4 stroke always pulls and wont idle

B

bioboi

New Member
So I cant get the bike to not go if that makes sense, I messed with the screw that pushes onto the lever that goes to the throttle, if its all the way down it wont turn over, if I screw it in a little it just wants to take off, so I cant get anywhere. Whats my issue here? I have a normal 4 stroke engine with the red cover.
 
My dumb question, before you made any carburetor adjustments did the Huasheng engine start and perform as expected?
Is this a second hand build? Wiser heads will want to know.
Tom
 
Tom from Rubicon said:
My dumb question, before you made any carburetor adjustments did the Huasheng engine start and perform as expected?
Is this a second hand build? Wiser heads will want to know.
Tom
Click to expand...
Yeh actually everything did work for maybe a ride than I'm guessing something came loose and is starting to use higher rpms I had to tighten the head tho cause I could feel air leaking through. But i still haven't messed with it since this post so it's still doing the same thing any idea what needs to be done.
 
bioboi said:
Yeh actually everything did work for maybe a ride than I'm guessing something came loose and is starting to use higher rpms I had to tighten the head tho cause I could feel air leaking through. But i still haven't messed with it since this post so it's still doing the same thing any idea what needs to be done.
Click to expand...
Btw I built it myself
 
bioboi said:
Btw I built it myself
Click to expand...
I have a 2 stroke that works flawlessly I've been playing with these bikes since I was 16 so I'm 26 now this is just my first 4 stroke build I'm guessing it has to do with the gearbox since it has higher rpms the clutch is engaging.
 
bio,
These members should provide aid. PM them.
Greg58
FOG
Tony01
maniac57
MEASURE TWICE
My Huasheng ran great for miles. Stock carbs are problem prone. I bought a NT but have yet to install it. My second built distracts me which is my avatar. Photo is my DNR, Tom
1597965465318.png
 
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As was said an I confirm, even if not an air leak, some carbs are just that way. I found that carbs that have both idle and high speed needle valve adjustments more likely have capability to idle. Some carbs from lawn mowers don't need to idle slow, so they many mowers do not have the 1750 rpm slowness necessary to not pull on many centrifugal clutches. If they are self propelled mowers with carb that won't idle very slow, even with a governor spring assembly and air-vane or internal fly weight hooked up, those movers usually have a manual engagement to move. I think far back they made it mandatory that you have to hold that spring loaded bar in the handle for it to move. For a way to get by temporarily without a better adjustable carb if that is what it is, I have just pressed the kill switch button a bunch of times fast while wanting to idle. I also have a toggle switch in parallel with the kill switch to shut the engine off. Hit and miss engines can really idle slow and they are something of interest. Know the miss is actually intended and done for exceptionally low idle. This is not used on motorbikes as I know, but interesting none the less for using in old farm equipment at shows.
 
Sorry for not including you to the wiser heads list MT, I will amend my error.

bio, the nt is vastly superior to stock Huasheng carb and cab be got for less than twenty bucks.
MT raises a good point about governor troubles.
Tom
 
There is no differences in carbs 2stroke to 4stroke, excepting as I think is just is the throat size similar in range diameter. Is the physical connection going to work. Adapters are available from clamp to bolt on. Thread hole spacing on the cylinder or head where ever it be. Just because oil is mixed with fuel on the 2 stroke, I might see that it could be slightly more viscous. So a 4stroke carb would it get gummed up for maybe the jets are smaller? Anyway from what I've heard many 2 stroke carbs as labeled have worked on 4stroke engines. I would have actually tried, but I bout a cheap briggs carb. Unfortunately 20 or more years ago they were made with both low an high speed fuel needle valves, as current they skimp and don't. As the need for slow idle on like most lawn mowers, it does not matter. Governor only really just is for when going over pavement and transition to tall grass, so engine won't stall out. Actually I should say there probably are Briggs carbs new sold today that have 2 needle valve adjustment, but I was trying to save some money. The Briggs 25 dollar carb I bought 3 years ago is made in china, but the one mentioned many people use and it obviously too is made in china. I had a carb that was supposed to be similar to a Tecumseh. That clone was horrible though. The way the bowl and the main jet operated with some gasket that always leaked. I sent it back.
 
