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Message started by Guido on 08/26/06 at 07:09:59

Title: Jetting a Jardine?
Post by Guido on 08/26/06 at 07:09:59

Have a question. Had my bike all dialed in, no backfires. No exhaust leaks. Now for some reason it's decided to do it again, though not as bad as originaly. Haven't changed a thing and still no exhaust leaks.
I have a 55 pilot, 152.5 main, 1/3 spacer, K&N drop in, and a Jardine. 2 turns out. 1 1/2 is the happy middle, but backfires.
Who on this forum runs a Jardine and what are your jets, spacer, and mix settings. And do you have the backfires?

Title: Re: Who runs a Jardine?
Post by lancer on 08/26/06 at 12:22:07

If it was working good before and you have not changed anything, then something somewhere has loosened a little and developed a little leak.

Title: Re: Who runs a Jardine?
Post by Guido on 08/26/06 at 14:17:25

I did the soapy water trick on the exhaust and the header, no leaks. Checked the intake boot and there doesn't seem to be anything there either.
It only does it at throttle roll offs of less than half and kind of has a "slight" wavering idle. Full throttle roll offs don't backfire at all.
My guess is I need to go with a larger pilot jet, 57.5.
I haven't had to re-torque the header bolts for a few days now so I don't think the gasket is the issue once it's warmed up. Doesn't do it much at all during warm up to normal temp.
Since I went 2 sizes up on the main and only one on the pilot, and it doesn't back fire at full roll off, only half..........

Do you think this is the right way to go??

Title: Re: Who runs a Jardine?
Post by Brewbrother on 08/26/06 at 15:43:25

Guido wrote:

My bike still has an occasional backfire with engine braking. I wonder if its just a thumper thing??

Title: Re: Who runs a Jardine?
Post by Guido on 08/27/06 at 16:07:17

It may be just a Thumper Thing. But I'm trying my darndest to straighten it out!
I took it out for about 20 miles today, started at 2 turns out. Started good, wavering idle, still the backfires between shifts after it warmed up. Idle seemed a little inconsistent at stops. Sometimes fast, sometimes slow.
Adjusted to 1 3/4 turns rode a few more miles. Improvement with idle speed at stops, more consistent. Improved throttle response. Still backfires between the first 2 or 3 shifts.
Adjusted to 1 1/2 turns out. Best throttle response and strongest most consistent idle. Still backfires between shifts if I close the throttle all the way.
Now, if I hold the throttle open a little between shifts it won't backfire! This is in all of the above scenarios!!
I've adjusted the the idle up and down, really slow to really fast and it has no effect on the backfire. I've adjusted the mix, at a warmed up idled it slows at 1 turn out and at 2 turns out.
One of the mechanics at the dealership asked if I tried taking the spacer out completely (they know it's at 1/3 thickness), and I told him I was afraid that would make it flood at idle. He said either try that or go up to a 57.5 pilot.
Keep in mind, after it's warmed up, it will backfire at 1/4 to 1/2 throttle roll off, but will not backfire at full throttle roll off.
I'm gonna try one or the other but can't decide which.
What's the majority opinion here??

Title: Re: Who runs a Jardine?
Post by SavageDude on 08/27/06 at 16:14:44

From my own riding experience, the longer you ride the hotter the engine gets. So it is running lean when hot but rich when cold. I still get a little pop here and there on deceleration. I'm current running with 155 main with Sporter muff. Because our bike is air-cooled so it is quite difficult to maintain a constant engine temperature to get the optimal carb tuning. I guess we just have to learn to easy off the throttle slowly on decel.

Title: Re: Who runs a Jardine?
Post by Guido on 08/27/06 at 17:19:01

SavageDude wrote:

That's a good point about engine temp. It won't do it during warm up. So it would follow that richening the pilot circuit by either taking the spacer out or going up to a 57.5 would help, correct?

Title: Re: Who runs a Jardine?
Post by SavageDude on 08/27/06 at 17:31:37

Well I'm no carb guru around here; but if you are a little richer when engine cold then you will end up with the livable point when the engine is hot. Richen up the pilot circuit is the goal here. Ask Lancer--our carb guru here--he'll concur ;D

Title: Re: Who runs a Jardine?
Post by Guido on 08/27/06 at 17:57:24

Well, if I remember correctly, with the stock set up it ran like CRAP til it warmed up. Sputtered, surged while trying to maintain speed, etc. After it warmed up those problems would go away.

lancer?????

Title: Re: Who runs a Jardine?
Post by lancer on 08/28/06 at 15:17:22

You RANG?? ;D

Howdy there friends and neighbors!!

Keep in mind that the pilot jet is primarily responsible for idle to 1/4 throttle.
The needle is primarily responsible for 1/4 to 3/4 throttle.
The main jet is primarily responsible for 3/4 to full throttle.

Based upon that, look at the symptoms and decide what part of the throttle range the problems occur in.
If it starts and idles ok, and full off decel is ok, then the pilot should be right. If not then adjust screw &/or rejet.
If there are issues in the 1/4 to 3/4 throttle range then an adjustment of the needle is appropriate... like removing the white spacer for example.
Running at wide open full throttle should be crisp and powerful, without bogging down or shortness of breath. If there is a problem then the main jet needs to go up or down as appropriate.

You started out saying that everything was working OK, then without any changes on your part the engine starts to backfire a little. In that case, something did change ... otherwise the symptom would not show up.

You're only getting a little backfire at less than 1/2 throttle, and the idle is now wavering. A wavering idle sounds like an air leak at the carb or a clogged passageway.

Adjusting pilot from 1 to 2 turns out, slows at each end of it (as it should with the correct pilot jet installed), so 1.5 turns out should be about ideal.
.

