SuzukiSavage.com - Fine tuning jetting question

911radioman

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Fine tuning jetting question
08/03/06 at 16:14:42

OK, the Dyna exhaust is on, no backfires or pops, everything is fine there. Stayed with the K&N drop in filter, no problems there.

Right now, I'm just playing with jetting. I'm not having running problems, just trying to decide which direction I want to end up and I need a bit of advice.

Here's what I've done thus far...

FIRST SETUP

#55 pilot jet, #152.5 main jet

Bike ran really well (it's best, actually), pilot screw was 1/4 turn out. No dead spots, no bogging, but never was able to get that "happy medium" on idle with the pilot screw.

SECOND SETUP

#52.5 pilot (stock), #152.5 main jet

Bike ran OK, I felt it was a bit sluggish on the 1/4 to 3/4 throttle range. Able to hit the "happy medium" with the pilot screw at 1 1/2 turns out. I attribute the "sluggishness" to the smaller pilot jet.

THIRD SETUP

#52.5 pilot (stock), #150 main jet

Again, bike ran OK, still sluggish in the 1/4 to 3/4 throttle range, no huge difference on top end with the smaller main jet that I can tell.

OK, here is where I need your wisdom...

Given that the bike ran its best with the #55 pilot and 152.5 main jets, would you recommend going back to that even though I never was able to get my "happy medium" in the pilot screw adjustment and that will most likely make me a bit rich?

If you were to recommend this setup, would there be a harm in taking the pilot screw to a totally closed setting or should I stay at, say, 1/8 turn out?

OR, should I stay with the stock 52.5 pilot, knowing I can get the "happy medium" on the pilot screw?

If you were to recommend this setup, would installing the stock air filter serve to take some of the "sluggishness" out at 1/4 to 3/4 throttle? Would the K&N be leaning me out with the Dyna setup too much?

I know I've thrown a lot out here, and thankfully I'm not troubleshooting at this point, just looking for the optimal setup to run.

Any comments would be greatly appreciated!

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babbalou Serious Thumper Offline Posts: 814 Lewisville, Texas Gender:	Re: Fine tuning jetting question Reply #1 - 08/03/06 at 17:42:05 Sounds like the mid-range is a little lean. Did you thin out the white spacer? That affects the 1/4 to 3/4 throttle range.
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911radioman Ex Member	Re: Fine tuning jetting question Reply #2 - 08/03/06 at 17:44:15 White spacer is at half thickness.
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steelwolf

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Re: Fine tuning jetting question
Reply #3 - 08/03/06 at 17:51:58

911radioman wrote on 12/31/69 at 16:00:08:

FIRST SETUP

#55 pilot jet, #152.5 main jet

Bike ran really well (it's best, actually), pilot screw was 1/4 turn out. No dead spots, no bogging, but never was able to get that "happy medium" on idle with the pilot screw.

Given that the bike ran its best with the #55 pilot and 152.5 main jets, would you recommend going back to that even though I never was able to get my "happy medium" in the pilot screw adjustment and that will most likely make me a bit rich?

If you were to recommend this setup, would there be a harm in taking the pilot screw to a totally closed setting or should I stay at, say, 1/8 turn out?

Ok that's how my bike is set except I am still running the stock air filter and that's how mine runs to the letter. I am even just a bit rich. Not fouling the plug rich, but a little rich. As far as the pilot screw. I'm pretty sure with it all the way closed it will die at idle. Like when it is warming up but not nessacerily when comming to a stop sign. JMO

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babbalou

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Re: Fine tuning jetting question
Reply #4 - 08/03/06 at 17:57:59

My guess at this point would be to go with the first set-up but go a little thinner on the white-spacer. But, since the spacer mod can't easily be reversed & it's more time consuming than changing jets, I'd let some other members here give their input first & then go from there. Some use 1/3 spacer & that may be optimum for you. Good luck with it & let us know what works out best.

