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Message started by arteacher on 05/12/12 at 17:11:32

Title: Temporary enrichment problem.
Post by arteacher on 05/12/12 at 17:11:32

This started last year when I tried the "cut spring" mod to get rid of backfire. It got rid of the backfire but the idle was all over the place, So I bought a new spring. Ever since then when I let go of the throttle, or back it off when coming to a stop, it wants to shut off. The idle drops right off. I have to be very careful, and run it at 12-1300 idle speed. Still sometimes it happens. I occurred to me that I had damaged the diaphragm, so I replaced it. No better. Today I pulled the carb, dis assembled it, used a carb cleaning tool in all the passages, cleaned it with carb cleaner, and blew it out with compressed air. I found nothing. The carb was basically clean to start with.
I have a Raask exhaust with baffles, a K&N slab filter in place of the stock filter, a 55 pilot with bleed holes, and a 150 main with a Dial-a-Jet to assist. I did a plug read today and it is a beautiful tan colour.
When I have the choke pulled out a notch it runs rich, but the RPM falls down to idle as it should. I have set the idle mixture as per Serow's thread. It is 2 turns out.
I can only get the smallest wire in the carb cleaning set through the hole from the TEV to the throat. Is that right, or should I be able to get a larger wire through?
Do I need to go up a pilot jet size?
I am stumped, and starting to get very discouraged. :(

Title: Re: Temporary enrichment problem.
Post by justin_o_guy2 on 05/12/12 at 17:13:28

I dont know about your carb problem, but my checking account could tolerate some enrichment. I promise, it would only be temporary.

Title: Re: Temporary enrichment problem.
Post by built2last66 on 05/12/12 at 18:06:07

Try the method I was told for idle mixture screw (also known as pilot screw, NOT pilot jet screw) tuning... here it is, I forgot who posted it:

- with the bike off, turn the idle mixture screw all the way in, then count it two full turns out
- start the bike and using the idle speed screw (left side), bump up your idle a bit (makes things a bit easier to hear, less likely to die).
- back the idle mixture screw out slowly, count 1/4 turns at a time (waiting a tad between each adjustment), until revs start to drop
- from that position, count 1/4 turns in again until the revs drop again (so you'll turn the screw through the "happy idle" range).
- divide the number of turns from "screw too far out and rough idle" to "screw too far in and rough idle" in half, and set the screw there. should be pretty close to ideal jetting if the pilot is the right size.

Title: Re: Temporary enrichment problem.
Post by Routy on 05/12/12 at 19:06:48

Quote:
Ever since then when I let go of the throttle, or back it off when coming to a stop, it wants to shut off. The idle drops right off.
------------------------------------------------------------------------
The way you explain this, it sounds like when you back off the throttle, the fuel supply is temporarly being completely shut off.....incl the idle fuel. This is more than an idle adjustment. It seems you know about when this started,......in that case I think I'd still go back to anything you mite have done,.....or done wrong, and go from there. If I knew the carb better, I mite be able to help you better ;)

My '07, w/ stock carb (except 1/2 spacer mod) runs and idles, better than any bike I've ever had, and it still has the brass plug over the mix screw.
But,......yep, it backfires,.....its supposed to ! ;D

Title: Re: Temporary enrichment problem.
Post by CaptialThumper on 05/12/12 at 19:37:13

6C6379627E786B69616F780A0 wrote:

My '07, w/ stock carb (except 1/2 spacer mod) runs and idles, better than any bike I've ever had, and it still has the brass plug over the mix screw.
But,......yep, it backfires,.....its supposed to ! ;D

My '07 with stock everything and brass plug also runs and idles ideally, and backfires are rare. Maybe they just got things right in '07? ;)

Title: Re: Temporary enrichment problem.
Post by built2last66 on 05/12/12 at 20:20:31

I tuned mine as per the instructions I posted and the decels pops stopped almost entirely.. no spacer mod.. but I'm gonna throw in that spacer mod to see if I can't get some more throttle response.. I liked the little pops though :D

Title: Re: Temporary enrichment problem.
Post by arteacher on 05/12/12 at 20:33:43

61766A6F77316F6270773535030 wrote:

Did that.

Title: Re: Temporary enrichment problem.
Post by built2last66 on 05/12/12 at 20:36:35

You did it already or just now? Did it work?

Title: Re: Temporary enrichment problem.
Post by Fish on 05/13/12 at 06:04:56

Your issue sounds really similar to my fluctuating idle. It's really annoying.

