I have a 78 mini trail 50 that has a problem of losing power after riding for about 15 minutes. It has been sitting in my parents shed for over 10 years. I did search for "no power" and came up with a few things but none of the syptoms seemed same. It starts up just fine and revs just fine at first but then after riding for about 15 minutes it gets to bogging down and won't move when put in gear. Even when it's in neutral and you rev it, it seems like it's bogging down and exhaust note gets deeper. I've taken the carb off and cleaned it but that didn't help. If you guys have any ideas I'd really appreciate it. This is my new project and I want to get it running right.

Thanks, I look forward to talking with ya'll

So no one has any idea? No one has ever heard of this issue?

Could it be the points or some other electrical issue, or do you think it could be something with the carb? I don't want to just start throwing money at it. Like I said it runs ok at first then after a few minutes loses all power and just bogs down and won't move. A good example would be like trying to take off in third instead of first. But it is in first or even in neutral if you rev it, it sounds like it's bogging.

Again I would appreciate any help.

Thanks,

Have you noticed the exhaust getting red? I had a similar problem with a CT70 once and it was due to a loose flywheel slipping which would cause the timing to change.

OK, lets assume it's not a carb problem. You say it won't move when you put it in gear, it bogs down. It sounds like a sticking clutch issue, maybe. Or as "Harry" (Flash) states you might have a slipping flywheel. You NEED to take the engine covers off and take a look at what is happening. Make sure to use a impact driver on the pesky cover screws.
As I write this a thought occured to me, are you using a motorcycle oil in the engine. One specifically for a wet clutch application? That just might be a issue also.
Good Luck and keep us posted on what you find AND try.

Brian

Thank you guys for the quick responses. I never noticed the exhaust getting red because it doesn't seem like it runs long enough to get it that hot. I'll check out the flywheel though.

As far as oil goes, before I started it the first time, I drained it and I just put regular 30 weight in it. I guess I should I drain that. What motorcycle oil do you suggest?

Thanks again! I'll let ya'll know how it goes.

I have had good luck with Honda GN4. 20w-50 over 70F, 10w-40 under 70F. Any motorcycle oil designed for bikes will work OK if you don't have a Honda store in your town. Lots of different people on this site use all kinds of different oil.

Ok thanks, we have a Honda store here.

I was just looking around some more, and I found a thread up in the CT70 section. A guy has at similar problem (he has no spark after 15 minutes) and a suggestion people gave him was to check the wiring coming from the left side of the engine to where they go into the frame. I'm going to check that out too.

Thanks again, and I'll let you know.