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Had an S40 Jul '04-Jan '07

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911radioman

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Re: Fine tuning jetting question
Reply #5 - 08/03/06 at 18:03:03

steelwolf wrote on 12/31/69 at 16:00:08:

Ok that's how my bike is set except I am still running the stock air filter and that's how mine runs to the letter. I am even just a bit rich. Not fouling the plug rich, but a little rich. As far as the pilot screw. I'm pretty sure with it all the way closed it will die at idle. Like when it is warming up but not nessacerily when comming to a stop sign. JMO

I may slap my OEM filter back in and see what that does before I shave the spacer any further. I'm seeing too many guys here running the 1/2 spacer to think I need to go further with that right now.

Maybe the K&N is running me too lean, I don't know. Then again, I may need to look at putting the snorkel back in with the K&N as well.

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LANCER

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Re: Fine tuning jetting question
Reply #6 - 08/03/06 at 18:49:34

Were you checking your spark plug during these runs to see what it had to say about the lean/richness? If not, you need to. It will be one more piece of info that can help you learn what is happening inside the engine.

From what we know now...

-if the engine idle's well with the #52.5 pilot at 1.5 turns out, then that sounds like a good setting there. Stay with it.

-Leave your drop-in K&N in the filter box, it is not the source of any problems for you.

-You can check your midrange by going back a little on the lean side by adding a tiny washer to the white spacer. If it runs STRONGER with that leaner setting then you know that is what the engine wants. Since the engine was a bit sluggish in the midrange (typical with a rich setting) with just the filed spacer I would expect the leaner setting to improve the performance.If it does not improve with the leaner setting then I would think that something else within the carb is malfunctioning.

-You said that going from a #152.5 to a #150 main jet did not really change anything in the high range ... you did not say that it was sluggish so I assume that it is still lean in the high range. Keep going up with the main jet until it is sluggish (too rich), then back down one jet size. That should give you max power & speed with a wide open throttle. That is what you want with a proper main jet ... max power & speed WITHOUT SLUGGISHNESS.

***Remeber ... check your spark plug between each single change you make and listen to what it tells you. Then compare that to what you feel ... power, speed, smoothness, responsiveness. Nice clean responsive power.
Also, all of this takes a good bit of time to do properly.

Let us know what happens

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911radioman

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Re: Fine tuning jetting question
Reply #7 - 08/03/06 at 19:05:22

LANCER wrote on 12/31/69 at 16:00:08:

Were you checking your spark plug during these runs to see what it had to say about the lean/richness? If not, you need to. It will be one more piece of info that can help you learn what is happening inside the engine.

No, I haven't been doing plug checks. I'll do that, it's been more of a time thing with me rather than just not wanting to do it.

Quote:

From what we know now...

-if the engine idle's well with the #52.5 pilot at 1.5 turns out, then that sounds like a good setting there. Stay with it.

-Leave your drop-in K&N in the filter box, it is not the source of any problems for you.

-You can check your midrange by going back a little on the lean side by adding a tiny washer to the white spacer. If it runs STRONGER with that leaner setting then you know that is what the engine wants. Since the engine was a bit sluggish in the midrange (typical with a rich setting) with just the filed spacer I would expect the leaner setting to improve the performance.If it does not improve with the leaner setting then I would think that something else within the carb is malfunctioning.

-You said that going from a #152.5 to a #150 main jet did not really change anything in the high range ... you did not say that it was sluggish so I assume that it is still lean in the high range. Keep going up with the main jet until it is sluggish (too rich), then back down one jet size. That should give you max power & speed with a wide open throttle. That is what you want with a proper main jet ... max power & speed WITHOUT SLUGGISHNESS.

***Remeber ... check your spark plug between each single change you make and listen to what it tells you. Then compare that to what you feel ... power, speed, smoothness, responsiveness. Nice clean responsive power.
Also, all of this takes a good bit of time to do properly.

Let us know what happens

On the main jet, it ran like a scolded dog at 152.5, so yeah 150 is more than certainly leaner.

I've got a handful of extra spacer laying around, so I'll probably file one down to 2/3 thickness and try it and see how it goes.

On the plugs... are you using a new one on each pull or just pulling the current one?

