89 KDX rebuild

bagpuss · Jan 7, 2009

Hi here's my 89 KDX im in the middle of rebuilding the bike has not run for 4-5years and was in a bad way but i was given it so i started one night and so its at this stage now but i need some help. Had a look at the main jet and the no on it is 122 and the needle no is N68K can this be right im going to fit boyesen reeds and ive done the pipe mod im still waiting for parts to finish but heres some pics for ya PS im in Sydney Australia thanks mike

bagpuss · Jan 7, 2009

I cant post my pics so ive put them on bikepics under bagpussbrown take a look

julien_d · Jan 7, 2009

You should be proud, it doesn't look to be in a bad way anymore. Great work!

As far as the main jet, I would think 155 would be closer to what you need.

bagpuss · Jan 7, 2009

Thanks Julien a 155 jet was recommended on the JUST KDX site but i cant find a N68K needle on there has anybody got any ideas :bang:

julien_d · Jan 8, 2009

Is this an oil injected model? N68K was def the stock needle in the KDX200 SR. It would be cool If you still have the oil injection setup! It seems the SR had a 160 main jet stock, which would be quite rich. 155 - 158 should be safe. Try the clip in the middle position on your needle if the needle is still in good shape. I wouldn't run with a 122 main jet. Too much risk of overheating and engine damage from an overly lean condition.

Did you paint the shrouds? I painted on mine, but it's already wearing off despite many layers of clear. I need to find some clear sticky back vinyl and apply that on top of the painted panels. I think that will help the durability.

WARNING, bikepics is redirecting me to AV 2009 website. Be careful browsing there!!!

J.

bagpuss · Jan 10, 2009

Hi Julien thanks for getting back to me hope you don't mind but ive got some more questions for you but first yes your right its an oil injected model but sadly its long gone so im having to premix dose 32-1 sound right
Im looking at fitting some boyesen pro series carbon reeds should i still fit a 155 main jet
Is a NGK B9ES plug right
sorry for all the questions im new And yeh i painted the shrouds as they were faded I cant get pics up on here using photobucket thats why i used bikepics

PS i cant wait to ride this bike :cool:

julien_d · Jan 10, 2009

32-1 will be perfect, and B9ES or B8ES will be fine. I personally run the B8. I would avoid the CF reeds, I hear they have a habit of flaking apart after a while. The standard boyeson 607 power reeds seem to be the reed of choice. I would start with a 155 or 158 main.

J.

bagpuss · Jan 11, 2009

Thanks for all the help i will let you know how i go

mike

bagpuss · Jan 30, 2009

OK she runs i've put a 155 main jet in and cut the airbox lid new procomp2 airfillter new B9ES NGK plug .8 gap fresh 32-1 gas using motul 800 stock reeds when i re built the motor the power valves moved ok (new left side fitted) and i followed the cyclepedia step by step i also repacked the silencer the bike starts 1-2 kick runs ok a bit oily and wont rev after 1/2 throttle just bogs :bang:

Please help

julien_d · Jan 30, 2009

bog after half throttle. Is that dependent on RPM at all? Like, once it's wound out can you open it up?

I have no idea if the SR needed a smaller main jet. I hope I did not steer you wrong there.

Let me ask you this, when you open up the throttle and it bogs down, does it sound steady and consistent like "boooooooooo wahhh", or does it sputter and miss? The noisy high air velocity sound would indicate a lean condition causing the bog. The latter would point towards a rich condition.

J.

*edit*

Just had another thought. Are all the openings from the now long gone oil injection system that could be leaking air into the cylinder?

bagpuss · Jan 30, 2009

Hi mate oil inj blocked no prob's there and it sounds rich9IE spluttering at WOT) i will put the 122 jet back in and see if that helps as it so say ran ok last time it was running thanks for your help

bagpuss · Jan 30, 2009

Ok so its now revving with the 122 i'll take it for a spin and see what its like now

bagpuss · Jan 30, 2009

:yikes: WOW now it GO's. Its about 35deg's here and it wants to spin the rear in1-4 gears on the road :)

Now it feels worth all those nights in the garage :bang:

But there's still more to come i bet :rotfl:

julien thanks for your help :cool:

the bike is a KDX 200 F 1989 but its close to a SR and has the 28mm carb

julien_d · Jan 30, 2009

Cool man. I never would have thought to try and run a main jet that small. Congrats! Be sure and keep posting about your troubles and your successes.

J.

89 KDX rebuild

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