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View Full Version : Yamaha Shaft 50cc two stroke trike problem



TXJcustoms
08-22-2015, 05:41 PM
A customer recently droped off a 50cc two stroke Yamaha shaft It doesn't run I've cleaned the carb check the plug and fuel flow everything seems to be fine but when it does start and you give it the gas it sits there and bogs or tries to move but doesn't then it just quits I have no clue what's going on with it and I have no idea what the mixture screw should set to or the idle. any help on getting this thing to run right would be greatly appreciated.

danbur55
08-22-2015, 06:48 PM
Welcome. And check to make sure engine is likely a 60 they had a start circuit and a run circuit controlled by the kill switch will not not accelerate on the start have to switch to run. May need to check clutch springs inside right side cover. Sorry can't remember carb setting but there is a free manual that is downloadable from this site also make sure the choke plunger is working. You might also unscrew the spark plug cap and trim 1/2" off of the plug wire then replace the cap. My zinger drove me nuts trying to start it until I trimmed the wire

TXJcustoms
08-22-2015, 07:14 PM
Attached more photos to the first post

yaegerb
08-22-2015, 08:17 PM
How do the reeds look? They may need to be replaced

TXJcustoms
08-22-2015, 08:50 PM
Where are they located at? The carb attaches to a long silver tube that connects directly to the motor

yaegerb
08-22-2015, 11:24 PM
Pull the silver tube off, that's your intake manifold. The reeds will be under that, below a couple of gaskets. If they are chipped or warped they will cause problems. Even if they are a fraction warped they can cause problems. I would order a new set with all new gaskets regardless of condition considering its age.

350for350
08-22-2015, 11:34 PM
I hope you were running it with the air filter attached. If not try it.

onformula1
08-22-2015, 11:55 PM
You might want a free manual for that trike, they come in handy.

http://www.oscarmayer.net/atc/manuals/

TXJcustoms
08-23-2015, 04:09 AM
In the picture is how it sits and how it was brought to me from what I understand they pulled it out of a scrap pile at the junkyard

onformula1
08-23-2015, 04:13 AM
In the picture is how it sits and how it was brought to me from what I understand they pulled it out of a scrap pile at the junkyard

That's cool, that's where I find all my stuff. :lol:

Doug8765
08-23-2015, 01:30 PM
Ex pipe clogged


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Doug8765
08-23-2015, 01:34 PM
Remove oil injection too ! Use premix at 20:1 ... Make sure carb slide is opening all the way these are all common problems on this machine


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TXJcustoms
08-23-2015, 05:26 PM
https://youtu.be/s4NzwmKX3HY

Video link above is of it running and how its acting. Any ideas???????

danbur55
08-24-2015, 06:31 AM
Was it on run or start at the switch?? Won't rev up in start mode. Cut back on oil mix I use 32-1 and doesn't smoke that bad good luck

muthey
08-24-2015, 11:30 AM
it's definitely fuel loading into the cylinder time to go through the carb and match the jets to see if they are right the main jet was originally a #90 and the pilot jet was a #40. Then pull exhaust check for a blockage in the pipe and also check to see if the restrictor plate is still there a the cylinder as it could be a culprit as well. I would definitely check the reeds over as well and also look at timing on it as it seemed really high idle which can be carb or timing. really hard to say what all is going on until you have went over it with a fine tooth comb since they found it used and abused in a scrap yard. I'm gonna go out on a limb and say that original owner was tinkering and adjusted things way out of whack. Mix screw stock settings is 2 turns out from seat, and idle screw I have found with mine is until the start and run settings on the switch have the same idle, however that one sounds really fast on start so I am betting the timing is advanced.

TXJcustoms
08-24-2015, 02:41 PM
After I get it to start I switch it to run

TXJcustoms
08-24-2015, 05:43 PM
After I get it to start on the start setting i switch it to the run setting it runs for awhile and quits sometimes it'll set and idle for quite awhile as long as you don't mess with the throttle other times it just back fires out the pipe with a puff of smoke

Doug8765
08-25-2015, 11:00 PM
Check compression


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John Tice
08-27-2015, 08:03 PM
Every new to you 2 stroke needs a compression & leak down test. If this looks OK then you’ll know that any troubles aren’t from the cylinder
JT