carb problems, hoping dax carb would solve it, not really

You're welcome fischer550, I know this is all odd and seems a bit complicat d to those who have no experience with it, but honestly these little engines are so simple that they make a perfect engine to learn these little tricks and the basics on, once you mess with them a awhile and get a better understanding, you will enjoy them more and more from my experience, the main reason some people get discouraged and quit on them is because they expect way more from them than they were designed to deliver or can deliver, best part is that they are relatively cheap to repair and replace so even a big bad boo boo with one of them wont break the bank to fix or replace.

Just hang in there and ride that bike and you'll see in time what we have been telling you start coming into shape.

Map

Glad to see that we got a gameplan here... You'll enjoy the bike a lot more once you got some miles on that new engine, There are some sellers in here that won't turn a new bike over to a customer until the engine is run in just for the same reasons with what you're going thru and it also ensures that the engine is set up and tuned correctly for the customer as well as drastically reducing customer complaints. I know if I was building these things to sell I'd run them in for the customers too because the only time I want to see a customer come back to me is when they want to buy more, and not to return thinking something is wrong or out of tune.
I do firmly believe that everyone who owns a 2 stroke kit bike should get to know their engine so when maintainance is needed, they can do it quickly and easily and get back on the road, but most people give up and say these things don't work etc...

As long as you don't give up on getting it right, I won't give up on helping you when you got questions.

fischer550 said:

Alright will do, thanks guys. I should get my opti-2 in the mail soon, and I'm gonna switch to that when I get it, I will just ride it for now and see where it goes.

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This might create a whole new set of problems. I got a brand new engine and started mixing a 70 to 1 ratio of Opti-2. I told my friend about Opti-2 and he tried it in his engine and it seized on his first tank. I later read that it's not good to switch engine oil, that once you pick an oil you should use the same oil for the life of the engine but I don't know if this is correct or not. I have been sticking with the opti-2 at 70 to 1 and my engine is still running strong but I'm only on my 3rd gallon of gas however. I'm kinda afraid to go 100 to 1. It does 4 stroke a little bit on the low end with the Dax RT carb, .65 jet. It seems to run cooler than the Caster 927 at 32 to 1 that I was using with my old engine. The plug is kinda a light brown color (like the color of a Reese's peanut butter cup) and I'm wondering if that is too lean or not but it sure does cool down fast after shut down compared to the last engine.

I have to agree with Tom here Tyler,

No one is doubting you at all Tyler or attacking you here at all, just from our experience with Opti2 we know that it is a superior product compared to many others on the market, this has been proven over many years, and considering we are talking China Girl engines here and the possibility of a tuning mistake, I have to say that the friends engine seizing up 100.1% had nothing to do with the Opti2 oil, as Tom mentioned a bad bearing or even something else coming loose or breaking in the engine can cause a major failure no matter what oil someone is using and we have seen a butt pot load of different failures on here from about every single component in and on a China Girl engine.

One thing I will add about Opti2 from personal experience and not at all meant to shoot down anything that Tom said here is that if someone buys the small packets of Opti2 which have 1.8oz in them and mix according to what is recommended on the packet you end up with roughly a 72:1 mix ratio and not 100:1, I ran these packets myself at the 72:1 mix for a good while, engines ran great and could honestly tell very little difference in how they ran when I switched from the 72:1 to the 100:1 ratio which I currently use in all my 4 bikes, the main thing I did notice is when my engines were running on the 72:1 mix the pistons and exhaust ports would be a little gummed up with a thick sticky residue, it didn't feel like oil to the touch but more like a build up of an additive that is in the Opti2, it actually reminded me of Castor oil residue like I get in the exhaust of my Nitro powered R/C vehicles, after switching to 100:1 that residue is much less now so the exhaust port and pistons run much cleaner, personally I think just as I know Tom does that since Opti2 is actually designed for 100:1 mix, it should be run at that ratio for best overall performance, why Opti2 makes the small packets that mix @ 72:1 and then the next size larger packets mix at 100:1 is a puzzle to me, never have heard an explanation to why they do that, all Iknow is that the Opti2 oil runs fine at either mix but does its best job @ 100:1 because it runs cleaner, Tom is correct that to much Opti2 isn't a good thing, in my experience is didn't make a noticeable effect on performance in any way but the engines combustion chamber and exhaust port will run much cleaner at 100:1 that it will at 72:1.

What I do now is I mix 1.3oz of Opti2 to each gallon of regular gasoline and then I add about two cap fulls of Maxima 927 Castor to a 5 Gallon gas jug of mix, I live in a very Hot dry part of the country so having a little Castor oil in the mix is just a tad bit of extra insurance since is does a great job of protecting bearings and other internal parts in high heat conditions.

