Greetings:
The low compression might mean poor ring/cylinder seal, or even a cracked piston or deep gouge in the cylinder wall. However there may be another explanation:
The reed valves prevent most of the crankcase volume from simply blowing back into the intake manifold. If they are leaking it could account for an apparently low compression. I would assume you've checked them, but after all these posts I have found no indication that you did.
My Aero would only start reluctantly and after prolonged cranking at WOT when I had a reed valve issue. It's possible that this is your problem. Let us know?
No Start
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Wheelman-111
- Moderator
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- Location: Deepinnaharta, Texas
Compression And Reed Valves
Wheelman-111
Most of my money is spent on scooterparts. The rest is just wasted.
"ISO": '03 Vespa ET4 Malossi187 74MPH
Flash 9: 2001 Elite SR Contesta 72 ZX Tran, 9:1 Gears, Stock Airbox/Carb/Pipe 58.8 MPH
Punkin: 2010 Vespa/Malossi S78, 61MPH
Most of my money is spent on scooterparts. The rest is just wasted.
"ISO": '03 Vespa ET4 Malossi187 74MPH
Flash 9: 2001 Elite SR Contesta 72 ZX Tran, 9:1 Gears, Stock Airbox/Carb/Pipe 58.8 MPH
Punkin: 2010 Vespa/Malossi S78, 61MPH
Not to sound like a broken record here, but in his second post he claims he got it to run for about 5 seconds by spraying some carb cleaner into the cylinder, so my bet is still a clogged carb. I thought that I had "cleaned mine the right way" several times, but until I actually looked through the pilot jet and finally saw a pinprick of light, well, that's when I knew it was finally clean. These carbs are a major PITA. Touchy little devils.
Anyway, he combusted carb cleaner, so spark and compression were present. Gasoline is all that is lacking. But, hey, I'm no pro. Let's see what Kenny or Keith think...
Anyway, he combusted carb cleaner, so spark and compression were present. Gasoline is all that is lacking. But, hey, I'm no pro. Let's see what Kenny or Keith think...
1986 Honda Spree - Running amazing.....body work still needs to be done, but that's a Spring job.
i see...i just figured it should be a lot more than that. hmm.
getting an air filter and the air filter cover next. also the complete exhuast, becuase i only have the pipe...must have been cut?
Would it be wise to get reeds and piston rings?
What about crank seals, i hope they dont go bad often, becuase i'd rather not dig too far with internal engine work. where are they crank seals located even? on each side of the crank on the outsides of the bottom of the connecting rod?
Bike has 3500 miles...
thanks guys, drew
getting an air filter and the air filter cover next. also the complete exhuast, becuase i only have the pipe...must have been cut?
Would it be wise to get reeds and piston rings?
What about crank seals, i hope they dont go bad often, becuase i'd rather not dig too far with internal engine work. where are they crank seals located even? on each side of the crank on the outsides of the bottom of the connecting rod?
Bike has 3500 miles...
thanks guys, drew
1985 honda spree 49cc
2007 lifan 50
2007 lifan 50
ok, I've never run my bike without the muffler, but, I will admit that, during testing on my Spree, I have run it with the airbox completely off of the carb. It seemed to run fine (even though I didn't actually take it out on the road like that, just on the stand, as I was checking a reed-valve issue at the time, and I didn't want to re-attach the airbox just to take it apart again). But, in the colder weather, I could see that contributing to hard starting, as it is making a lean condition, and these bikes are hard enough to start in the cold.
Case in point, right now, I am helping Markymark (a new member here) with his carb. He lives in East Lansing, where I work, so I tore his bike apart while it was still on the bike rack, and discovered his carb is extremely gunked up. It has been sitting in my carb dip for 18 hours now, with me agitating the mix and trying to blow compressed air through everything every few hours, and I still cannot see through his idle (pilot) jet. It's bad. These carbs are very hard to get clean, and, they're hard to keep clean. I left gasoline in my Spree's carb for 3 weeks while I couldn't ride it, and the bike wouldn't start, it wouldn't even combust. I had to dip the carb overnight, then she started right up.
