Harley BT bogged down

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Harley BT bogged down

Postby scbrice » Tue Sep 04, 2018 8:41 pm

Got my Harley BT dropped off from the guy I bought it from. Friend of a friend. He went through the whole engine and carb and it ran like a dream. Rode it a bunch yesterday. Stepson wanted to try it out. Took it once around block and as he rounded corner it bogged down died and never started again. I got it started with the fuel off and thought somehow it flooded. I even push started it and got it running but whenever you add gas it bogs down. The bike will not start with the Kickstarter. What could have happened to make it go from perfect to not? The fuel tank was empty when I got it so I mixed up a batch of two stroke. Could something have clogged the main jet and or something in the carb? I cannot figure out how it can go from amazing to 30 seconds later unstartable or unable to keep it running... please help also what is the best setting for main jet as it screws in and out? I didn’t touch anything before it died.
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Re: Harley BT bogged down

Postby Mutt » Tue Sep 04, 2018 9:36 pm

Either the fuel filter in the tank is clogged or some trash in the main nozzle. Best main jet setting is about 1 1/8 turns out from lightly seated
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Re: Harley BT bogged down

Postby hennesse » Wed Sep 05, 2018 12:42 am

Yep, it sounds like a fuel delivery problem - especially since you said it came with the gas tank empty.

Use a clean glass jar. Turn off the petcock. Remove the rubber fuel line from the carb. Turn on one flipper of the petcock, and allow fuel to flow into the jar for maybe 10 or 15 seconds (not just 1 second), then turn off the petcock. Look at the fuel in the jar - any dirt/particles in it? If clean, pour it back in the tank. Repeat with the other flipper of the petcock.

Sometimes one side of the petcock works, and the other side does not. The "reserve" side often gets clogged since it seldom gets used. I usually turn on both sides for short around the block type trips - just to keep the reserve side exercised.

If you do NOT get a good flow of fuel out of the hose, either the filter in the tank (it's on top of the petcock) is clogged, or the petcock itself is clogged. The flipper-type petcocks are prone to clogging, especially as the years keep going by. The reproduction ones are even worse! If your problem is up here - shout.


In the carburator, there are two common places where a fleck of dirt or rust can gum up the works - the float valve, and the main jet. Let's hit the main jet first. Carefully turn the main jet needle clockwise - counting the turns - until it seats lightly. As Mutt said, it's about 1-1/8 turns. Take a piece of shiny paper junk mail, and crease it long-wise. Have a helper use this "ramp" to direct fuel from under the main jet needle to your clean glass jar. Turn the main jet needle counter-clockwise until it comes out. Now turn on the petcock. You should get a good flow of fuel out of the hole. Any dirt in the jar?

Turn off the petcock, screw the main jet needle back in until it seats lightly, then back it out the number of turns you counted before (about 1-1/8). Sometimes this dislodges a tiny piece of dirt or rust, and it will start and run now. Over the years, I've had this solve the problem many times.

If not, it's time to look at the float valve and float setting. Remove the rubber fuel line from the carb. Remove the three screws holding the top of the float chamber on. Carefully (don't damage the gasket!) remove the top. The float bowl should be about half full of clean gasoline. Clean it out if not clean. Flip the top of the float upside down. Remove the little pin which holds the float in place, and carefully remove the float. Give it a shake - it should be nice and light - full of nothing - but sometimes (not very often) the float will develop a pinhole leak. Turn the float cover upside down, and remove the float needle. Any dirt where the needle is? Blow into where the fuel line goes - to make sure there's no dirt stuck in there.

The last thing is to check the float level. Here's what it should be.

float.jpg
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OK, as you've started to disassemble your carburator, you've realized: YOU NEED A SERVICE MANUAL. One place to get one is your local Harley dealer. Have him order Part# 99444-93 called 1958-1966 American-Made Lightweight Parts, Service, Color and Accessories. $40 He should be able to get it within a few days. Some folks listed in the Parts section of this website may offer reprints.
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Re: Harley BT bogged down

Postby HarleyHummer.com » Wed Sep 05, 2018 2:48 am

Also....2 things come to mind.
1. You mentioned you mixed up new fuel. 28 to 1 right?
2. Choke lever operation. Its difficult to see whats going on with the air cleaner installed, but the lever should be in the forward position when cold, and aft position when warmed up.
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Re: Harley BT bogged down

Postby hennesse » Wed Sep 05, 2018 8:17 am

hennesse wrote: Carefully turn the main jet needle clockwise - counting the turns - until it seats lightly. As Mutt said, it's about 1-1/8 turns. Take a piece of shiny paper junk mail, and crease it long-wise. Have a helper use this "ramp" to direct fuel from under the main jet needle to your clean glass jar. Turn the main jet needle counter-clockwise until it comes out. Now turn on the petcock. You should get a good flow of fuel out of the hole. Any dirt in the jar?

Turn off the petcock, screw the main jet needle back in until it seats lightly, then back it out the number of turns you counted before (about 1-1/8). Sometimes this dislodges a tiny piece of dirt or rust, and it will start and run now. Over the years, I've had this solve the problem many times.


Forgot to mention - loosen the packing nut around the main jet needle before turning the needle, and don't forget to tighten it when you're done.