As Tom pointed out and most all of us with experience will point out, the most important aspect of all of this conversation can be summed up with one word ( TUNING ) no matter which oil you run and no matter what the recommended mix ratio of that oil is, the carb has to be properly jetted for all conditions or you will seize the engine if running to lean or on the other side have bad performance from a to rich condition, tuning the carb for the mix and engine set up is the most important thing about having a reliable china girl and a good performing china girl if the engine itself is what it needs to be inorder to provide good reliability and good performance.

Opti 2 will not cause an engine to seize but a bad component in the engine or incorrect carburetor tuning will.

map

fischer550 said:

how much did you have to down jet when you switched to opti-2?

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Until I got it right...!

honestly there is no universal jetting, but if it helps you I live at an elevation of 1,242 ft above sea level, I run good flowing exhaust and on all of my bikes I have soldered and re-drilled the jets with either a #73 or #72 wire gauge bit and mine run good that way.

Hope this helps and remember # 72 or #73 wire gauge bit is not the same as a #72 or #73 jet size

Map

2door said:

Tyler,
I have to doubt that switching to Opti is what caused your friend's engine problem. And it certainly wasn't from using Opti-2. There might have been other issues that would have occured no matter the oil. A bad bearing for example or him running way too lean. Without a lot of information we can only guess on that one.

That said, I have to question your decision to mix Opti at 70:1. Opti is a very, oily, oil. At 70:1 you are getting down into the 16:1 ratio problems that we try to dissuade folks from using. Too much oil.

The evidence, based on users like me and others is that mixing at the recommended 100:1 ratio is safe and will not damage your engine. I think you'll be happier with how your engine performs with a little less oil. Keep in mind that the less oil you use the leaner you'll need to tune the carburetor. But be careful there and don't go too far.

You plug color sounds okay, if, the color is more like the inside of a Reese's cup than the outside Although with the local gasoline that I use my plugs are shades of grey, never brown. Don't know why but it has been suggested that different gasolines use different additives that might impact plug color.

Tom

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Okay, I was trying to remember where I read that Opti-2 is not good for engines already running a regular 2 stroke oil and I finally found it. It was you who said it on this thread (100 to 1) on the sixteenth page.

here's where I stand with the Opti-2 experiment.
The high milage engine doesn't like it. I have some theories but that's all. I've tried it three times and did comparisons between my old oil mix which is Stihl 2 cycle oil and the Opti-2. All three attempts resulted in a decrease in power and speed but when I go back to the original mix the engine regains its previous performance level.

Now...the other two motors: Both are Dax 80s, one is very low milage, under 100 and the other is in between the three with just less than 500 miles. Both of these engines display a marked increase in power on the Opti-2 mix. Not just barely noticable but a marked increase. The 500 miler used to top out at about 28mph on the only flat area near my home. It will now do that same stretch at 32 with ease and sounds better than it used to. The power is smoother and more consistant. I do not feel that this engine is suffering from a lack of lubrication but I assume only time will tell. I've put about 165 miles on the motor using the Opti-2 mix and so far it has shown no signs of coming apart, running hot or making any strange noises that you'd expect from oil starvation.
The low milage motor is probably still in the break-in stage even with 100 miles on it because I typically treat my engines easy and don't abuse them. It has been my experience that running them like I do my break-in is a little longer than some. This engine, like it's higher milage brother is also running smoother and stronger on the Opti-2 oil. I was able to discern a difference rather quickly after the first tank and subsequent running has proven to display the increase in power and top end speed.
The high milage engine has a little over 1500 miles on it and runs strong and smooth on Stihl 2 cycle oil mixed 32:1. I have a 48T sprocket on this bike for the hilly neighborhood where I live and it will top out at about 26 mph on the Stihl oil. If I give it Opti-2 my top end is somewhere in the mid teens and I have to pedal up hills that it typically climbs unassisted at 20mph.
Theory: Something to do with the piston rings' inability to seal properly with the Opti-2. Even though the engine feels as if the compression is good there might be something about the Opti that is just too slick, for want of a better term, to allow the rings to seal and under load allows some blow-by. This is just a theory but it is the only one that makes sense to me at this time. To clear up a misconception that I've read here; the Opti-2 is not "thick as molasses" but in fact displays about the same viscosity as any 2 stroke oil that I've used. When mixed as per the instructions at 1.3 ounce per gallon of gasoline the mix is not any thicker than regular 2 stroke mix. It's apparent that the lubricating abilities of the Opti are very good but maybe too good for a high milage engine with some wear on the cylinder walls and rings and will not allow for proper ring seal. Just my theory.
Conclusion: The old motor will get regular 2 cycle oil, probably the Stihl that I've always used and the other two, and probably any future engines will be run on the Opti, obviously depending on what happens as time passes and the miles accrue. I'll report it if there's problems. Oh, by the way, Dax cringed when he rode one of my Opti-2 bikes a couple of days ago. He is not a believer. "Go to 50:1" He said. Sorry, Duane.
Tom

