I have a thumper engine, am i in the right place?

[gomulletgo]

Hi everyone,

I have the go kart described in this listing: http://www.trademe.co.nz/Browse/Listing.aspx?id=379070745

Important info:

ENGINE: Modified GB400 engine. Has the stroke of the 400 but has the barrell and head from a twin port XR600. Engine was from a Motard racing bike. Carbie is a large flat slide off a KXF250 (jetted to be similar to a KXF450). Dry sump oil supply. Electric start.

I'm trying to find the forum that would know the most about this type of engine, so first off am I in the right place or is there somewhere bigger or more geared towards this type of engine I should be?

My main questions that I need answered at this stage are to do with the carb. The engine runs rough higher in the rev range and I'm concerned that it may not be getting enough fuel because of the carb, leaning out higher in the rev range where it needs the extra juice. As I don't want to blow my engine I want to know what type of carb I should be looking for. Also what is the appx cc of the engine? 500cc?

If it is leaning out higher in the rev range is there some easy way to check? like will the spark plug points be a different colour? Or will it not affect the spark plug because we don't spend much time with it running rough (As soon as it runs rough we just change up a gear which drops the revs and it runs fine.)

Thanks in advance