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Discussion Starter · #1 ·
Ok I have a .40 over cylinder and the other one is getting .20 over. CAN I DO THIS? will it hurt anything? Some mechanics i've talked to say it's ok, but alot of people say it will break the crank. It's a 86 phazer. I'm really relying on you guys to give me good information, because if you say it should be ok...i'll go ahead and put together on monday, if not then I guess i'll have to change it.

Thanks.
 

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i would say go for it, i used to run all sorts of yamaha's, burned them up left and right(not realy, only a couple) but i would have them sized once or twice over depending on the damage. i never had a problem after any rebuilds.
ride on!
 

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every time you bore, your crank has to drag something bigger back and forth. think of it that way. boring them both the same is just an old machine shop come on to get more of your money.[:D]
 

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If you have 2 carbs, it'll work fine. Not to the optimum but with no problems.One carb (unlikely, but for others) for get it. The cyclinders cannot be balanced. Air fuel mixture that is. If it was me I would have match the 40 over.
 

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comon cat you cant say that! do you think 020 thousands of 1 inch we are talking like tin foil here! have you ever (no offence)worked on stuff like this? i was just trying to help him out. no hard feelings i hope[xx(]
 

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giver man you will probably have other things pop up wrong but none will have anything to do with odd size borring. just for the hell of it back a few years ago i saw one engine with one side stock and the other 060 over and that sled won us 4.9k in one day! dont let the machine shops or the the other guys that are not paying your bill foolyou think about it if that other side is so bad how did you get home?
 

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Discussion Starter · #9 ·
The one side is perfect (.40 over side) I figure .20 to .40 is almost nothing..we are talking .10000 of an inch. We get it back monday...Hopefully everything goes well. We think it was the carb that wasn't working that made it go. There was deep scratches in the cylinder wall...We could turn the carb air screw right off and it would turn off, but if we did that to the other one it would shut off. So we're gonna get the carb cleaned and vroom vroom!!
 

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I have run many sled engines that have .20 diff. between cylinders for years with no problems.Don't even worry 'bout it,put 'er together and ride!
peace...willie
 

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I don't think the little extra weight will make any difference. But if you are concerned about it, take the pistons and have them balanced by a machinist.
 

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My brother ran an old JLO with a .020 399 jug on one side and a stock 440 jug on the other for two years with no problems. He finally just quit riding it when he got something better. Don't know exact difference but I'm sure it was more than .060.
Single carb.
 

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It really will make little or no difference at all. After break-in, I would do a high throttle plug check to see how the fuel ratio is, then adjust accoringly. You probably won't even need to re-jet.

The Phazers have 2-carbs so you can adjust the carbs by themselves if needed, but before re-firing I'd probably rebuild the carbs. Something caused the melt-down in the first place.

(o;

DNO.
 

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since its a twin i see no trouble at all. if it were a triple then troubles could arise. but being a twin and only .020 between cylinders i see no problems. just be on the safe side throw some richer jets in there and then tune from there dont want ya burning it down again
 

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Discussion Starter · #16 ·
haha...Sorry guys, but my dad decided just to get the .40 more expensive piston so they will be even, it will be here tomorrow and will be bored and back hopefully wednesday. Thanks for the info though!!
 

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Probably the best choice.why bore only 20 over when for another 20 bucks and you can match cillenders.it wouldent have hurt anyway,but to save 20 bucks it just doesent make sence,
 

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Discussion Starter · #18 ·
Yea, well actually it was more like 40dollars more...60 for the Kimpex Piston and ring...100 for the Wiseco. This is Canadian Funds by the way.
 

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i wouldnt see to much trouble on that engine, especially for trail riding,

but .020 is huge on motors, make sure you get the top ports put back to where they where,

I have seen engines fail on .006 out of spec. In college one kid locked an engine up from .001 to tight on stuff.
 

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Originally posted by madcow
[br]I have seen engines fail on .006 out of spec. In college one kid locked an engine up from .001 to tight on stuff.
I'm just trying to learn here; is this not apples and oranges? The original question is about .020" difference between cylinders, but the .001" engine lock up would be a too-tight piston? Just trying to understand, and wondering if I'm reading this right.
 
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