builder bob
New Member
I can't seem to get my engine tuned quite right, where is the idle mixture screw that I keep seeing mentioned?
Hausheng tuning
- Thread starter builder bob
- Start date
MotorBicycleRacing
Well-Known Member
It's hiding under the brass plug next to the motor.
Drill that sucka out but don't tell the EPA! ;D
builder bob
New Member
Why'd they cover it up?! I've spent the last few days trying to get it running good by rejeting the carb and all I had to do was drill a plug out 
builder bob
New Member
I thought there was a screw under that cap, it's just a bypass point for air to get around the throttle valve
MotorBicycleRacing
Well-Known Member
We are talking about a mixture "screw" on a 4 stroke carb.
He has not drilled the plug out yet probably because he just read the post.
Bam, you misunderstood.
Mixture screws are tapered to s point.
scotto-
Custom 4-Stroke Bike Builder
builder bob
New Member
I drilled out the only brass plug i found on the carb and there was no screw behind it. All there were were a couple tiny holes that allow air to bypass the throttle valve. Can someone post a picture
MotorBicycleRacing
Well-Known Member
The brass plug would be to the left of one you drilled.
Is there a mixture screw right next to the one you drilled?
Post a pic would help.
Is there a mixture screw right next to the one you drilled?
Post a pic would help.
builder bob
New Member
I found the screw, thanks
MotorBicycleRacing
Well-Known Member
Ok, did you drill out another brass plug?
Would be good to know what happened.
Where did you find the screw?
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KCvale
Well-Known Member
Have you relieved your HS 142 of the stock box exhaust and put an NGK 7544 (CR7HIX) plug in it yet?
That's the magic first instant ~.5hp upgrade combo, and even a 2-stroke pipe works great.
You'll forget all about idle issues when you get great fire and it can breath.
Msiert
Member
That screw is a fuel mixture screw it's on the engine side of the carburetor not the air filter side. I truly believe there is not a standard setting of that screw done at the factory. Mine was set at 1 and 1/4 turns out and a friends bike carb was set over 2 turns out.
Drilling out the brass plug that's covering that's screw to be able to tune the carburetor is a must thing to do if you want your HS engine to run well.
Drilling out the brass plug that's covering that's screw to be able to tune the carburetor is a must thing to do if you want your HS engine to run well.
trialnerror
New Member
I saw a thread once that explained which way and why to turn the screw to tune it correctly--- but forgot where it was. can anyone steer me in the right direction?
builder bob
New Member
Right next to the engine, I just drilled out the wrong one thinking it would be the one with the thinner plug.
I haven't put in a new plug yet but I did make a new exhaust for it which does smooth out how it runs.Have you relieved your HS 142 of the stock box exhaust and put an NGK 7544 (CR7HIX) plug in it yet?
That's the magic first instant ~.5hp upgrade combo, and even a 2-stroke pipe works great.
You'll forget all about idle issues when you get great fire and it can breath.
I was getting pissed at my carb and figured there was still some junk stuck in it from sitting with gas in it I so bought a new one. With the stock jet (.021 I think) I can get it to idle perfect and hardly bog when i rev it but when it's wide open it revs up and down. With a .019 jet it'll idle and hold WOT but it bogs when I rev it. The plug's the right color in both cases. What do you think it is?
I can't remember which way is which either but if you turn it until it bottoms out you know it's fully leaned out. Loosening it from there is richening it.
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KCvale
Well-Known Member
I don't know if it's the dry hot air or altitude here in Phoenix but I never have to mess with the carb.
I put an NGK plug in and a pipe on and it rocks.
38 mph up a slight hill in 7th gear pulling 11,500 RPM's with no problem at all.
Just a lovey ride on a hot summer day.
Yes, it is summer here, just got our first 100F day.
I put an NGK plug in and a pipe on and it rocks.
38 mph up a slight hill in 7th gear pulling 11,500 RPM's with no problem at all.
Just a lovey ride on a hot summer day.
Yes, it is summer here, just got our first 100F day.
trialnerror
New Member
I don't know if it's the dry hot air or altitude here in Phoenix but I never have to mess with the carb.
I put an NGK plug in and a pipe on and it rocks.
38 mph up a slight hill in 7th gear pulling 11,500 RPM's with no problem at all.
Just a lovey ride on a hot summer day.
Yes, it is summer here, just got our first 100F day.
I want my engine to turn 11,500 rpm's
builder bob
New Member
Have you got an internal geared hub on there giving you the 7 gears? How is your engine even staying together at 11500 RPM?I don't know if it's the dry hot air or altitude here in Phoenix but I never have to mess with the carb.
I put an NGK plug in and a pipe on and it rocks.
38 mph up a slight hill in 7th gear pulling 11,500 RPM's with no problem at all.
Just a lovey ride on a hot summer day.
Yes, it is summer here, just got our first 100F day.
trialnerror
New Member
I agree this little four stroke with a history of blowing the connecting rod caps, when revved too high, turning at 11,500 rpm sounds kinda- ?
Let me know what parts i need to get, for that rpm range? because the stock engine won't spin that fast, and a spark plug won't make it do that either.
Let me know what parts i need to get, for that rpm range? because the stock engine won't spin that fast, and a spark plug won't make it do that either.
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trialnerror
New Member
Msiert
Member
It can spin that fast.....one time then BANG!