Sportster .65 muffler leaks (& other ??)

[BerwynBill]

I'm breaking in a older Sportster .65 with a new muffler I just ordered from Mecoa. When the engine is running, oil comes out from the front cap joint of the muffler in copious quantities. I tried taking the muffler off and re-seating the stud, baffles and cap but still cannot get an air-tight seal at the front end of the muffler. How mush leakage there, if any, is normal? My break-in stand is a mess!! :lol:

Also, how tight should I screw in the high end needle to have it "seated?" If I turn it in to where it stops under light torque, unscrewing it to the recommended 2 1/2 turns takes it all the way back off the threads. I can tighten it in further but don't want to over do it.

And one more ?, I have read tha the older Sportster .65s prefer a low nitro (%10)/high castor (20%)fuel. I run Morgan's Omega fuel in all my other engines (which is 15% nitro and 17% oil at a 30/70 Castor/Syn ratio). Is this OK for the Sportster or should I be adding a bit more castor to it?

Thanks,
Bill

Bill

[MECOA]

Use a little clear silicone adhesive to seal the joints of the muffler. Apply while dissambled.

Screw it in just enough to stop lightly. the nipple may be screwed in too far. Loosen the nut that holds the ratchet spring and nipple. The nipple should be screwed into the mixture disk only 2 turns.

See this..
http://www.mecoa.com/kb/carbs/carbsptstr.pdf

READ THIS...
http://www.mecoa.com/faq/carb/needle_aero.htm

Add about 3 oz of oil to your fuel.

[BerwynBill]

Add about 3 oz of oil to your fuel.

Per gallon I take it?

Thanks for all the info.

Bill

[MECOA]

In a gallon adding 3 oz of oil will boost the oil content about 2½ percent.

[BerwynBill]

Screw it in just enough to stop lightly. the nipple may be screwed in too far. Loosen the nut that holds the ratchet spring and nipple. The nipple should be screwed into the mixture disk only 2 turns.

The nipple was in about 5 turns. I backed it out to two turns and re-tightened the nut. I started working it on the test stand and still can't get it to turn up past about 2/3 - 3/4 throttle. Here's how it's set-up:

Prop: apc 12x4
Fuel: Cool Power 10% with 3oz Morgans Castor added per gallon
Plug: K&B long reach (glows well when connected)
The tank is pressurized by the factory pressure nipple on the muffler adapter.

Starting is not a problem. I can get a nice idle at around 3000rpm. The pinch test here gives an increase of about 400 rpm and then it falls.

With the nipple reset to two turns in, I start with the needle set at 2 1/2 turns out from bottom. This results in a very balky transition with smoke and burping and finally cutting out. The pinch test ruselts in a jump in rpms to about 10000 and a definite absence of the "four-stroke" burble. The rpms don't fall back much at all from this level, even when the pinch is released.
At 1 1/2 turns out, the transition is much improved but begins to stutter and stall at about 2/3 throttle (about 7500 rpm). Giving more throttle does not increase the rpms and will cause the motor to quit. Pinch test is about the same as above.
At just under 1 turn out, A maximum rpm of about 8750 can be reached and held but the sound is rich and the pinch test results in the same leap up to the 10000 rage as describe before.

I'm wary of running it with the needle anymore in as it's just about as far as it can be set, but the indications seem to be that it is still too lean. Should I just go by the sound and the pinch test and reset the nipple a bit more into the mixture disk than two turns to lean it out a bit more?

[MECOA]

I think you may have a mixture disc issue.

It the barrel is operating the wrong direction you can have this problem but I doubt that as yours is an older carb ans should have the barrel stop screw.

The mixture disc may be way out of adjustment or broken/modified.

it should look like the one at the bottom of this page.
http://www.mecoa.com/faq/carb/mixdisk/mixdisk.htm

See if anything on this page helps.

and this one
http://www.mecoa.com/faq/carb/debris/carbdebris.htm

[BerwynBill]

I got the new mixture disk, nipple and needle I ordered and installed them. Well, except for the new needle. It was too large a diameter to fit the new nipple. The parts numbers were all correct for what I needed but the new needle I received was just too thick. I used my original needle and it fit the new nipple fine. How do I go about getting a refund on the new needle (the package was opened, of course)?

With the new parts, I can get a nice idle around 3000rpm and run it up to about 12100rpm with an APC 12x4 prop on the test stand. If I get it set at the top and bottom using the pinch test, the transition smooths out nicely. Except if I let it idle for about 30 seconds or so. Then a medium to quick move up in throttle results in a very rough, smoky transition which usually ends up with a stall. If I don't let it idle at 3000rpm for too long, the transition stays smooth and the top is very strong (needle is about 1 3/4 turns out). I can improve the transition by leaning out the low end needle but then my pinch test results seem too lean. Perhaps it's just not quite there yet as far as being broken in. It's had 5 test stand tanks through it (smallish tank ~ 8oz or so).

My questions are:

- If I'm getting about a 100rpm rise during the idle pinch test before it starts to fall, is that too lean? I like to have about 500rpm on my other motors for this but with the .65, that makes the transition really rough.

- What is a good idle rpm range for the .65?

- Is there any power to be gained by removing the baffles in the muffler? I'm not worried about the increased volume of the exhaust sound.

Thanks again for your continued help. So far, I'm impressed with my Sportster .65.

Bill

[BerwynBill]

I got the return situation handled on the phone. Thanks!!

I also got a lot done with the motor today by switching to a hotter plug. With an OS A3 in the engine, it runs like dream!!! The transition is very smooth and the power is nice and strong.

Thanks for all the help.

Bill