I've looked all over this forum, studying the back fire issues others have had. My 2002 Savage had been taken to a dealer by the previous owner to get the issue resolved, and I had no backfiring when I bought the bike.

In my thirst for power I halved the white spacer, causing much backfiring. I swapped the main up to a 150, also still backfiring. My question is this:

When I turn the Idle Air Screw out I get very few large "CRACKS!"

When I turn the screw in, Iget lots of little "pop,pop,pop, pop,pops"

I am thinking my Pilot is too small to meet fuel demands when the throttle plate closes. Could I be right?

Background:

Filthy air filter
1/2 white spacer
#150 Main
47.5 Pilot
Idle set at "who knows"
Small tear in outer edge of rubber on the "Diaphram Assy" #32 @ http://www.ronayers.com/fiche/300_0271/carburetor/carburetor.cfm?man=su&group...

Advice is appreciated.THX!

Check for both intake and exhaust leaks. Fix that diaphram. If you have stock exhaust, your jetting should be fine. Only if you need to go beyond 3 turns or so do you need a larger pilot jet.

Add up the cost of the various things you will need to do the job, then decide if it is worth fixing or possible be better off going with a new carb.
It can be a hard decision to make, especially if the cost is not real high but the hassle of trying to make it work pushes the whole thing to the edge of frustration.

Do you have the Clymer and/or the shop manual?  If you are going to try to FIX the carb then you NEED the books.  At the very least spend some time on the Mikuni.com website reviewing the steps involved in tuning "by the numbers".

When thinking about a new carb the cost for the basics ... carb, mounting flange, throttle cable ... will run close to $200, while the full monty is above $300.

It all depends on your knowledge and skills with carbs.

I don't know if this has helped much but there are some things to consider.

One thing for sure, if you are keeping the stock carb to fix it, then the diaphram needs replacing if it is damaged.

sorry didn't follow the post to see which diaphram you meant - I believe anti-backfire is it's function  - if I remember correct savage_rob should have a used but working order spare - might make you a deal

If you have a tear in the air cut-off diaphram you are going to get backfires - suggest you fix this before you change anything else - these folks have it for ~$18
and a description of it's function.

partnumber# 13480-05A10

http://www.cyclewareables.com/pages/air_cutoffValve_replacements/aircutoff.htm

Since we're talking about possibly replacing the carb...  so while I was adjusting stuff I managed to strip the F/A screw.  Nicked it with the drill just a hair when removing the plug and...  well, you know.

Oops.  

From those of you who've done it before (I know you're out there) -- should I try to extract the screw or should I just get a whole new carb?  

If the former, how would you recommend?

If the latter, can I use any carb from any Savage/S40 on my '96?

Thanks!

--Jaeger

jaeger wrote on 12/31/69 at 16:00:07:


strip the head or the threads? - heard of folks cutting a new slot on the head - check  the other post a used one was bought for the bowl - maybe there's deal there

55 pilot jet went in today, due to the fact I couldn't get rid of the backfire through the idle air mixture screw alone. I can adjust the screw so all I get are pops, but I can't get rid of them completely. I'll try again when I get the air cut off valve replaced.
One question though, how do you know if the idle is in the correct range?