Tuning my factory 6.5 Clone

[Paticus]

Its been while since I tuned a carburetor, but I think my HF 6.5 is running a little lean. It takes about 15-20 minutes of ride time before it will idle which the choke engaged and the motor just seems to lag a bit.

Can somebody give me a quick 101 on how to tune the factory carb on these motors?

I know I can't be the first one to ask this but my search didn't yield results. Thanks!

 

[5horsebriggs]

the carbs are non ajustable

 

[OND]

Evening Paticus, are you just trying to adjust idle or the air/fuel mixture screw on your Clone ? Next question is did it come with the air/fuel screw open where you can adjust it or does it have a plug over it ? :hammer:

 

[Paticus]

OND, I'm looking to adjust the air/fuel mixture. Here are 3 pics from left to right of my carb:

 

[gumpit]

Looks like the only thing you can turn is the big round black plastic screwhead with a phillips screwdriver.

 

[Paticus]

So it looks like i need to buy a larger jet if I'm running lean then, it appears?

the carbs are non ajustable

 

[OND]

Its on the back of the carb, on the top picture behind the brass plug, you can try to get it out with a small drill bit and a screw, but sometimes you will break off the air/fuel screw its self, I would go ahead and take off the carb and then take off the bowl, float and pin, take out the high side jet and E-tube, clean it with some brake cleaner and blow it all out . Clean all the air bleed holes in both ends of the carb with cleaner and air to, put it back together just like you took it apart and it should run as good as when it was new, no adjustment necessary.:grind::grind:

 

[ITSWILL]

Hi there,

I just put together the same engine on my Bonanza. I found it to be seriously lean on the high speed circuit. There are no mixture adjustments on these carbs.

Here's what I did.

I took off the float bowl and pulled out the jet under the bolt that hold the bowl on. This is the high speed jet.

The original jet measures 0.028" if memory serves. I drilled mine out by hand to 0.032". No more lean bog and not more breaking up at higher rpm.

You can either drill out you own which is super easy if you have the drill bits or you can buy a new jet. They are readily available online.

Many people change the emulsion tube which sits under the high speed jet. But I have not seen any need to do this. My engine runs spot on.

 

[OND]

Low side jet is under the big idle screw and it is plastic you can clean the low side jet by screwing the big plastic idle screw all the way out , then pull out the low side jet , clean and install it back in like you took it apart.

 

[Paticus]

Great, may try to drill out the jet. I guess in a worst case scenario I can just order the proper jet if it doesn't work. Thanks for the input on this :drinkup:

 

[Paticus]

Ended up ordering a .032 jet from OldMiniBikes. Got it in 2 days! The motor runs much better now (like I expected it to). I don't know if it's because I got the CA edition or what but it seems like the original configuration is wayy to lean.

Also, I took the filter out of the air box, which compliments the new jet nicely. Im thinking I need to make a permanent high flow solution.

 

[cxbra]

Yeah, the CA model runs very lean to pass small engine emissions testing. All it needs is a bigger jet and all is well. Are you running the stock airbox? If so, take off the airbox lid and examine it. You will see 4 runners along the front of the airbox top lid and the 4 holes on the airbox itself where its drawing air in from the front. You will notice that only the center two runners actually draw air into the carb, the outside 2 are blocked off. Cut with a dremel so that all 4 runners are drawing air into the carb. Next, take the airbox off the carb and open up the air filter hole until it port-matches the rest of the airbox. Roughly double the bore of the filter hole. You will notice HUGE gains in power over the un-modified box.

 

[Paticus]

Yeah, the CA model runs very lean to pass small engine emissions testing. All it needs is a bigger jet and all is well. Are you running the stock airbox? If so, take off the airbox lid and examine it. You will see 4 runners along the front of the airbox top lid and the 4 holes on the airbox itself where its drawing air in from the front. You will notice that only the center two runners actually draw air into the carb, the outside 2 are blocked off. Cut with a dremel so that all 4 runners are drawing air into the carb. Next, take the airbox off the carb and open up the air filter hole until it port-matches the rest of the airbox. Roughly double the bore of the filter hole. You will notice HUGE gains in power over the un-modified box.

i hadn't really looked at it very closely- this is great info

 

[bigmoebbq]

Yeah, the CA model runs very lean to pass small engine emissions testing. All it needs is a bigger jet and all is well. Are you running the stock airbox? If so, take off the airbox lid and examine it. You will see 4 runners along the front of the airbox top lid and the 4 holes on the airbox itself where its drawing air in from the front. You will notice that only the center two runners actually draw air into the carb, the outside 2 are blocked off. Cut with a dremel so that all 4 runners are drawing air into the carb. Next, take the airbox off the carb and open up the air filter hole until it port-matches the rest of the airbox. Roughly double the bore of the filter hole. You will notice HUGE gains in power over the un-modified box.

hey bud you got a pic of this mod by chance?

 

[cxbra]

hey bud you got a pic of this mod by chance?

Here is the airbox lid. See the 4 runners? Stock, only the two middle runners are feeding into the airbox. Cut across so all 4 are getting air. Look at the bottom of the front of the airbox (facing towards the engine) and you'll see the 4 segments that are drawing air in, it all makes sense one you see how that works :thumbsup:.

Heres the intake port under the air filter. I bored this out about twice the diameter that it was stock. Just bore it out until it matches the diameter of the rest of the intake. You'll see what I mean once you get in there.

Make sure to either re-drill your carb jet or get a bigger jet because your bike will need a good amount more fuel after these simple mods! I was running lean before the mods, then I bored the jet (I thought I went too big, I took no measurements haha). Its getting the perfect amount of fuel now, almost running lean even with the bigger jet, thats how you KNOW it works :thumbsup:.

 

[Paticus]

^ I just did that mod last night. Thanks for showing me. seems to run well with a .032 jet here at sea level. I Also carved out the mouth of the air box manifold that bolts to the carb. Basically widening it all the way until it reaches the gasket seals.