One note here. When I say "sluggish" it's not that it bogs down, it is more of a thing that I can feel it ever so slightly when applying throttle that it isn't quite as smooth on acceleration as I would like. It isn't bad at all, just not exact. I suspect it is the tiniest thing, that is doing it, not anything major at all.

Based on what you say, it does sound like the culprit could be in the spacer. Maybe I should've originally took it to a 2/3 thickness rather than a 1/2 thickness.

Now, on the spark plug, I changed the plug here a month or so ago just so I'd know what I had in it since I only bought the bike in February. It didn't look bad at all, nothing fouled looking but I haven't pulled the one I'm running in it now to see.

Could the brand of plug have an effect on my acceleration? I put a Champion in it when I replaced it. Maybe that plug isn't as good a quality a plug as the one I removed. Just a thought...

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Reelthing

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Re: Fine tuning jetting question
Reply #8 - 08/03/06 at 20:06:59

Man your getting down to business now - but in the end it's worth the time if you end up where you want to be.

yes, need to use a new plug on each test - I used at least a half dozen might of a been a dozen in the end tune'n on the '95 of the champion ra6hc - they're like a $1.50 at the auto store. Best color for performance is a very light tan - best color for the coolest running engine - what I was after - is a bit darker - there's a post around here on plug chop reading - it takes a good bit of time and road as you need to steady state the rpm your trying to get a read on for several minutes pull in the clutch and kill the engine - little tough on the WOT/mainjet without getting a ticket

on the spacer 1/2 or 1/3 is almost yard stick measurements if your going to get to this type of tune

read this one a bit

http://suzukisavage.com/cgi-bin/YaBB.pl?board=RubberSideDown;action=display;n...

now this is a highly modified engine where woodworker ended up with a #175 main - but the deal is the amount of change to the spacer -needle lift - .025" at a time -

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911radioman Ex Member	Re: Fine tuning jetting question Reply #9 - 08/03/06 at 20:50:20 Truth be known, I'm not really interested in getting to a Lancer stage of tune. I just don't have the time nor the inclination to do that! I'm just wanting to see if I can get that tiny bit of hesitation/sluggishness/whatever ya wanna call it just a little bit smoother.
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911radioman

Ex Member

Re: Fine tuning jetting question
Reply #10 - 08/04/06 at 15:06:19

Well, I'd say Lancer was just about spot on!

I tore into the carburetor, replaced the 1/2 spacer with a 2/3 spacer and went back to the 152.5 main jet and then put it all back together.

Put in a fresh spark plug and took it out for a run. Did the chop thing and pulled the plug and it looks real good.

The bike idles better and pulls stronger through the midrange area. Now the bike still is a bit rough when the engine is cold, but it has always been that way since I've had it, and I would expect weather has something to do with it as well.

So far, I'm pleased with how its doing. On the open highway, I can nail the throttle wide open and it just screams. From 40 mph, I can nail the throttle open and it just pulls super hard.

From what I can tell, it looks like the spacer may have been the culprit but I guess time and running it will tell.

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LANCER Serious Thumper Alliance Member Offline Savage Beast Performance Parts Posts: 10875 Oklahoma Gender:	Re: Fine tuning jetting question Reply #11 - 08/04/06 at 21:15:31 WELL DONE GRASSHOPPER.
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911radioman Ex Member	Re: Fine tuning jetting question Reply #12 - 08/04/06 at 21:53:27 While it appears to be running better, I did notice on the way in to work tonight that it seems to be popping through the exhaust a bit more when I shift gears. I wonder why that would be? Think I missed something somewhere?
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LANCER

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Re: Fine tuning jetting question
Reply #13 - 08/05/06 at 20:24:05

You said it was "popping", which is distinctly different from backfiring. A well tuned carb on a good running big single with crackle & pop on decel and occasionally during shifting. There is nothing wrong with that. It is the backfiring (sounds like a gun shot) that is harmful.
If this is what is happening then worry not.
If it is still backfiring then go back to the basics, because 95% of the time there are only 2 reasons for the backfire ... lean pilot circuit &/or exhaust air leak. Recheck both of those things again.

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