I have a '96 Savage completely stock with 5800 miles on it.  Running at 500' elevation.  The kid I bought it from had installed a Supertrapp muffler on it.  It had five disks installed and he had drilled a number of holes in the end cap to make it louder.  He never did any tuning.  Stock jets and the idle mixture was still sealed.  It was obviously running lean.  It popped like a pack of firecrackers on deceleration, the muffler was black, and all of the packing was burned up with chunks of melted glass rolling around inside.  (He thought the noise was a "loose baffle").  I took the Supertrapp off and put the the stock muffler back on.  Rode it for a few hundred miles.  It ran well, but was still on the lean side.  The other day I pulled the carb, cleaned it, shaved the white spacer to .070 and uncorked the idle mixture mixture screw.  The factory position on the idle mixture was only open an 1/8 turn from seated...  I tried it at 1 turn open.  The bike fired right up without any choke (which is quite a change in itself, it would not start before without choke).  I took it for a ride and the throttle response was much improved, it pulled strongly from a stop and through the mid-range, but it was running pretty rich at idle.  The fumes almost ran me out of the garage. I turned the idle mixture in, and then in some more, until it was completely closed.  There is no peak.  With the engine idling at 1100 RPM the highest RPM is with the idle mixture turned all the way in.  I pulled the air filter to make sure it wasn't choking the engine, but it made no change.  I can't lean it out any further to find a definitive peak. Any thoughts?

Also, be sure that the engine is completely warmed up before trying to adjust the pilot screw.  Ride it for several miles before adjusting it or your effort will not be successful, it needs to be at operating temp first.
You can use the Supertrapp muffler but will likely need more than 5 discs if you have them.  If you don’t have more you can pick them up from eBay and they usually are not costly at all.  If you do use it, install a 52.5 pilot first if not there now, and then install discs so the sound level is as you desire and then go back and fine tune the pilot screw.  The screw and the discs both affect the pilot system so it is a bit of a balancing act.

LANCER wrote on 06/01/19 at 02:28:49:


According to Al Baker's XRs Only, White Brothers, and other tuners a 600cc engine needs 18-20 4" discs.  According to Frank Nye at Engines Only I use 8 discs and an open end cap on my SRX600.  Even a 250cc engine at 10,000 RPM needs 10 discs.

A 650cc engine with too few discs is being strangled.

LANCER wrote on 06/01/19 at 07:59:31:


Al Baker was a Honda XL/XR 600 specialist and White Brother was Honda XL/XR 600 and Yamaha TT/XT 600 specialist so same air-cooled big single thumpers.  When punching the Honda out to 640cc and the Yamaha out to 680cc more discs were needed.

Frank Nye has done extensive dyno testing with CRF230 and it needs 10 discs for sure.  Honda XR250 needs 12 discs and guys with 270 strokers need 14 discs.  The CRF230 engine is basically an XR200 engine with hemi head and only two valves.  Assuming a similar VE math yields the following:

(650cc / 223cc) X (6,000RPM / 10,000RPM) = 1.75 multiplier
(650cc / 223cc) X (7,000RPM / 10,000RPM) = 2.04 multiplier

Therefore a 650cc needs 1.75 to 2.0 times the number needed by 223cc so 17-20 discs.

When I got my Yamaha SRX600 it only had 12 discs and it was stuffed up.  I went to 16 discs and then 8 discs and open end cap.  It got better every time.  All the SRX600 riders are using 16-20 discs and that engine is very similar except for twin carbs and twin pipes (i.e., one per valve).

My buddy used to race GNCC on 1991 Honda XR600 and he used a stock engine with opened airbox and adjusted jetting and Rob Muzzy pipe and he also used 18-20 discs.  All this work was done with direction by Al Baker's tuners.

I have old WB data and a big spreadsheet at home with all the SuperTrapp disc data and will share it when I get back...

All of the above is with respect to 4" discs, not 3" discs...

What pilot does it have now ?  I did not see a ref. to that.
Unless the pilot screw is damaged you do not need to change it.
Also, if the carb has a #50 or 52.5 pilot you do not need to change it, they should work.
If you are not getting any variation in idle speed as you adjust the pilot screw then you should pull the carb and check each and every passageway in the carb body.  There are a number of them.  

-Brass tube coming down from the carb body in the float bowl, 3 tiny holes.
-The intake of the carb in the lower right side as you look in, 1.
-The needle jet, 8,  2 on each side.
-Engine side, 4
-TEV, 2 or 3

Insure those are all clear, along with the pilot & main jet.  With all of those clear it will work.

When I was fooling around with the TEV I tried a spring from a Q-Jet pump which turned out to be too light.  One of the symptoms was the idle mixture screw had no impact as fuel was bypassing the valve.

Just a thought...

The pilot screw is usually difficult to turn, especially if you need to remove it.  I think the factory dimples the top threads a bit to make it so.  I don’t see any other reason for it to be that way.  Just another obstacle installed to try to prevent “us” from tuning it ourselves.  

If your carb wants to increase rpm when turning the pilot screw IN then you need a smaller pilot jet, drop to a #50 from the 52.5 and retune.

Dipping your carb will usually help a bit, but it is common for grit to clog passageways preventing or hindering proper tuning.  Blasting them with carb cleaner aerosols and blowing out with compressed air is better, and chasing the passages with a carb tool IS the best and will absolutely clear them.