Something to think about...I believe it's Kenny that says, "Clean the carb again." Well, sometimes those cranky old guys know what they're talking about
Case in point, right now, I am helping Markymark (a new member here) with his carb. He lives in East Lansing, where I work, so I tore his bike apart while it was still on the bike rack, and discovered his carb is extremely gunked up. It has been sitting in my carb dip for 18 hours now, with me agitating the mix and trying to blow compressed air through everything every few hours, and I still cannot see through his idle (pilot) jet. It's bad. These carbs are very hard to get clean, and, they're hard to keep clean. I left gasoline in my Spree's carb for 3 weeks while I couldn't ride it, and the bike wouldn't start, it wouldn't even combust. I had to dip the carb overnight, then she started right up.
Something to think about...I believe it's Kenny that says, "Clean the carb again." Well, sometimes those cranky old guys know what they're talking about
1986 Honda Spree - Running amazing.....body work still needs to be done, but that's a Spring job.
i see, seems like it should be a lot more, but i'm just assuming. If yours runs fine though.. i guess thats ok
where should i start now? i need a new air filter, and air box top piece to start, and a full exhaust with muffler, not just my pipe.
new rings and reeds as well? or should i wait?
hopefully its not the crank seals...
3500 miles on the bike
where should i start now? i need a new air filter, and air box top piece to start, and a full exhaust with muffler, not just my pipe.
new rings and reeds as well? or should i wait?
hopefully its not the crank seals...
3500 miles on the bike
1985 honda spree 49cc
2007 lifan 50
2007 lifan 50
To be honest, I wouldn't replace anything until you narrow down the problem. So many mechanics and technicians have the mentally, "Replace parts until the problem goes away." What a shame we can't even take the time to do the job right the first time....sorry, I went off on a tangent there. Now, as for your crank seals...I don't know...I imagine they would have about the same symptoms as a bad reed-valve.
Say, have you tried holding your hand over the carb's intake (choking it) while you've been starting it? I mean, really restrict that sucker. Even choke it off all of the way if you want to.
Just remember, don't fix what isn't broken, unless that "fix" is an upgrade. It is expensive and time consuming.
Say, have you tried holding your hand over the carb's intake (choking it) while you've been starting it? I mean, really restrict that sucker. Even choke it off all of the way if you want to.
Just remember, don't fix what isn't broken, unless that "fix" is an upgrade. It is expensive and time consuming.
1986 Honda Spree - Running amazing.....body work still needs to be done, but that's a Spring job.
woops, theres a page 2. I kept posting according to the last post on page 1...haha...
Well, i did that the carb apart many times...finally doing it the right way. Took the pilot jet out, and sprayed it and used my carb tool kit to clean out the little holes, and cleaned it with spray again, then compressed air. I hope this jet doesnt have a certain way to go in, becuase it just popped out and i didn't get a look on the way it was positioned. should be ok?
What is the function of this jet?
What do you soak, the whole carb? in what 'carb soak'?
Also, how do i test the reeds? Something with a flashlight? the reeds are on the engine block good, so i dont want to take them off if i dont need to. What is it...gasket, reeds, gasket, intake?
Wheres a cheap place to get piston rings and reeds?
3500 miles a lot? how far can these babies go?
getting closer! thanks again, drew
Well, i did that the carb apart many times...finally doing it the right way. Took the pilot jet out, and sprayed it and used my carb tool kit to clean out the little holes, and cleaned it with spray again, then compressed air. I hope this jet doesnt have a certain way to go in, becuase it just popped out and i didn't get a look on the way it was positioned. should be ok?
What is the function of this jet?
What do you soak, the whole carb? in what 'carb soak'?
Also, how do i test the reeds? Something with a flashlight? the reeds are on the engine block good, so i dont want to take them off if i dont need to. What is it...gasket, reeds, gasket, intake?
Wheres a cheap place to get piston rings and reeds?
3500 miles a lot? how far can these babies go?
getting closer! thanks again, drew
1985 honda spree 49cc
2007 lifan 50
2007 lifan 50
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Wheelman-111
- Moderator
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- Joined: Wed Oct 22, 2008 5:09 pm
- Location: Deepinnaharta, Texas
No Start, But Excellent Fuel Mileage
Greetings:
Drew states:
, but it lasts forever if you keep it sealed. Take the carb apart and yes, other than the plastic bits, soak the whole thing.
