big chick Posted August 30, 2005 Report Share Posted August 30, 2005 Mechanically minded I am not so any help greatly appreciated. Ben's Rookie has run fine for a couple of months since I got it, but suddenly stopped straight after starting from cold. It sounded like he ran out of petrol. Put a new plug in and he rode the trial no problem. On to the trailer and two hours home, cleaned it then same again, sounded like he ran out of juice. New plug and away she went. Went to ride it yesterday - no go. Yet another new plug and away she went. The plugs are very black, but I put this down to it being a 70cc. Any ideas or do I just need a large stock of plugs? Thanks Big Chick Quote Link to comment Share on other sites More sharing options...
charliechitlins Posted August 30, 2005 Report Share Posted August 30, 2005 What color was the porcelain insulator in the plug? Quote Link to comment Share on other sites More sharing options...
telecat Posted August 31, 2005 Report Share Posted August 31, 2005 Sounds like the plug is sooting up. What Oil and mixture are you using? It looks like the mixture has too much oil in it or the carb is not adjusted correctly. The 2 solutions are:- Change the Fuel/oil Mixture. Most bikes have a recommendation of 2 to 2.5% oil to fuel. This is probably good when new but can be leaned off with modern oil's. The other is to adjust the air fuel mixture via the screw on the carb. Check with a Gas Gas dealer as to the best position if it isn't covered by the manual. As a stopgap you can simply shut the fuel valve and let the bike use the remaining fuel in the line when you have finished. It cleans off the plug. To revive the plugs clean the soot off with a rag and then use a plug cleaning brush, (wire brush) to get any remaining soot deposits off the plug. Quote Link to comment Share on other sites More sharing options...
big chick Posted September 1, 2005 Author Report Share Posted September 1, 2005 Thanks Telecat. I generally run it on a fully synthetic oil at about 60 to one. There does not appear to be a manual so i will e-mail Gas Gas UK to get an answer on that one. It seems strange that it ran fine for a couple of months though if it is the mixture that is wrong. Charlie - there is no colouring to the porcelain Thanks for your help guys Quote Link to comment Share on other sites More sharing options...
charliechitlins Posted September 1, 2005 Report Share Posted September 1, 2005 Duh...I didn't notice you said the plug is black in your first post. I stopped reading after the smiley thing. I tend to use "too much" oil.I run our bikes at 64:1, and the plugs on my son's Rookie are a nice, toasty brown. You probably need carburetor jetting, or your spark is weak. What plug are you using? Quote Link to comment Share on other sites More sharing options...
brian r Posted September 1, 2005 Report Share Posted September 1, 2005 Just a suggestion but I'd try to run a little rich on a kids bike. They tend to rev the off them. Quote Link to comment Share on other sites More sharing options...
scorpa3 Posted September 1, 2005 Report Share Posted September 1, 2005 We had a new 2002 Rookie for a year. It too used plugs for no reason. It would run for a couple or three trials without missing a beat then suddenly just stop. Plug always looked fine. Perhaps a little on the sooty side but no ammount of cleaning would persuade it to spark again. This happened perhaps 10 times in 12 months then we sold the bike. And got a 125. Young lad soon got the hang of changing the plug and kept a spare close at hand. The plug problem was the only thing that ever went wrong with that bike. After a whole year the tyres still looked like new, it didn't have the power to wear them out which was just what the rider needed as an introduction to trials. He could start it easy. pick it up himself and used 1st gear everywhere. Magic little bike. Quote Link to comment Share on other sites More sharing options...
scraggydog64 Posted September 17, 2005 Report Share Posted September 17, 2005 Had the exactly the same problem with my sons 05 Rookie. It was using a spark plug a month and starting became a bit temperamental. The original plug was a Champion so were the following two. Changed to NGK BR5ES / B5ES (?) plugs and we don't seem to have a problem now. Hope this helps. Quote Link to comment Share on other sites More sharing options...
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