Anyone familiar with Walbro 716 carb?

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Gassaholic

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So I have a KM T1000 36cc with a Walbro 716 for over a year now. A PITA to tune seems every other time I use it (about twice a week) I have to re tune the carb. I look literally everywhere for info on this carburetor but no real knowledge out there. Even went to Walbro site and found it but says the product is obsolete or discontinued lol. I like a challenge and is the main reason I went for a gasser not electric. Nothing wrong with electric I just like the sound and the stink of the petrol in the air ?. Anyways I finally threw in the towel and order a Wt-668 from DDM. My question is if anyone has dealt with the 716 and tried the 668 is the tuning a little easier more durable like maybe just need slight adjustments here and there. I don’t mind that just hate not been able to get this thing even started most times. Stock setting never really work on this carb so I have to fiddle with different settings to get it to start which hardly ever works and it is never the same settings. Have all new gaskets, have spark with good NGK plug, new gas tank holding pressure, drain hole on cap doing its job. No pinch lines or leaks, prime bubble priming away like it should. Good compression. I always end with the same culprit. Hopefully the new 668 gives me a better experience ??. Thanks for any input I really appreciated ?
 
Gassaholic said:
So I have a KM T1000 36cc with a Walbro 716 for over a year now. A PITA to tune seems every other time I use it (about twice a week) I have to re tune the carb. I look literally everywhere for info on this carburetor but no real knowledge out there. Even went to Walbro site and found it but says the product is obsolete or discontinued lol. I like a challenge and is the main reason I went for a gasser not electric. Nothing wrong with electric I just like the sound and the stink of the petrol in the air ?. Anyways I finally threw in the towel and order a Wt-668 from DDM. My question is if anyone has dealt with the 716 and tried the 668 is the tuning a little easier more durable like maybe just need slight adjustments here and there. I don’t mind that just hate not been able to get this thing even started most times. Stock setting never really work on this carb so I have to fiddle with different settings to get it to start which hardly ever works and it is never the same settings. Have all new gaskets, have spark with good NGK plug, new gas tank holding pressure, drain hole on cap doing its job. No pinch lines or leaks, prime bubble priming away like it should. Good compression. I always end with the same culprit. Hopefully the new 668 gives me a better experience ??. Thanks for any input I really appreciated ?
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Expert carb tuning takes a LOT of practice. It's not something you easily learn by watching Youtube vids. Vids will give you a good understanding of the process, BUT you need experience to tune a carb because you need a really good "ear" by listening to how the engine sounds while idling, and while accelerating to then be able to make a correct needle adjustment. Tip #1 , Low speed needle FIRST , adjust so you have a clean sounding idle. Also important is to listen very carefully while the engine is idling. If rpm's slowly drop your needle setting is too rich and the engine is loading up. When you make a needle adjustment always wait about 45 seconds before you make another adjustment. There is always residual fuel in the crankcase that needs to be burned off before you can hear a true change in the engine behavior. I also like to occasionally do a high rpm "cleanout" by WOT for about 4 seconds. This also burns off any excess raw fuel in the crankcase. If your idle slowly increases now your setting is too lean. Do exactly the opposite. The high speed needle can be a frustrating PIA to get correct especially if the base setting is way off. My Rovan carb settings are quite a bit different than advertised, and I can't explain why. General rule of thumb is if you accelerate and you get an abrupt stall , or you hear the rpm's "flutter" this is usually too lean. If you accelerate and the rpm's are slow to reach peak, and the exhaust sounds low and "burbly" this is too rich. If you have another person that can help you can have your helper securely hold the rear of the RC off the ground and attempt 3/4 throttle while adjusting the high speed needle . This is sometimes an easier method to get the high speed needle "in the ballpark" so at least it will accelerate normally on the ground under it's own power. Just be VERY CAREFUL when revving the engine while a helper is supporting the rear ! Lastly if you hear a peak rpm "crackle" this is bad, and this means you are too lean. When I tune my peak rpms, I listen for the crackle, richen the needle until the crackle is gone, then go ANOTHER 1/16 of a turn richer. Remember to perform the same WOT "cleanout" for HSN adjustments as well. This method works really good for me. over the past year I only had to adjust my tune once and that was because of much colder air. Good luck with the new carb !
 
Dam it!! I was conducting some maintenance on the pull start since I noticed that the cord would not snap all the way back in like it used to when it was new. probably from all the pulling to get it started due to the difficult tuning of the carb that I can’t find a single shred of info on. I took it apart clean it but I over tighten the screw that holds the reel and the spring and snapped the plastic in half ?. So now I am waiting on a new Wt-668 and a new pull start ⚰️??.
 
So I took my top end apart because I could not get the dam thing started. Come to find out my piston has some gauges on one side that I can almost get my finger nail snagged on it ?. The cylinder head also has some gauges on the same side as the piston wear. I have put maybe 6 tanks on this motor. Need more a little more reliability so I am thinking of buying the top end that DDM sells Zenoah G290RC 3.5 HP Engine (4-Bolt Topend) - bb211. Now I just have 1 question as I called couple of times but is kinda late now. Does this come with all the top end parts piston, ring, ect and is it a direct bolt on to my KM 36cc T1000?? Feedback is appreciated thanks ?
 
The part number you posted is a complete engine. Depending on your final choice you may or may not need to swap you clutch. Someone else will have to answer your fitment question. My guess is that it will bolt right in.
 
Ty guys guys for the feedback! NOOB here was is the difference between the long block and this complete engine I posted?
Z.hb71 said:
What they said? 320 longblock is 170 and the 290 long block is 160, so they aren't that expensive and will save you alot of time and headache ?
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Can you point me where you found that price plz
 
Last edited:
Ok I have a brand new Walbro-668, new 8k clutch, my ignition still firing well and have shrouds. This is definitely a lot cheaper. I checked their specs and it says stroke 28, Bore 38mm. From what I understand my KM 36cc is 39mm. Will this work with my set up as a direct bolt on. I would definitely like to upgrade if possible.
 
Gassaholic said:
Ok I have a brand new Walbro-668, new 8k clutch, my ignition still firing well and have shrouds. This is definitely a lot cheaper. I checked their specs and it says stroke 28, Bore 38mm. From what I understand my KM 36cc is 39mm. Will this work with my set up as a direct bolt on. I would definitely like to upgrade if possible.
Click to expand...
The g290 head might not bolt up, the bolt pattern might be different, you have to check
 
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