Rejet when switching to DynaCoils?!?

[conquest87tsi]

I pulled the pods off, leaving the velocity stacks. Just went for a 15 mile ride. There has definitely been a change. Yesterday, with the pods installed, it started stumbling at 6,500rpm and never really came out of it. Today, without the pods, it starts stumbling at 5,000rpm, but comes out of it around 6,500 and then runs like a raped ape up to redline. I just checked the plugs and they have a light brown color. No indication of being overly rich. I put the pods back on and went for another short ride. It definitely does not run as well in the high engine speed with them on.

Do you think I’m running out of air in the higher engine speeds? Any idea why removing them moved my problem range? The pods are MOXI brand that I’m sure I got off eBay years ago. Recommendations on replacements?

[bikerphil]

I went back and read your first post where you said you installed Dyna coils. Did you remove the ballast resistor?

[conquest87tsi]

I know I saw a ballast resistor in my parts crate last weekend, but since I salvaged a ‘81 XS11 for parts years back I pulled my tank to be sure it was from this bike. Yes, the ballast resistor has been removed.

[Schming]

I pulled the pods off, leaving the velocity stacks. Just went for a 15 mile ride. There has definitely been a change. Yesterday, with the pods installed, it started stumbling at 6,500rpm and never really came out of it. Today, without the pods, it starts stumbling at 5,000rpm, but comes out of it around 6,500 and then runs like a raped ape up to redline. I just checked the plugs and they have a light brown color. No indication of being overly rich. I put the pods back on and went for another short ride. It definitely does not run as well in the high engine speed with them on.

Do you think I’m running out of air in the higher engine speeds? Any idea why removing them moved my problem range? The pods are MOXI brand that I’m sure I got off eBay years ago. Recommendations on replacements?

Maybe, but a few questions if I may.

1) Filters clean?

2) Running fuel levels set correctly ?

3) Brass washer under the Mains ?

4) Vacuum diaphragms checked ?

5) Butterfly shaft seals good ?

6) Carbs synchronized ?

You're close to the same elevation as me at 1300' so I'm thinking you may be a bit rich.

If you have the stock jets 137.5 mains and 42.5 pilots you could start there and see how she goes.

[bikerphil]

The floats should be set to 1" with the float bowl gasket removed. Gray plug color is what you should have with today's lower quality gas.

[jetmechmarty]

FWIW, XS650 runs similar stock carbs to XS11. Lots of them run pods and have the same issues as over here. Those who stick with CV carbs and pods swear by UNI Filters. I'm not sure they fit on the bank of four, but there you go.

[conquest87tsi]

Maybe, but a few questions if I may.

1) Filters clean?

2) Running fuel levels set correctly ?

3) Brass washer under the Mains ?

4) Vacuum diaphragms checked ?

5) Butterfly shaft seals good ?

6) Carbs synchronized ?

You're close to the same elevation as me at 1300' so I'm thinking you may be a bit rich.

If you have the stock jets 137.5 mains and 42.5 pilots you could start there and see how she goes.

1) The filters certainly look clean. I can see through them.

2) I have honestly never checked this. I’m assuming I would need some barb fittings with the same threads as the drain on plugs for this to attach hoses to. I always am just very anal when setting the float heights. Next time I have the carbs open, I will set them to Phil’s recommendation.

3) Yes, the washers are installed between the main jets and emulsion tubes.

4) The diaphragms all look good. Also, they all four respond identically to throttle.

5) I’m not quite sure how to check the butterfly seals.

6) Yes, I sync the carbs after every time I have them open. I calibrate my four individual gauges off of one cylinder prior to syncing.

I do have the stock 137.5s and 42.5 jets. I’m waiting to get the stock air box before tearing into them again.

[Schming]

To check the fuel levels I made these out of Metric grease fittings (silver) and brass ells that I ran a metric die over and cut 8 x 1.0 mm threads which is what the float bowls are. I drilled the grease fittings out on the drill press but the brass ells are less fuss and the hoses stay on better. I use o-rings on them to seal and it helps to clock them properly.



Here is a good thread from our friends over at XJBikes.com that may answer some of your questions. It tells you how to check your shaft seals and goes into really explaining how to adjust and what those adjustments do to help or hurt different scenarios.

https://xjbikes.com/forums/threads/l...t-seals.37423/

[3Phase]

I think I like the brass idea!

From the picture it looks like they ran out of barbed ells in the bin and you had to scavenge up a separate '90 and a nipple.

[Schming]

I think I like the brass idea!

From the picture it looks like they ran out of barbed ells in the bin and you had to scavenge up a separate '90 and a nipple.

Thanxs, and yep you nailed it, almost. I had to run back down to Busy Beaver, what we have for a local lumber/hardware/ and everything else, to fetch another 'cause I F@#$%& up the fourth ell.

I was tired of the hoses fallin' off of the brake bleeders.

[3Phase]

Ouch...

Yep, I hate when I'm running the engine for the dynamic fuel heights, drop and recovery levels, then a hose pops off one of the bleeder screws and fuel goes everywhere.

[conquest87tsi]

I thought I'd give a little update on my progress, or lack of. I removed the carbs and separated them to check the butterfly shaft seals and to install the stock jets. In the middle of this, I sprained my ankle in an unrelated event. So I hadn't touched the bike for a little over a week. Anyway, I checked the seals, and 3 and 4 allowed oil to enter the carb throat after a short time. I ordered seals and am waiting for them to arrive. Also, I found that my idle mixture screw broke off in it's bore of the number 4 carb. I was able to drill out the center of the needle with a tiny drill bit and a pin vise and remove it. I did get a factory airbox from my Dad. I haven't installed it yet, I'm just hopeing it's not for the XS1100 standard I used to have. As the XS1100 I still have is a special and I'm sure they are different.

My diagrams seem to test good when testing by holding my thumb over the kidney shaped hole. I was thinking, once I have everything back together, I might mount a GoPro camera behind the carbs with no filter installed and watch the diaphragm cylinders dynamically while running. Just a thought to see if I can witness an issue with them.

[mn2346]

...
My diagrams seem to test good when testing by holding my thumb over the kidney shaped hole. I was thinking, once I have everything back together, I might mount a GoPro camera behind the carbs with no filter installed and watch the diaphragm cylinders dynamically while running. Just a thought to see if I can witness an issue with them.

Good thinking, please upload to youtube, I'd be interested to see this also

[Schming]

I did get a factory airbox from my Dad. I haven't installed it yet, I'm just hopeing it's not for the XS1100 standard I used to have. As the XS1100 I still have is a special and I'm sure they are different.

My diagrams seem to test good when testing by holding my thumb over the kidney shaped hole.

Airboxes are the same for all years, only different side chrome trim.

Hold the diaphragms up to a light to see if there are any pinholes, usually found near the edges where the rubber is flexed during operation.

New replacements can be found here:

http://jbmindustries.com/index.html

[skids]

Airboxes are the same for all years, only different side chrome trim.
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That is mostly correct. 78 and 79 carbs had vent hoses from the carbies to the nipples on the airbox. The 80 and 81 carbs did not have the vent hoses and the air box nipples were filled with plastic.