Racing Kart Problems HELP

[DeionGriffin]

Hello i Have A KT100s Kart Racing Engine On my Coyote Sprinter, It Was Running Fine the Other Day, This Morning i Went to Start it And, It Fired Right Up But When i Went to Give it Gas and Take off it Just bogs out, ive checked the H & L Idle screws Still haveing the Same Problem, All Advice is Welcomed

 

[anickode]

Disassemble and thoroughly clean the carb.

 

[DeionGriffin]

Thank You, Ill Do it And You Will Hear Back From Me This. Thanks In Advance! And What Would i Clean The Carb With This Is an Amazing Kart With Great History Behind It Just, Want to Get it Runnig Agin, But Am Really New To Working Witg Motors and Thing as such?

 

[Joe-405]

Put a new spark plug in it first. It’s a 2-stroke.

 

[aj992]

No need to clean carb, maybe if it were a 4 stroke but you're able to adjust the jets from the outside on these. There should be 2 little screws on the side of the carb (like the red and black one in the photo I attached), turning these effect the amount of fuel going into the carb, you're likely running too lean on your low speed adjustment screw (the one by the "L", the red one for me in the photo). What I would do is first turn both screws counter clockwise all the way closed. Second, turn the high speed needle about 1/16-1/8th of a turn open and leave it, you can pretty much keep that one there permanently. Then turn the low speed needle 1 1/2 turns clockwise as that's a good starting point (these engines seem to need endless adjustment depending on whether your starting it, or full throttle, or cold, or warm). From there if it bogs out turn it farther clockwise to richen it. If it starts four stroking, turn it back counter clockwise. Additionally, your idle screw should be just touching the throttle so it's only open a crack.

Finally, you want to make sure you're not running to lean because that could really mess up your engine so smoke coming out of the exhaust at start and lower RPMs is normal and expected.

 

[landuse]

No need to clean carb, maybe if it were a 4 stroke but you're able to adjust the jets from the outside on these. There should be 2 little screws on the side of the carb (like the red and black one in the photo I attached), turning these effect the amount of fuel going into the carb, you're likely running too lean on your low speed adjustment screw (the one by the "L", the red one for me in the photo). What I would do is first turn both screws counter clockwise all the way closed. Second, turn the high speed needle about 1/16-1/8th of a turn open and leave it, you can pretty much keep that one there permanently. Then turn the low speed needle 1 1/2 turns clockwise as that's a good starting point (these engines seem to need endless adjustment depending on whether your starting it, or full throttle, or cold, or warm). From there if it bogs out turn it farther clockwise to richen it. If it starts four stroking, turn it back counter clockwise. Additionally, your idle screw should be just touching the throttle so it's only open a crack.

Finally, you want to make sure you're not running to lean because that could really mess up your engine so smoke coming out of the exhaust at start and lower RPMs is normal and expected.

The thing is that the engine was running fine with the settings that he had. Something is clogging up the carb now for it to suddenly have this problem. Trying to "fix" it by messing with the adjustment screws is not going to fix the root cause of the problem

 

[Karttekk]

Does it have a fuel filter? Did you happen to get bad gas recently with water in it possibly? Start with the basics. Fuel hose collapsed, partially clogged fuel filter. Check the needle & seat if equipped. Like Joe-405 mentioned, throw a new plug in it or like anickode mentioned, the carb needs cleaned or the diaphragm could have torn in the carb if equipped. This is a good carb cleaning option.

Thanks

 

[DeionGriffin]

Thank You For all The Help And Reply s Have Been Busy First Time I'm Free Since I Made the Post I'll keep you guys up to date in a few Thanks agin

---------- Post added at 03:34 PM ---------- Previous post was at 02:39 PM ----------

Have took off the fule filter is there any way to clean it or should I buy new? Fule filter does look clogged with black old mucky oil

 

[gr8hairy1]

Definitely replace it. You can clean it up, but it won't be the same. It might work "for testing" purposes, but the flow won't be what it should.

Plus, fuel filters are super cheap. You don't want to foul up the spark plug and cause issues for just a few bucks.

 

[DeionGriffin]

Looking into that now

 

[itsid]

sudden decrease in performance can be as harmless as a (sp)oiled spark plug and as severe as a compression loss...
these engines are tiny and powerfull, and that's a combination that's asking for thorough maintenance every couple of "working" hours... (which in the case of a KT100 means racing/training laps)

So yeah, while the carb , fuel filter and spark plug are certainly amongst the first things to check..
it's quite good to check the engines logbook as well to see when it's last serviced, and then decide if engine maintenance is due by now.

It's about the most durable of all 100ccs I'm aware of, still it's a tight schedule you're dealing with.

Unfortunately, older 100ccs more often than not end up in amateur hands unaware of the tight maintenance schedule, more often than not without any documentation about
what was done where and when the last time...

IDK, I can't tell if you own the engine since this spring or since the dawn of time,
in any case.. ask the yamaha kt100 service manual (matching your exact kt100 model) for advice when in doubt.

it's perfectly okay to run an engine like that for slightly too long under -say 'cruising'- condition,
it's NOT okay to treat it as you would a twice as large and a quarter as powerfull four stroke engine

I'll keep my fingers crossed it's a fuel/spark problem you're facing!

