MOPED ARMY

If it stops running after idling for a while and the plug is wet, that’s a fouled plug.

If everything is stock, it should have the stock jet. Too rich and it might let you ride it at anything but idle. But, drown that plug at idle.

No leaks, wet plug, down jet.

Sounds like it was upjetted before to compensate for a leak and now it’s too much fuel after the rebuild.

Just a few observations because some big problems are a combination of a bunch of little shytes.

SHA 15:15 on a stock AV7 needs to be jetted with around 59-62 depending on which factory cylinder you have, so your jet is very fat.

The stock intake on a Ranger 7 is 13,8mm bore, so it is under size for the 15mm carb You will likely want to ream out the intake to match the bore of the carb or have a terrible time with jetting.

Pick your screens - stock inserted of the fancy red one. If you go for the red one,carry the other cartridge as a spare on the bike in case the other one decides to go AWOL.

You will likely want to clean out the exhause,the stock peashooter exit pipe on the backing plate must be pretty gummed up after running cold and wet for a while. You might want to consider derestricting the exit pipe as well.

The spark should be visible in just the shadow of the bike as a nice bright blue snappy spark. I fit is yellowy and anemic you would want to change out the condenser and do the external condenser mod. That poor component cooks inside the Novi unvented magneto and heat is the enemy of capacitors.

Also as Jay suggested, replace the bonding strap so the frame and engine has good electrical continuity.

No there is no way to De-foul a plug. It is bad at an internal level when they go out. It will need to be replaced. I typically just buy out my local auto parts store of they b7hs so that I always have plenty of spares. My kitted bikes I always carry an extra plug because it is no fun fouling a plug during your ride. And kitted bikes foul plugs a lot faster than stock bikes. If you find you are fouling plugs often move a step up. B8hs or even a b9hs those handle higher temps. Can be a little harder to find tho.

The engine mount is not the place to ground your engine. As I mentioned the French bikes have rubber bushing that the engine mount bolts go through. This will not ensure an adequate ground. Move the wire up to the next spot on your frame you can put a good bolt on. Even chip of a touch of paint where you are bolting it to ensure you are connecting with the metal really well. Just a suggestion because it will be your gremlin even if it isnt at this moment.

I also noticed that the idle screw position that lets it "run without dying" changes with the temperature of the engine. Having it screwed in all the way is the only position that consistently idles, but even then sometimes the engine dies with the brakes on or wheels on the ground. It seems to be "better" when the engine is warmed up but not always. Is this probably just related to running too rich, and changes in temperature making it slightly more rich and starved for air?

Thanks! Lot's of little things for me to keep working on. Gonna start with jetting and make sure it at least works consistently and then derestricting the intake/outtake. Though -- Once I bore out the intake and exhaust I'll probably need to upjet back to 63-65ish if I understand correctly?

Hey Rebel, had a couple follow-up questions. I got the Ranger 7 running pretty good stock, but then recently I've had a couple complications. I was running a B7HS plug with a 61 Jet and it was running well, and recently it started having trouble idling when cold. I compared the spark on the plug to a new B6HS I had laying around and noticed it wasn't sparking at low RPMs while the new plug was (does that mean it's... partially fouled? ) Anyways, I decided to finally run a plug-chop -- Warmed up for 4 miles, put in a new plug, ran about 0.75 miles on WOT and killed the engine -- The plug still looks brand new. What's up with that? Does it have to do with the fact that I'm killing the engine using the decomp instead of the killswitch (I don't have a working kill switch right now).

Also you mentioned in another post that rather than getting a 70cc kit, which would be too powerful for this bike I could just port my existing 50cc. Would ordering an airsal 50cc kit achieve a similar thing as porting mine? What improvements would one or the other give me (extra hill climbing power, maybe an extra 5mph?) I'm going to try to weld the header at the new angle for my Ninja exhaust this week, so I'm starting to think about giving the engine a little more oomph after that.

Yes you could get an arisal 50cc kit but porting yourself is sooo easy with a couple easy to find tools. Slapping a kit on is not always easier. After I ported my first engine I felt a lot more confident in working on my bike. I felt like I knew it better.

One more thing to check if it hasnt been mentioned is your condenser. I love replacing my condenser with an inline one off of the stator plate. A karmenghia condenser from autozone is perfect for this.

After running a brand new plug hard for 3/4 mile and killing the engine that plug's insulator, at the electrode, should still look brand new. If it doesn't that plug is too "cold". Please read this until you understand it. Especially this part, "So how can you tell whether you've chosen the right heat range? It's easy: a spark plug should be getting hot enough to keep its insulator nose completely clean, with all deposits burned away, but not so hot that its electrodes show signs of serious overheating. These are things to look for on a new plug that has been subjected to a few minutes of hard running. After many miles of service insulators acquire a coating of fuel deposits, with some coloration from oil in two-stroke applications, and there will be some erosion of the electrodes even when everything is normal. Don't try to read old spark plugs; even the experts find that difficult. New plugs present unmuddled information about what's happening inside an engine, and can give you a complete picture after just minutes of hard running. At least they will if they're running hot enough, and that should be hot enough to keep the insulator clean". http://www.strappe.com/plugs.html

The picture below shows where to look to "read" a plug.

(edited)

Also I just noticed -- I had orderd BH6S plugs from treats but the plugs I got all say BH9S...

No doubt Bosch is the way to go, however I only mentioned aoutozone cuz that was where we were able to find the condenser on the fly. You know when your bike doesnt start an hour before the rally ride. ;j

If you put a external condenser you must remove or at least cut the wire for the old one. Wire is the Blue with Black stripe going to the points.

Best to not assume anything with moped repair. But yes you can just snip the wire that leads to your condenser and run an extension from that to the new condenser and then to your coil.

It will be the wire coming from your points.

For your porting/kitting questions:

Renewing the spi seals is important for any mods on the engine for higher output. Also a goodly measure of patience will help you get the best out of your choice, read informations available and understand them first. Ask questions to folks who have done it before successfully and follow their lead.

Stock AV7

A well kitted stock ported AV7 will give you higher revs andabit better power band. Someone has one I suggested posted on the wiki somewhere, that port event recipe will get someone in the 30-40mph range if they have a goodly pipe, SHA15:15 with 15mm intake and matched intake duct, 1,5mm BTDC timing (1,2mm for CDI because hotter kernel). It will give you reliability all day long and into the night.

There are other port event recipes for a av7 that will give you higher revs, but you will start to move the power band too high and would lose idle ability and pushing up higher starts to risk the reliability day to day.

Aftermarket AV7 50cc

Better port timing events rightout of the box for you. Also the casting has allowed for more robust castings which allows for more space to add better bigger ports.

Aftermarket AV7 overbored kits

Same as the 50cc kits, better port timing events rightout of the box for you. Also the casting has allowed for more robust castings which allows for more space to add better bigger ports.

Added bonus of more piston crown surface area so you have added torque, that will yield you a more robust power band and less scrubbing off of power on hills.

NOTE: all and any aftermarket kits will need you to index the cylinder to the engine, you would also need to go over the finish of the kit and give it some quality work, deburring, chamfer on the port windows, attending to casting marks in ports as well as polishing the exhause port. Matching the cylinder to the carter to remove any shelfs and ledges that can cause fuel stripping and puddling. Better port timing events rightout of the box for you. Also the casting has allowed for more robust castings which allows for more space to add better bigger ports.

You will also need to consider a good exhause as well as a multi circuit carb bigger than 15mm.

I'd like to read the reason that the BP6HS plug will not help out. Please post a link to a reference.