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Message started by vroom1776 on 05/30/07 at 06:25:19

Title: Carb Leak Diagnosis Pt. 2
Post by vroom1776 on 05/30/07 at 06:25:19

hey all!

remember this thread (http://suzukisavage.com/cgi-bin/YaBB.pl?board=RubberSideDown;action=display;num=1176142433;start=)?

FYI: I'm at 4000 feet above sea level.

well, I finally had some time and put the VM 38 back on there and got it to start.

with a 260 main and the clip on the needle 1 down from the top, the top end pulls like a SOB and scares me (need a fork brace :o) .

but the leak is still kinda there. I am 100% sure it is not the float needle valve. Why: When I pour gas into the fuel intake spigot and push up on the float arm, no fuel leaks at all. When I let go of the float arm, all the fuel comes out. This does not mean that the float is adjusted correctly, though.

I think the pilot and idle circuits are WAY off. I'm running a #30 pilot (bleed type), and the air mix screw (it's on the air intake side of the carb) is somewhere around 2.5 turns. The idle is nearly all the way in.

What do I mean by leak? Okay, so I got the carb back on, and decided I needed to tune the pilot and idle circuit. So I pushed the idel up (i.e. turned the screw in), and started playing with the air mix screw. when I had it way out (I think it was out) fuel started pouring, and I do not mean a trickle) out of one of the overflow tubes. well, I killed the bike, and the flood stopped after a bit. It does not seem to make a difference if the petc0ck is in PRIme or RUN (both work properly with stock carb). Eventually got it to idle more or less okay.

So if the float valve works, why the heck is it overflowing? Float height adjust? It did it a little bit this morning to witht he same settings as last night's test run (as below).

took it out for a test run. Top end is scary. cruising at 15-20 mph, it is kinda choppy, surging, even after it was warmed up. it hesitates jsut a little at, say, 1/10 throttle. these usually indicate a lean condition, correct? well, this AM it started right up, and ran fine for a bit. then it started to idle poorly and wanted to die all the time, and I was getting puffs of black smoke on restart. This usually indicates rich, correct? by the time i got to work, it was idling pretty well.

Also, it backfires ALL the time, but I think that is partially because of the cherry bomb I've got on there. Stock BS40 carb did it too, though not as much. Some of the backfiring is prolly due to the nature of the cherry bomb, some to the nature of the savage, some to poor jettinhg, and some to to exhaust leaks at the header/muffler joint (probably).

Any useful input is appreciated.

Thanks,

V

edit:
PS as from the CLD Pt1, the purpose of the independent floats is evidently to keep the feul level constant while accelerating, decelerating, leaning, going uphill, downhill... at least that's what I got out of the (Sudco or Mikuni) manual. they said the not independent floats are "ideal for small carb. bore applications" I may edit this a bit later.

Title: Re: Carb Leak Diagnosis Pt. 2
Post by tuxedo on 05/30/07 at 08:03:22

I'd definitely mod the petc0ck first.

Once you know what's going on there, tune the idle circuit.

For a while.

Until you know it's right.

And carry a plug and plug wrench with a u-joint with you for a while.

One thing I can speak knowledgeably about is the cherry bomb. Pull the thumb screw and put a stack of washers in there. You can tune the number of washers to raise or lower the flat spot in your throttle.

You will always have crazy popping while cruising around, scaring kids and old people, we both know this. My Cherry Bomb was STUPIDFUGGINLOUD when my bike was running richer than Bill Gates. It always sounds edgy, but it sounded somehow meaner. Lowered my float.

Also maybe a hotter or cooller plug. I dunno which you'd really need at 4000Ft, but I think that's a problem no one's thought of mentioning to you.

THIS JUST IN: crazy idea I had. Maybe when the bike's on the side stand the float is sticking. But not when upright. That would mean it would lean out just sitting at idle on the stand, but only in whacky cold situations like when you start it in the morning. Maybe try some Mystery Oil or Sea-Foam in the gas.
float_ \._ <wedged in there? \_float
Small bike's sit more upright, but yours should be almost straight up and down with struts.

Title: Re: Carb Leak Diagnosis Pt. 2
Post by vroom1776 on 05/30/07 at 08:42:19

thanks for the input tux!

hmmm... not a bad idea about the floats sticking while on the side stand... but I think one is enough to close the valve... but maybe not.

The petc0ck is definitely not the issue. Works 100% perfect with the stock carb.

not sure what you're getting at with a stack of washers... so they are piled up, with the holes perpendicular to the exhaust flow?

and besides the leak, since it seems to be showing symptoms of both lean and rich, which doesn't make any sense, I have no idea what to do with the pilot jet... up or down? ARG!

the length of my struts makes the carb run petty much level, but since it is only held on by the rubber intake flange, it tilts back just a hair (an arrow throught he bore would point up about 5-10 degrees.) This COULD be the problem.

Thanks,

V

Title: Re: Carb Leak Diagnosis Pt. 2
Post by vroom1776 on 05/30/07 at 08:56:31

okay, went outside and held the carb level. no difference. it is reasonably warm out.

though I had to turn the idle screw all the way in to get it to go.

Also, the thing sucks so much air that when it's running it sits level!

I'll check the plug later and fool with the pilot jet based on that.

