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Author Topic: Free flow exhaust  (Read 2034 times)

Gaffer

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Free flow exhaust
« on: February 23, 2008, 08:19:30 AM »
I'm about to fit a free flow exhaust to my Electra. What do I do about changing the main jet? I reckon my bike's running a bit rich at present - bottom of plug black, electrodes grey and it backfires when I close the throttle going downhill. How do I know what size jet to put in and what's the procedure for changing it? My mechanical skills are about 3 out of 10 so would appreciate simple advice.

Vince

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Re: Free flow exhaust
« Reply #1 on: February 23, 2008, 04:18:43 PM »
    The old fashion way is to jet up until it \'s to rich (it will "burble") then back down one. Get a box of spark plugs.  You will be jetting three stages -main, mid, and low. Start with the main jet. Install a fresh plug. Go up one size on the main. Ride a couple of miles, then check the plug color. You want a light to medium tan electrode, and dark gray to medium black around the rim. Repeat this trial process until it is too dark, or the engine runs ragged (burble). Use a fresh plug each time and ride long enough to get color on it. You can use the plugs later in normal running. Once the main is right go to the mid-range. Raise the needle by lowering the clip. Same sequence for testing. Then do the same for the low speed (pilot) jet. Then re-check each range. Fine tune as necessary. It it tedious, but this way works. You should pull the carb each time to change the jet. Consult a service manual to identify the parts. Good luck!

Thumper

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Re: Free flow exhaust
« Reply #2 on: February 23, 2008, 06:53:31 PM »
Gaffer,

In addition to what Vince said:

- If you are currently running rich and you put on a freer flowing exhaust, you might luck out and not need further tuning. I would definitely try that first.

- Once the exhaust is on, should there be performance issues: Make sure the bike is thoroughly warm, then ride it enough to understand consistently what issue is happening - and when it happens.

- Personally, I would not worry about exhaust sounds (popping, burbling, etc) when you close throttle at higher RPMs. These can be expected and not always eliminated completely. Regardless, that can be the last issue to address.

- I have not changed the jet in my Electra X (I swapped in an Amal instead) but have done so on many other bikes. I expect that you will access the main jet by removing the carb and turning it over. Remove the float bowl. The main jet is typically the center-most jet. Upon unscrewing it you should see the end of the needle where the jet was. (Which will confirm that you removed the main jet).

- The needle is accessed from the top of the carb. Remove the cover and you should find a diaphragm that raises and lowers the slide that houses the needle. The needle is held at the right height in the slide by a clip. A spring usually holds the needle/clip in position.

- I'll try to get out to the shop and confirm that my 2006 Electra X carb is like this. UPDATE: SEE NEXT ENTRY FOR DETAILED STEPS.

- Only begin tuning the carb on a thoroughly warm engine. This is important.

- While you're checking the main jet, remember that it controls at and near wide-full-open throttle. It is at that open throttle position that you'll want to pay attention to performance. Too rich and it might noticeably stumble. Too lean and it might backfire. Plug condition should confirm performance indicators - especially overly rich being black, sooty, and or gas fouled.

- While you're checking the needle position, remember that this affects off-idle and up (until you are in the upper throttle range where the needle is no longer causing any blockage and you are effectively running on the main jet). It is a transitional control where both the height and the taper of the needle come into play. Visualize the needle as it goes in and out of the the tube effectively blocking it and freeing it, respectively. If the needle is too high, too much gas will get through and it will run too rich. If it's too low, not enough gas will get through and it will run too lean. Both can cause the bike to feel like it stumbles. However there are ways to distinguish. Again, the general rule for lean is white spark plug and backfiring. Too rich: black plug, white smoke. ALso: Lean conditions improve as bike gets up to temperature; rich conditions worsen as bike is ridden. One way to understand which is occurring is to exaggerate symptom: If you have an issue and you're not sure what's happening: raise the needle again: does that make it even worse? If so, the needle might have been OK in its original position - or you might need to raise it 1/2 position.

