Titan misfiring problem

My Titan ran great for the first 400 miles then it started to misfire. At least it seems like a misfire. It started in the last mile of an 11 mile commute. It only did it a couple of times so I didn’t investigate and road it to work the next morning. It ran like ****.

It starts great, it idles great and above 25 mph it runs great. It’s getting up to 25 mph that’s the problem. I have gone through the electrical system. Checked the kill switch for intermittent shorts and checked the magneto for proper resistance values and everything was fine. I disassembled the carburetor and blew out the jet and all the other ports with compressed air but neither of these things helped.

It’s very strange. It really does seem like an electrical issue. When starting from a dead stop I usually accelerate gradually to around 20mph and then open it up and cruse at around 30 mph. Now during the gradual acceleration I am getting a lot of popping and hesitating. Throttle position doesn’t seem to make much difference. It does it whether I am accelerating gradually or if I hold the throttle wide open from the start. Once I’m over 25 mph the popping stops and it cruses great.

Any ideas?

Also; does anyone know where I can get a decent spark plug (Champion, Bosch, AC, etc) to replace the Chinese one that it came with?

Thanks
Bacon

thatsdax said:

Hey Bacon.. If you can not figure it out, send it back to me and I will replace it with a new one under warranty. Sorry for all the trouble. Sincerely.. Duane..

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I appreciate that Duane. It has to be something simple. There isn't much to a single cylinder engine. It's either starving for fuel or has an electrical problem. I don't think it jumped time, the problem is too intermitent. The carberator float may have gotten out of wack. On my daily commute, when traffic is heavy and I am forced way to the right I hit some decent bumps .

I am going to go through it tonight. I am headed to the motorcyle shop now to get a new plug and see what they have in the way of magnetos or at least plug wire. I'll let you know how it goes.

Thanks for the plug data Lrg. Fili

Problem Solved!!

Prior to working on the engine I pulled the fuel line off of the carburetor to drain the gas tank. The fuel started to drain, but very slowly. I took the gas cap off and it flowed fine.

The problem was restricted ventilation in the fuel tank. This is why I had no low end power but plenty of top end. When the RPMs were low there wasn’t enough vacuum to suck the air through the restricted vent, but when the RPMs were high there was.

The restriction appears to be the result of removing the screen/filter that comes installed in the tank filler neck from the factory. I removed it and installed an inline fuel filter because the screen slowed down the refueling process. (I am very impatient) Apparently the way the screens flange sat on top of the filler neck facilitated the gas caps ability to ventilate the tank. I drilled a 1/16” hole in the center of the gas cap and it runs great. There is a small rubber nose looking thing in the gas cap that prevents fuel from splashing out of the hole.

When this all started my first thought was that removing the screen allowed crud to get into the tank plugging up the carburetor, that’s why I removed it and cleaned it last night. This morning it ran good for the first few miles of my commute and then started acting up again. DUH!! It should have registered then. The tank only has enough air in it after refueling to run for a few miles without ventilation. All I would have had to do was loosen the gas cap and I would have been okay, at least temporarily.

Anyway; Life is good and I am back on the road

FYI: The NGK CR7HSA sparkplugs are available at any Honda Motorcycle dealer. They also had 4s and 6s but no 5s. I installed a 7 and it works well so far. I assume the number represents the temperature the plug runs at. I will have to look into it.

Thanks again for the help.

Bacon

robin said:

Wow!! Dax sure stands behind his poduct

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Yes DAX does stand behind the products he sells and they are good products.

I love this Titan engine. It has more power than I can use on a bicycle. I’m not comfortable over 40mph so I have mine geared to stay below that, but I know it would have no problem pushing my 225 lbs to 40mph and above. I never pedal up hills. There is one hill on my commute I would estimate to be between a 25 and 30% grade. I do 25 mph up that hill every day. It did 20mph up that hill with the restricted fuel tank ventilation. It’s not a long hill but I still think it’s amazing that an engine that small can push that much weight up any hill.

Dax is right about the Torch spark plug. It had nothing to do with the problem I was having and it performs very well in the Titan, I just like having a local supplier for “normal wear parts” like spark plugs.

The 1/16” hole I put in the cap solved the ventilation issue, so I am going to leave the screen out of the filler neck and just replace the washer occasionally. I didn’t know about the screen in the fuel line nipple. I will leave it in place unless it becomes a problem.

Agreed; I am digging the Torch out of the trash this morning and will probably order a few spares from Dax. As you stated in a previous post the #7 NKG works but the engine likes the #5 or “hotter” plug. There isn’t a big difference in performance but it’s enough to where you notice it.

It’s usually safe to run one or two increments hotter or colder than the manufacturer recommends depending on the engines application and/or the fuel being burned. If you are in a country where quality fuel is hard to get a #4 or “hotter” plug may be better. Ambient temperature can also be a factor in selecting a spark plug, especially in air cooled engines