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Rebuilt a 97 220..The previous owner grenaded the stock piston so i got the bike for a good deal. Cleaned all the debris out, crankcase has no holes. Did new top end, rebuilt carb, good reeds, new plug...Fires up pretty good but bogs/stitters as soon as you give it throttle.RPM only climbs moderately to about 4-5000. Does idle, but not bad. Checked and rechecked the carb until I can do it blindfolded. Redid the jet block gasket. No change. No blockage in the exhaust. Strange thing though, when I run it with the petcock off, just before it runs out of gas, it comes to full life for about 4 seconds. Then of course it quits from no gas. Its obviously running really rich and the running out of gas leans it out. Using stock main and needle. Stock PWK carb. I've worked on bikes and cars for 40 years and this one has me stumped. Its not often I'm baffled, but I am on this one...any suggestions.

Welcome to kdxrider.net.

See if the float needle valve is sealing properly. The rubber tip may be shot or the conical area where it rests may be corroded.

Also, check the float level and proper operation.

If the float is high it should give you a sign by overflowing out of the vent tubes as with all used bikes assume nothing is right and you will be better off be sure the jetting is close to stock with the needle in the 2nd or 3rd position with a clean pilot that you have run a wire through and be sure the choke plunger is working and seating correctly sounds like you already covered the sneakiest one with the jet block gasket it wouldnt hurt double checking with a little air pressure those can be very finicky if they want to

Going to open the jet block on the weekend to see if a gasket is pinched or out of place. Played around with float height (at 18mm) and air jet this morning. Not much improvement, but when I did get a chance to do full throttle run, it lit up nice n the main jet once the rpm got up. The low and mid are a different story. Might just switch to a 35mm Stryker and get up to date with a better, new carb. Will add more once I open things up again. Thanks the advice.....

Spoke to a mechanic at Stic. Gasket is an issue and also check the guide hole for the needle has no play. The wear out. If there is any slop, gas can get pulled in from the jet body. I had 10 thou side to side and about 15 front to back. Stic has rebuilt jet blocks for about $50 with the gasket, No need to buy a new carb. When the guide hole is worn, you get bad idle, stuttering performance and can't jet the thing worth a darn. Truth will arrive in a week and we'll see what happens.

MHbarnhart, did you order a rebuilt jet block from them?

Thanks for letting us know they sell them. I had never heard of that.

They have them, comes with gasket too! They have the short body and the screw top one that we use on the KDX series. They Are at 715-479-7822

That’s great to hear. I’ve seen the reviews for their metering blocks and people seem to really like them. I never knew they sold rebuilt jet blocks for $50.

Sorry I don’t have good recommendation.
But, If you wear out on old carb. I have (looks almost new) 35mm striker.
It has all stock jets, so will bubbler on top until you dial it in. I went with RB carb, so never tuned it properly to my KDX.

I've never heard that either, curious as well. If that doesn't do it, what about a restriction upstream of the fuel inlet to the carb? Is there a chance the petcock could be blocking flow? I''ve seen those little filters in the tank break apart some when they are older, maybe something broke off and is blocking it up? I'm thinking along the lines of trying to suck through a straw with the opposite end pinched closed. Just a thought, hope you get it figured out!

Goat wrote: 07:07 pm Sep 22 2020 Sorry I don’t have good recommendation.
But, If you wear out on old carb. I have (looks almost new) 35mm striker.
It has all stock jets, so will bubbler on top until you dial it in. I went with RB carb, so never tuned it properly to my KDX.

Greetings, been fussing with the carb for too long. I think its just plain wore out. Idle screw doesn't affect much and the air screw does not affect much either. Only runs good for 5 seconds after I turn the gas off and its about to run out of gas....

What are you looking for for the carb Mr. Goat...
Regards..Mike Barnhart....just north of Toronto, but given the weight of a carb I can't imagine shipping would be too much, just very slow these days with the border stuff.

I am thinking $125 + shipping. I will PM you.

Sorry. Looks like your PM isn’t activated yet. I think a small donation to the site is required for PM-ing.

Tried to make donation but paypal wouldn't connect. The fact I can't PM means I can't send a note to the admin folks. Can you let them know there is a problem with paypal from up here in Ontario. You can email me at mike.barnhart@humber.ca thanks..

I'll ask Julien D (site owner) to look into it. Thanks.

MHBARNHART wrote: 09:11 am Oct 05 2020 Tried to make donation but paypal wouldn't connect. The fact I can't PM means I can't send a note to the admin folks. Can you let them know there is a problem with paypal from up here in Ontario. You can email me at mike.barnhart@humber.ca thanks..

Odd. It's been working, but every so often it breaks and will just time out on paypal's end. Payments to admin@kdxrider.net are always fine, just make sure to put you username in the comments so I know who it's from.

It was a little goofy last time I tried it also. But eventually worked.

Same. I have been testing it every so often. Unfortunately whatever the issue is seems to be on paypals end, so not much I can do to troubleshoot.

Sent a small to admin@kdxrider.net lets see if you get it. Will that open up my PM and such capability?
Still interested i the carb Mr. Goat, night you have a spare CDI unit as well? Checked the resistance in the manual and several are out of spec. Might explain why it runs poor and won't rev under load on top of the carb problems. Looks like my fixer upper is preventing me from riding for 2 months now. My snowmobile will be of use sooner....

I think you will see Member 1 by your name when the PM is opened. I will hang on for you. Looks like shipping to Toronto would be about $21 from here.
We can sort out details once PM is fixed up.
Sorry I don’t have a CDI.