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Message started by jdeluca on 06/07/11 at 06:38:32

Title: Bike stumbles at idle
Post by jdeluca on 06/07/11 at 06:38:32

Hello all! I am a long time lurker here and have learned a ton from all of you. I apologize for such a long post for a first post, but I figure no sense in just coming on and saying I have a bike problem. I have an '86 Savage that I picked up for my first bike last year. Since then, I modified the air filter in a similar fashion as Oldfeller spoke about in his Jedi thread, and also thinned out the white spacer and tuned the pilot screw per Lancer's recommendations. When I put it up for the winter, it was running pretty good. Of course, being a relative idiot, I didn't add any stabilizer to the tank when I stored it.
Realizing what I had done, I pulled the carb off 2 weeks ago and cleaned it out, and also drained the tank and refilled with fresh fuel. The first time I fired it up this year, it idled roughly before fuel started flowing out the vent tubes on either side of the carb. Figuring it was a sticky float or something along those lines (I ruled out a petcock/vacuum leak) I pulled the carb off again and found a small tang on the float that looked like it was supposed to hit against the towers, yes, the float was upside down. Flipped it over and that solved the vent tube problem.
Put it all back together again, but this time I recorded all the jet sizes, as I had figured they were all stock, but just in case...
This is where I found out that the carb had been replaced, as it had the equivalent jets as a '95 stock mikuni would have, 45 pilot air jet, 52.5 pilot jet, 145 Main jet, with a 5C39 Jet Needle and an X-7 Needle Jet.
So anyways, got the carb back on the bike, fired her up, and found that she won't sit at idle. Period. To keep her running, I need to keep the throttle open just a crack. I have the idle speed screw in all the way, and she just stumbles and dies as soon as I release the throttle. My gut is telling me that I need to rejet; I'm thinking that one of the passages might have been clogged and now everything is nice and clean and because I have a low resistance filter in, it's running way too lean? Also, if I give it a couple good revs, it backfires really bad, definitely in the exhaust, not in the carb. I also tried removing the white spacer completely, but with it like that she wouldn't run at all.
So any ideas?
:)

Title: Re: Bike stumbles at idle
Post by Serowbot on 06/07/11 at 08:00:20

Check that you put the washer back, under the main jet.
If it is in place,... you need to pull both main and pilot, and run a thin wire through them,... and run the wire up though the passages that they go into.
A strand of wire from a wire grinding wheel, or a guitar string, or something quite thin.
There is lacquered fuel deposit in the passage somewhere.

Title: Re: Bike stumbles at idle
Post by jdeluca on 06/07/11 at 08:58:06

I am positive I put that washer back in, but I will double check. Lunch time here, so back to the garage to pull the carb off...again...
At least I'm getting pretty quick at it!

Title: Re: Bike stumbles at idle
Post by jdeluca on 06/07/11 at 09:56:30

OK, so I pulled the carb and am sitting at my desk with it disassembled. The washer under the main jet was installed, and I ran some copper wire through the pilot jet and main jet. I pulled the Needle Jet out again, all 4 holes in it are clear, as well as the large passage through the center. I ran the same piece of copper wire through the pilot jet passage, but I can't get it around the corner in the float bowl, so I did the old fashioned blow test...put my mouth on the pilot jet "tower" and blow, and there seemed to be no restriction there...
I also pulled the TEV and verified no blockages there as well...so I guess I'm still a little stuck...

Title: Re: Bike stumbles at idle
Post by Serowbot on 06/07/11 at 10:35:36

There's also some tiny idle passages on the intake side of the carb right near the edges of the throttle plate,... they flow constant and are not metered by the pilot jet... run the wire through them, too...
Spray carb cleaner through'em,... blow compressed air,... pray...
There's probably something, somewhere...
...it only takes a speck to screw you over... ;D...

good luck...

Title: Re: Bike stumbles at idle
Post by jdeluca on 06/07/11 at 10:57:02

If you mean the itty bitty teensie weensie pair at the top of the throttle plate...I can't for the life of me figure out where they go, and the bit of wire that I have that is small enough to fit in them goes about a quarter inch in before it bends and I can't push it in any further...either it's a blockage or there's a turn in there...I shot some cleaner in there and instead of trickling down like I'd expect, it just puddles, so I guess (?) that's a good sign, it shows that's the blockage at least. Next question though...how the heck do you clean THEM out...lmao

Title: Re: Bike stumbles at idle
Post by Serowbot on 06/07/11 at 11:10:43

Spray cleaner up through the pilot jet and any other holes down there, while watching those tiny holes,... and see if you can see fluid coming out from them...
Spray a lot.... you can get partial flow and still have blockage, that's why I try to get wires through them...

Title: Re: Bike stumbles at idle
Post by jdeluca on 06/09/11 at 12:18:02

So I cleaned it all out (again) and sprayed CRC into every orifice I could get to (with the carb disassembled, of course) and got her cleaner than when it was new...Also figured I'd pick up a couple new jets for it at the dealership as I was in the neighborhood. Picked up a 47.5 Pilot Jet, and then also a 150 and a 157 Main Jet. Kinda figured the Pilot would be the only one worth changing, as there was a 52.5 in there to begin with. Changed it to the 47.5, bringing it back to stock at least. Also put the 150 Main Jet in, as stock was 155, dealer didn't have any of those though.
Anyways, long story short...put the carb in today and started her up...after screwing the idle speed screw in all the way, I was able to get her to thump along at a relatively slow idle. After playing with the mixture screw, I got her running almost perfectly, however I lost count on the turns and think I'm around 6-7 turns out...which I think means go up to a 50 Pilot Jet, if I'm not mistaken.
Of course, if it means I should go up 2 sizes to a 52.5 (which was in it before) then I guess that last heavy soak with CRC dislodged whatever was left in there!
Thanks Serowbot!