loosing power. help!!

[jarz24]

gday guys, from adelaide. i have a 70cc starfire engine on a trek mountain bike. good fun having few problems though.

loosing power have no idea why. it's on a flat road so isn't because i going up hill the chain is very tight could that be it. any ideas let me know cheers

 

[GearNut]

Welcome to the forum!
A tight chain will certainly rob available power due to increased friction. It won't help the life span of the bearing assemblies involved either.
A good freeplay is 3/4", or 2cm as the rest of the world measures, adjusted at the tightest spot the chain gets to as the wheel turns around. (Sprockets are never truly round and the chain tension will vary.)

 

[jarz24]

also it runs great starts first go and idals great, dosn't seem to go any faster the like 20km"s.

 

[GearNut]

How new is it?

 

[jarz24]

i bought it around 3 weeks ago, i been on another bike it was running great. and now i have put it on a new bike and just doesn't seem to have any power i will change the chain. see if that makes a difference

 

[Stan4d]

you might want to use the search at the top of the screen....or search the threads listed below your thread. A good place to start would be: http://www.motoredbikes.com/showthread.php?t=20838

There are many active and knowlegable people that have subscribed to that thread that would be more than happy to help. They might not see a new thread on the same subject....that is why it is wise to search, read, search and read somemore. Also it is better for all to post to an existing thread under the same subject....keeps all the info in one neat place for other newbies.

 

[jarz24]

sorry i only join today learning how to use the site.

found the problem i change the chain didn't change anything. found out that the spark plugs were covered in oil needed a clean running great now.

cheers 4 all ya hep

 

[GearNut]

If the spark plug is covered in oil then it is an indicator of a too rich fuel mixture, too cold of a plug, or the exhaust is starting to plug up as like in the thread that Stan4d linked to.
You have found the problem, now find the reason for the problem so it can be corrected and it won't happen again.
I think that a weak spark can be ruled out for now.