Smoking scooter  By  lain (Read 2,819 times)

John as in tvnacman?

I've installed alot of ring sets in my time, meaning hundreds, and never had to do an adjustment. I have had customers in the past insist on installing new rings without a new oversized piston and reboring and rehoning to break the glaze, and it never works. Customers that have bought rings and swore up and down the rings have excessive gap, when they are measuring the gap incorrectly. the cylinder is much larger at the top than at the middle, or at the bottom, which effects gap reading. also making sure the rings are perfectly square. Again, I've never had to adjust a set of rings. better to have them too wide than too tight.
What I have found is that smoking is the result of incorrectly installed oil rings and separator, and/or gaps all lined up and not staggered. I've done it myself and gotten in a hurry, or when I was a rookie mechanic (late 70's).
there is a process and procedure and things don't just bolt up and work unless you are a natural at it or have done extensive research in proper installation or have experience. I have noticed the more professional the mechanic, the less the mechanic blames parts...
my personal observation and opinion. not the opinion of SDS.

I said this in another post ,but I didnt even bother to measure the gap . I just opened the kit , installed the rings , and when it came time I spaced the rings at close to 10 & 2 and she worked just fine for the past 17,000 miles.

I installed my rings exactly as the guide told me to. Yes I am inexperienced. I am trying to diagnose and solve a problem, and your input is greatly appreciated, but I already knew all that because I followed this guide: ebay.globaldc.com/scooterparts/borekits/100ccGY6/install/bbk.html

Since you think I am doing something wrong could you please look over that guide and tell me where the mistake is, because I followed it to the T as instructions to install the rings.

Obviously I am doing something wrong, but I do not know what, and if this guide is teaching me the wrong way it would definitely explain a bit. People keep saying I must have measured them wrong, must have messed them up myself, and on and on about how I am the cause of the problem when I am only acting out what a guide tells me to do. I measured the rings like ti says in the guide, with the piston in the cylinder. It gets very frustrating when looking for new rings, this is the poop sellers tell me and won't take their defective rings back! I mean this is a serious issue, I order parts they come in and are defective, then they play the blame game. I have yet to find a seller who will take the time to check the parts he sells... The last set of 50mm rings I got, the second compression ring had a gap so large I could fit my pencil through it in the cylinder!!! How is that a useful ring??? This is why I do not just pull the rings out of the plastic and install them.

The scooter is using immense amounts of oil, I went from over the top of the markings on the dipstick, to 1/5th of the marked area of the dipstick in just one ride around town for about half an hour. The smoke seems to go away at higher RPMs but comes back when at stop lights or lower RPMs.

Couple of things:

1.  Seriously - you need to deglaze and use new rings every time.  Skipping either will lead to a problem.

2.  The top 2 rings - the compression rings - are not designed to keep oil out of the combustion chamber (that's the job of the "oil ring sandwich" of 2 thin rings ands the spacer.  A messed up combustion ring will not, generally lead to oil burning EXCEPT that you then get "blow by" ~~ high pressure combustion gas escaping past the bad ring into the crankcase.  This can push oil OUT of the engine past seals or out the vent on the top of the head cover, or even possibly damage the oil ring sandwich (thus leading to oil burning).

3.  Since I kept messing up with my own BBK, I bought 5 head gaskets just to have on hand (they are extremely cheap).  And messing up does not only belong to novices - I messed up over, and over, and over ..... and I've rebuilt lots of auto engines, including several exotics,  It's just that I'm not familiar with these little lawnmower engines and, like everything else, "experience" is only partly generalizable.  These engines, like everything else, are unique.  Oh - and if you take time away from back yard mechanics, as I did, your skill set fades pretty quickly!  Don't lose heart!

4.  One suggestion I might add is to slow down and be a little more methodical.  You appear to be pretty knowledgeable about electronics, and maybe in your heart expect too much from yourself about mechanical issues.  Unless you are stranded and have no choice, just take it slow.  Use assembly lube.  E A S E the piston & rings up into the cylinder (a tip is to get a large stainless steel pipe clamp and use it to compress the rings a bit (not too tightly) to help getting them into the jug w/o damaging them).  Gentle ~ unless you are very experienced consider it all fragile.  Don't try to do 10 things at once; just a slow and methodical step at a time.  And soon ... presto!

The problem with installing rings in a used bore mainly is that new rings will ALWAYS have too large of an end gap. The reason is that the bore had been worn larger than the standard size. It will also be much wider at the top where compression gases put more force on the cylinder and therefore made the bore even larger at the top 5 or 10mm or more, which is where most amateurs check end gap, and the top of the cylinder. new rings, no matter where they come from, will have excessive ring end gap because they are going in a used cylinder. If the cylinder is properly de-glazed with a hone, that will break the glaze, but will also make the bore even larger, and larger end gap you will get as a result.
Bottom line. These things have cheap parts. Heck, a set of rings for my MV Agusta cost 10 times as much as a complete top end rebuild kit does for these. If you've spent the time to tear the engine down, why not do the job right and get everything new, and pay for decent parts from a reputable business? If it's to save money, you may realize it will cost you more money and time in the long run trying to save a few bucks up front.
For those that disagree, and want just rings, we certainly sell them separate, and use higher grade rings to last longer. They may look the same, but they are not. The customer is always right in this regard of what they want, so we give them whatever they please.
Just my personal opinion, and if you have any further tech questions, please contact MO! at tech@scrappydogscooters.com
or give us a call to order, or order off the website.

I think I will be ordering a brand new BBK soon to just start fresh. I went for a 45 min ride last night, used up 75% of my oil (was full) and melted the end of the spark plug!