Moped trouble

[lone wolf]

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?

You would have to look. First do a compression test if low look at it.

 

[NovaMan]

Compression tested A-OK, so I'm thinking the pipe and muffler are carboned up just like the exhaust port was. Could this be caused by running Quaker State 2-cycle oil?

 

[Rookie1]

Im not sure about the oil but I would use some type of synthetic once you get it cleaned out.:msp_wink:

 

[fubar2]

Compression tested A-OK, so I'm thinking the pipe and muffler are carboned up just like the exhaust port was. Could this be caused by running Quaker State 2-cycle oil?

The pipe don't usually carbon bad cause they are smooth walled. Quit yer damn procrastinating a pull the baffle. Should take half an hour and done once a year anyways with a 2 stroke motorcycle.

 

[brokenbudget]

Compression tested A-OK, so I'm thinking the pipe and muffler are carboned up just like the exhaust port was. Could this be caused by running Quaker State 2-cycle oil?

although i don't recomend anything quaker state, i have a feeling the oil injector pump is set a little richer than it needs to be.

 

[NovaMan]

My uncle is still convinced it's not the pipe/baffles because it didn't SEEM like it was excessively heavy when he took it off. Because he's not interested in me messing with the pipe, I've just been letting him live with the decreased performance. Then it wouldn't start again, so I went over and had a look. I tried a few things that didn't make much difference, and then I closed down the spark plug gap considerably, and it started. The coil resistances checked almost double what the manual said they should be, but they approximately matched a known working coil off another moped that ran fine, so we don't think it's the coil. Other than just swapping parts ($$$$), I'm not sure what to do next.