Engine bogging

[bigcitybikes]

Man, ive built alot of these bikes with just about every motor kit out there ..and im with you guys !!! i put a bike together outta extra parts i have and i have the bawging issue -! im stumped ! i made better gaskets for the carb intake and the exhaust out take ......im not sure whats up= i did change out the carb so i may have mixed carbs from 50 cc and 80 cc - equates to 48 to 66 ? i guess - i have no clue where the jet is but - i have dremel tools with every type of bit size and an extra carb layin here to expeiriment with - maybe drill the jet ? but how big is too big for the 80/66 cc motor?
frustrated!!!
[email protected]-for chat

 

[DuctTapedGoat]

I wouldn't go larger than the #76 for a 66cc. #74 is my peak on the 48cc.

 

[thunderbolts]

Check your head and base gaskets for leakage some head gasket's don't fit correct and will pull in air as well as the base, carb to intake clamp remove the screw and replace it with a Allen head screw, install a o- ring in the carb where the intake seats, add a second tube to exhaust end cap same size as the one that's there, spark plug gap at 28 on a ngk BR6HS That depends on your air temp. Drilling is like cutting a board to short!!! there is no getting it back. Do all your air leak checks first and I mean every inch of that little motor that will!!! you will be way ahead of your problems A nt speed is what you want on it for a carb, Think the jet's are fitted to the needle if you drill you loose the taper in the jet now your needle don't fit right move the clip on the needle start at the middle notch. if your bogging you have air leaks #1 thing to fix or no other fixes will help

 

[bigcitybikes]

well goat, i actually remoived the spark plug and gapped it a bit - didnt measure it and cleanned it with sand paper and power is restored to a degree -does anyone remember the correct gap for the 80 cc?

 

[bigcitybikes]

also i think the cap on the spark is crappy would love to buy a replacement plug cover that actually clicks in!!! autozone didnt have one!

 

[www.cowboy]

I had the same issues with a my grubee 48/ cns carb. After trying everything but re drilling the jet I switched to a speed carb. Now the bike makes it the 10 miles round trip to work an back. So us that are junking the cns carb must be taking the easy way out.

 

[bigcitybikes]

you guys are great thanks for the help= the cj8 plug is the one im usiing as i remebered it on another bike i built so bought that - never gapped it tho - meanwhile i will check for leaks at idle somehow - any ideas?
thunder ?
and cowboy were can i get a bettrer carb ? so called speed carb?

 

[www.cowboy]

I got my engine and carb through bicycle-engine.com they are located in Montana. They ended up swaping out the carb under warranty. Another place to look is Pistonbikes.com There is a company on the East Coast (forgot who) - that sells a better - larger od - intake for the cns - has anyone tried one of these with any luck?

 

[DuctTapedGoat]

Speed carb can be gotten from _

PirateCycles1.com
ZoomBicycles.com
JNMotorsBikes.com
and I think Bicycle-Engines.com sells them too.

ZoomBicycles.com has the best price.

 

[Ride Like The Wind]

The answer to the engine bogging problem is to get the NT carb, while supplies last. I now accelerate up hills and go as fast as seems safe to rev the engine and for road conditions. This is my first build, and I am past the break in period. I've commuted reliably for a week and am quite satisfied, now that I put the NT Carb on.

 

[bigcitybikes]

after i realized something was amiss i openned the carb to see a jet that looked clogged or too small - so i pulled one from another carb - i think i may have put the 50 cc carb on the 80 cc bike - simplu removing the brass jet shaft and adding the one with the bigger hole has the bike running like a wild horse - no issues after over 30 miles ...i would agree most issues with these stem from inside the carb- what i would say to anyone building one for the first time a small engine fuel in loine filter is a must ! keeps debrie out of carb- meanwhile i appreciate all the suggestions thank you all-meanwhile im looking to build more ..but want the best price on motors - any ideas ??

 

[VMIN]

Had a chance to test the bike tonight, and she ran much better with the jet drilled out. Night and day difference! So here is where I am currently: The jet was drilled out with a #69 bit. The needle is in the 4th notch down and the air mix screw is 2.5 turns out. I'm still on break in mix @24:1. Hope this helps all who are struggling with this carb. Don't give up on it. Not a bad carb if you can get it tuned. I still feel like it starves very slightly @ WOT, may go to #68 bit but will wait and finish break-in first before doing that. My observations on this carb are: the carb seal at the intake must be done using sealant or an air leak is likely. The float may not be set correctly at the factory and lastly the carb may be under-jetted as mine was. I'll continue to mess with it and tune it until I break it and am forced to buy another one!LOL.

I had the same problem and did as you said and drilled out the jet to as close to the next size up as I could get. I put the needle in the 4th slot from the top but I really think the main problem with those carbs is getting an air tight seal at the intake. I opened up the carb clamp with a scewdriver and seated the teflon bushing against the internal o-ringthen pushed the carb onto the intake as hard as possible and clamped it really tight. All is good right now I am about 185lbs and cruise up most hills. Still got some pinking going on. ( Pinking is the same as 4 stroking) how would I stop that>

 

[motoxjosh]

try taking the black tube out of the air filter and plugging it with a screw

 

[DuctTapedGoat]

The black tube is the AIR intake for the AIR/fuel mix for the two idle screws. That has nothing to do with the actual problems this carb has.

It only helps if you can't get your idle set right, aside from that, it's a BS way of people looking for a quick and easy fix, when it's in fact 5-6 quick and simple things to do to fix it properly.

 

[ManOMagik]

Hey guys, I too am having bogging issues... Only diff is I'm running a 2009 Star Fire Gen 11- A "58" cc Phantom, w/the NT speed carb (I'm sure its prolly just a 48 in disguise, those China Girls... always lying about thier age!) I also have a hp plug wire, and the grim works happy pipe both from Pirate Cycles. Compared to the 66 I had on my last bike, this thing is a beast! At least it feels that way at first... I can't get passed about 1/4 throttle without it starting to seriously bog, and generally run and sound like crap-olla! I've tried the needle clip in all positions, and tried tightening and adjusting this, that, and the other, with no luck at all! She sounds great in idle, and when reving the engine w/the clutch engaged. Any suggestions or ideas will be welcomed and greatly appreciated!

 

[James912]

try running with the gas cap loose, or off.

 

[DuctTapedGoat]

ManOMagik :

Ensure choke is off and disregard it the entire time, even when starting.
Ensure carb is level.
Tighten both jets.
Check for air leaks around manifold and intake.
Tune for proper idle.
Adjust float height.
Adjust needle position.

That's really all there is to getting them working - if it still doesn't run right, lather rinse and repeat all of that in the order it's written.

 

[wan37]

I found something that help mine there was a small hose coming from carb that goes to air filter take it off and see if that don't cure the boggie

 

[DuctTapedGoat]

If you read back a few posts, you'll see it's been suggested and I explain what that does, and why it's not a proper fix.