New member here, having problems with kz250d1 carb

Well, after getting my exhaust finalized, i thought that i would mess with the carb some more... I was able to get it to run fair with a 110dj main by cutting the bottom out of a soda can, triming a 1"x1/2" hole in it, and taping it over the pod filter. It fires and idles good, but it won't go over 5k while riding, no matter where the fuel screw is. It seems to be loading a little on Idle but lean on throttle. I guess i need to look again at my carb diaphram.



Btw, i scored a nos manx reverse cone muffler for $30. I am pleased with the look, but i may angle it up a tad more.

matt_finish wrote: Well, after getting my exhaust finalized, i thought that i would mess with the carb some more... I was able to get it to run fair with a 110dj main by cutting the bottom out of a soda can, triming a 1"x1/2" hole in it, and taping it over the pod filter. It fires and idles good, but it won't go over 5k while riding, no matter where the fuel screw is. It seems to be loading a little on Idle but lean on throttle. I guess i need to look again at my carb diaphram.



Btw, i scored a nos manx reverse cone muffler for $30. I am pleased with the look, but i may angle it up a tad more.

The slide itself may be binding. What I do is I polish the slide and the carb slide cylinder itself with 1000 grit wet/dry sandpaper and WD40 or other lubricant. Make it smooth and slippery. You should be able to reach in and manually raise the slide and drop it... and the carb should go "clunk." It's called the Clunk Test. If it doesn't do that, you have a problem.

Here is a post from XJbikes.com (Yamaha) in regards to this:

There have loads of Posts, recently, concerning performance and mixture settings. Generally speaking, the mixture settings of the carbs won't un-set themselves and cause your bike to start running poorly. Other factors, unrelated to Jets, floats, sync and pilot screw settings will. The Number-1 cause of a decline in performance -- "Related" -- to carburetors is "Slide Piston Stiction." The brass piston part of the diaphragm assembly needs to have 100% absolutely FREE travel in the carb body cylinder bore. No. A tiny bit of drag IS NOT OK. There needs to NO drag. NO friction. NO binding. NO 'Nuthin!!! When you get done CLEANING a set of carbs; you need to do "CLEAN-TUNING" too. You do this by conducting a "CLUNK TEST."
With the top off ... spring out ... and diaphragm un-seated to its locating channel -- LIFT the brass piston to the top of its travel and let it fall. It needs to FALL! It absolutely MUST drop ... from being raised-up and let-go ... like a safe out a second-story window! If it chatters down, hesitates, acts like it being hydraulically controlled, is slow, stops and goes ... or, does anything, other than drop ... like a wet bag of cement ... you got a performance problem. SLIDE PISTON STICTION. Get rid of it. It's easy enough to do.
Polish the brass piston. It should be a shining brass object a Marine Corp Recruit would be proud to show his Drill Instructor. You can polish the needle, too! BUT -- DON'T bend it!
The carb body bore is usually where the problem is. A film of oxidation forms on the Inside Diameter of the cylinder bore surfaces. This film reduces the inside diameter's already close tolerance to make the brass piston's travel become impaired. Elbow grease and finishing papers will restore the original shine to the alloy.
Use # - 800 Wet-'O-Dry to clean the surface. Vertical motion only. Refinish the bore with 800 using WD-40 as the wetting agent. Using sections of 800 about the size of a pack of matches ripped in half ... refinish the inside diameter of the bore. Throw-away the 800 section as it becomes fouled. Refinish UP and DOWN ... moving ALL AROUND. Don't do anyplace where you think its sticking. Keep the bore round.
Feel like doing another 15-minutes of work that will give you a stage closer to RACE-PREPPED??? OK ... after you clean-up the bore with the 800 Wet ... Hit the bores, AGAIN, with 1000 - 1200 and 1500 !! WD-40 is your wetting agent. When you are done, there should ZERO drag. Nothing preventing the diaphragm from raising the piston when vacuum is present. And, NOTHING from preventing that SPRING and NO VACUUM from allowing those slides to slam-shut for some ABSOLUTELY wonderfully controlled engine braking.
I know you! You're a sneaky little devil ! You ride like an accountant all the time, huh? Until the "Ride-Hard" bug bites you in the butt and you want to twist-again ... like you did last summer. We'll ... now you get to appreciate having sore fingers and elbows for a little while, doin'-up your carbs.
You'll be coming into a nice sweeper or a really sweet decreasing radius turn ... you tach-up for gear-change and the bike sounds like Formula-1 ... right-up to where you need to match RPM for the downshift -- immediately. No farting-around with the throttle -- "Asking Scotty for a few more revs. You're there ... on the hairy edge of sweetness. You matched your revs and now want to loose some speed ... close the throttle and you have On-The-Track engine braking. You're power goes back on without a hitch as you start looking like the guy in the commercials and sales brochures ... leaning over in the turn.
You exit the corner and wrist-open for the straight.
Hang on tight, brother ... you'll be going fast in a second!

