Engine problems post-alignment

[vadermonkey]

hey guys,

this week i put a new sprocket (same size) on my kart. while the chain was off, i ran an engine test, and let it run, but it kept sputtering and ran with me having to jimmy the choke, until it eventually died on me. i thought this was strange, but i attributed it to the fact that there was low fuel in the kart. after this, i put the chain back on, aligned the engine, and tightened it into place, to a point where the chain is not very tense, (close to its previous tension when it ran fine.) after all was in place, the engine just wouldnt start. i have a 6.5 hp lifan horizontal with a centrifugal clutch. when i first started yanking the ripcord, the rear axle would turn as it does regularly, but after a few yanks it stopped, only the inside of the clutch would spin, giving no friction to pull the chain.

i was wondering if anyone might be able to diagnose this as a fuel system problem, a clutch problem, or something else entirely. i can have pictures up sometime tomorrow if that helps.

thanks very much

john

 

[edgeblade]

after all was in place, the engine just wouldnt start

Does it not turn over at all?....check to see if there is any trash in ur carb..when u ran it low it might have sucked up what trash was on bottom of tank

 

[Half-breeder]

I had the same clutch issues as well(every so often when first start it would take off on me not even being on it). I found that the clutch 'drum' had slid off the slip race(copper race pressed into the sleeve of the drum allowing free spin. the 'drum' was actually catching alil bump of rust that was on the rotating part of the clutch causing it to slightly engage w/out the rpms. I took the clutch apart... filed any burrs on the race and slide, lightly. before pressing the copper ring/race/bearing I cross hatched grooves on the outside of the ring, and the inside part where the ring was pressed in. I then took .5+.5 gorilla glue and locktite "red". I lightly coated the exterior of the ring and rubbed the excess on the inside of the drum part. W/ a vice, I pressed it back in place(copper ring 'should' set flush w/ outside of lip of drum race. On the inside i took a flathead and dimpled an edge outward, to help prevent the race from sliding back out again if the glue/'red' didnt hold. Replaced the 'c' clamps after oiling the slide and the bore. Reinstalled, let dry over night. Did a 'free' turn of the wheel(no motor running) to see if the clutch had binded up(it didnt... I made sure the 'glue' was ONLY where I wanted it... used alcohol immediately to clean up). Now it's like a 'new' clutch.

I have no pics of this process... but its the 2nd time ive done it and the 1st was for a friend afew years ago on another kart(which he still drives today w/ the same clutch, untouched).

Indications of something like this needing/soon to be needing, to be done(for me)...

The clutch drum tends to 'ring' when the motor is running, and a shiny copper ring/race, can be seen next to the lip between the teeth and the 'outer' 'c' clamp.

When clutch is 'cold', there will be an abnormal amount of 'play'/wobble of the 'drum'. and the lip of the outside of the drum will 'cover-over'(recessed in) the clutch plates/shoe housing(part inside that always turns when motor is running).

 

[vadermonkey]

half-breeder,

this seems like a problem which needs the motor running to come into effect. did your clutch issues prevent the engine from starting?

 

[edgeblade]

I'm assuming u can't get it to start...check for compression...fuel (u can try to spray some carb cleaner straight into the carb) and fire to start an engine without any of those it won't start I still think its ur carb picking up trash from tank since u ran it out..either clan the carb out or try carb cleaner

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[vadermonkey]

im gonna try checking the carb and cleaning it, but does that explain why the axle wont rotate even slightly?

and if i ran through on fuel, the trash should still be stuck in the carb right?

 

[edgeblade]

If u block the cart up will it turn freely then?...if not try taking the clutch off or better yet just the chain and see if it turns free then if the engine turns and the axle spends then ....tjen its prob what half breed said it would be ur clutch

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[vadermonkey]

thank you all,

i cant work on it right now, but ill be able to in the next few days, maybe up until thursday, and ill update my condition then.

thanks very much

 

[OzFab]

im gonna try checking the carb and cleaning it, but does that explain why the axle wont rotate even slightly?

and if i ran through on fuel, the trash should still be stuck in the carb right?

To irrefutably determine that the carb is the problem, first, check for spark; remove the spark plug, attach it back to the spark plug lead, rest the plug on the engine & pull the starter while watching for spark at the plug.

Once you've determined you have spark at the plug, pour about a teaspoon of fuel into the plug hole, refit the plug & pull the starter; if it tries to start, go ahead & clean the carb...

 

[Half-breeder]

... a 'binding' clutch (while running) will 'seem' like a motor sputter/hesitation because the race only binds at certain angles/times...add a chain/axle/wheel/ground/traction/gravity to the mix... and it's possible the motor wont even turn over...just cant figure a 'reason'/how a carb/motor would have an issue w/ a sprocket change... other than that.


...or like I said...'Karma'... lol

 

[vadermonkey]

alright guys, i've cleaned the carb, replace some fuel lines, and checked the spark.

after all this, the engine will start, but it starts to struggle and die off. i have to keep jimmying the choke for it to stay alive, and it wont stay if i leave the choke still, so i feel like it might be flooding/starving. do any of you have experience with this?

 

[vadermonkey]

for further info, my kart has a rear-side mount engine, and the gas tank sits between my legs, so the tank is connected by a fuel line which runs from under the steering column to the engine behind me

 

[rocketkart]

check your intake gasket between the carb and the cylinder you may have a vacuum leak. make shore you cleand all the little holes in the carb and jets.

 

[OzFab]

What's it like without the choke? What's it like above idle?

I had a similar situation a short while ago (but not as bad), engine simply wouldn't idle unless the choke was on & even that was unstable. Turns out the idle jet was blocked, a bit of carb cleaner in the correct hole cleared it & everything was good again

 

[vadermonkey]

fuel/air problems

does anyone know what this part is?

i opened it and found tears in the thin rubber lining inside of it, i assume this is where my fuel problem is coming from.

(apologies if this is very newby of me)

 

[edgeblade]

Fuel pump


DidU have the gas lines running from ur tank to that pic then from the pic to the carb right?
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[vadermonkey]

Fuel pump


DidU have the gas lines running from ur tank to that pic then from the pic to the carb right?
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that is correct

 

[vadermonkey]

do you know where i can find a similar one, or where i can look to repair it?

 

[edgeblade]

If u know make and model of engine just do a quick goggle search or look on ebay I'm sure its less then $30

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[danssoslow]

Here's the cheapest Walbro I could find on ebay. It's a tank of a pump, and rebuild parts are plentiful if it ever becomes necessary.
http://item.mobileweb.ebay.com/viewitem?sbk=1&nav=SEARCH&itemId=380702884419

You might find a model number of some sort on that pump you have. With that, you might be able to find yourself replacement diaphragms.

You might also want to check (pun intendes) into installing a gas line check valve to keep the fuel from settling back into the tank between runs. No doubt, the diaphragm ripped after it was ran dry, and the pulse from you turning the engine over tore the old brittle diaphragm. As long as the pump stays full of fuel, it shouldn't happen again.
If you would rather not worry about the check valve, you can easily prime the line by either loosening the carb bowl drain a little bit and blowing into the gas tank untill fuel seeps out of the bowl; or by placing your hand over the carb and turning the engine over a couple times (while the kill switch is in the off position).