Two Stroke Prob

Got a Kawasaki KMX200 with KIPS valves,at first it wouldnt idle so cleaned out all the jets etc from the carb and replaced it now it idles ok but if the bike is revved to 4thou it takes a long time for it to return to idle 1250rpm.
checked for free play in cable and with engine turned off you can here the carb slide hit the bottom of carb straight away so it seems the cable/slide can be ruled out.
have been told could be slide dragging when engine is running so dont return quickly or poss could be the Boyesen read valves. jets are all standard and new air cleaner aswell
Any other theories to what could be causing this problem?

I would be suprised if it was the reeds. However, I always used Hy-tech competition reeds in the X7 with no probs. Check the opening distance for the reeds isnt too wide as this can cause extra fuel to be let in :) but it can crack the reeds due to the harmonics! :( I had a set shatter on me making the bike a very sluggish 135.5cc bike instead of a 271cc flyer!!

Just a thought! Hope you get it sorted.

Andrew

alan iam not to clued up on the bike in question or 2 strokes but just a thought are you able to alter the position of the needle within the slide as on amal carbs, only if the needle is set to high it maybe allowing to much fuel through from the mainjet even when the slide is fully shut and when it should be running on the pilot jet

I got the idle mixture right now, set at 1.25 turns and ticking over at 1250 rpm very nicely cause before mixture was wrong and it was gasping when i opened the throttle wide. but now when open the throttle to 5000 rpm and i release the throttle it takes about 3 seconds to slow down to tick over.
ill look at the needle as the clip could be set too low thus making needle to high.

alan may may also be worth checking the float hight is correct in the float chamber as this also can cause a high or irregular tickover

try looking for air leak most likely on the inlet manifold this will cause revs to fall back slowly

Alan I spoke to Dave up the pub last night and he recons it might be the exhaust

He says try and run the bike with the exhaust off

See you Tomorrow, Taff

Checked float height thats within the tolerance done that when i cleaned out the jets ,ill check the inlet for cracks aswell to see if i got some leaks.

My RD400 had the same problem last year. Bike was sucking in air somewhere around one of the carbs.

It was so hard to find the exact leak point. I changed the 30 year old "flattened" O ring at the top of the choke lever. Refitted the cards and the problem had gone

Try posting your question on a tech section of a stroker site - you will probably get the same answer though.

Ain't gotta clue how removing the exhaust will cure it or cause it!

Had a look at the reeds last weekend they were ok went through the carb again incase i missed anything,but all seemed fine checked all the intake rubbers and going to fit a new gasket (got to wait for fowlers to restock )between barrel and reed block so hoping that might do the trick also looked at choke starter plunger wasnt sure on that so going to have more free play in the cable, so hopefully should have it going again this weekend ,going to put a colourtune on it see if that shows anything up if its sucking in air it be light blue if rich it will show yellow.
I always thought two stroke exhausts were designed to produce back pressure for the engine and taking it off would be friggin noisy to start with anyhow so wouldnt be able to ride it at all.
if dont get no joy this weekend prob suss out a forum!!

SupeRDel wrote

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Ain't gotta clue how removing the exhaust will cure it or cause it!

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Don’t shoot the messenger I just asked the lads up the pub who race 2 strokes

Hope you get to the bottom of this problem soon Al

if all your carb settings are ok and you have no air leaks on the inlet i would take a look at the ignition timing is it over advanced? is it retarding as it should when you drop the engine revs? is the power valve opperating as it should do?.as said before iam no two stroke expert but have owned a few in the past,can remember having to remove the exhaust on one due to it being completely clogged with coke although the bike did still start and tickover ok it was as flat as a pancake in the power department,but what a difference when the exhaust had been decoked and the engine could breath.http://justkdx.dirtrider.net/kips.html. you may find some usefull info on this site.

Iv decided to take the logical approach to this problem and im now reading Zen and the Art of Motorcycle Maintenance lol ;D

Still waiting for reed block gasket >:(

Well bike is sorted ;D
Looked in the Haynes manual apparently the throttle cable is in 3 parts and splits at a junction top part to twist grip, one from junction to carb and the other to the autolube which syncs with the lower cable for carb.
who everhad the bike before hadnt adjusted the lower carb cable properly so it had no free play so keeping cable or rather the slide up by about 8mm so thats why it wouldnt go below 4-6krpm.
though the slide sounded to be hitting the bottom of carb it wasnt, only the idle speed screw. sussed it when i took air cleaner cover off looked down the air intake to carb and saw it :) at least the carb had a good clean out 3 times lol

Glad all is well and good again.
Good biking now to be had

good to hear its now sorted