Help with my KDX 400 bogging at high rpm's

[guitarman11]

Hi. I have a 1980 Kawasaki KDX 400a two stroke. The bike is in nice shape and has good compression but has a problem. It runs real well off of first gear and stands right up and goes right up to a full wind, However, when I shift into second gear it doesn't respond as well.. It bogs and never really gets up to a full wind. It doesn't bog terribly, just enough so it won't go to full power before I shift to the next gear. If I really gun it quick it will bog and die almost. If I feather it a bit, I can get it up to full power that way. It doesn't run rough but just lacks the response and power....It also does the same in 3rd 4th and 5th gear. I've adjusted the needle height and seems to run best when the needle is all the way down and the clip is at the top. If I proceed to move the needle down, the bike runs rough. It also starts a bit hard cold but once it is warm, it starts right up. Any advise?

I also have a 1988 kdx 200 that bogs out when I rev the throttle up real high. If I feather it, it will get up to full power. If I throttle it up in third, fourth or fifth gear quick it will die. It is very similar to the 400. I cleaned both carbs thoroughly and changed the gas. Could it be the type of oil I'm mixing?

 

[KDXRyder200]

Hey it might be leaking crankseals, sucking in air through the seals instead of gas through the carb?

 

[KDXRyder200]

Compression test the motor....if the compression is good then do a leak down test. If the gauges lose pressure rapidly then you have an air leak in the motor and that might be causing it to bog out.

 

[levert]

Ditto above advice.
When was the top end done last?
If you haven't touched the bottom end I'll almost guarantee those crank seals are dried right up.
Drain your tranny, flush with oil, start and drain oil, if your seals are leaking that oil will be black.