Fuel or spark? Murdercycle runs like garbage.

When you ride all the time, you notice when things aren't right. I convinced myself that it wasn't until it did.

The 1980 Honda TwinStar CM200T is bucking at the top end and dieing coming to stops.

Possibility #1

The tank that is on it now wasn't in the best shape. I burned out the rust with HCl, but it might not have been enough. The float stuck open once. I cleaned out some crud from the bowl and it seemed to be fine. I also installed an inline filter. I'm thinking more crud may have made its way to the jet and idle circuit. Solution: clean the carb, new filter, check the tank.

Possibly #2

Ignition issues. The bike is the last year of the 6 volt Honda. It has points. I've never adjusted them, nor have I replaced the plugs. The battery is less than 6 months old. I know nothing about stators, or rectifiets.Being 6 volt, parts aren't easy to come by but I have a same year parts bike to rob from. That bike's condition is unknown. Solution: New plugs, adjust/replace points.

Where would you start? I'd rather test components than throw parts at it. Any online/YouTube tutorials?

Since you never replaced the plugs I would say a fresh set shouldn't hurt and at least that is one less variable. Take a looks at the old plugs while you at it, might give some clues to the current fuel mixture.

Doubt its the points a its running well through the rest of the range but its a cheap thing to fix if it is.

Did you put a fuel filter immediately on after burning out the tank. Is it a real filter and not one of those plastic pieces of crap that the VW guys use.

In my history tanks will still throw crap out long after you clean them, if not then the idle circuits are more then likely clogged with something, main jets as well.

Check point gap, replace plugs gaped to spec in manual, unscrew spark caps cut wire back 1/4 inch and re-screw on the caps (often the wire get corroded if you see green you know) Run it. If not better clean the carbs. Run it. If not better pull plugs close gap up by .007 and retry did problem move in RPM range or was eliminated then its ignition related look further in to the system.

The filter is a plastic piece of crap. Smallest filter I could find locally. Fuel line is tiny, 3/16th or 1/4 at the absolute largest. Might try to see what the Rebel guys use.

These sound like cheap, easy places to start.

Thanks.

Fuel filters on a gravity feed really restrict gas flow. This tends to lean out the mixture progressively as more air goes through the carburetors.

Didn't seem to affect the engine when I first put it on. However, it might have crap in it now blocking flow. Might take it off and see it it improves.

Appleseed wrote: Didn't seem to affect the engine when I first put it on. However, it might have crap in it now blocking flow. Might take it off and see it it improves.

They will flow fine for a little bit then clog up, at least that is my history. Get some gas in a clean container and a clean line and take the filter out of the equation and see if it improves.

Clean the grounds and all contacts inside the fuse box. Unplug bullet connectors and clean them too. It's free and all old Honda motorcycles need it done.

Sometimes the filter is a great place for fuel vapor to collect and build, resulting in vapor lock. I don't think it is very uncommon for motorcycle factories to install filters.

I wonder about the vacuum petcock, assuming it's still got one, restricting flow or acting up. Placing the petcock in the reserve position should take the vacuum part of the petcock out of the equation. I want to think 1/4" fuel line in good condition should be enough to feed a 200cc bike but if the line is swelling internally or what-not it could be an issue as well.

I would take a float bowl off one of the carbs (I assume this is a dual-carb engine) and see what kind of crud is there or not to help deciding on what to do next.

The CM200T is a single carb, so that's nice. The petcock is old school, no vacuume.

New line is going on, and filter will be removed. I'm going to cut it open and see if it was full.

Again, gravity feed. There is barely any fuel pressure from the gravity height. So even the faintest of restrictions will drastically curtail flow. I've seen it many times.

I think I found the problem.

Now to re-clean the tank and coat it with phosphoric acid.

In reply to Appleseed:

Yup, that could be a problem. Reminds me of the rough running I was chasing on my Suzuki Goose 350. I knew there was a little debris in the fuel system, but kept going back to the carb until about the third time I rebuilt it before I really dove into cleaning the tank and petcock...

That's nothing compared to the crap that came out of the tank on my gy6 Vespa wanna be. I bought the biggest see through filter that I could get from Napa, and changed it several times in the first couple weeks of running it. However, that bike didn't have a petcock, the tank was mounted in the floor boards, and it had a vacuum fuel pump. Your petcock is likely clogged.

Pull the petchock there's a screen on the brass tube. Or at least there should be often times people pull'em off....so the rust passes to a filter below or clogs the petchock. Evaporust works great that after the rust is gone go for the Ospho acid.

I vinegar'd and nuts & bolts rattled the remaining flakes out tonight. Letting it soak overnight. Pulled the float bowl and main jet. Clean as a whistle. Tank gets washed out ans coated tomorrow. Need to find my spare petcock, as the two O rings disintegrated when I removed the petcock.

Anybody ever restore O rings in a petcock before?

Have a caution with coating the tank. Many fail and the flakes plug up the filter/screen/carburetor/petcock. Many are also not ethanol safe and semi-dissolve in it. Personally, I would not recommend any tank liner.

Buna or nitrile rubber for the petcock o-rings. Pretty common, but beware of generic hardware store o-rings. If it doesn't say buna or nitrile, it likely isn't.

There's only one tank liner I'd ever trust and that Caswells. Un-like every other I looked in to (an contacted the MFG directly) you can safely use it with 100% alky and even with nitro once its cured. I've done 23 tanks with it an not one problem but I'm very overly cautious with prep. Steel, Alum, and Fiberglass.

What I meant was dump in some phosphoric acid and nutralize the rust.

Don't neutralize the rust, remove the rust. Flash rust from the drying out is fine and oem correct. But the larger true rust, get rid of it completely. Vinegar works well and is cheap, there are other products.

I poured rust out of my GL1000 fuel filter last summer in the middle of New Mexico. Was on the highway and couldn't go more than 45 by the time I got to the exit. Got the smallest lawnmower fuel filter and put another 500 miles on that day. But you should probably clean the tank

Do you know how hard it is to get all the rust particles out of a 1/4in hole? Fuuuuuuu...

just buy a whole bunch of cheap filters and keep changing them until it clears.