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Old 10-28-2012, 08:55 AM   #1 (permalink)
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Some guidance needed on TC88 carb headaches

Here are the details:

2003 Super Glide with stock TC 88"
Stage 1 SE Backplate with open K&N
Unknown Slip Ons seem very unrestricted
45 Slow Jet - 180 Main - Adjustable needle with 2 washers
Bike runs fine under load, will not idle without choke
SE Plug Wires

And now the rest of the story:

I picked this bike up for cheap. It has not been ridden much at all in the last two years. Prior to that, it was cared for and had all services done at a stealer.

The bike does not want to idle without about half choke. If I turn the choke off and give ever so slight throttle, it will idle. The bike runs fine on the interstate, in fact I rode it 90 miles home without issue.



Once home, I pulled the carb and found it dirty, but not anywhere near as bad as I expected. While cleaning, I noticed the jets are a 45 slow and a 180 main. I don't understand why its a smaller than stock main, but the carb does have an adjustable needle with two washers under it.

After cleaning and reassembly, it runs better, but with choke off it will still stumble and cough before dying.

Here is my current plan.

Pull and replace plugs
Drill out idle mixture plug and adjust
???



Here are my questions:

When do I adjust idle speed to add more fuel, versus idle mixture plug, versus larger pilot jet? I know this can be a balancing act, but what do you guys lean to first?

Why would a stealer install adjustable needle, but smaller main jet?

You guys have any more suggestions?

Later,
Chrome...
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Old 10-28-2012, 09:05 AM   #2 (permalink)
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Sounds like you have a kit, probably a Dynojet kit, installed. The kit replaces the emulsion tube (this is the tube that the main jet screws into) and allows use of a smaller main jet than stock because of its design.

Just a guess though. What groove is the clip on the adjustable needle set in? How's your gas mileage??? Probably would also help if you could get the instructions for the kit? I'm not a fan of them myself and another option would be to return to a basically stock setup and just shim the stock needle. Normally that's all that's necessary other than adjusting the fuel/air mixture (after drilling out the cap) for your setup.

For now, I'd increase the idle speed, drill out the cap, adjust the air/fuel mixture and see what happens.
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Old 10-28-2012, 09:06 AM   #3 (permalink)
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since the only problem seems to be too lean at idle,drilling the plug and richening the idle mixture ought to take care of it,one would think.
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Old 10-28-2012, 09:16 AM   #4 (permalink)
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Yeah Ed_Y my money is that this is a DynoJet kit. In the back of my mind I thought they could use a smaller jet, but I typically avoid those types of kits so I wasn't sure. No idea on the fuel mileage. After I got it home the weather turned to all hell and it hasn't been out of the garage

The needle is set on the 2nd or 3rd groove (I'm leaning towards the third) with two washers (appearing to be #4) under it. I am considering the back to stock approach, but if there is a simpler answer I'll shoot for that first. (I really hate putting the diaphragm back in)

Danglide, that's my current plan. Just wanted to bounce the idea off some of you guys. I'll give it a go and see what happens.

Later,
Chrome...
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Old 10-28-2012, 10:19 AM   #5 (permalink)
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Drill out the plug and install the EZ-Just Air/Fuel mixture adjuster, makes it alot easy to adjust for changes. Try swapping out for the next size up slow jet. Adjust your idle speed after changes. CV-Performance also sells an extention for your idle speed screw. It's getting enough fuel when running higher RPM's, but not at idle.
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Old 10-28-2012, 10:37 AM   #6 (permalink)
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Nitram_b4 is reading this now saying WTF is this?
once again I will send somebody to this site, saves a lot of typing and it has everything you need to know.
http://www.nightrider.com/biketech/hd_cv_mods.htm
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Old 10-28-2012, 11:22 AM   #7 (permalink)
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it doesn't sound like a dyno-jet kit, that kit requires 3 1/2 turns on the air fuel mixture screw, and the mains are quite smaller in over all diameter.
Get the needle number and google it, my bet it has a sportster needle. Also you can see if the slide lift hole is drilled to a 1/8".

My suggestion is to remove the two washers from the needle, then insure it's on the third groove. My belief is they shimmed the needle to compinsate for the air/fuel mixture not being adjusted.
I also believe in starting at two turns out on the air/fuel mixture screw would be a good starting point.

I would also go to the dealer or cv performance and get a new accellerator pump diapgram, they tend to get brittle on one side when they sit up for a while.