Here's the adjusting procedure. The main needle is a little finicky - 1/8 of a turn makes a big difference. I usually get it close, carry a little wrench and screwdriver in my pocket, and test drive - checking power on the flat, going up hills, etc. Once you get it right, it stays that way for a very long time.
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Re: Harley BT bogged down

Postby scbrice » Wed Sep 05, 2018 9:48 am

Awesome feedback guys. Btw I was told it was 24:1 but I see you wrote 28:1 . If so maybe I need to start over. Awesome details on the carb stuff I’ll def have my Harley buddy help me, he takes stufff apart and tries to teach me,I buy him breakfast. He’s not too sharp on this Harley bt though so I’ll shate your notes with him. Yes the tank was bone dry, we ran it off the reserve side when I test rode it. So maybe the huge tank of premix I added broke something loose. As I said I rode it a bunch then my stepson got one lap and it died. Thanks again for the feedback and warm welcome to the forum..Scott
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Re: Harley BT bogged down

Postby hennesse » Wed Sep 05, 2018 12:35 pm

The service manual says:
Code: Select all
Use Harley-Davidson two-cycle oil mixed with unleaded gasoline, or gasoline with the least lead content for proper lubrication of engine.  Proportion: 1 part oil to 25 parts gasoline., or 5 liquid oz. oil to 1 U.S. gallon. (Fuel tank has oil measure attached, use two measurefuls to 1 U.S. gallon.


There's a big history lesson in that statement. I kinda doubt that Harley still sells two-cycle oil. The cans used to say "Two-Cycle Motor Oil" then underneath that, "SAE 40". I'm not sure if it was detergent or non-detergent oil. Good luck finding any non-detergent oil today. Any brand of modern two-cycle oil is fine. Unleaded gasoline? The last time you could buy leaded gasoline in the US was 1995, although 100LL aviation gas still has it. U.S. Gallon - what other kind is there? Well, England and the British Commonwealth countries (e.g. Canada) used to use the Imperial Gallon (about 1.2 U.S. Gallons) but I don't think they've used that since the 1990s. My understanding is that the fuel economy stickers on new cars in the UK and Canada currently list both kilometers per litre and miles per gallon - but the MPG is measured in Imperial gallons!


I just put 1 (U.S.) gallon of regular gas in a 1 (U.S.) gallon can, then add 5 ounces of two-stroke oil, and shake to mix. I usually use two of these in a season. Besides quart jugs of two-stroke oil, many stores sell little 2.6 oz jugs for weed whackers. These little jugs are handy to carry on a long trip. Just remember that weed whackers use 50:1 ratio. so you need TWO of the little jugs (5 oz total) per gallon for your Hummer.
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Re: Harley BT bogged down

Postby scbrice » Thu Sep 06, 2018 3:37 pm

Update: bike push starts, runs for 3 seconds and dies. Set idles and main jet as told in previous post. Fuel filter today is clogged with brown looking sediment resembling dirt, moves around as I hit on filter. Took empty clear cup, ran fuel into it post filter side. Cup filled with sediment or small particles of it, even after the filter. My little bike knowledge tells me that got into carb. So what’s next? Throw that can of premix away? Drain tank and find some kind of cleaner. Change petcock out? I will remind you most of the presale riding was done on the reserve petcock side cause the tank was so low. Maybe the tank was dirty. None the less maybe iam slowly narrowing this mess down, maybe I’ll just take to local Harley guy and have him repair.

Also this site keeps saying photos to large to add, can’t I add a simple photo from iPhone?
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Re: Harley BT bogged down

Postby hennesse » Thu Sep 06, 2018 5:55 pm

Uh oh, bad news. The brown sediment is rust. Drain the gas tank. Take a good flashlight and carefully look inside the gas tank - you will probably see rust covering the sides and bottom of the tank (you can only see one side of the tank - the "tunnel" blocks your view of the other side). Maybe take a long screwdriver and scrape a little to see how bad it is - especially on the bottom.

This is a common problem for tanks that have been sitting for years. The fix is to clean and seal the tank with one of the many products made for doing this, like POR 15. It is not difficult, but it is a real pain in the butt to do. It's 95% likely that you will mess up the paint on the outside of the tank while doing it, but that is expected. Depending on how handy you are, and if you have a good place in which to work, you may want to farm this job out. But nobody else likes doing it either.

Apparently you have an add-on gas filter in the line between the petcock and carburator - and it is filling up with the rust. Just imagine what that rust will do if it gets past the carburator and into the engine - bye bye piston rings, etc. You need to get this fixed before doing anything else.

I did this for my K-model tank a couple of years ago. My tank was VERY rusty, and it took me more than a week to get it clean, dry, and then sealed. I'm pretty sure I did a good write-up of the process - let me see if I can find it, so I don't have to re-write the wheel.

Meanwhile, take a look inside the tank, and tell us what you see in there.
Dave

Here's the instructions for POR 15. Sounds easy, but the devil is in the details...
http://qr.absolutecoatings.com/QR-asset ... airKit.pdf

Other Products: Red-Kote, KBS, Kreem, Caswell company, Eastwood company. I think they're all about the same.
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Re: Harley BT bogged down

Postby scbrice » Thu Sep 06, 2018 6:09 pm

I was just down at a local shop that the guy does only Harley work. He saw the photos and said yeah prob rust. I don’t think much got past the filter . I didn’t see anything in the after part. The more I looked at the gas after posting. The tank sat for awhile and he has some cleaner kit that he said takes forever. More than likely I’ll drain it, check tank and just have him work on it this winter when his business slows down and he takes on vintage bikes. So dumb question, if the filter is grabbing the rust why won’t the bike run post filter into the carb? Did some rust taint that gas?
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