- When you don't have much experience, sometimes it seems like you really can't tell what's wrong - just that it's not running right. This is is why you concentrate on one change at a time and one throttle position at a time. Don't panic if what you feel isn't immediately recognizable (as lean or rich) by the symptoms. Keep test running the bike to reproduce the symptoms until you get a good feel for what they are and when they occur. Do this before trying to correct them (so that you'll definitely know that you resolved the issue). Again, sometimes the best way to make sure you understand the symptom is by exaggerating the problem. As with the clip example, you can also use this technique with the main jet. Buy two or three larger jets. If a larger jet produces a *specific* symptom you don't quite understand, put in yet a larger one and see if it exaggerates that *specific* symptom.

- As they are precision devices, there are times when you actually have to raise or lower the needle by 1/2 increments using an ultra thin washer under the clip.

- Every time I have my diaphragm out, I take the opportunity to soak it 24 hours in vinyl dressing. If you choose to do this, make sure you wipe it off real good before reinstalling so that excess dressing doesn't affect the running (in the short term).

Matt
« Last Edit: February 23, 2008, 08:13:20 PM by Thumper »

Thumper

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Re: Free flow exhaust
« Reply #3 on: February 23, 2008, 07:36:51 PM »
Gaffer,

I just did the disassembly and reassembly.

Here's what I found:

Main jet:
- 2 phillips screws hold the float bowl on.
- Remove them and you'll see the main jet is the tallest brass fitting.
- Mine is a 110 jet.
- Unscrew the jet with a flat blade screwdriver. Only the round threaded jet should come out. If the jet holder with the hex sides comes loose, use a wrench to hold it in place as you unscrew the jet itself.
- You will be able to see the needle up in the jet tube.
- Assembly is reverse.

Needle:
- 2 phillips screws hold the carb top on
- Look at the brass colored carb top. Note the rubber tab protruding. Note the metal tab that fits over a positioning stud.
- Remove the top and a big spring pops out.
- Peek down in the slide and you'll see a butterfly-shaped brass holder with 2 small phillips.
  This holds the needle assembly in place. *Make a mental note of its postion: long side, short side, 2 holes in slide.
- Carefully remove the slide and diaphragm assembly
- Remove the 2 small brass screws inside the slide and turn the assembly over.
- The brass fitting and screws will come out. Also a smaller spring and a washer. Finally the needle.
- The needle has a clip and a white plastic spacer. The clip is probably in the middle slot of three.
- The white plastic spacer has a little stud that helps locate the needle in a hole in the slide when you go to replace it.
- Remove the clip with needle nose
- The white spacer *will* move. Turn it around and around to start freeing it a bit (almost as if you were screwing it in or out). Once it moves freely, some pressure will slide it down so that you can place the clip in the bottom-most position (towards the pointy end), thus raising the needle.
+ Assembly +
- After the clip is relocated, slide the white spacer back up snug against it
- Drop the needle back down into the slide and make sure the stud on the white spacer fits into the little hole in the slide.
- drop the little washer back down over the end of the needle
- place the little spring on next
- Place the butterfly back in resting on top of the spring. Long end is positioned between the two holes in the slide, while the short end butts-up against the slide and no holes can be seen on that back side.
- Replace one screw into the tapered hole. Compress it and screw it in just enought to get a bite.
- Put the next screw in and tighten both down progressively.
- Reinsert the slide and diaphragm assembly. The rubber tab will fit into a positioning slot.
- Reinsert the long spring
- Replace the metal cap. It too has a positioning slot. Screw in both phillips screws.

Good luck!

Matt
« Last Edit: February 23, 2008, 08:08:20 PM by Thumper »

Gaffer

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Re: Free flow exhaust
« Reply #4 on: February 26, 2008, 09:54:12 AM »
Many thanks Vince & Thumper for your detailed advice. I get the new exhaust in a week or so and might be in need of more help then.

scoTTy

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Re: Free flow exhaust
« Reply #5 on: March 07, 2008, 11:49:40 PM »
which exhaust are you getting?

Gaffer

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Re: Free flow exhaust
« Reply #6 on: March 13, 2008, 09:47:05 AM »
Scotty
My dealer, who is over 400 kms away, recommended not to buy the Royal Enfield short silencer as it would rust out in no time. He wanted to sell me a Triumph Hot Dog exhaust which he said would fit with a bit of modification to the brackets. He didn't have any in stock and said he'd post it to me. Haven't heard from him since and anyway I've decided not to buy sight unseen.
The bike is running fine so maybe I shouldn't mess with it. Its just I wish it sounded more like my old BSA 350, a few extra horses wouldn't go astray either!