Friday, May 27, 2011
Taming the DT 250
Yes, you read that right! A two stroke engine can run backwards if the timing is too far off. It was more than odd starting it up at a service station, putting it in first and then rolling backward as I attempted to head out. ...but now I know.
I also know more about the mechanics of fouling plugs and have actually been accorded some finesse with regard to avoiding it. For the most part the plugs on this type of bike foul when you funnel too much fuel through the engine. It can't burn off properly and the rest is predictable. These things tend to bang and pop a little even when they have fresh plugs, and I do mean, a little. If, like now, the bike is tuned well for how you ride it, when the plug is going stale you can develop a sense of when it's going to be shot and how to stretch out your time before you absolutely have to swap it.
Doing things like riding up hill under full throttle, into a headwind or whatever, where you can't get the RPM's up is a sure way to foul that thing out. Riding for too long at higher RPM's will also burn the plug. You just have to get a feel for it and every engine will be different based on the engine itself and how it's tuned.
The DT is currently tuned to start a little harder but have slightly advanced timing to better handle higher speeds. It seems to be working OK and I've gone from replacing one or more plugs a day to maybe one a week depending on how I ride it. They're cheap and easy to swap out so it's not a huge deal to replace them and I've come to think of it as part of the gas budget.
Still hunting a new twin plug head and a bigger fuel tank but that's way down on my priority list at the moment. Just happy to have a reliable bike until something else catastrophic happens to it. I can only hope these repairs will continue to be further and further apart. Finally getting out on it enough to be back in the realm of knowing who's out and about by their bikes and being known the same way. That's certainly a nice thing about riding custom and vintage bikes. You can roll by and know immediately if your friends are about.