shifter kart bogging help

Synchros shot? Weird noises while shifting? Not sure what needs to be replaced?
Post Reply
User avatar
gizmo
Master Standardshifter
Posts: 1000
Joined: Sat Aug 02, 2008 1:22 am
Cars: tC

shifter kart bogging help

Post by gizmo »

my new toy. ra64t has been owning me on the road courses lately so i got a shifter to level the field. it's almost racing season and i'm trying to get this s.o.b. to run right. i'm going to rebuild the fuel pumps this weekend. and while it's very cold here, i'm running a fairly rich needle jet, with no intention of tweaking the jetting until temps rise closer to race season temps. i think the motor is stock, but the previous owner told me i needed to run 118. so right now i'm running 100LL avgas. i can get 108 cam2 down the road but it doesn't store well. avgas does. 24:1 premix.

if you have any suggestions as to what would cause the bogging. let me know. cr80 motor. pump around fuel system (pulse line fuel system / vacuum line fuel system ).

i'm hoping i can avoid having to rebuild the motor, since i don't have all the tools to do it, and i'm not totally convinced i can do it without screwing it up. i might be able to rebuild the top end if i can get ahold of a circlip plier, a feeler gauge, and a torque wrench.

http://www.youtube.com/watch?v=fqW0BZ5VinM


note: you can skip the first 50 seconds, just trying to get some warmth in the tire carcass first.
ra64t
Master Standardshifter
Posts: 1057
Joined: Sat May 20, 2006 9:14 pm
Location: VA, USA
Contact:

Re: shifter kart bogging help

Post by ra64t »

It looks and sounds decent, good enough to have fun and learn the basics on. I think you know I'm currently having more major problems with my kart :(
My racing blog: aracingdream.com
User avatar
gizmo
Master Standardshifter
Posts: 1000
Joined: Sat Aug 02, 2008 1:22 am
Cars: tC

Re: shifter kart bogging help

Post by gizmo »

you're having problems with your kart?

everytime the kart sputters, that's not me intentionally blipping the throttle, that was me trying to see if maybe i was flooding the carb. i was doing anything i could to cure the bog, but she just wouldn't go. i think it's quite the problem. =/

surprised between ropeburn and cowmilk that i haven't gotten a single response.
Rope-Pusher
Master Standardshifter
Posts: 11607
Joined: Mon Mar 16, 2009 3:44 pm
Cars: '08 Jeep Liberty
Location: Greater Detroit Area

Re: shifter kart bogging help

Post by Rope-Pusher »

Fine - It's too rich or too lean.
Image
'08 Jeep Liberty 6-Speed MT - "Last of the Mohicans"
ra64t
Master Standardshifter
Posts: 1057
Joined: Sat May 20, 2006 9:14 pm
Location: VA, USA
Contact:

Re: shifter kart bogging help

Post by ra64t »

gizmo wrote:you're having problems with your kart?

everytime the kart sputters, that's not me intentionally blipping the throttle, that was me trying to see if maybe i was flooding the carb. i was doing anything i could to cure the bog, but she just wouldn't go. i think it's quite the problem. =/

surprised between ropeburn and cowmilk that i haven't gotten a single response.
yeah the frame may or may not be scrap, I don't know yet can't tell by myself.
My racing blog: aracingdream.com
User avatar
gizmo
Master Standardshifter
Posts: 1000
Joined: Sat Aug 02, 2008 1:22 am
Cars: tC

Re: shifter kart bogging help

Post by gizmo »

as an update, here is how the kart has progressed.

i determined that the motor was low on compression. when i spun the flywheel and the piston moved beyond top dead center, there was no real additional resistance. the motor is only 80cc, so it wasn't immediately clear whether that was abnormal. research soon proved it was abnormal. so i bought a piston replacement kit.

i went to remove the head on the motor. the engine is water cooled, so to do that i first had to drain the coolant. turns out, simply removing the drain bolt on the water pump will not completely drain the coolant. the cylinder has a drain "screw" on its side, and that needs to be removed in conjunction with the pump's drain bolt to completely drain the system. long story short, when i removed the head, i learned the hard way that the cylinder needed to be drained by itself. and antifreeze spill into the cylinder, past the ring, into the crank case. i decided against disassembling the crankcase to remove the coolant, in hopes that it would just clean itself out/work itself out.

so i rebuild the top end, the first time i've ever rebuilt a motor, and i get the feeling i improperly filed the ring to its proper gap. so i get the feeling there are some burrs and i wonder if they'll wreak havoc on the cylinder's nikasil plating. ignoring that, there is a ton of resistance TDC, so I'm hoping the rebuild will prove to be a gain in HP. i only drove the kart for about an hour after i bought it, so i'm hoping when it bought it it was already low on compression/power. with all the aggrevation, it would be a real buzzkill to find that all this work gained me nothing in the way of power.

i put all new fuel lines on the kart, since the old ones were hard/brittle. i rebuilt the fuel pumps, which runs off the vacuum (pulse) in the crankcase. so basically the kart came with a modified carb, it has no floats, and it uses pulses from the crankcase to serve the functionality of a float, without the worry of the float sticking during high-g turns.

i was torque-ing all the bolts down, when i snapped the waterpump drain bolt off in deep in the water pump itself. it was a pain in the ass to easyout, but luckily i managed to get it out. my torque wrench snapped off another bolt, that holds that radiator in, and i almost forgot to get that out.

i don't think i reinstalled the clutch cable properly, the cable works, but to work it relies on the sheathing being in a static position, and i'm not convinced the sheating won't come dislodged from its holder, since there's nothing retaining the sheating in the holder. if the sheathing were to come dislodged from the holder, the clutch would fail to engage/disengage. so i'll have to do my homework there.

took me a long time to find someone who could explain what i had to do to prime the fuel pumps. apparently they're intended to work at really high RPMs, so to prime them, i basically have to spin the motor very fast. it can't reallly be done by hand, so you have to put a tow strap on the rear axle and rev the motor that way.

i repacked the silencer hoping i could get some gains in power from that.

the o-rings on the exhaust manifold melted, and premix was spewing out all over the electronics. so i replaced the orings, and the springs that keep the pipe on the manifold, in hopes that with a better seal i'll get a little more power... since these pipes are tuned to give the motor more power.

i bought a new air filter, and clenaed the old one, in hopes of the clogged air filter causing the motor to run rich.

i took parts of the carb apart, to the point where i was convinced it was clean and nothing was preventing it from working properly. the needle looked maybe a little worn, but the piston i replaced showed signs of being well tuned, so i was inclined to leave the carb the way it as, even though i do have a couple of extra jets and a new needle.

that's all i can remember for now.
Post Reply