crank shaft repair

[asmeninis]

Hello All,<br>Just got confused discussing the topic with the friends. There was one and firm opinion, that crank couldn't be resurfaced. It will never last.<br>Note: most of them driving Hondas and seems Honda not giving repair plain bearings.<br>According to my knowledges, it depends. More over Yam spare books showing few positions of plain bearings (color coded).<br>IMHO it means, that metal surface is deeper treated and could be resurfaced safely.<br>Any comments, please?<br>Also, what is the dimension's step for those plain bearings? <p></p><i></i>

[exupturbo]

The total variation from the biggest to the smallest Yamaha bearing is less than 0.001 inches if my memory serves correct. Meaning there is no real allowance for re-grinding and the colour coding was just used in selective assembly of the production parts.<br><br>I made the HUGE mistake of getting my crank "coated" then re-ground down to stock sizes. Damn thing cost me a fortune in new gaskets, bearings etc and was never any good <!--EZCODE EMOTICON START >: --><img src=http://www.ezboard.com/images/emoticons/mad.gif ALT=">:"><!--EZCODE EMOTICON END--> I must have rebuilt and run in at least 3 times before I got so pi$$ed off with a damaged and knocking bottom end that I bought another engine.<br><br>Sorry, there's no easy way out.<br><br>Mark <p></p><i></i>

[Matt at PSB]

I need to know a lot more about what is wrong with your crankshaft and/or how it is damaged. Then I might be able to fix it.<br><br>As an example: We had a customer spin a connecting rod bearing wasting that con rod journal on the crank & the con rod. The journal was damaged to the point that no regrind to larger bearings was possible. The crank was removed, the damaged journal was welded up to a larger size, the journal was re-machined & refinished to the exact right size and then the entire crank was re-heat-treated. The engine has run for two years now without problems.<br><br>It is not a fast process. It is not cheap. It does work. The end results are known as opposed to just going out & buying a used crank or engine. Other issues in the engine are normally addressed at the same time such as head & piston rebuilds. It is significantly less costly than a new crank. New crankshafts go for $667USD.<br><br>Matt at PSB<br> <p></p><i></i>

[ChuckD]

How about the one from the 89? I would let it go for $200. OBO<br><br>CHUCK D. <p></p><i></i>

[asmeninis]

Okay,<br>So, the luck of shaft repair is really variable <!--EZCODE EMOTICON START :( --><img src=http://www.ezboard.com/images/emoticons/frown.gif ALT=":("><!--EZCODE EMOTICON END--> <br>Actually the one I have, also got a plain bearings spin on one journal (wheelie, I suppose?).<br>But the damage is minor. <br>Knowing the cost of alternative (i.e another shaft), I'm like to collect the info all about.<br>Thanks for replays.<br>Chuck D, I'll report you back, when will finish research here, locally.<br>Just once again wondering concerning missing info in spares or service books re. colored bearings?<br>BR,<br>Mindaugas <p></p><i></i>

[asmeninis]

So, but anybody, how to know exact dimensions of those colored bearings?<br>Asked few dealers, no one could or want to say. <!--EZCODE EMOTICON START :( --><img src=http://www.ezboard.com/images/emoticons/frown.gif ALT=":("><!--EZCODE EMOTICON END--> <br>Thanks,<br>mindaugas <p></p><i></i>

[flyingcircus68]

The color code is based on the numbers that you find on the left hand side of the crank and on the back of the upper half of the crankcase. The five digit numbers are for the main journals of the crank, and the 4 digit is for the con. rod pins.<br><br>the main journal bearings are determeined by:<br>crankase # - Crank# = bearing<br><br>1 - blue bearing<br>2 - black bearing<br>3 - brown bearing<br>4 - green bearing<br>5 - yellow bearing<br><br>Crank pin bearings are determined by:<br>con rod# - Crank pin# = bearing<br><br>1 - blue<br>2 - black<br>3 - brown<br>4 - green<br><br>the clearance for a conrod should be .0013 - .0022 in, or .032 - .056mm.<br><br>The clearance for a main journal should be .0008 - .0017in, or .020 - .044mm.<br><br>No actual journal sizes are listed, but you can use a black, or brown bearing, torgued down in the assm. and get the dimension with an ID mike and grind the crank to this dim. This allows you to size up, or down, on the bearing to get the req. clearance. Based on the above calc. It appears from the calc. above that the yellow/ green are the tightest of the series. <p></p><i></i>