Moped trouble

[NovaMan]

Hi guys, having trouble with my 1989 Yamaha Razz again: it won't start. Sometimes it'll half-heartedly try to start, but mostly you get nothing when you kick it over. Once in a while it'll have a small backfire out the exhaust. I cleaned the carb, and that didn't help. It has good spark. It's obviously getting air, and it's getting fuel because one of the times I took the plug out the ground strap was wet. I checked for compression by kicking it over with my thumb on the spark plug hole, and it blew my thumb off (I wasn't pushing down terribly hard). Before this happened, it didn't want to idle and it was down on power. Does anybody have any ideas?

 

[brokenbudget]

does that bike have a spark aresstor in the muffler (more commonly known as a noise reducer)? i have seen a few other mopeds with the mufflers plugged up.

 

[NovaMan]

It might... I'll have to check. The tip of the exhaust has become kind of cruddy, so you may well be onto something.

 

[brokenbudget]

havent had to many of the raz's but the little hondas and suzukies have a brilo pad type of material near the end of the muffler to lower the noise down. it gets built up with carbon and other crud over time.

 

[Eccentric]

Compression could still be low. Your thumb won't give much resistance before it's blown off of the sparkplug hole...

 

[brokenbudget]

Compression could still be low. Your thumb won't give much resistance before it's blown off of the sparkplug hole...

i agree. it's an older bike, with probably alot of hours on it. could be time for retirement or a re-ring. however, these little engine don't really work to hard and i haven't come across any that has gone that far. but without knowing the history of this one in particlar.....
usually they plug up before anything else. they run pretty rich.

 

[Vibes]

I had a guy give me a little Yamaha Tri Zinger trike. I think it was a 60CC. Had similar problems and the guy had it in a shop and had it gone over pretty good but only ran for a couple days. I pulled the expansion chamber and it must've weighed 12 lbs. I burned it out with a torch. I had that little trike for both of my kids and my nephews kid.

 

[NovaMan]

The exhaust port was 10-20% blocked by carbon build up. Thanks guys!

 

[Wagnerwerks]

Plugged

I had a similar problem with my Razz that I could not figure out. It sat for a bit and when I got it out... No go.

After checking EVERYTHING, I let it sit, frustrated. Turns out mud wasps plugged up the muffler

Glad you got yours going!

 

[lone wolf]

Try a new Spark plug.You said it was wet it may be fouled at this point!

 

[fubar2]

Look inside your muffler too. If its got baffles in there pull em out soak them in gas and scrub em.

 

[NovaMan]

The muffler does have baffles, and they probably have crud on them. The trouble is that you have to cut the muffler open to get at them, which means welding it back together again. I have a welder, so I can do the job, but it's alot of work. If the performance nose-dives again, then I'll clean the muffler.

 

[fubar2]

Look closely at the sides of the muffler near the rear and see if there isn't a sheet metal screw or two going in from the sides, if there is take them out and pull the baffle. Most all two stroke motorcycles I've seen, in fact all of them had removable baffles so they can be cleaned. If not maybe slosh some gas around in it and blow it out really good, more of it you can get out the better off you are. I've never messed with Mopeds before, so maybe they're different.

 

[fubar2]

Hey, very few had a steel pin that went across the very end of the muffler you could grab with vice grips and screw the baffle out. Don't know your circumstances but I'll bet it is made to come out without cutting and welding.

 

[lone wolf]

OP did you try a new plug yet?:bang:

 

[fubar2]

OP did you try a new plug yet?:bang:

Hey Lone Wolf, empty your inbox. I can't figure out what your message yesterday was all about and its driving me nuts.

 

[Walt41]

Every time I hear talk of mopeds I think back to the 70's gas crunch and the company my dad worked at....seems one of the machinists had a connection to import some Italian "class c" mopeds and the guys all bought them and went to tuning on them, even my dads boss had one that sported a different sprocket and custom pipe, I still remember my dad riding that thing to work every day for years, until the famous "chipmunk" incident that left him bloody and bruised enough to go back to driving the car.

 

[fubar2]

Every time I hear talk of mopeds I think back to the 70's gas crunch and the company my dad worked at....seems one of the machinists had a connection to import some Italian "class c" mopeds and the guys all bought them and went to tuning on them, even my dads boss had one that sported a different sprocket and custom pipe, I still remember my dad riding that thing to work every day for years, until the famous "chipmunk" incident that left him bloody and bruised enough to go back to driving the car.

They have definitely been around forever. I'm a big fan of the Merkel Motorwheel myself.

 

[lone wolf]

Hey Lone Wolf, empty your inbox. I can't figure out what your message yesterday was all about and its driving me nuts.

Try it now Fubar

 

[NovaMan]

My uncle bought a battery at a motorcycle shop today, and told the guy that he's only getting 40mpg and 23mph out of it. The cycle shop guy said he should be getting twice the mileage and 28-30mph. I never kept track of mileage, but I used to get it up to 27-28 on a smooth, flat road, so there is a performance problem. The cycle shop guy says the carbon in the exhaust port made it difficult to dissipate the exhaust heat and the rings are cooked. I think it's carbon in the pipe and muffler. What do you guys think?