'sid

 

[DeionGriffin]

I have Loads of documents for the kart, Race Stats Sheets Logs All kinda Stuff & I have The OG YM100s Kart Racing Manual aslo

 

[itsid]

race stats are the least important documentation of them all, yet named first

Anyways.. great, browse through that pile of paper and see when the engine was last rebuilt and what was done servicewise after that (good racing mechanics tend to note down wear even within specs to be prepared and list minor problems to keep an eye on etc.)
And also crosscheck your manual for maintenance cycles.

Keep in mind that racers have a very close eye on their engines (checked before and after each race)
Hobbyists like us don't most of the time...we tend to react to "issues" only,
and that's a perfect way to ruin an engine like that.
I wouldn't be concerned just yet, but I'd be cautiously observing let's say

'sid

 

[DeionGriffin]

Getting Fuel Filter tonight, Whats a 15:1 mix He used racing fuel Orange and white looking can and 2 Different Burris Brand oils? ( High Rev Blend & And Castro Are The Two, How Do I Get 15:1 Ratio With Racing Fuel & Both Of Those Oil) Thats what his Docs Say " Only Run 15:1 and So On" His Words & another thing I've found someone to rebuild the engine $650 in PA Def want to get it blueprinted tho Overall So Would The Rebuild be a Waste? and have a Question Can I Get up to date Plastics on my kart FP7 & Or MK14 Kit I don't want them now just wondering for down the road chassis Coyote? Have Much Engine Work And so Forth And Lot Of Number Crunching To Do B4 All That To Get Everything Right I def want to race this kart, Thought

 

[itsid]

So now we got an idea of your curent experience

you mix 15 fuels per oil by volume
(no matter what unit, liters, quarts, gallons, cups, tablespoons as you like and need.. 15 fuel one oil)
you should NOT mix oils IMHO, but you can if you like..
what ratio to mix the oil at is up to you; again I wouldn't.

pick one, then the other, see what your engine likes better, then stick with that.
if PO doesn#t say he mixed oils in certain amounts, then he unlikely did.
(he just used different oils for different tracks most likely)

engine rebuild in race engines is done every now and then,
it's part of the "usual maintenance"
it's usually honing the cylinder walls (remove wear),
refitting either oversized piston rings OR oversize piston (depending on wear and age of the cylinder - eventually replacing the cylinder piston combo),
replacing the bearings against fresh ones (done every time),
Assuring good sealing surfaces (head, deck, case halves, ports)
and where necessary replacing the crankshaft.

Blueprinting is essentially a marketing gag most of the time!
They rip you off and do nothing most of the time.
TRUE blueprinting is an INSANE amount of work, and pretty useless on a single cylinder engine.
What it would be on a single cylinder engine is bringing the engine back to ideal stock.
(new cylinder and piston, new crankshaft, crankcase replaced when worn..)
THAT is exactly what a rebuild does when due!
At best it'd be matching a few conrods/pistons against a few crankshaft to see what set runs truest in fresh casing halves, but new race parts have such tight tolerances that it essentially is pointless.

On a multi cylinder engine it matches piston/conrod weights against each other balancing the ghost out of every moving part normally requiring 4 to 6 spare sets of engine internals to get one perfectly blueprinted one, sometimes more.
IIRC Suzuki used 25 RF900 engines to make the record breaking one back in the nineties...

Anywho, it's BULLDUNG on a single cylinder (marketing gag to rip you off)
and likely unaffordable on a multicylinder for us Homegamers.
(you bought a used kart since it was cheaper, right? since you obviously are not thinking it looks better So, what do you want to spend? 650 for a rebuild or 3800++ for a true blueprint?)

'sid

 

[DeionGriffin]

Got the kart running after a new carb rebuild and Washing the tank out there was some kind of sand Looking substance All in the Tank when I drained the gas and cleaned it, Was Driving it Today, For the 1st time after all the fixes And It Smoked All White And it Was Thick, but when I mixed the oil I did 8oz oil and 1 Gal Of gas, 16:1 The Color it’s Like DarkDark Green Transparency ? the bottle said but The exhaust I have on it, ( Seen in Photos ) Now It’s Like it Won’t Fit On the Engine/exhaust mount bolts Correctly and Its just leaking have a Ton Of oil every where all over the engine and my seat, Bit when I drove it today I let it warm up for not that long about 5-6min then almost got around the block and it Bogged out, Then I Tried To Start it agin And Gas Just Pored out the carb I’m think Flooded, But idk I’m not and expert and not that experienced, But on my fuel tank there is a Dail/Knob To Start And Stop The Gas Flow and control how much goes in the line Should I Have The Knob Fully Open Or Should it barely Open what?

 

[ezcome-ezgo]

So it make so that the Fuel knob under on the tank lever is on off Make on so gas flows to the fuel.

Was that easy to read?

 

[DeionGriffin]

Thanks, Fairly Eazy To read And What Abput the oil problem

 

[ezcome-ezgo]

I'm sorry I don't understand. Hopefully someone will come alpng who speaks This Language.

 

[DeionGriffin]

Pics Say it All Let me Know What u Think