Exhaust Needs more gass? air? or exhaust?

[AdamT]

Ok so I have a dax 63cc and it was serously lagging. I removed the bottom of the exhaust cap and it really opened up. Super loud but tons of improvement. So I cut the little tube off inside the exhaust to bypass baffle and put a few holes in the bottom cap. Works great.

Then I put a slightly bigger jet in not sure if it was bored too big or not i just put a screw into the hole and twizzled it around a little. works prety much the same.

I also sanded .03 off the head to try for some compression improvements but not noticing much. (had some trouble sealing it back up with the old metal gasket but got it now.)

PROBLEM: super powerful getting to top speed but then it just sort of hits this spot and wont go faster , power just drops off. I feel like its missing something (fuel air or exhaust flow) because its not like its winding out or anything it just cranks to a certain speed and all of a sudden power stops and tone changes to more of a popping than a buzzing. I have felt it surge once after speed wall then hit it again.

Soultions:
can only think to maybe bent the float forks up in the carb for more fuel flow to the bowl...

What do you think...

 

[AdamT]

oh and spark plug is dark tan and i ride at wot mostly so I am pretty sure it is not running lean from the exhaust mod.

 

[pdxrhett]

Did you properly break it in? That could be a big issue as far as top end goes and not being able to wind out.

Maybe it has a new rev gonvernor on it? (doubt it )

 

[linnix13]

i know exactly what it is, i did the same thing to my exhaust and yes it got up to top speed like a rocket but then it just started popping like a chainsaw or wheed wacker, its your exhaust, i found that by leaving the tube in and drilling a 1/4" of a hole on the baffle i got better exeleration but kept the top end, i recently welded up the hole and i did loose exeleration but i gained high rps, trust me, its your exhaust,

 

[kiwirider]

Well, I now LOVE my bike.
I have been 'riding that THING' every weekend and this weekend I hit 220kms total and it has started to run like a kitten. I have been having all sorts of problems and everything I did made it a little worse. I had done the exhaust mod (drilled holes in the tube) was louder but no better, moved the e-clip all over the place, adjusted the float, new spark plug lead and plug etc. Nothing made a difference that I could notice. So, I decided to get everything back to standard, I bought a new muffler and new carb and put them on and just rode it every time I could. Almost as soon as I hit 200kms (NOT far in miles....) it started to run great. NO 4 stroking, NO hitting the wall at 20mph, just smooth and strong up to 30mph (and some...)
Yesterday I rode 50 kms (30 miles) and can keep up with the traffic with no problem. ITS GREAT.
So, lesson for today is to make sure its run in. I will reconsider doing some mods to the engine later on, maybe a new build with a better donor bike, but for now I am going to do nothing but ride the thing.

I bought an ECHO line trimmer from a yard sale on Sunday for $10.00 (about $4.00 US) and to keep me busy and not wanting to tinker on my HT I will mount it on a small frame for my nephew to ride on, or maybe a small go cart.. who knows. Its all fun..