200s Fresh Bore, Smoking Quite a Bit??

[DohcBikes]

If you turn the fuel/ air screw in, is that more air or fuel?

Hey that's a good trick question!

It is neither,

Its a fuel screw, in for less fuel (lean) out for more fuel (richer).

[yaegerb]

Alot of good info. I would think its exhaust is full of oil or rings need to seat. I have also seen this problem when you don't properly stagger your rings on the piston. I trust you staggered all the ring gaps correctly?

[mike84bigred]

Yes, I had the shop manual present when setting the ring gap locations.

[RIDE-RED 250r]

If the fuel/air screw, (AKA: idle mixture screw) is between the throttle slide and the engine it regulates fuel at idle. If that is the case turning it out (counter clockwise) it will enrich the idle mixture.

Conversely, if the idle mixture screw is between the throttle slide and the airbox it regulates air at idle. Turning it in (clockwise) will enrich the idle mixture.

Most 4-strokes (especially older ones) have a fuel regulating idle mixture screw, and most 2-strokes had/have an air regulating idle mixture screw.

Your 200s should have a fuel regulating idle mixture screw as DOHCBIKES said.

[mike84bigred]

Ran it again today. Ran real good but once again after about 4-5 minutes it started smoking again. I dont think it was as bad today. Borrowing my father in laws compression tester. Ill post the results when I figure it out.

[mike84bigred]

So unless the tester doesn't work right, I can only get 120 psi max out of it and that's after like 10 + pulls. Isn't it supposed to be about 160?

[Thorpe]

Did you hold the throttle wide open when testing your compression?

[RIDE-RED 250r]

Alot of folks seem to think there is a universal compression number that all engines should get. But in my years of wrenching on everything from my wheelers, to sleds and dirt bikes I have found there is no set number that applies to any and all engines.

120 psi may be fine for your engine. I would try to get ahold of some service specs and see what that says compression should be before condemning the numbers you get.

And as Thorpe asked, throttle wide open? It does make a difference. If you don't hold the throttle open, you are restricting how much the engine can take in and deflating your compression reading.

[mike84bigred]

Its been some time since I did a compression test, so I may have forgotten some of the rules. I know your suppose to check it with a warm motor, so I let it run a few minutes, but I did not hold the throttle open. I guess I also gave to figure that the piston and rings aren't broken in yet so low compression and being a bit Smokey may be normal for now. Just I live in the city and really need it not to smoke if I want to beat it around the yard. Ill finish putting it back together, and once my arm heals, because the decompressor cable is broken, ill put some hours on it and see what happens I guess.

[barnett468]

You can run syn in this fresh engine till the cows come home. You'll never have a problem.

Actually, you should NOT run synthetic “till the cows come home.” during break in. After that, you can run it till the cows are filet's on your plate and longer.

Amsoil as well as other companies recommend using non synthetic oil for initial break in. They have done testing which shows using synthetic oil for break in can increase the time it takes for rings to break in or prevent them from fully breaking in/sealing at all.

Amsoil only makes synthetic oil, so for them to tell people NOT to use their product seems to speak for itself imo. I also have personal experience with this.


Excerpt from Amsoil article.

"Breaking in a new engine is one area that petroleum oil is better for than synthetics.

…we recommend you run the factory installed petroleum oil for about the first 500 miles.

…these are our recommendations based on engineering studies and our extensive knowledge of this topic."

http://www.synthetic-oil-tech.com/d...._to_amsoil.htm


Although a percentage of certainly do eventually properly seat when synthetic is used from the beginning, an increase in the occasional seating problems has been proven when synthetics are used for break in. Knowing this imo as well as in Amsoils opinion, it seems like a simple, reasonable precaution to use non synthetic oil for break in.



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Hi, my name is Bacon Aren't I cute.

[DohcBikes]

Yes do the compreesion test throttle wide open, but honestly it will build pressure anyway. The most important thing is that you check until it stops goin up.

You need to do another compression test. If its at 120 warm after a rebuild, something ain't right. If you do get 120 with the throttle wide open, warm, I'd be doing a leak down test as well.

As barnett suggests, synthetic oil has been proven to be inferior for ring break-in.

[barnett468]

.
Hello Mike84bigred;


Typical post Model T, non high performance, normally aspirated gas vehicle engines have a cylinder cranking pressure of around 135 - 140 psi. 120 would be an extremely low number and not normal for any of these engines. In my experience most engines fail to run below 90 psi and run slowly/poorly at less than around 115.

According to the manual, your compression should be 156 psi plus or minus 14 psi. This means that if it is below 142 psi, Honda recommends repairs. This number is also at sea level. You will loose around 5 psi in cylinder cranking pressure for every 1000 foot increase in elevation. In other words, if you are at 3000 ft, your psi should be 15 psi lower than the Honda recommendations. If it's higher its a good thing. See free online manual in the link below.

http://www.atcmanuals.info/


One problem is that different compression gauges can EASILY vary by 20 lbs. Typically, the more expensive they are the more accurate they are. The length and id of the gauges hose can also affect psi. It is best to use a good gauge and use the same gauge every time so your results remain consistent.



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[mike84bigred]

Well I dont live on top of a mountain but I'm not sure where I am as far as sea level, so not sure if elevation is a factor or not. The gauge itself is only a harbor freight cheap gauge, so I guess there's a chance it may not be 100% accurate. One other thing is the cable for the decompressor is broken, so I'm pulling it with no decompressor. I have it tied in place where I think its supposed to sit with a zip tie temporarily. Ill try another test soon.

[barnett468]

Well I dont live on top of a mountain but I'm not sure where I am as far as sea level, so not sure if elevation is a factor or not.

Well, google says your elevation is 571 ft, therefore your compression will be .5 x .571 = approximately .2855 psi less than it would be if you were in a row boat. Please be sure to factor this in.

The gauge itself is only a harbor freight cheap gauge, so I guess there's a chance it may not be 100% accurate.

Your guess is correct.

One other thing is the cable for the decompressor is broken, so I'm pulling it with no decompressor. I have it tied in place where I think its supposed to sit with a zip tie temporarily. Ill try another test soon.

Did you tie it so it is open or closed?



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[mike84bigred]

I'm not positive, but I think its where it would closed. It never worked so I'm not exactly sure and dont know how you would be able to tell.