i recently bought a used 99 500 scrambler it came with a dg pipe and silencer and it had a k&n filter in it also.i was wondering if there was anyway to tell if it had been re-jetted.after insalling the pipe i cut 6 7/8 in. holes in the airbox lid.it seems like now when i run wide open it has flat spots or misses in it.any help would be graetly appreciated.

 

What pipe did you install and when you cut the holes did you rejet it?? The reason I ask is because you said "after insalling the pipe i cut 6 7/8 in. holes in the airbox lid". It should probably be rejetted in my opinion from what you done. You would have to take the carb apart and see what jets are in it to know if it has been rejetted.

 

the pipe is a dg supertrap with 10 disks in it.the reason i cut the holes in the airbox is because when i bought it the guy told me it had a jet kit in it.but he didnt install it the previous owner did.can the holes cause a dangerouse lean condition?thanks for the help.

 

It would be advisable to do a plug check. If you are unfamiliar with jetting go here and read up on tuning and jetting. That is really the only way to tell, you could be causing a lean condition with the mods, more air in means you need more gas in also, so I would do some plug chops and see what you get.

 

I have a scambler 500 and have done alot of research into this type of air box modification and have found out that on the CV carb if you open the air box very much the motor will not be able to build the vaccum needed to open the carb all the way. Also plug reading on a four stroke is not a very good way to check if you are running too lean. The best way to tell is to install EGT gauge or if you hear the engine backfire after a long run you are running too lean. My advice is plug the hole you cut in the air box and run the machine that way to see if it comes alive. If you want to mess with jetting I would install a dynojet kit from hotseat (note they recommend a dj150 main but I have found the dj146 runs alot harder) or you can put air box mod kit from HPD but this kit requires cutting the lid and drilling holes in the slide. Typically on a four stroke you want to run rich to get the max hp so you should jet up until you start lossing hp and then drop back one size. I hope I didn't give you too much information. [img]i/expressions/face-icon-small-smile.gif[/img]