Trailmaster XRS 150cc Bogging down

[Mkulrey13]

I'm running out of ideas and I'm hoping someone has a simple fix. Basicly the kart idles great, no issues. When you give it gas, it bogs down like it's being flooded and it doesnt get out of it's own way. Trys to move but does not. Ive cleaned the carb, I've replaced the carb, replaced the electric thermal choke. No difference. Fresh gas etc. Any ideas? I'm about to burn it lol.

[plee911]

Check and make sure that when you're hitting the gas your slide is going up and down if not check your vacuum to your slide

[plee911]

Also have you done any upgrades like a pod filter or something like that that would be increasing your air flow check for leaks around your intake neck

[Mkulrey13]

I've check for leaks and found none. The kart is 100% stock less then 5 hours on it. I've tried open throttle by disconnecting airbox and no change.

[Mkulrey13]

Also where would i find the slide to look? Never heard of it.

[plee911]

Look down the throat of the carb with the air neck off you'll see a slide when you hit the gas that slide should travel upward to allow more air in if it's not traveling upwards it's not allowing air or fuel in and you'll get that bog

[Mkulrey13]

Old carb cleaned and brand new carb, no difference it still does the same exact thing. ill double check though.

[Mkulrey13]

Ill record a video of what its doing this evening or tomorrow. My buddy said it could be a sheered flywheel nut. I can sometimes get it moving but its very rough going but 95% of the time it bogs and jolts like it wants to go but doesn't.

[JERSEYDEVIL]

there's two kind of bogs ive come across, the carb/spark bog and clutch bog.
does the buggy do the same thing in nuetral or just drive. what i mean by clutch bog is that when the buggy is in gear a clutch arm can break and continuously grab the bell when it shouldnt. some symptoms could be walking away at idle or idles find, kind of sluggish but when you brake from driving it cuts the motor out. not sure if thats the case but if nothing else works might be worth checking.

the other....
obviously the carb is not the problem , youve cleaned one and replaced it. a vacuum leak might cause this, but the main symptom of a vac leak would be erratic idle, up and down not smooth. where to check, 1. the vac lines, both the carb and fuel pump/petcock are vacuum actuated so it will efect both which is the whole fuel system. another place it could be leaking is the composite spacer under the intake....they will crack over time, or for no reason at all. if youve been through all of this and it looks good, the CDI might have just decided to take a dump.
thats a few things to check, let us know.

[Mkulrey13]

It does the same thing N L and R. L and R it trys to move, somethings it does barely but then bogs and then cant get moving again. when its in N it doesnt try and move and like i said the idle is perfect. vac lines are new with the carb. weve unplugged one and when we uncover it it goes to die but if we put a finger over the line it idles back up to normal.

Originally Posted by JERSEYDEVIL

there's two kind of bogs ive come across, the carb/spark bog and clutch bog.
does the buggy do the same thing in nuetral or just drive. what i mean by clutch bog is that when the buggy is in gear a clutch arm can break and continuously grab the bell when it shouldnt. some symptoms could be walking away at idle or idles find, kind of sluggish but when you brake from driving it cuts the motor out. not sure if thats the case but if nothing else works might be worth checking.

the other....
obviously the carb is not the problem , youve cleaned one and replaced it. a vacuum leak might cause this, but the main symptom of a vac leak would be erratic idle, up and down not smooth. where to check, 1. the vac lines, both the carb and fuel pump/petcock are vacuum actuated so it will efect both which is the whole fuel system. another place it could be leaking is the composite spacer under the intake....they will crack over time, or for no reason at all. if youve been through all of this and it looks good, the CDI might have just decided to take a dump.
thats a few things to check, let us know.

[JERSEYDEVIL]

so when you say in neutral is doesnt try and move.....it's in neutral so it shouldnt move..... does it rev w/out bogging in neutral or does it only bog when in gear For REV?

[Mkulrey13]

Like i said it bogs when you rev it in N or try and drive in L and R. It just jolts back and forth like its trying to move but it just doesn't have the power too. I misunderstood what you said when you said does it try walk away in N. Life got in the way so i was unable to get a video.

[Mkulrey13]

Bump, Still looking to fix this issue. Sitting in my garage gathering dust lol

[neo71665]

If it's bogging in neutral it aint the clutch. To me it kinda sounds like you might need to re jet the carb. Sounds like the jet in the carb might be a tad big or was never tuned out of the crate when new.


First lets rule out any trans issues. Jack the rear tires up, put the rear on blocks or jackstands so the tires are off the ground and you can safely rev the engine without it falling off. See if it's still got the bog.

If it does look on top of the carb and you should see a shiny silver metal (might be black plastic) cap held on by 2 phillips screws. Take that off and carefully remove the slide. Under where the spring was there will be a tiny screw holding a plate down, remove. Push the needle up (do not bend this) and look at the top and see if it has a little clip and about 5 or so notches. Carefully remove the clip and raise it up one notch. Be careful with that little clip as it likes to fly off into another world never to be found again. Once you have it raised (if you can) put it back together and try to run it again. You might have to keep moving it but once you get it to the last mark or if its a fixed needle you will have to drop one size down in jet and start over with fine tuning it with the needle.

Welcome to the "black art" of carb tuning. It's about the hardest thing to do on a small engine but you'll soon be able to do it in your sleep.

[SYCARMS]

Remove the air filter and look in intake of carb. You will see the slide and below it if you lift slide the needle. Where the needle goes through the bottom of carb there should be a bushing the needle goes through and will stick up slightly. Is that bushing there?

[Mkulrey13]

Thank you guys for responding! Last night my buddy and I dug it out of the garage. We can only get it to idle if we spray some carb stuff into the intake. Has a entirely new fuel line tank directly to carb no filter nothing as it doesn't seem to be sucking in any gas so we just ditched the filter for now. It will not stay idling unless we are spraying and even then it struggles to idle. Just to backtrack, This has a brand new carb, Brand new automatic choke, Brand new fuel line. The prone to cracking intake tube is not leaking either. New spark plug also. I will look at what you guys suggested today after work hopfully.

[neo71665]

Originally Posted by SYCARMS

Remove the air filter and look in intake of carb. You will see the slide and below it if you lift slide the needle. Where the needle goes through the bottom of carb there should be a bushing the needle goes through and will stick up slightly. Is that bushing there?

memory serves me correct the bushing should be brass and be easy to see in the silver aluminum carb throat

[SYCARMS]

Yes some are brass. Usually gets lost when cleaning.

[Mkulrey13]

Got the kart working. Something must of been clogged i honestly have no idea, We emptied an entire can of carb cleaner spray while trying to start the kart. got it started reved to the sky while spraying the cleaner into the intake and now it runs like it was brand new. We installed a new carb prior to this and still had the issue. Any ideas? lol

[neo71665]

Check the electrical connections. You might have a bad plug and while you were working on it bumped it making it get connection. I chased this very issue on mine for a month before I found it when I completely rewired and changed out every plug. Ended up a plug that looked fine on the outside but had melted the inside loosing connection. So when you check unplug and look at the inside good.

[SYCARMS]

What kind of compression do you have? What color is spark? Have you adjusted the valves? This will also tell you if timing has jumped. When you replaced the carb what main jet did it have and what jet did the old carb have?

[Delois]

Look down the throat of the carb with the air neck off you'll see a slide when you hit the gas that slide should travel upward to allow more air in if it's not traveling upwards it's not allowing air or fuel in and you'll get that bog