I've had the engine apart, checked all tolerances, cleaned and honed. Double checked the timing and no issue there. I know the carb is getting gas and the float fills up properly, but it's clearly not getting any fuel through to fire. I've cleaned the jets and soaked all components and air dried all parts and checking to the best of my ability all passages. I've also sprayed quick fire into the cylinder and it still doesn't pop (used to before I started messing with the vacuum lines) Vacuum lines appear to be correct and it is pulling gas from the tank properly (wasn't sure earlier as it was just about empty. Topped up the tank just in case there is a pressure issue. It is getting spark when I pull the plug and check it. I'm getting 4 ohms at the electric choke. I've been working with two old carbs that were pretty gummed up when I got them. I've soaked all parts overnight in a carb cleaner and air cleaned them properly. Does the air cut off valve have anything to do with the pressure required to move fuel in the carb? Is it worth my time to order a complete carb kit and new jets? or just bite the bullet for a new carb. Am I wasting my time by ordering a carb kit? I've checked the vacuum pump diaphragm and it kinda looks like it's suffering from "bacon neck" ie: looking a little stretched out in the body. It seals up well and when I run air through the front of the air intake, it pulls up like it should. I've tested the float and it rides where it is supposed to. Anyone got any tricks for this carb?
If you upgrade something like Free Flow Filter and maybe a Free Flow Exhaust you may need to just go with 2 sizes up on the main jet to match up with more Air the Free Low Filter is letting in. I had RapidRepair Bore out my case and put in a 62mm Big Bor Kit and a 60mm Stroker Crank and brought the Displacement up from 149.6ccs to 182ccs. The same 24mm carb is on there all it needed was a bigger Pilot Jet a #38 from Original #35 and a 122.5 Main Jet. And by the way a #125 main jet was TO MUCH FUEL it would cause it to POP had around 50-55mph had to order the 122.5 main jet. Ther is NOTHING wrong with the chinese carbs they are a very simple design that hasn't changed in decades and they work very good, no better than a high priced carb. High priced carbs you are paying for the name mostly and most are made in China. They all have the same passages and jets, they all function the sameo sameo.
They are really very simple in design and only a couple things can go wrong, Dirt may get into the fuel system and clog the jets and or passages and ONCE in a great while the Rubber in the ACV and or the Needle Diaphgram rip or something get tiny holes from AGE. And the replacement parts are everywhere.
Did you Verify when you spare into the PILOT JET HOLE that Spray DOES COME out in front of the Butterfly?
Alleyoop The Diaphgram(s) look like this: Just as long as there are no rips or tears and it is not leaking: Your tests showed that it is working fine.
This is the carb I have at the time I bought it the site I bought from had a special 3 of them for 120.00 bucks they each came with a spare Dighpgram complete with needle plus each came with a fuel filter to boot. I got the Special I have two brand new in thier boxes yet. So each cost me $41.00.
...BAD TO THE BONE.. PST150H 62mm BBK, 60mm Crank, 16/37 Tranny Gears..MOW-POWER
Is there a way to bench test the carb. Brace it, run fuel into it and blow air through the vacuum line to see if there is a throttle response from the tiny holes in the outflow?
This is the last time I throw this thing together... if it doesn't work now, I'm ordering a new carb. The exhaust carb exhaust sleeve isn't broken, but the little baffles in the collar that slide over the throat are looking a little rough. I'm pretty sure I'm getting sufficient vacuum, will test it again.
You would not blow air into the vacuum line but rather you need to pull vacuum. That can be done with a big needle syringe and I just posted this about carb cleaning and it might be helpful? You would also need to hook fuel to the carb and could by using a piece of fuel line and having it hooked up to a cup of some sort with gas in it and raised above the carb for gravity fuel flow just like on the scooter.
Does the air cut off valve have anything to do with the pressure required to move fuel in the carb?
Yes! Have you checked to be sure you’ve got good fuel flow from the gravity feed fuel petcock on the Elite 150? Here is some good videos and the fourth one from the top is a good way to check the fuel cut off petcock on a scooter;
Got a couple pops this time, but then nothing for a bit. After 5 minutes or so I tried it again... a couple quick pops, but it wouldn't grab. Looks like a new carb is in order.
Dryshave I would do the fuel test to make sure I had good fuel flow from the tank, it costs nothing. Would hate to see you buy a new carb and all it was all along is no fuel.
A small degree of success! I re-cleaned and rebuilt the carb again and this time when I cupped my hand over the intake, I could feel gas in the intake area.... still no ignition. So I got suspicious and pulled the plug, this time it was drenched in gas... good sign for fuel, lousy sign for spark. I grounded the plug.... and now NO SPARK! I test with the other coil (just in case) and all I was getting was a weak spark 4-5 times then nothing. Tested with both coils same result. I think this explains why I was only getting a quick pop. I've tested the coil I'm getting consistent readings of .7 (allowable range is .16 - .20) (I'm testing at the lowest setting on my tester 200. Measuring at 2K, I'm getting readings of .001) as well I'm getting .7 from another coil I have on a parts scooter. I'm a fool with a Tested the pulse coil (exciter coil?) and that is testing well 136 ohms tolerance is 50-350 ohms. Are both tested coils toast? I'm stymied and perplexed
WOOHOO! I swapped out the CDI unit with the parts bike, tested a strong spark. Installed the plug and pow! Instant ignition and throttle control!!! Thanks for walking me through my issues with this scoot. I will post video and pictures as I start the final assembly. Just need the seat recovered and I'm good as gold. Will tune it up as I move towards assembly, but after a couple of months with the carb, that was a purty sound I heard this morning. Thx
FANTASTIC!! Great that it was just the CDI, if it were the Pickup Coil or stator you would need a special FLywheel puller to get to those two last parts. GOOD JOB, happy that it finally fired up. Alleyoop
...BAD TO THE BONE.. PST150H 62mm BBK, 60mm Crank, 16/37 Tranny Gears..MOW-POWER
..BAD TO THE BONE..