Title: Re: Temporary enrichment problem.
Post by LANCER on 05/13/12 at 06:13:12

When you disassembled the carb did you remove the choke/enrichment assembly and check the passageways going to the pilot circuit ?
Was the diaphragm you replaced the little one on the right side with the spring you cut or the large on on the slide ?

No cracks in the slide diaphragm or pinches on the edge of it upon installation ?

Is the butterfly valve positioned perfectly in the carb bore ?

Title: Re: Temporary enrichment problem.
Post by arteacher on 05/13/12 at 07:30:00

6A67686563743431060 wrote:

I replaced the small diaphragm.
The butterfly seats perfectly.
I removed the choke assembly. Was there something else to remove?
I cleaned the large diaphragm and found no cracks in it.
I cleaned every passage I could find.
I can only get the smallest wire in the carb cleaning set through the hole from the TEV to the throat. Is that right, or should I be able to get a larger wire through?

Title: Re: Temporary enrichment problem.
Post by arteacher on 05/13/12 at 15:32:57

OK- I tore it all apart again today just in case I missed something. I didn't. Put it all back together and it still had the problem.
The only thing I can think of is that there is a restriction in the passage between the throat and the TEV valve. As I said before- I can only get the smallest wire in the K&L cleaning tool through it.
If someone has a carb sitting around could you please tell me what diameter that hole is before I drill it out and possibly screw up the casting.
I would appreciate it very much.

Title: Re: Temporary enrichment problem.
Post by built2last66 on 05/13/12 at 15:38:52

I can tell you in a day or two if no one gets back to you when I have my carb apart for the spacer mod, I'm just waiting on the screws to be delivered..

Title: Re: Temporary enrichment problem.
Post by LANCER on 05/13/12 at 16:20:50

7E75757C707F7E6465110 wrote:

The small wire through the hole is ok

Did you clear out the end hole and 2 side holes in the little brass tube sticking down into the side of the float bowl from the carb body ?
The carb cleaning tool smallest wires should go into the tube end hole at least a full inch...maybe 1.5".

Title: Re: Temporary enrichment problem.
Post by arteacher on 05/13/12 at 16:36:05

Yep. In the last two days I have studied Mikuni carbs and how they work, and cleaned everything. I would suspect the Dial--Jet, except the plug looks like the mixture is good. The thing is... it was working perfectly until I tried the "cut spring" mod, and no matter what I have done, it hasn't gotten back to normal.

Title: Re: Temporary enrichment problem.
Post by built2last66 on 05/13/12 at 19:10:01

Shoot me a pic of that stretch kit with the Raask showing if you can, I wanna see how the angles look :D

Title: Re: Temporary enrichment problem.
Post by arteacher on 05/14/12 at 04:43:20

495E42475F19474A585F1D1D2B0 wrote:

Shoot me a pic of that stretch kit with the Raask showing if you can, I wanna see how the angles look :D

Pics in Cafe. "chopper kit done"

Title: Re: Temporary enrichment problem.
Post by LANCER on 05/14/12 at 04:46:21

3932323B3738392322560 wrote:

The Dial-a-jet does not affect the issue you are dealing with; it's a mid-high range device.

Do you have the stock petc0ck or a Raptor ?
Good seal on the vac line if you still have one ?
This makes me think that the slide may be dropping down instantly instead of in a controlled manner, cutting fuel/air too quickly, resulting in hesitation or engine stop.

Is the pilot screw still set at 2 turns out ?
When the engine is totally warmed up, like after riding a couple of miles, is the setting giving you the best rpm ?
Have you tried adjusting it on the road; testing to see if going in or out will increase rpm ?
If not, try it on your next ride.

Title: Re: Temporary enrichment problem.
Post by arteacher on 05/14/12 at 13:52:44

Got the raptor.
If I let the throttle go at anything under 2000 rpm it behaves as it should. Letting it go at close to 3000 rpm and it drops way down, sometimes shutting right off.

Have you tried adjusting it on the road; testing to see if going in or out will increase rpm ?

I don't understand what you mean. Why would adjusting it on the road be better than in my back yard as long as the motor is warmed up? :-?

Title: Re: Temporary enrichment problem.
Post by arteacher on 05/15/12 at 15:50:42

I still haven't solved the problem, but I rode it around today and if I'm careful I can keep it from stalling. That will have to do for now, until I can figure it out. :-?

Title: Re: Temporary enrichment problem.
Post by justin_o_guy2 on 05/16/12 at 04:38:44

I was having that problem, it would flame out at 50 if I just pulled the clutch in & let the throttle go, I raised the idle & it stopped that.