SuzukiSavage.com - What else causes surging?

verslagen1 YaBB Moderator ModSquad Offline Where there's a will, I want to be in it. Posts: 28888 L.A. California Gender:	Re: What else causes surging? Reply #30 - 02/03/17 at 12:38:54 It may be a 'lerner' type thing. I'd say toss it. seated on the bottom, it's just extra weight and may slow the response a little. seated at the top, it'll reduce the diaphragm area (although open around the spring) and will reduce the amount/speed that it goes up. Or it may just be long enough to keep from fully opening.
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justin_o_guy2 Serious Thumper Offline What happened? Posts: 55279 East Texas, 1/2 dallas/la.	Re: What else causes surging? Reply #31 - 02/03/17 at 12:48:48 And it could be allowing the spring to catch on the tube, causing the slide to pause, then pop loose and jump.
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IslandRoad

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Re: What else causes surging?
Reply #32 - 02/03/17 at 18:59:03

You might be onto something guys,

In Australia we have a classification called Learner Approved Motorcycles (LAMS). New riders have to ride a LAMS bike for the first three years. The specs for LAMS include; no bigger than a 660cc, and a certain power/weight ratio. Sometimes, manufacturers restrict the throttle to come in under the specs. The S40 is classified as LAMS.

It's a beautiful sunny Saturday afternoon here, so I'm going to spend a couple of hours experimenting with the carb setup. I'll begin by removing the tube and see how she rides

Dave wrote on 02/03/17 at 05:55:31:

twhitus wrote on 02/03/17 at 05:42:11:

ive seen those tubes before on scooters which have similar carbs. They are used as a way to limit how much the slide can move and sort of a hp/throttle/speed limiter. first thing we did was remove them.

Some countries have controls on size/HP for certain tax classes....I wonder if this tube restricts how far the slide can open in order to limit the HP or top speed of the bike?

Put the spacer in the carb, then use your finger to open the slide and see how far it will rise in the venturi. If it won't go all the way up.....get rid of it!

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« Last Edit: 02/04/17 at 01:29:21 by IslandRoad »

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 #33 - 02/03/17 at 19:55:46

Justin, I'm bothered by the surging in normal riding. It affects the way I 'read' the bike. Normally when the surging gets my attention, I at first think the road surface has changed, then I think about my fuel level (am I getting low?), are my wheels loose?, then I realise it's the bike surging. It's very distracting.

Having said that, when I'm tuning and test-riding, I pay close attention, looking for the exact conditions that correlate to the problem. If I get close to a solution, I forget about tuning for a while and run the bike as per my normal riding. I find out soon enough if it's been sorted out.

justin_o_guy2 wrote on 02/03/17 at 12:26:43:

Are you Hunting for a throttle setting that you can feel a surge in or, in the Normal course of riding, you're bothered by a noticeable surging?

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justin_o_guy2 Serious Thumper Offline What happened? Posts: 55279 East Texas, 1/2 dallas/la.	Re: What else causes surging? Reply #34 - 02/03/17 at 20:05:36 If it's like that, yeah, worth hunting down.. wish you luck.
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IslandRoad

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Re: What else causes surging?
Reply #35 - 02/04/17 at 00:17:24

Well, it's been an interesting afternoon!

I tested the bike without that plastic tube inside the large spring in the carb slide.

I reckon that tube is a limiter, as some of you have suggested. And I reckon it's there to get the bike into the LAMS classification here in Australia.

Without the tube in there the bike had considerably stronger acceleration on full throttle, and it added about 10 kph to the top speed the bike could hit. Having the tach installed was handy. I reckon the bike was able to rev higher as well. (I had to hang on a little more when I opened up the throttle).

I reckon that limiter would mess with road testing for the main jet, because it prevents the bike from reaching full open throttle. I'm speculating a bit there.

As for the tuning, I did two things. I would have done them one at a time so I knew what was going on, but I've had the tank off that many times in the last couple of weeks so I just wanted to get done.

1. I had the bottom and top of the carb off while the carb was still in the bike. I doused what ever I could reach with carb cleaner. I hate to confess this, but as a newbie, I had previously done the spacer mod and re-jetting without realising the need to ensure everything was really clean after handling the needle, slide etc.

2. I sourced some stainless steel washers with an outside diameter that fits nicely down the hole where the spacer sits. Previously, I was using modified brass washers which left a bit of play on the sides. I wondered if that play may have caused the needle to not sit exactly vertical while lifting.

One of those two things, or both of them, sorted out the surging at low throttle ☺.