Holding the throttle open a little while shifting and during decel will keep the idle up a little higher which will help prevent backfires. Throttle off decel at higher speeds will enable the carb to keep a stronger air flow through the carb bore, creating enough vacuum to pull the fuel up from the bowl and making a decent fuel/air ratio, which prevents backfire. Throttle off decel at lower speeds creates less vacuum, pulls less fuel, making a leaner fuel/air mix, which will enable some backfire.

Idle speed adjustment alone only affects engine speed at idle ... ;) ... in order to affect the typical backfire the adjustments MUST
be made to the pilot circuit. Adjust the screw and/or change the jet ... as needed based upon the symptoms of the engine.

PAUSE: GOT TO RUN TO THE PHARMACY ... BE BACK IN 30 ;D

Title: Re: Who runs a Jardine?
Post by Guido on 08/28/06 at 16:12:10

Thankyou lancer for your timely reply.
The wavering idle is gone since backing down to 1 1/2 turns out. It's strong and steady.
I can't find any leaks on intake or exhaust, although the intake would be harder to detect.
The backfires are fairly consistent at roll off of around 1/2 to 1/4 throttle I guess. It seems to be only in the first two or three gears.
Full throttle is very strong!! Like hang on man!!
So Dr Lancer, I guess from what you say here, taking the spacer out should help this condidtion? I was afraid it would make the carb flood at idle. That's why I never tried it and thought the pilot jet would fix it. If I take it out will this affect the mix screw setting also?

Title: Re: Who runs a Jardine?
Post by Guido on 08/28/06 at 16:14:22

Oh, I'm also guessing that it probably wasn't right before. I just didn't test enough before crying EUREKA!!!!

Title: Re: Who runs a Jardine?
Post by lancer on 08/28/06 at 16:59:48

Taking out the spacer should not affect the pilot circuit at all.
Take it out and see what happens. If it is too rich then just put it back in...no big deal.

Since the idle smoothed out when you got down to 1.5 turns that is showing it was running a little rich at that setting, AND that the carb is responding properly when you are adjusting it, so no clogged passages are eveident.
Don't be afraid to experiment with the carb, if you go the wrong way it will tell you by the way it runs. Playing with it will NOT hurt it or the engine. Enjoy.

Title: Re: Who runs a Jardine?
Post by Guido on 08/28/06 at 18:15:28

Allrighty, I took the spacer out, and all it seemed to do is change the happy middle to 1 1/4 turns out. Had to turn the idle up a little. Still backfires with a pretty blue flame, in the same areas as before. I don't work on it much after dark so it probably did this before.
What I'm doing to get this to happen is holding the throttle at 1/4 to 1/2 for a few seconds then letting it snap back.
You said the 1/3 spacer at 1 1/2 turns out and the smoothed out idle means it's a little rich? Should I put that spacer back in and back it down below 1 1/2 turns?
I did order some 57.5 pilots just in case, that should be here by Thursday. Should I give one of those a shot?
I'm gettin pretty good at takin the tank off ;D

Title: Re: Who runs a Jardine?
Post by Guido on 08/31/06 at 16:58:02

Okay, now I have put the spacer back in (1/3). And I swapped out the 55 pilot for a 57.5. Happy middle is again 1 1/4. Just fiddling with it on the patio (raining for three days now), it seems to be a little better and doesn't seem to be getting as hot either, course it's only 70 degrees right now.
But it's still backfiring. Less often than before, but still there.
I know it's not an intake leak because the carb had to come out this time due to the 55 pilot head being stripped and had to use an easy out on it. When I put it back together I paid close attention that everything seated properly.
Any more suggestions? Or should I just live with it?
Probably won't get to road test til Sunday. :(

Title: Re: Jetting a Jardine?
Post by Guido on 09/01/06 at 14:19:28

I'm beginning to think I might as well be chasing a UNICORN! ::)

Title: Re: Jetting a Jardine?
Post by lancer on 09/02/06 at 01:40:16

Just keep in mind that when trying to solve a backfiring problem stick to the pilot jet and pilot jet adjustment screw (or also called the air adjusting screw). That is the primary cause of backfiring problems. And is confined to idle to 1/4 throttle.
The white spacer affects the midrange of 1/4 to 3/4 throttle, where backfiring is typically not an issue.
When changing a pilot jet from one size to another, you should see a change of about one full turn on the adj screw setting.

Title: Re: Jetting a Jardine?
Post by Guido on 09/02/06 at 06:23:51

From just the little testing I did. The happy middle seemed to be between 1/2 and 1 1/2. So the correct setting should be 1 turn? The most consistent return to idle seems to be at 1 1/4 turns. It actually died on me a couple of times when revved to nearly full throttle and snapped shut at settings above and below the 1 1/4 turns. Didn't want to fire right up after that either. Had to crank a little longer and give a little throttle. Could it be the idle speed needing to be turned up? I have moved it up and down trying to compensate but not much.

Title: Re: Jetting a Jardine?
Post by Guido on 09/02/06 at 15:02:11

Went for a ride. Adjusted along the way. Started at 1 turn out and backed all the way to half in 1/8th increments. And all the way up to 1 1/2 in 1/8th increments. The farther up I went, the back fire got worse. Got better the farther in I went but still there. When I got back, I turned it all the way in just to verify my setting. Guess what, the idle never slowed!! Checked the end of the muff, and a good bit of soot had accumulated. So.....I'm assuming this pilot is just too big.(57.5) I guess I'll put the 55 back in and give it another shot. Maybe it was boogered up or something since I had such a hard time getting it out.