need help with carb

[warx]

Hi all

So I was at Davis today with my son and after a winter of storage (in a garage) and just one practice session on them both my yellow clones were acting up.

I cleared out the old gas and replaced with fresh. One machine was OK - except the idle needed turning up quite a bit. The other engine? Well it was just never happy and I could see gas leaking from the carb and I popped the air filter off to see gas pooling. This was on my sons kart so I swapped mine after a few laps (knowing that would be all I would get!) and he was happy for a few sessions.

I stripped the other carb down and the float valve was working fine - tested by pressurizing the fuel tank (with mouth). Everything looked good. Checked the 36 emulcian tube and jet. All well. Not much else I could do so put it back on. I did notice that if I tip the carb to 45deg it leaks out of the float bowl I think - at least it must be. The rubber o-ring was seated ok. When running it has a spray from under there too - hard to see really where though.

Not sure where I go from here. New carb? Any recommendations for box stock (box stock carb from ARC :-))

Plus thought these things where so low tuned that I was surprised the other engine did not run exactly the same as it did last time (although it was cooler that it was in Fall).

I did try tweaking the idle mix screw for giggles had no effect on any range - probably as it was majorly rich (and plus was black and a bit wet). Could it be the needle jet is not working when running AND the float bowl leaks as well?

thanks
Mike.

[joshgarwood]

Probably got something tiny plugging up a little hole.clean the whole thing with Carb cleaner. If not you can get one super cheap anywhere.

[warx]

OK - thanks. Did not feel like taking too much apart sitting on the parking lot. I just KNEW I was going to lose something. I will order a new one and then start working on this one. At least if it ever happens again I can still go drive with my son. Ah redundancy - what a great word.

$18 unbored stock
$55 for 0.615 bored out stock - which is what I have on my ARC engines I guess.

I'll think I'll pay for them to bore - I do have a 5/8" stubby drill - but think that is 0.625 - then when I beat y'all and my engines gettin' stripped ...
[totally kidding!! - not bloody likely at all]

Thanks!
Mike.

[warx]

Well I opted to order a whole spare race prepped engine from ARC after all. I mean given it takes me 1hr 30 mins to drive each way to the track I don't want my trip spoiled by a cheap engine not running.

Plus I have the old non-legal mufflers so I ordered a couple of mini-91 ones.

I did see something changed about chain guards but can't find the details hopefully these ARC ones are OK.

[brad42]

Problem is not cheap engine as much as a poorly informed mechanic......california pump gas goes bad in 4-6 weeks. Initially it will just gum up everthing, then it starts clogging stuff. Eventually it becomes a corrosive and starts eating things. You either need to drain the tank and float bowl anytime it will be sitting a while , or use Sta-bil fuel stabilizer. In a race, fuel stabilizer is illegal.

[Simon]

"$55 for 0.615 bored out stock"

That's not legal by our rules is it ?

[warx]

Was not negatively implying anything by "cheap engine" - other than for a cheap price I can get whole spare engine so I will less likely suffer disappointment at the track.

Surprised it went downhill so fast - I last ran the karts around late November when the rains started in earnest. I will drain from now on as I do store karts at 50deg angle on their kart-kaddies and always worry about gas leaking into cylinder/oil. Also got Sta-bil in my jerry cans (use for generator/racing boat/hovercraft) - but not in the actual kart tank - but must remember to use dedicated can for the kart....

Also worried now - if you buy the AKRA box stock ARC engine DJ-1015 it comes with the 0.615 bored carb. Now I am getting my third I hope they are legal here!! (Gulp!). It also lists DJ-1055T "Trick" valve springs (Double Gulp??)

www.arcracing.com/servlet/the-5/Box-Stock-Project-BSP/Detail

[brad42]

Ask Tom at ARC if that package is AKRA legal. If he says it is, it is.

I had a John Deere riding mower bend an intake valve pushrod because I started it with bad fuel in the float bowl. Cost me a buncha cash to fix it.Gas was in tank from Nov to March1

[warx]

Crikey! - yeah the gas that was in my sons Top Kart tank was real orangey brown - maybe it had started to dissolve some dye in the red fuel pipes. I had drained that even before trying to start it.

I'll work on the stripping the carb tomorrow. I'll do a better inspection of the the float bowl o-ring too. Doubt its worth getting a rebuild kit! I've learned my lesson.

I'll also call Tom tomorrow - pretty sure he lists it as AKRA but to hear straight the from horses mouth...

[Simon]

My mistake. I just was confused by the statement in the ARKA rules that say "No machining or alteration of parts is allowed unless specifically noted." ... but later they talk about the venturi being max no-go of 0.615. I guess that means that's an 'specifically noted' part, so it's fair to get machining.

[sean51]

They are legal...however for some reason i was always faster with the pure stock one by about .1.. i could feel the difference on the straightaways.... maybe a lucky carb?

[warx]

Huh! That's interesting... almost worth trying a stock carb (for an investment of $18!!) I wonder what the stock bore is. By the sound of it pretty close if all they are doing is taking it to the max allowable tolerance really.

Perhaps that stock carb was out of tolerance and larger than 0.615? Or maybe at certain crucial points on the circuit the smaller venturi actually improves torque?

I presume to change the carb during a raceday would not be legal? [sorry - still new to this!]

[Scott Conway Racing]

Have been checking carbs and finding them to come around .611, most of the clone stuff back there is oval and running wide open most of the time, alot of people I have talked to also say the stock carb was best for them, just like the improved CL1 the bigger carb might make more power above 5000 rpm, but on our sprint tracks time spent at that rpm is not as much as on ovals, the smaller bore and less duration cam will make more torque and power from 3000 to 5500 where we run the most, maybe Atwater the big stuff would be better, best way to find out is try it and see for yourself

[warx]

Hmm - I am thinking perhaps I call ARC and change my order to a stock motor - I mean I already have two of their prepped stock ones (springs and carb work).

Actually maybe since I am happy for them to prep it and put the better springs in and remove governor I'll just ask them to ship it with the stock carb and maybe get $30 credit or something.

These ARC engines come with the stock cam I believe. From my reading here that is what most folks are using.

[Scott Conway Racing]

Get the cam and springs, better than stock, also get a thin head gasget,but maybe not the newer cam, you need the springs for sure, ask them they will get you the rite stuff not sure if you need carb though, carbs are tricky, I think some are just better than others, never know what your gonna get blueprinted or not