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« Last Edit: 02/04/17 at 01:29:58 by IslandRoad »

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 Serious Thumper Offline It doesn't vibrate, it purrs! Posts: 1147 The Kiewa Valley, Australia Gender:	Re: What else causes surging? Reply #36 - 02/04/17 at 01:32:36 Thanks again for all the suggestions. It's terrific to have all this combined experience to draw on ☺
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Kenny G Serious Thumper Offline SuzukiSavage.com The Singles Club...LOL Posts: 1754 Robson Ranch, Denton, Texas Gender:	Re: What else causes surging? Reply #37 - 02/04/17 at 06:56:59 Island Road, It is always good to hear stories with a happy ending. Kenny G
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justin_o_guy2

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Re: What else causes surging?
Reply #38 - 02/04/17 at 12:44:42

IslandRoad wrote on 02/04/17 at 01:32:36:

Thanks again for all the suggestions. It's terrific to have all this combined experience to draw on ☺

The Professional Mechanics at the dealership rarely have a good working knowledge of these bikes. I remember one person commenting on finding a dealership with a mechanic who knew enough to be considered Knowledgeable. The combined knowledge and experience found here is mindbogling.

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IslandRoad

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Re: What else causes surging?
Reply #39 - 02/04/17 at 13:13:14

I can't imagine the time, money, and frustration that would be involved in trying to work through this stuff with a local mechanic.

That's not to question the ability of the local guys, just saying the bike has many little nuances. And when you want to tune it just the way you want it, you need experienced backup ☺

justin_o_guy2 wrote on 02/04/17 at 12:44:42:

IslandRoad wrote on 02/04/17 at 01:32:36:

Thanks again for all the suggestions. It's terrific to have all this combined experience to draw on ☺

The Professional Mechanics at the dealership rarely have a good working knowledge of these bikes. I remember one person commenting on finding a dealership with a mechanic who knew enough to be considered Knowledgeable. The combined knowledge and experience found here is mindbogling.

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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 #40 - 02/04/17 at 22:12:43

For the sake of completeness I'll add a final anecdotal observation to this thread.

With that plastic tube sitting in the carb, the bike could accelerate strongly, and in 5th gear it peaked at about 5500 rpm and 140 km/h (87 mph).

With the tube removed it peaked at about 6000 rpm and 150 km/h (93 mph).

That's just off a one-off test so it's not exactly scientific data (I was kind of busy holding on while reading the tach). And I'm not gonna do the testing required, at that level, to provide more substantial data. But, there it is, for what it's worth Cool

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eau de sauvage

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Re: What else causes surging?
Reply #41 - 02/06/17 at 15:31:55

The LAMS power to weight ratio is 150kW per 1000kg then you have to add a further 80kg for the rider and 10kg for petrol, so that would put the S40 at 173kg plus 90kg = 263kg

So that's 3.8 times the power of the bike which is 23kW gives the S40 87kW per tonne, which is so far inside the requirement of 150kW/tonne that it does not make sense that it would be their to make it fit under the LAMS scheme.

In fact it still comes in under the LAMS limit without the extra 90kg!

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IslandRoad

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Re: What else causes surging?
Reply #42 - 02/06/17 at 17:21:04

Thanks for doing the sums ☺. I was wondering how they stacked up. So now I'm really curious what it's there for.

I did put it back in until I work out what it is. As I said earlier, my testing has been anecdotal, while I was testing other things.

When I first took it out, on the first test ride, I lost all throttle response above 1/4 turn on the throttle. I assumed I hadn't seated the spring properly in the carb cap (fitting it while still in the bike is a bit fiddly). I took the cap off and refitted while really making sure the spring was seated properly - and being very careful with the diaphragm ). The power gain at open throttle was noticeable.

I'm going to pull the carb when I have time to see if it limits the range of the lifter.

The other thing I thought it might do is guide the large spring. But it's interesting that no-one else on here seems to have seen it in the S40/savage before.

If you do the spacer mod it would be interesting to know if there's one in your carb, given that you are also in Australia.

eau de sauvage wrote on 02/06/17 at 15:31:55:

The LAMS power to weight ratio is 150kW per 1000kg then you have to add a further 80kg for the rider and 10kg for petrol, so that would put the S40 at 173kg plus 90kg = 263kg

So that's 3.8 times the power of the bike which is 23kW gives the S40 87kW per tonne, which is so far inside the requirement of 150kW/tonne that it does not make sense that it would be their to make it fit under the LAMS scheme.

In fact it still comes in under the LAMS limit without the extra 90kg!

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eau de sauvage

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Re: What else causes surging?
Reply #43 - 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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justin_o_guy2 Serious Thumper Offline What happened? Posts: 55279 East Texas, 1/2 dallas/la.	Re: What else causes surging? Reply #44 - 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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