HP Carb

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I have an HP carb and after jetting it down? (I'm assuming, stock one didn't have a number on it) to a 65, my bike picked up a ton of extra power... I can go at least 5mph faster, I haven't pushed it past 35 yet though because I'm babying it because it's just barely broken in (and also safety or something..)

The only problem is , it dies during idle... hell, it dies as soon as I apply break / disengage clutch... I tried backing off the idle screw 2 full left turns... it seems to improve as it only dies 80% of the time instead of 100%...

I guess my question is... I have all the jets for the carb... would increasing or decreasing the jet size help me out? (or any other suggestions)

I ran a search of the forum and see you guys don't really like the HP carbs but I love it compared to the speed carb and the NT carb... I had the same problem w/ the speed carb but I just had to back out the idle screw a couple turns and it solved the issue

Thanks in advance... you guys are a Godsend... the information I've gained on this site is amazing... you guys rock.

 

[DAMIEN1307]

I'm assuming, stock one didn't have a number on it)

Almost all stock NT and/or JRL BoFeng carby's have #70 jets as stock.

I haven't pushed it past 35 yet though because I'm babying it because it's just barely broken in

You used full synthetic oil in your attempt to break it in which actually means the rings are not seated in properly...I left instructions on your other thread covering this for you to follow so you can get them seated in properly.

The only problem is , it dies during idle

HP carby's can be pure hell to tune properly to these motors, especially when they are not properly broken in yet...Just ask @Chainlube about this.

How to port for more rpm

The jug has a 40mm intake this refers to the bolt centers or spacing not the actual size of the port, since what you've listed is still basically a stock type setup your really only going to benefit from improving the blow down period and getting the cross section of the ports correct. I would...

motoredbikes.com

Help needed to identify carb

I ended up getting a few parts for a cheap price, For $20 I got a 80cc engine (I will be asking about at a later date) and it included this carb. Now for the question does anyone have a name or model number and any documentation on it. It has a locking mechanism on the choke that is supposed...

motoredbikes.com

Can't get it to run right

I have a yd 100cc bicycle motor it has a windowed piston, 2in reed valve, a hp carburetor, with a 65 jet in it, expansion chamber, and a bbr stage one cdi ignition. It idles good and runs OK down low mid and high it just doesn't want to go. Could eny one help me out

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Bikeberry Stage 1 CDI Questions

How do you hook up that catnip cdi? It is different than the stock one.

motoredbikes.com

 

[Chainlube]

I love flat slide carbs, just not those ones. I convert old sleds to Keihins.

If it won't stay running then it's not getting enough fuel. Try a 68 jet.

Set your idle with the carb off the bike. Look into the throat and watch the slide as it clears the body, if it is 1-2mm above then it should stay running.
The slides are not a precision made part and are poorly cast with extra casting that can hang up on the body. This is after I filed a bunch off and it still looks bad, but it does move up and down.

 

[DAMIEN1307]

The slides are not a precision made part and are poorly cast with extra casting that can hang up on the body. This is after I filed a bunch off and it still looks bad, but it does move up and down.

YUCK...lol...When I magnify that pic, I can actually see a crack running through it too...lol.

 

[Chainlube]

YUCK...lol...When I magnify that pic, I can actually see a crack running through it too...lol.

No it's not cracked, that was some extra material cast on to it. I didn't dare file any more or it would be too loose in the body. ee none the less.