V

Title: Re: Carb Leak Diagnosis Pt. 2
Post by LANCER on 05/30/07 at 08:58:21

Go smaller on the pilot jet ... what sizes do you have on hand?

Title: Re: Carb Leak Diagnosis Pt. 2
Post by vroom1776 on 05/30/07 at 09:31:57

Thanks for the input Lancer!

20, 22.5, 25, 27.5, 30

was gonna run to the local dealership and pick up a 32.5 & 35. skip?

uh, can a really messed up idle and pilot flood the carb with a properly working float needle?

Thanks,

V

Title: Re: Carb Leak Diagnosis Pt. 2
Post by Greg_650 on 05/30/07 at 12:59:47

vroom1776 wrote:

You might have 2 problems but just looking at the float....does it float?

You said the arm works to close the valve, but it doesn't shut off the full when installed. Try putting in some gas outside of the carb.

See if that boats your float :P

Title: Re: Carb Leak Diagnosis Pt. 2
Post by vroom1776 on 05/30/07 at 13:56:21

now have a 32.5 as well (they were out of 35s).

The floats float. I checked them very well in the first thread. no leaks in the floats. Will check again tonight. It's not leaking right now, but if I fiddle with the idle and air mix screw, I can make it leak.

Thanks,

V

Title: Re: Carb Leak Diagnosis Pt. 2
Post by Greg_650 on 05/30/07 at 20:16:01

Have you removed the float valve seat and/or looked really really close at the float needle for any depressions around the tip?

Cutting off the fuel is a major issue. That is the float's job.

If you have dripping faucet in the bathroom you don't check the water meter.

Just a thought...

Title: Re: Carb Leak Diagnosis Pt. 2
Post by vroom1776 on 05/31/07 at 07:33:26

the floats float.

went down to a 27.5 pilot, about 2 turns out on the mix screw. runs better, needs to be tuned, or maybe even the 25. no gas pouring out of the overflow tubes. not even a drop.

SO, how can an oversized pilot jet and high idle cuase the carb to pour gas out the overflow tubes if the needle valve works?

Title: Re: Carb Leak Diagnosis Pt. 2
Post by LANCER on 05/31/07 at 13:06:45

I have not been feeling well and my brain is not functioning properly...some would question if it EVER does so nothing new there. However, give the #25 a try and see if it will work properly without having to go more than 2 turns out.

Title: Re: Carb Leak Diagnosis Pt. 2
Post by Greg_650 on 05/31/07 at 18:58:47

vroom1776 wrote:

You know what?....sometimes when you're just banging around in the wrong direction, you can actually fix something that was wrong without even knowing it. I've done it. It's like "WTF?"

Best answer that I got with the information on hand....besides, don't forget the side of your engine ;D

Title: Re: Carb Leak Diagnosis Pt. 2
Post by vroom1776 on 06/05/07 at 15:20:13

allright got the 25 pilot in there... haven't had time to tune it much... about 1.5 turns out... seems okayish.

had to go to the shop to get one as the one I had was a 12.5, but looks like it says 25

another thing I don't understand is why the bike ran reasonably well last spring, summer and fall, and ran like crap this spring... ???

Title: Re: Carb Leak Diagnosis Pt. 2
Post by vroom1776 on 06/05/07 at 18:04:51

oh, and yanking the throttle wide open from idle should stall the bike with this carb, right?

uh, what else was I thinking abo

oh, darn!

uh uh uh petc0ck!

this carb still hates it when it is set to "RUN" "PRI" works fine.
stock carb has no problems with "RUN," and I'm using the same vac. hose...

Title: Re: Carb Leak Diagnosis Pt. 2
Post by Max_Morley on 06/05/07 at 18:37:17

Is the spigot you are using for vacuum source actually meant for that. Do you have an old vacuum gage hanging around from the past? If so make sure it is a vacuum point and not something else. Older bikes and performance bikes did not use vacuum operated fuel shut off valves so maybe it isn't what you think. B-i-L's carb had to be drilled and a spigot put in for the vacuum part. The tubing pulled out when we removed the tank to do the maintenance on it and needs to be epoxied in at this point. Max

Title: Re: Carb Leak Diagnosis Pt. 2
Post by Savage_Rob on 06/06/07 at 05:22:52

Max_Morley wrote:

Older bikes and performance bikes did not use vacuum operated fuel shut off valves so maybe it isn't what you think. B-i-L's carb had to be drilled and a spigot put in for the vacuum part. The tubing pulled out when we removed the tank to do the maintenance on it and needs to be epoxied in at this point. Max

Yeah, I had to do that to my Amal Mk2. It works very well though.

Title: Re: Carb Leak Diagnosis Pt. 2
Post by vroom1776 on 06/06/07 at 05:28:48

that's very itneresting max!

hmmm... mybe I'll just cap it of and run on PRI anyway. I know when I remove that tube, it kills the bike.

25 runs pretty good, but still jerky in the AM at low speeds. and now the float bowl drain gasket is leaking! ARG! It never ends! (NOT the previous leak)

oh, ran the piss out of it last night. really wrung it's neck. on the main jet: uphill, perfect; flat or downhill, sputters just a little (above redline). will try a 250 main.