Suzuki 2 Strokes

So while I'm working on my Titan, I'm riding... let's say... an off-brand bike.

I was riding home from work, driving about 10 minutes and all of a sudden the
thing starts coughing, sputtering and back firing. I had just filled it up with gas
the day before. I had ridden it to work... fine. I had left work... fine. 10 minutes
later I'm limping along the side of the road. It idled fine, It would propel me
forward as long as I didn't rev too much above 2000 rpm. It was really, really
sudden. Luckily I was able to make it home (after pissing a few people off).

So I pulled apart the carb to make sure nothing was stuck in the float bowl. I checked
the battery connections to make sure they weren't loose. Checked the air filter
and there were no dead birds floating around in there. I plan on replacing the
plugs tomorrow but until then I wonder... Can bad gas be the cause? It starts easy,
runs and idles great, I just CAN'T rev past 2500 rpm. I put in a little gas treatment,
let it sit and it seemed to be better but there was still a trace of the loss of power,
sputtering and backfiring.

Normally I wouldn't be too worried but I'm leaving on a 3 day bike trek (the Gypsy Run
in NY and NJ in the middle of September) and I've NEVER had any trouble with this bike.

Any ideas?

Hi,two stroke,four stroke,diesel ?? might help to know what we are dealing with ? Sounds like fuel,as you say you filled up then had the trouble !
Cheers,
Roger

Single carb. Might you be talking about a Harley?

Maybe you have an ignition problem.
Dwell time decreases with rpm, so you might get a good spark only when the rpm is low.

Advance/retard stuck (points)?

Yes, it's a Harley. Like I said, it's only my rider until I can get my Suzy on the road. So it is a single carb to a V-Twin
engine. I filled it the day before, rode it home. Woke up and rode it to work. Left work and started riding it home, about
half-way home it was just like someone pulled the rug out from under me. At first I thought I had to switch it to reserve
(before realizing I had just filled up. But it was that sort of feeling. Then it just started coughing and backfiring and
the needle would get up to 2,500 rpm then instantly drop to 2000 or 1800 and just cough and sputter. I was only able to
limp it home by keeping it under 2500 which meant up-shifting quite a bit, often much earlier than I normally would.

My father was suggesting that the gas I filled up with may have had water in it but it seems to me that it wouldn't happen a
day later and after I'd already gone 30 miles or so...

Can you tell if it is one or both cylinders? I usually tell by BRIEFLY touching a WET finger to the header pipes (don't let it burn ya!), but if ya have an IR thermometer, all the better! If it's fuel related with the single carb, both pipes should be about the same temp.
If it's ignition related, one will probably be cooler than the other.

Also, if you suspect bad gas, why not just drain it out & try some new gas from a trusted source? It's cheap, quick, & easy to do (a rare combination!). But run it for a while with the new stuff to be sure you've flushed all the old out of the system.

Could be a clogged filter, either within the tank, or external, or another possibility may be the fuel cap is not venting properly to let gas out of the tank....Try running with the cap open for a while.

Good Luck.

Thanks all for the suggestions.

I changed the plugs (because they were due, not because I thought they were really the problem) and let the
fuel additive sit over night. I took it out for a spin today and there's no sign of the issue.

I'm confused about it being the fuel. If that were the case wouldn't it also idle roughly? The idle was just fine,
like it always is. I wonder if something small got through and was just clogging up one of the jets and the fuel
additive may have cleaned it out? Again, it was so sudden it doesn't make any sense.

Fingers crossed for the Gypsy Run, don't want to go through all that while out on the road. That gives me an
idea for a new thread....

Might have been a faulty plug. Are they resistor type? Could be a resistor breaking down as the revs rise or just a dud plug. Test resistance from top to centre electrode. Even possible that some carbon has built up inside.
Glad it's sorted even if it was a Hardly Ableson!!

It doesn't happen to have the Delphi fuel injection does it? It sure sounds like one I troubleshot a while back....

If so, you might have your hands full without the proper equip.

jeff

Check gas caps, could simply be vapor lock. Seen it more then once on many Vtwins. From your description it seems like fuel problem.

well... turns out it's not sorted. I guess I'm going to drain the tank and see what's going on. In the meantime I've learned that, when it happens, all I have to do is up-shift way too early, let the bike bog down, pick up some speed, get the rpms up and when it starts to buck and shudder again I just up shift again and keep going until I run out of gears.

Replaced the coils, no good. It's definitely happening when the bike heats up to a certain temp as
it runs beautifully for the first 10 minutes then gives up the ghost after that. Methinks my trip is off...

Check the simple things first. Water in the fuel, fuel supply, clogged/restricted fuel filter or screen, vacuum leak to the petcock, water in the float bowl.

You could use an induction timing light to see if you still get a spark when the motor is hot.

As it turns out, the Ignition Module is heating up too much and cutting out, funny since it's located in
the engine just above the exhaust pipe

The part is back ordered across the country so ordered an aftermarket replacement and am having it shipped
overnight to me. I'll have to retrofit the wiring but I think I'm good for it... trip may be back on...