matt_finish wrote: Well, after getting my exhaust finalized, i thought that i would mess with the carb some more... I was able to get it to run fair with a 110dj main by cutting the bottom out of a soda can, triming a 1"x1/2" hole in it, and taping it over the pod filter. It fires and idles good, but it won't go over 5k while riding, no matter where the fuel screw is. It seems to be loading a little on Idle but lean on throttle. I guess i need to look again at my carb diaphram.

DUDE! You've got to post a picture of this, it sounds friggin hilarious! :woohoo:

The bike needs nearly the entire surface area of the pod filter to run in the top end.

leave the pods alone (they never did anything to you), just play with the carbs and bring that fuel level up a couple mm from stock.

Good luck!

matt_finish wrote: Well, after getting my exhaust finalized, i thought that i would mess with the carb some more... I was able to get it to run fair with a 110dj main by cutting the bottom out of a soda can, triming a 1"x1/2" hole in it, and taping it over the pod filter. It fires and idles good, but it won't go over 5k while riding, no matter where the fuel screw is. It seems to be loading a little on Idle but lean on throttle. I guess i need to look again at my carb diaphram.



Btw, i scored a nos manx reverse cone muffler for $30. I am pleased with the look, but i may angle it up a tad more.

What kind of soda can? I may want to start marketing a mod for the pod! Sounds like a fortune waiting to be made. :laugh:

Most probably aluminum.

Specs should include the more fuel resistant yellow teflon tape.

Hope this helps.

650ed wrote: What kind of soda can? I may want to start marketing a mod for the pod! Sounds like a fortune waiting to be made. :laugh:

:laugh: :woohoo: :pinch:

HEY BUDDY! Just buggin -no sweat! I've seen everything from tape to epoxy put on pods in the "Ultimate Search for Pod Power".

Peace!



HONESTLY thou -quit F'in with the PODS. It's not thier fault, its improper carb setup!
Work at just one part of carburetion at a time! Like start with idling (no choke) and having best/highest idle mixture screws at around 1.5 - 2 turns out. Then go onto to just the light pull away (like 1/8th - 1/4 throttle) if it hesitates there, try raising your needles a bit.
Then on and on...

Riding the bike, and feeling things out can be not so great for the engine - it should work damn near perfect on the stand first.

it's cool, i can take a little razzing if it gets me somewhere in the long run.... :laugh:

Sadly, after i tried it, i took it of and trashed it.

So today i stopped by a friend's house and picked through his race spares. i grabbed a new mikuni vm28 and a proper cable off the shelf, loaded it with a 120 main and a 17.5 pilot jet. I'm going to get it bolted up and see where I'm at in the morning. I was looking for a vm26, but I'll see how this works out. he mainly deals with 2 strokes, so 120 was the smallest main that he had. if it ends up being too big, i'll have to wait until tuesday to grab smaller ones.

I know that the mikuni vm is a top choice for an upgrade on the mojave 250 and the klx as well, so I'm hoping it sorts my little Z out...

Matt

So after about every carb/ jet combo that I could have tried, I found out that my coil was the culprate... I had a good spark , but just not every time, and not as good in the cylinder as out... I went back with the keihin 29 with a 100 main, and .040 needle shims. after replacing the coil, she runs good now. thanks everyone for the suggestions, and ribbings.

Matt

matt_finish wrote: So after about every carb/ jet combo that I could have tried, I found out that my coil was the culprate... I had a good spark , but just not every time, and not as good in the cylinder as out... I went back with the keihin 29 with a 100 main, and .040 needle shims. after replacing the coil, she runs good now. thanks everyone for the suggestions, and ribbings.

Matt

:laugh: A good self taught lesson: It requires alot more voltage to produce a good spark under compression than in the open air.
Check for poor ignition quality with a timing light, bike running. look for any miss in the flash at all, as this indicates ignition system issue - completely unrelated to engine/carb issues at all.

Cheers.

Right, right...

I should have known, but it seems that subconciously I enjoy making things harder than they need to be. :laugh:

A plug chop earlier today at 40mph still showed white/lean. I'm getting a hesitation on top end, so I think that I'm going to try a 102.5 main and see if that clears it up.

I will probably try to get a tail light and maybe an old plate on it before I do too much more riding, considering the fact that I don't have a valid mc license right now. :whistle:

Matt.