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MEASURE TWICE said:
There is no differences in carbs 2stroke to 4stroke, excepting as I think is just is the throat size similar in range diameter. Is the physical connection going to work. Adapters are available from clamp to bolt on. Thread hole spacing on the cylinder or head where ever it be. Just because oil is mixed with fuel on the 2 stroke, I might see that it could be slightly more viscous. So a 4stroke carb would it get gummed up for maybe the jets are smaller? Anyway from what I've heard many 2 stroke carbs as labeled have worked on 4stroke engines. I would have actually tried, but I bout a cheap briggs carb. Unfortunately 20 or more years ago they were made with both low an high speed fuel needle valves, as current they skimp and don't. As the need for slow idle on like most lawn mowers, it does not matter. Governor only really just is for when going over pavement and transition to tall grass, so engine won't stall out. Actually I should say there probably are Briggs carbs new sold today that have 2 needle valve adjustment, but I was trying to save some money. The Briggs 25 dollar carb I bought 3 years ago is made in china, but the one mentioned many people use and it obviously too is made in china. I had a carb that was supposed to be similar to a Tecumseh. That clone was horrible though. The way the bowl and the main jet operated with some gasket that always leaked. I sent it back.
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ahh, yeh I see the purpose in those governors, I have a tractor that comes under tremendous load when the blades are engaged but it maintains rpm. I hear briggs went out of business recently.

I couldn't figure out all the different carbs for my 49cc 4 stroke so I ordered the NT carb with what looks like alum 2 bolt adapter manifold, don't know if it will match up to my engine because the intake on the block is square but the one on the carb looks round.
I can order a seperate intake manifold for $12 with square intake if needed.
I didn't find any gaskets for sale to bolt it to the engine, these suppliers really don't have their act together.
The whole field of motor bikes is like a wild free for all.
 
I made adapter that I use to connect a manifold that would not line up. Additionally made another to set the bowl of the carb level as the engine is tilted about 15 degrees back to fit my DIY motorbike with Briggs 80202 series from 80's era side shaft 3.5hp. The gasket sheet material is quite inexpensive. I have sometime cut my own gaskets. HF tools has a leather punch kit that could work well to assist making gaskets along with one sided razor blade. Come to think of it the Briggs Vacujet carb, not a bowl type carb, only had 1 needle valve, but with governor I had it idle incredibly slow. But as many has said good stuff about this NT Carb, I'll possibly one day get one? Air filter is another thing you will have to see what work on the NT as it may be different than what you currently have from a different carb. I found that a foam air filter would not work even though I was able to make it attach to a carb I had. The foam one I scrounged from other parts off a trashed Lawn Boy mower. Even a new foam filter it would not run. Finally looked on ebay for a paper filter and housing to attach to the carb and it ran.
 
It looks like it has a filter already installed.
The original carb was foam filter, I think changing to paper filter would have a choke effect requiring mixture adjustment, I'll just try as it comes and find out.
I have all the tools to fabricate, lathe/mill/tig/plasma etc but can't be bothered. I just wanna ride before the snows come.
I'm up in northern Maine , snow comes early, I've been riding the snowmobile trails, we have them everywhere here.
Cops don't bother me because there aren't any cops here.
Engine is installed in a huffy nel lusso, cheap bike but quite comfortable and fine if you don't go nuts on the trails.
https://www.gasbike.net/products/4-stroke-nt-carburetor
 
Gotta love the old Pulsajet engines with 3/2hp. These devices are, as other posters have said, very basic. As others have said, just check the lash of your valve first. If that's all right, pop the carb off, disassemble it and clean it full. Put the new diaphragm back together and pop it in. Replace the mounting gasket of the carb with the intake outlet. Start your mixture up and adjust. You can bugger your idle screw setting (set too low) Normally if a pulsajet is thoroughly cleaned and has a new diaphragm, not much else can go wrong.
 
bioboi said:
So I cant get the bike to not go if that makes sense, I messed with the screw that pushes onto the lever that goes to the throttle, if its all the way down it wont turn over, if I screw it in a little it just wants to take off, so I cant get anywhere. Whats my issue here? I have a normal 4 stroke engine with the red cover.
Click to expand...

This sounds like an air leak, That causes high idle.
NT carb is a simple fix.
 
bioboi said:
Yeh actually everything did work for maybe a ride than I'm guessing something came loose and is starting to use higher rpms I had to tighten the head tho cause I could feel air leaking through. But i still haven't messed with it since this post so it's still doing the same thing any idea what needs to be done.
Click to expand...
Huashreng? Ha ha ha ha!
 
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