Need help with micro drill bits and drilling out jet

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Super

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Sep 19, 2011
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Gas fog at the carb intake is normal for a piston ported 2 stroke. A little gets pushed out before the piston closes the port.
Ok so don't worry about the gas coming out of the carb. But what about the vibrations. I'll make a vid later to give you a better idea what I'm talking about. Because on my old bike it didn't sound like that. This is the same kit too just a different bike. I wonder if it my be the mounts. But it only vibrates like this when I hit a certain rp, about where the 3/4 mark is.
 

killercanuck

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Dec 17, 2009
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Hmm, glad its running better but Grey sounds on the lean side for mineral @32:1, you want a nice chocolate colour, ideally:


Could you get a couple close ups of your front mount? What do you have for an extension on there? Hard to tell from the first post pics.
 

Super

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Sep 19, 2011
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I don't understand this. I dam near had my bike running perfect. Only trouble I had was the vibration at really high rpms. I did a plug chop and I know I have to be running way to lean. The plug still looks new except for the burn marks on the tips, where the spark ignites. The white ceramic part is solid white. But remember its running good. I then go up a hair on the jet and I'm still running lean but now my bogging issue is back. I just know if I keep going up on the jets to a richer proper level then the bogging will just get worse and worse.
 

Super

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Sry, I didn't see your post, killercanuck. Here are some pics of my mounts and my plug that I had mentioned above.


The piece the arrow points at, I'm using as an extension and is the only thing different from my old setup.




 
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killercanuck

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Well, for the vibes, I'd say you're going to have to scratch the paint a bit. Rubber under the mounts will make vibes worse, not better, sorry to say. Plus it'll add to the risk of snapping a rear mounting stud with the engine trying to shake itself off. That'll help the vibes.

Oh, and if the engine's vibrating that bad, you could be 'foaming' your bowl up. Know what I mean? Like if the engine is shaking the bowl up like a soda pop, it can't properly feed the froth to the engine. That's something to think about too.

Did the engine take any damage in the wreck? Can you check if your main seals are leaking? Like, pop of the mag/clutch cover, and if there's any oily residue a seal could be leaking trying to suck in air from inside the cover. The clutch side will be harder to notice, as you should have a bit of grease on the gears. Look on the inside of the covers and swipe with a dry finger for oil residue.

A case leak might be another thing to check too, spraying with WD or something around(and under) while idling can check for that.

There's alot of suggestions there, but I'm thinking the Foamy float bowl is going to be the culprit. Anyone else think that too?
 

Super

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Sep 19, 2011
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I will check into what you said.

One question though. What should the fuel level be in relation to the jet? Should it be even with the jet, 2mm below the jet, 2mm over the jet, etc?
 

wayne z

Active Member
Dec 5, 2010
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Somebody told you wrong. The jet has to be substantialy submerged. It needs to pull raw fuel into the venturi to be atomised.

Excessive vibes could cause foamy floatbowl and a lean conditon. Excessive vibes could also affect the float valve, causing it to leak and make a rich conditon. If you ever look closely down a carb throat with an engine running, you can see the raw gas exiting the bowl and mixing with the airflow in the venturi.

I would bet that the bad vibes would dissapear if the rubber is removed from the mounts.

Then you may have to re-tune your carb!
 
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Super

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Sep 19, 2011
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Yall were right!!! I removed the rubber and now it's running as smooth as ever. My bogging issue also has ceased to exist. Now like you said I'm gonna have to retune carb, cause I have float at 24mm, which means fuel lvl is a few mm below the jet. Also I belive I'm still running a bit lean. I just got back from a test drive and man it felt good to see my bike go full speed again without spitting and sputtering.
 

Super

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Sep 19, 2011
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I'm still having trouble with getting the fuel mixture right. I've drilled out my jet all the way to a .8mm and it's stiil running too lean. It just won't get tan or light brown on so short a run. If I leave it in for a week, while driving around daily, it will.

Let me explain what I'm doing on my plug chop runs, maybe I'm doing something wrong. First I drive to a secluded road down the street. This gets the motor at normal operating temperature. I remove my normal plug and put in a new plug. I peddle up and let go of the clutch and quickly accelerate to full speed for about 600ft. Right before the end of the road I hit the kill switch and pull in clutch at the same time. I turn around and repeat for the way back to the other end of the street, just for good measure. I then pull over and remove the new plug and put back in the old plug.

