My Mini-Bike or what ever creative name you can

[geldartb]

looks like a weird little piece. at least it didn't damage anything. sure looks like it had a go around more than once.

i gotta tear mine down too..partly to re-gasket it, who knows how long the gaskets have been there and see what condition the inside is like.

[geldartb]

did an oil change and cleaned/regapped the spark plug. threw some of the rotella t6 5w40 in it since it calls for high detergent oil.. built a handle for the cart to use on the hitch setup.

haven't done a top speed run again but cleaning and re-gapping the plug plus the new oil and actually being able to open the choke all the way it's got more off the line power.

and started getting my mower and trimmer ready for the grass.. fun times.

[Superdave]

Nice!

I took my 390 apart again and actually did find some damage, the gear on the balance shaft and the one on the crank are pretty beat up.

The gears for the cam are in good shape though, just posted up on the 4 cycle forum about it. Hope I can run w/o the balance shaft.

[geldartb]

which 4 cycle forum are you on. i've been scanning through a few but keep forgetting to bookmark them. lol sucks about the damage.

do you know of any of the GX cams that would swap in to the 140 for a little boost...

now i just need a tire with decent tread on it. the steer tire turf tread leaves little to be desired in the woods. mostly dirt with some leaves and tiny branches on my path coming out of the woods and this thing fish tails like a mofo. it's kinda like one of the snowy hill where you gotta get a running start and gun it.

EDIT
just finish rebuilding the front of the cart. the had some 2 piece tie-rod setup on the front that was held on the axle by a couple of rivet with the ends bent over. crazy slop on that setup and it was flimsy as hell so i used a piece of thick L metal and some rod ends. that part should be good for awhile now.

[Superdave]

Not sure on the cam, i've seen people re-grinding their own lately though. I did that back in the 90's to a few flathead cams and it worked out pretty good.

http://www.diygokarts.com/vb/index.php

http://karting.4cycle.com/index.php?

[geldartb]

the diy go kart one was the forum i was peeking around. forgot the other one probably end up scanning my browser history later.

any real benefits on porting the heads on these things. might do that to start..

found a thread on muffler silencing and they talk about making your own muffler. might build myself a baby flowmaster 80. got my old one off the GA i could use the metal from. lol


thinking about tires again and i think i might stick with the size tire i got now but a way different tread. really isn't much to choose from besides the turf tires and snow blower tires. probably gonna pick this one up.

[Superdave]

lol, you'll probably see me over there in those threads. I'll see if i can find pics of my mini FM 40 for you.


That tire looks mean, should do great offroad!


If you find the thread called "stretched my kart" i posted some porting info in there on a 340 head. There are a few spots that can be fixed but overall they aren't bad. Shaving it down is always a great way to pick up some power though.

[geldartb]

saw your thread on the balancer. just gotta remember where i put the flow 80 it's buried somewhere. lol don't remember if it was your screen name but i saw someone's custom FM 40 and the other guy who made a mini cherry bomb..

it's either that or the traditional snow blower tread. this one looks like it will still give a smooth ride on pavement. the turf tires for the riding mowers get caked up with crap and don't unload very well..the dirt just stays there

either the one i posted above or this tire..


as for the porting i was looking to do the smoothing of casting marks..forgot what engine it was but i checked some porting stuff out on there and on the exhaust side they just smoothed things out and the intake side removed very little metal.

i'd have to find somewhere to shave it though.. the thought crossed my mind on shaving it.

[geldartb]

this popped into my head after looking at a thread about cyl head lapping. gonna break out the compression tester and see where i am at as far as compression goes. that won't happen till the end of the week though.

can't seems to find the psi i'm looking for. you ever dealt with the 140..

[Superdave]

These engines have a compression release on the exhaust lobe of the cam. I'd loosen and flip the rockers off before testing.

Not sure on the spec for PSI but valve lash should be .003-.005 if i remember right. I need to set mine bad..

[geldartb]

ok thanks for the tip. that would make me WTF when i was doing the test if i was getting no reading.

found something awhile back that said something about .002 on the intake and .003 on the exhaust... iirc. never looked at that stuff on mine. it ran so i ran it.lol

[Superdave]

Sounds right, my 390 was at .040 on each when I got it... imagine the noise.. lol

[geldartb]

i think i popped the valve cover off once to peak in there to see if it was clean or not. was pretty clean given the engine is from the 80's.. lol

must have been a noisy little thing. lol my spark plug was like that. gap wasn't open far enough it was at around .20. set it to around .30. think it was that more than the oil that helped it run better..

[geldartb]

compression is still good. popped off one of the rockers and i'm getting 120lbs before the gauge doesn't move anymore.

cold engine BTW..

good think i decided to do this.. the valve cover gasket fell apart and a piece was missing. knew i bought that gasket set for a reason.

[Superdave]

Sweet


I set mine to .005 lash last night, the compression release actually works now. Much easier to start, now if i could only get the rebuilt carb to keep it running.

I re-jetted from a 90 to a 105, but also tanked the carb in the process. Now it fires up but only runs with the choke on. Gotta be something stuck in the idle jet..