I am noticing when on 1st or 2nd gear..  When i reve the bike and  say i keep it at 5k..  my bike will tend to go fast and slow?  ahh.. hard to explain. hmm..

so if i kept the rev at 5k.   my bike is not actually going fast then slow in terms of speed..the speed is kept the same from what i can see on the speedometer..  the bike in a very minimal but i can sense it since i ride it all the time..   it surges then stop surges then stop.  i am thinking its the chain.  tight spot..then loose spot?? does this make sense?

does it do this only in 1st and 2nd gears or are those the only gears you have noticed it on?

yea those are the only gears.. that i have tried and been at low speed.. so the speed is usually i think around 20-30mph... when i am at 1st or 2nd at 5k.  I dont notice this when i am 3rd 4th and up because usually at that point i am going 50+ .   So its def only noticeable at low speed.. i  am sure if i put it on 3rd and i go really slow.. between 20-30 i will feel that deal again.. i havent tried but i am 95% sure it is due to low speed.   i guess i can test it out after work.  i have a 14t sprocket front.  stock rear.

sounds like it could be a jetting issue (I had a similar problem while tuning my bike). I notice you changed just about everything but the motor, what jets are you running now?

What does it do if you hold it steady at any other RPM? Is 5k where you tested it, or is that the only place it does it? If it's only at 5k, then it has to be an engine thing. If it does it at any rpm it could be the chain. Does it do it the same speed in 1st and 2nd gear? If it's also the chain, it'll do it faster in the higher gear, even at the same rpm since the chain/gears are spinning faster. If the engine is hesitating at the same interval in a higher gear, but at a higher mph, it would also be the engine.

It sounds like you need to do some more testing to find out exactly when it does and does not do what it's doing, and whether it seems to do it faster based on a faster engine speed, or a faster mph speed.

It sounds like an issue I had with my old chain.

The easiest way to check if it's the chain is to put your bike in neutral and on its center stand.  get behind the bike and spin the rear wheel slowly and evenly and feel for any resistance.  If you feel resistance then no resistance, start watching the chain go around the rear sprocket and feel the chain for any extra tension.

If the tension on the chain changes, then it's probably a chain issue.

thanks for response guys.. i will have to check when i get home.. different gear same speed.  which means not same rpm..but i will try speed first.. then i will try different rpm same gear 1 and 2.  will get back with you guys tonight.

If you try TurkeyChicken's method, make sure the bike is off and you're just spinning it by hand. I know that sounds like common sense, but just making sure.