on 02/08/17 at 05:23:39:

@IslandRoad, thanks for the photos, I'll definitely be removing the tube if I find one. I assumed that you would already be aware of the pilot mix screw turnout. Anyhoo, are you saying the surging is now solved? And what pilot jet size and how many turns out have you settled on. I'll have the dyna in mid next week.

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S40, 2014, Dyna, Raptor, 52.5/152.5, spacer mod, sea level, cat-eye LED tail light, bullet style halogen turn signals, 'Superbars' with custom 40mm risers, modified stock seat, Metzeler tyres.

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Re: What else causes surging?
Reply #54 - 02/08/17 at 11:18:17

If your backfire issues occur when you close the throttle to shift gears, or when you close the throttle to slow down.....that is normal and occurs even on a well jetted carb - you should be jetting for how the bike runs when you are accelerating.....not for what it does when the throttle is closed. If you install a larger pilot jet to "fatten" up the mixture when the throttle is closed....your engine will be running too rich at low throttle settings, and this can carbon up the engine and spark plug, hurt fuel mileage, and also cause premature wear of the piston/rings/cylinder.

When you are decelerating or accelerating and shifting - you don't want to snap the throttle all the way closed.....or you will get a backfire (or a lot of them). Just roll the throttle toward the closed position part way, and there will be little or no backfire. When you allow the throttle to close completely the only fuel to the engine is coming from the idle circuit, and the mixture goes very lean....and the exhaust gets noisy. You can easily control this by just opening the throttle up a tiny bit.......that is what the TEV valve on the stock CV carb is supposed to do - it just doesn't seem to provide enough extra fuel to solve the problem completely - so you just have to do it manually by rolling on a tiny bit of throttle. If you want noisy while you are decelerating you just close the throttle....if you want to be more peaceful you just open up a bit of throttle until the noise goes away......after a bit of riding with this method it all becomes instinct and is part of the fun of riding this big, primitive single.

Modern fuel injected engines don't have to be treated this way - but the Savage engine does. It is all part of what it takes to be a good rider on the Savage.

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IslandRoad Serious Thumper Offline It doesn't vibrate, it purrs! Posts: 1147 The Kiewa Valley, Australia Gender:	Re: What else causes surging? Reply #55 - 02/08/17 at 11:51:24 Thanks for the advice Dave ☺
Back to top	S40, 2014, Dyna, Raptor, 52.5/152.5, spacer mod, sea level, cat-eye LED tail light, bullet style halogen turn signals, 'Superbars' with custom 40mm risers, modified stock seat, Metzeler tyres. IP Logged

eau de sauvage Serious Thumper Offline Posts: 2565 Queensland Gender:	Re: What else causes surging? Reply #56 - 02/08/17 at 14:44:15 @IslandRoad, you will find this article relevant, I saw bits of it quoted around the web and I eventually tracked down the full original post. tl;dr scroll down to 'Burn Baby Burn' http://www.vtxoa.com/forums/73-how-step-step/21714-air-fuel-motors-missives-a...
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IslandRoad

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Re: What else causes surging?
Reply #57 - 02/08/17 at 15:41:25

Thanks heaps. Really informative article

eau de sauvage wrote on 02/08/17 at 14:44:15:

@IslandRoad, you will find this article relevant, I saw bits of it quoted around the web and I eventually tracked down the full original post. tl;dr scroll down to 'Burn Baby Burn'

http://www.vtxoa.com/forums/73-how-step-step/21714-air-fuel-motors-missives-a...

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S40, 2014, Dyna, Raptor, 52.5/152.5, spacer mod, sea level, cat-eye LED tail light, bullet style halogen turn signals, 'Superbars' with custom 40mm risers, modified stock seat, Metzeler tyres.

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