We haven't established that you need those yet. You still have not checked the reed valves. Buy from Honda-san. Not cheap but neither is having to do the job over again in a few weeks.
Drew states:
I used a gallon of some stuff from NAPA. Comes with a little basket you lift out of the gallon bucket. Cost was (shudder) $50.What do you soak, the whole carb? in what 'carb soak'?
, but it lasts forever if you keep it sealed. Take the carb apart and yes, other than the plastic bits, soak the whole thing.Unless you have a Fiberoptic Colonoscope you can thread into the exhaust port to look from the other side, you need to. The gaskets on mine were a botch to get off, and you'll need new ones most likely. Honda-san again.the reeds are on the engine block good, so i dont want to take them off if i dont need to.
Yes, that's the sequence. Look up your Service Manual - free in Technical Documents. There should be a diagram.What is it...gasket, reeds, gasket, intake?
Wheres a cheap place to get piston rings...
We haven't established that you need those yet. You still have not checked the reed valves. Buy from Honda-san. Not cheap but neither is having to do the job over again in a few weeks.
I can make some for you. Need the originals or a cardboard copy for a template....and reeds?
Wheelman-111
Most of my money is spent on scooterparts. The rest is just wasted.
"ISO": '03 Vespa ET4 Malossi187 74MPH
Flash 9: 2001 Elite SR Contesta 72 ZX Tran, 9:1 Gears, Stock Airbox/Carb/Pipe 58.8 MPH
Punkin: 2010 Vespa/Malossi S78, 61MPH
Most of my money is spent on scooterparts. The rest is just wasted.
"ISO": '03 Vespa ET4 Malossi187 74MPH
Flash 9: 2001 Elite SR Contesta 72 ZX Tran, 9:1 Gears, Stock Airbox/Carb/Pipe 58.8 MPH
Punkin: 2010 Vespa/Malossi S78, 61MPH
ouch, I misjudged the age...ha. I'll give myself a pat on the back for that.
Anywho, drewkuch, the jet that you have taken out is actually the main jet (it screws out via flathead screwdriver, and should have a number stamped on it somewhere). The tube that came out with it is called the emulsion tube. And when you put the emulsion tube back in, the smaller diameter end needs to go up into the carb, so that way it is actually sticking out into where the throttle-slide goes. The all-important pilot jet is the problem. That little sucker is the brass tube right below the main jet (if you look at the carb from below). That, too, leads to the throttle slide, but it is MUCH smaller in diameter inside. Very hard to get clean. Very easy to gum up.
To test if the pilot jet is clean, hold the carb up to a bright light (make sure the throttle-slide insert is facing the light), put one of your fingers over the hole where the main jet goes, and see if you can see a TINY pinprick of light coming through the pilot jet. You will know it when you see. If you think you might see it, you don't. You will definitely see it. It helps to do this in a very dark room, holding a flashlight up to the other end of the carb. If you don't see anything, you need to clean it again. Sorry. But, I found that my Spree would not start, yet alone run, without this being clean. As I said, it took me several tries (on the order of 6 or 7, I can't remember precisely) to get this clean.
We have a couple of good carb cleaning guides in the Technical Documents on this forum, they even include pictures with arrows! They were invaluable in helping me teach myself.
Anywho, drewkuch, the jet that you have taken out is actually the main jet (it screws out via flathead screwdriver, and should have a number stamped on it somewhere). The tube that came out with it is called the emulsion tube. And when you put the emulsion tube back in, the smaller diameter end needs to go up into the carb, so that way it is actually sticking out into where the throttle-slide goes. The all-important pilot jet is the problem. That little sucker is the brass tube right below the main jet (if you look at the carb from below). That, too, leads to the throttle slide, but it is MUCH smaller in diameter inside. Very hard to get clean. Very easy to gum up.
To test if the pilot jet is clean, hold the carb up to a bright light (make sure the throttle-slide insert is facing the light), put one of your fingers over the hole where the main jet goes, and see if you can see a TINY pinprick of light coming through the pilot jet. You will know it when you see. If you think you might see it, you don't. You will definitely see it. It helps to do this in a very dark room, holding a flashlight up to the other end of the carb. If you don't see anything, you need to clean it again. Sorry. But, I found that my Spree would not start, yet alone run, without this being clean. As I said, it took me several tries (on the order of 6 or 7, I can't remember precisely) to get this clean.