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Tom, first I want to say that this thread (100 to 1) is over 100 pages long and I have not read the entire thing. I'm not trying to trip you up on your own words or anything. I know you have much more experience than I have with everything 'motorbicycle'. I value your opinion here, which is probably why I remember reading this in the first place and putting such high stock into what I read because you wrote it. I defer to your expertise on most everything I read here. When I have a question about anything I always try the search function on this website and usually find the answer without the need to ask something that has already been answered. But I'm a little confused this time, have you changed your mind on this?

As to my friend's motor. I have since talked to him about this and he told me that his bike lost power when he switched to opti-2, much like you describe happened with 2 of your own engines in the 100 to 1 thread. But instead of going back to the original mix he tried to fix the problem by changing his jet down to a .60 and that is when his engine seized. I suspect it seized from running too lean.

In any event, with regards to my engine, I took it for a little ride today, about 35 miles, running opti-2 at 70 to 1. It ran pretty well with just a little 4 stroking at low RPMs only. I'm using the RT carb with the .65 jet. I took a couple of pictures of my spark plug so you can see what color it is. Do you think I'm running a jet that is too lean?

I think my engine is broken in now, at least, I hope it is. I have burned 2 1/2 gallons of gas through it using opti-2 at 70 to 1. I'm going to start mixing my opti-2 at 100 to 1 now as you suggest and hope for the best! My question now is: Wouldn't I need to jet up with the leaner mix?

Map:
Thank you for telling me that. I got a gallon of Opti-2 so I don't and never have used the packets. Since I have been running at 70 to 1, I will take the exhaust ports off and clean them. I will also check the piston for residue. Is it best to use carb cleaner to remove it? I do have the drill bits for drilling the jets and tried to drill a .67 jet, although, it didn't turn out so well, I think I used too much solder when I filled the hole. It took forever to drill it by hand. Ha, ha, I will try again. I'm still trying to learn how to jet correctly.
Thanks for your reply!

A trick with soldering is to cut a small piece of solder, just as much as you need, place that where you want it and then heat the job. For soldering jets, you will only need a 'pin head' of solder.
The other trick is with using flux, and only put flux where you want solder.

Yep just a pin head size piece of solder and if you use rosin core solder like I do no flux is needed, just spray jet off with carb cleaned to remove any oil, put that tiny piece of solder over the jet hole and heat from underneath the jet, solder will melt and be drawn into jet hole from heat being applied this way, do not put torch heat directly onto solder because it will melt almost instantly, best to heat jet and let it be what melts the solder and just as soon as solder flows into hole, remove heat source and you are good to go and drill as soon as it cools off.

Map

Tom, Ok, that explains things a little bit, a mystery, haha.

Map and Theon, well what happened with the drilling is that I put a small amount of flux over the hole, then I took some solder and melted a little bit in the hole from the threaded end with a soldering iron, then I let it cool. After it was cool I tried to blow into the cupped end to make sure it was filled but air came out through the jet hole and I knew it wasn't sealed, so I put the soldering iron in the slot again and tried to heat up the solder again to move it to cover the hole but that didn't work either. So I tried to melt some more solder in the hole but melted too much and filled it more than half way up the side of the cupped hole of the threaded side. When it cooled the hole was filled but the drill didn't exactly drill all that extra solder out very fast, I kept turning it and turning it and turning it to try to drill it out. The problem was that it took a good 20 mins to drill it out and after that many turns my hand didn't exactly stay straight so I kinda drilled it out at different angles with each turn and when I finally got through it, it wasn't drilled very accurately at all. Yikes!!

I will try a new one. I think you are right Map, heating from the bottom and cutting out a small amount of solder first so I don't fill it too much should work much easier, haha, I'm such a rookie as stuff like this. I'm certain you guys get tired of explaining stuff to rookies like me on this website so I want to say thanks to all you guys for sharing your knowledge. I really do appreciate it!

By the way, does anyone have an opinion on the color of my sparkplug? The second photo I posted on page 3 is a pretty good representation of the color, a light brown slightly red color. Is it too lean? Should it be darker using Opti-2?

Based on that pic it looks like the plug color is just fine.