Break'n up!

[jamman]

Hello 2-stroke fans!!!!
When I go anywhere over half throttle, the engine seems to choke and bog. I've got a Boyesen Rad Valve that has carbon reeds and they seem to stay open a hair. Some pro's claim that it doesn't matter since they are bouncing back and forth 100 times a second, it's imposible to make a complete seal!? With the Valve off I can blow through it backwards and for the most part seems to close and seal. My Warrior had a problem with the pick up coil, but I would have figured the coil either works or it doesn't. I could try and flip my reeds around maybe? Do I really need the Rad-Valve reeds or has anyone ever tried to put any reeds for the stock reedcage in in a quadracer with a Rad-Valve???Rep from Boyesen just told me the part #'s for my paricular 1992. Didn't say if I could do it or not though.
Thanks for any help!!!!

[1upfront]

It sounds like your jetting is too rich. What type of machine do you have and what size is your main jet?

[jamman]

It's a 1992 Suzuki LT250R. I bought it second hand, so I'd guess stock. It also has a full FMF gold series exhaust. And I just put a twist throttle on it. The Rad Valve would allow for more flow, making it a little richer. But it ran fine until I parked it for almost three weeks. Then it just went downhill. I can hold the throttle wide open with it running and it just pulses without building up any rpm's.
Kind of like a rev limiter on a car.

[1upfront]

Are you familiar with a plug chop and what it takes to perform one?

[jamman]

1upfront
No!!!!???But I'm very intrigued!!!!Please do tell.......This sounds like a "secret" recipe. I shall bestow upon you a great honour on behalf of myself and any other who reads it!

[1upfront]

A plug chop is a procedure to determine weather your main jetting is rich or lean. I will do my best to explain, first you get your spark plug wrench in your pocket then ride the bike to a wide open location, next you run the bike through the gears at wide open throttle until you reach the bikes maximum speed ok next step is to simultaneously pull in your clutch and kill the engine then just roll to a stop, keep in mind you don't want to let the clutch back out until you are completely to a stop, next step pull you spark plug and inspect it this is the only truly accurate way to get a spark plug reading, now if the plug is wet and/or black your main jetting is to rich and you need to go leaner. When your main jetting is dead on the plug should look a light coffee brown/mocha color I hope this helps you

Also one more suggestion check your air filter and make sure it's not dirty it can cause similar symptoms that rich jetting would.

[jamman]

It won't go over half throttle without breakin up. if I were to try, it would just slow down and start chugging and buckin. It's alot like my Yamaha Warrior when the parking break sensor was acting up. The sensor would stay engaged even when the parking brake was off! I also recently tried wiring another keyed ignition for it, so I just removed it and put it back the way it was....still the same. I'd really like to try the wide open test, but I can't even get past half throttle. I've got a manual with the coil resistance specs but I seem to lack the ability on where to set the digital mutimeter. I have a way of making the numbers go up and down until they finnally just disapear!LOL Can't seem to find my analog one!!!! OldSchool Analogger. Could I still attempt the plug chop with it running the way it is anyways?

[1upfront]

Yes perform a plug chop even if it's breaking up at wide open throttle just get up to speed and hold it there for a few seconds then go through the rest of the steps I explained to you. I think it's a jetting issue and I believe it's rich on your main jet, this is just a test to prove or disprove my theory.
Also there is one other experiment you could try turn on your gas petcock start up the bike and go for a short ride and while you're riding turn the petcock to the off position and keep on going till the carb runs out of fuel, if it starts to run a lot better and become more crisp at higher RPM's just before it runs out you will know your jetting is rich, I hope this helps

[jamman]

Thanks! I'm going to try it now. Might take a bit, but I'll write back with results!

[jamman]

Whoa! I stumbled across the problem. The freakin spark plug cap!!!! It was a little loose, so I tried a little peice of aluminum foil to fill the gap. Presto!!! Spark plug is kind of dark golden brown unlike the perfect pizza I cooked Light golden brown, while I was doing this test!!! I hold my perfect slice of pizza up to you 1upfront. As I am now on a quest to find the perfect jet to to make my engine shine with a golden spark plug!! I'd guess just a size smaller. many thank you's