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General Category >> Rubber Side Down! >> enrichment circuit...FIXED!
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Message started by JohnBoy on 06/03/10 at 11:32:34

Title: enrichment circuit...FIXED!
Post by JohnBoy on 06/03/10 at 11:32:34

I was looking at doing some carb adjustment and cleaning.

I wanted to get a price quote prior to removal...just in case.
The enrichment circuit diaphragm and spring for my 2004 were quoted at 57.00!!!

My initial plan was to remove the diaphragm and spring to clean them and check for possible damage that might be leading to “after-fire” on decel. Now, I am thinking of putting red tape over the cover saying “Do not touch!”

Can any of you give me feedback on just how durable the diaphragm is and what the risk of removing it and reinstalling are.

Also...I understand that this carb is listed as a Mikuni BS40 (?)
All the images I find for a BS40 show a flat slide carb, with no enrichment circuit?

Title: Re: enrichment circuit?
Post by dasch on 06/03/10 at 12:09:37

JohnBoy, you'd have to act like a rhino to do it harm. Take it easy and be gentle and no worries.

Title: Re: enrichment circuit?
Post by Bubba on 06/03/10 at 14:19:01

Also, check this out. From what I can see the spring listed here would run you 12 bucks shipped.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1268545171

Title: Re: enrichment circuit...FIXED!
Post by JohnBoy on 06/04/10 at 12:59:50

I think that I got the after fire issue fixed!
I went to my local carb shop and purchased a used spring from a Rochester 2BBL accelerator pump (see image)
http://lh3.ggpht.com/_TCSH6bqjHEM/TAlVjSiQ4jI/AAAAAAAAAzY/2iqntZqARA0/s576/enrichment%20spring1.jpg

The dimensions are the same but the wire diameter is different.
The original is .036 while the Rochester spring is only .025 making for less compressed tension.
The removal and replacement took much less time than driving to the carb shop.
I made several runs through the gears getting on and off the gas as hard as I could and I could not make it back-fire! I stopped several times, blipping the gas and shutting it off; but I could not induce the little burp we know so well.
The intake and exhaust on my bike are heavily modified, so I can't say that this spring will fix a stock bike...but I have a plan!! There are a couple of other riders here in Phoenix that I believe are riding stock machines. I will attempt to locate one of them and offer to “Fix”his bike for free ($2.00) and report back.
Once again...Thank you all for your help and support.
JB

Title: Re: enrichment circuit...FIXED!
Post by Oldfeller on 06/04/10 at 13:27:26

Johnboy, it would be nice if you could identify a web source for the correct spring and post it so folks can try out your solution. Tech posts with no widespread source for the needed components aren't as helpful as them that have de pieces for the mices.

If you could post the spring OD and length mebbe you could get a little help from the techie crew that reads these things ....

Title: Re: enrichment circuit...FIXED!
Post by justin_o_guy2 on 06/04/10 at 18:20:28

I went in the carbs on the W today. The accelerator pump diaphragm is shot.. It Too is 57 bux,, but I dont get no stankin sprang with mine..

Title: Re: enrichment circuit...FIXED!
Post by verslagen1 on 06/04/10 at 21:59:44

If you can JB, post the diameter and length and I'll keep my eye out for such a spring.

Title: Re: enrichment circuit...FIXED!
Post by JohnBoy on 06/05/10 at 05:50:12

This was posted by Jespoker4fun on 3/15/10
____________________________________________
Ok, here is the link to order the spring for the air-cut valve.
http://www.carburetion.com/r2.asp
Just scroll down to part# 66-15
.95 plus shipping

Inside dia. = .385
length = 1.580
wire dia. = .025
I just checked the shipping charge from this site. They charge shipping & handling.
Total for the spring will be about $12.00
_______________________________________
As can be seen on the photograph the number of coils and the overall dimensions appear to be the same. The outside diameter and inside diameter of both springs leave plenty of “wiggle room” for the post on the inside of the cover, and the cup on the diaphragm.

Title: Re: enrichment circuit...FIXED!
Post by Oldfeller on 06/05/10 at 08:00:08

They want $11.00 in shipping and handling to ship a tiny spring?

That's just wrong .....

Title: Re: enrichment circuit...FIXED! Updated info...
Post by Bubba on 06/11/10 at 06:58:19

Johnboy was nice enough to send me one of the springs he found for the air cut diaphram so I popped it in to see what would happen.

There is definately a correlation to the backfiring going on here, if there is someone around Denver that has a stock bike and wants to see what happens I'm willing to help them try it.

P.S. my guess is this method would be similar to tuning your jetting except not as precise (seems to influence the whole range of circuits) and the spring tension would be different for various elevations and conditions.

FWIW, my feedback to JB is below...

thanks for info John,
BTW, got the spring yesterday. I think the 5 buck impact screwdriver I bought from Harbor freight a while back is the best investment I've made on this bike...

Anyway, here are my results...I installed it and it made the bike run horrible...no really!

I took your advice and upped the idle screw (same as you, I wasn't expecting that)...could barely keep it running even with the screw almost all the way in, turned the air mix screw in almost a full turn too.

Took it around the block and sure enough, there was absolutely NO backfires no matter how much I wound it out. I had pretty much eliminated the backfire on shutdown anyway so that was all good too.
Pulled into the garage and it smelled like a refinery + plenty of black smoke when you blipped the throttle...

I think with me being at a mile in elevation (richer) I was pretty dialed in with the jetting I'd set (#52.5 pilot w/bleed holes, 150 main and 2/3 spacer) and that when I replaced the spring it just made it too rich. I could probably go back to stock jetting and give it another go but I've already got it pretty much where I want it. I stuck the stock enrichment spring in and rode to work today and it was fine.
I'm thinking you may be right...someone with a stock bike could probably be successful with this as long as their elevation was near sea level...
It definately has a bearing on the backfire issue. I may take the spring you sent and see if I can find something kinda in-between what's stock and what you sent.
Thanks for all your help tho'...