I keep going up in steps on my jet and each step up it don't seem to make any difference. Although yesterday it did sound like my motor back fired one time right after I hit the kill switch. I was at a .7mm then on my jet. Today I decided to go up in big steps untill I get close. I went up to a .75mm and then a .8mm. From what I understand this is a big change an I should be running too rich at .8mm.

I live in a very humid environment, so close to gulf as I am. I live in Houston, Texas. Could this be a factor in my fuel mixture problem?

The motor runs fine, I just don't want to run too lean and damage my motor.

I'm also using 32:1 Royal purple synthetic oil 2-cycle TCW III with super unleaded.
 

wayne z

Active Member
Dec 5, 2010
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A good safety regardless of plug reading or measuring head temps ect is to adjust mixture so that you get a very slight intermittant 4 stroking at full rpm and speed. This is the old school way to adjust chainsaw carbs to keep from burning up the motor. As long as you hear slight 4 stroking you know you're not running too lean.

You shouldn't remove or replace plug while engine is hot. The aluminum threads will suffer and soon fail.
 

Super

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Sep 19, 2011
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ok, I think I can do that. The plug does eventually turn black after a week of driving it.

And about removing the plug on a hot motor, I do usually wait a few mins before I remove the plug. It's still warm but not hot. Is this ok?

BTW just had someone ride along next to me to see what my top speed was and it was 35mph. I was like, "No way!" The top speed on my old build was only 25mph. I'm rather skinny, so that helps. :p I'm 6'2" and only 170lb. I Never could gain wight and I eat like a horse too. But man 35mph thats fast for a bicycle. ****, if I put a smaller rear sprocket on, instead of the 44 tooth one, I might be able to get up to 45mph and would be able to leagle travel on the hwy. LOL xct2

Edit:
LOL, can't say the H word. You know heaven or h***.
 
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SdCruizer

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Feb 15, 2012
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San Deigo
ok, I think I can do that. The plug does eventually turn black after a week of driving it.

And about removing the plug on a hot motor, I do usually wait a few mins before I remove the plug. It's still warm but not hot. Is this ok?

BTW just had someone ride along next to me to see what my top speed was and it was 35mph. I was like, "No way!" The top speed on my old build was only 25mph. I'm rather skinny, so that helps. :p I'm 6'2" and only 170lb. I Never could gain wight and I eat like a horse too. But man 35mph thats fast for a bicycle. ****, if I put a smaller rear sprocket on, instead of the 44 tooth one, I might be able to get up to 45mph and would be able to leagle travel on the hwy. LOL xct2

Edit:
LOL, can't say the H word. You know heaven or h***.
when I plug chopped a 70cc scooter I big bored from a 50cc I had no results either. Even on a website for that scooter no one ever posted plug chop pics but all had claimed to do them
maybe its the newer oil or fuel or the small size engine but im a big believer in driving it for a week to check
I went through 5 jet sizes, 8 plugs, all needle ranges and never got anything but white on my plug ceramic

even when everyone used the same jet for the same engine, same altitudes

even my 4 stroke fuel injected scooter I did a plug chop when it was stock fresh from the factory all white
when I big bored it, threw in larger fuel injector all white
added a fuel controller and purposely added more fuel all white

but waited a week and got the nice tan color and its stayed the same for over 4000 miles, on my scooter


So I would go with jetting until it bogs from being too rich then go down one set at a time
with drilling I guess maybe you can be more precise after soldering it back up if you kept track of the drills used in order


here is an example of my 2 stroke chops, note I was always told to look for the smoke ring deep in the ceramic for main jet chops
the normal ceramic you usually see is the lower jetting like the needle

See the tiny smoke ring under the threads I cut off but the tip has a touch of black
this jet was too rich
I ended up at 87 I believe they only went 80, 82, 85, 87, 90 so I didnt have too many to choose from
Stock was 80


this was after 2 weeks, note: it looks what is considered good
tan on the ceramic, hard to see