We have a couple of good carb cleaning guides in the Technical Documents on this forum, they even include pictures with arrows! They were invaluable in helping me teach myself.
1986 Honda Spree - Running amazing.....body work still needs to be done, but that's a Spring job.
hey dg,
I see the light! ha..Yea i see a small light. That small hole is offset.
I learned that you can take that piece out and clean it, but i dont want to mash anything up, esp if i can see the light.
I do think my carb is plenty clean.
I did learn today that my spree will start without an exhuast or airbox. I've started bikes in this case before, jsut not 2 strokes. The spree will start and idle, but without the airbox on, revving it will kill it.
So, what's next? The guy said nope, dont replace reeds, shouldn't be the problem. Shouldn't be the rings, but i could bore the cylinder, but with 3500 he said i shouldn't.
he said 30 psi should be enough to get it started at least, but its low.
"get that jet cleaned out good, take the piece out if you have too, carefully" and let me know if that doesnt work.
whats next..
I see the light! ha..Yea i see a small light. That small hole is offset.
I learned that you can take that piece out and clean it, but i dont want to mash anything up, esp if i can see the light.
I do think my carb is plenty clean.
I did learn today that my spree will start without an exhuast or airbox. I've started bikes in this case before, jsut not 2 strokes. The spree will start and idle, but without the airbox on, revving it will kill it.
So, what's next? The guy said nope, dont replace reeds, shouldn't be the problem. Shouldn't be the rings, but i could bore the cylinder, but with 3500 he said i shouldn't.
he said 30 psi should be enough to get it started at least, but its low.
"get that jet cleaned out good, take the piece out if you have too, carefully" and let me know if that doesnt work.
whats next..
1985 honda spree 49cc
2007 lifan 50
2007 lifan 50
Ok, once again, I'm no expert here, but I think you're just running very, very lean without an airbox and a proper exhaust, so when you try to rev it (give it some gas), it will just stall out on you......did you try running it with your hand over the carb air intake? You may be able to cover that up by a fair amount, and then try revving the bike, it may work for you. If it does rev up with your hand over the intake, then you are running too lean....that's about all I can think of for now, these little engines are very touchy when it comes to intake restriction and exhaust back-pressure...
1986 Honda Spree - Running amazing.....body work still needs to be done, but that's a Spring job.
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scooterwerx
- Elite
- Posts: 894
- Joined: Tue Oct 07, 2008 11:43 pm
- Location: redlands, ca
when i bought my elite e, it was advertised as having a "man made part" turns out the airbox was missing, so to get it to run at all, the dirty hippie tied, with string, a piece of inner tube with a small slit in it over the carb opening. he was perplexed as to why it would not start and run well, and cut 200$ off the price because of it. i immediately put an air filter on it and rejetted it, ran like a champ! just a funny story...
Yeah, hippies drive mopeds, real men drive scooters. At least, I do, and I own several firearms, so, doesn't that make me a man? 
At least I don't go out and buy the biggest d*** truck on the market (you know, quad-cab, longbox, dual-axle, tall-topper, 4x4 type of truck, the kind that actually doesn't fit in a parking spot) just to prove I'm a man. I prefer small cars...wait, maybe I just don't have anything I need to compensate for!
Witty remarks aside, it does suck to buy new parts and have them not be the problem. The plus side is, when you eventually get it running, you don't need to worry about replacing those parts for a long time.
At least I don't go out and buy the biggest d*** truck on the market (you know, quad-cab, longbox, dual-axle, tall-topper, 4x4 type of truck, the kind that actually doesn't fit in a parking spot) just to prove I'm a man. I prefer small cars...wait, maybe I just don't have anything I need to compensate for!
Witty remarks aside, it does suck to buy new parts and have them not be the problem. The plus side is, when you eventually get it running, you don't need to worry about replacing those parts for a long time.
1986 Honda Spree - Running amazing.....body work still needs to be done, but that's a Spring job.