180 main and 45 pilot is stock for that bike, and should be in the ballpark.
Although there is no pilot change on the kits the dyno-jet recommendation for your bike would be a 185 or 190, not saying that it's right, just what would be suggested.
The dyno-jet mains have a tapered bore to them so they flow more than the stock mains, so don't get confused on any coarallation with the numbers on the different jets.

Just my thoughts....
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Old 10-28-2012, 12:24 PM   #8 (permalink)
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Quote:
Originally Posted by Gaff View Post
180 main and 45 pilot is stock for that bike, and should be in the ballpark.
....
Hmmmm...Never seen a Twin Cam with a 180 main. Are you sure about this??
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Old 10-28-2012, 04:24 PM   #9 (permalink)
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Nitram, I had read that link several times before posting. You're right, that's a good one.

Gaff, I'm certain 180 main is not stock. What I have says 190/45 stock jetting.



Okay, here is the update.

Pulled and replaced the plugs. Got to the idle mixture screw plug and...its gone. Last night, I swear it hadn't been drilled, but I guess that's what I get for wrenching last night when I should have been sleeping.

Any how, I seated the mixture and guess what. Only 2.5 turns to seat. I backed it out to the 3.5 dynojet recommends and then began to adjust the idle speed until I got a decent speed. I settled on about 3.75 turns out on the idle mixture and let it idle for about 15 minutes. My pilot jet is likely too small as I suspected. The dealer didn't have a 46, only a 48 (I'm thinking 48 would be too rich). I'll be ordering an EZ Adjust screw and #46 jet in the future.

I pulled the plugs to read and got a nice tan (although somewhat uneven) appearance on both cylinders.

The only issue I'm currently having is some hesitation and farting with hard, sudden throttle input off of idle. It isn't every time, but once or twice out of five revs. I do suspect the gas in the tank (it was 1 gallon of older gas topped off with new and 6 oz of Seafoam, I had no way to drain the tank before I picked it up). So that may rectify itself once the weather breaks and I can ride again.

Later,
Chrome...
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Old 10-29-2012, 07:57 AM   #10 (permalink)
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I was sure the twin cam was a 180 main, but now you have me guessing, I'll check again but I'm getting old so take it with a grain of salt.

The 3 1/2 turns out is for the 45 pilot and you going 3 3/4 out is no surprise, exspecially how cold it is at the moment.
The 48 pilot and that kit is kinda tricky to get right, the 46 is much eisier to dial in.

Ihave chrome werx slip ons with a V&H filter and generaly the 180 Dyno-jet main works good, although I have a 175 in there now. But that darn 48 pilot is messing with me again.

The hessitation is probably from the gas, but take a look at the accellerator pump diaphram. If you question it replace it, $8 if I remember right.

Yall have me stumped on that main I'm going to have to go look at that......damn stupid human tricks.....
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Old 10-29-2012, 08:49 AM   #11 (permalink)
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WVChrome,

Different size jets are available from places other than Harley dealers. Some Japanese bikes use the CV carb and I've gotten different size jets from their dealers, Kawaski and Honda. Drag Specialities also sells some.

Here are a couple of places also:

http://www.phatperformanceparts.com/...OTJETS&CartID=

http://www.cv-performance.com/carburetor-parts/
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Old 10-29-2012, 03:33 PM   #12 (permalink)
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Yeah Gaff, I'm going to end up replacing that diaphragm if the problem doesn't correct itself with better fuel. The pump is working, but of course I have no way of measuring if it's working at 100% capacity.

Ed_Y, yup I called the only other motorcycle joint in town, Morgantown Honda, and they only stock $75 kits. Since I'm sure a 46 would suffice, I hate to spend that much. I've got a 46 on order and an EZ Screw for the next time I get into it (likely for the accelerator pump).

Later,
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Old 10-29-2012, 05:00 PM   #13 (permalink)
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Nitram_b4 is reading this now saying WTF is this?
https://www.denniskirk.com/cv-main-j...prd/H17001.sku
for main jets

complete kit
https://www.denniskirk.com/s-and-s/c...prd/173335.sku

Last edited by Nitram_b4; 10-29-2012 at 05:14 PM.
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Old 11-10-2012, 05:03 PM   #14 (permalink)
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Verify you don't have a vacuum leak. I have been chasing a poor idle condition for a while, been getting progressively worse over the last few months. Found the diaphram on the petcock causing a rather serious vacuum leak. Started dripping a drop or two at cool down. Problem solved, idle back as it was. Good luck!
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