Topic: BEST BANG FOR MY BUCK---BUCK BEING 0

[juliorice]

Advice plese.  This is a continuation from my earlier post about 900cc vs. 836cc.  I am putting together a new engine.  Over the years I have accumulated some decent parts and I want to do the best job I can with what I have.

 I had built a Wiseco 836 engine that I put about 10,000 miles on.  Ran great, but had some problems.  Most notably very high oil consumption.  As in a quart every 300 miles.  And for some reason it would burn the electrode off of the #3 spark plug.  Interesting enough, I did a search a moment before posting this and found a question I had asked in 2010 when I first started this engine.  Apparantly my #3 cylinder had issues then also. 

This is what I have. 

Wiseco 836 pistons, used(by me)
Henry Abe/Hainst 900cc pistons, used(scored them from a guy, don't know their history)
Webcamshafts 63a cam
Heavy Duty valve springs(bought from Webcamshafts when I bought the cam)
Titanium keepers(bought from Webcamshafts when I bought the cam)
Adjustable Cam sprocket(bought from Webcamshafts when I bought the cam)
1971 Head ported and polished by a reputable local head guy. 
29mm Mikunk smoothbores

I think that's it.  This is going in a 77' Supersport chasis.  I don't intend to race, and do like to take longish road trips.  All I am after is a powerful dependable engine/bike that I built.  Nothing too crazy, just the best I can do with what I have.  In my earlier 900cc vs. 836cc post it was pointed out that if I went with the 900cc I would at a minimum need sleeves and preferably rods.  When I first saw that I figured it settles it, 836 it is, until a fellow mentioned he had a set of Goldenrods.  Naturally my brain started shceming again.  It seems clear that the 900cc puts out more ponies than the 836.?  I thought perhaps the higher compression of the Wisceo might make up for the increase in displacement but I guess not. 

As a side note:  I work in a machine shop a have the capability to do my own boring work.  In fact I did on the first engine, but I think that might be what is contributing to my issues.  I really didn't know what I was doing as far as clearance was concerned and I think I made the bores much too big.  I'm going to tear that engine apart this weekend and see exactly where they are.  It's been while and I don't remember, plus I honed them a few times. 

So, that's the just of it.  What do you guys think?  Opinions on what you would do in my shoes.  Dollars are limited, but I have few.  Very few.  Pros, cons, gain vs. problems??  Thank you much and take it easy.  Julio

[BPellerine]

from what I understand going over 849cc starts costing big bucks as there is a lot more strain put on everything just having a used set of pistons to start a 900 engine would be expensive!you have everything for an 836 with maybe the possible need for new rings and another set of jugs to start fresh that wpuld be my path and then work up a 900 on the side.just my thoughts.bill

[Geeto67]

Well since you are a machinist the most expensive part of the conversion is cancelled out. However, have you considered the screw up cost? If you bodge the 836cc kit you can still get a set of the cast 849cc pistons and bore for those. If you screw up the 900cc kit you need a new set of liners and possibly a new cylinder block. Maybe the cost is comparable, last I checked liners were more expensive but you also lose time starting over. I guess what I am saying is there is more room for error with the 836 and the components you have. 

[Duke McDukiedook]

That sounds like a lot of oil loss for an alleged 'decently done' 836 bore.
If you don't plan on racing it just go up in gradual volume increments, you do want this engine to last for a while don't you?

[754]

Just how much piston clearance did you have?

[juliorice]

So, I pulled it apart.  Took #1 piston off and measured the skirt.  It measured 2.555"  I measured the bores.  I measure with calipers, I'll get a bore gage out tomorrow, I can get within .0005" with calipers.  Anyways, the bores measure 2.560.  So.. .005" clearance.  Seems like a lot.  Mr. Hondaman says clearance should be .001, I'm thinking this might be where all my oil is going.  He also says pistons shrink during break in.  Or someone says that.  How much?  A couple of tenths or a couple of thousandths?  Or more.   Like I said, I have no idea where I started and I've put about 10,000 miles on it.  Thanks.  I'll probably start another thread about reusing pistons and rings. 

[Geeto67]

reuse pistons - ok. Reuse rings? eh....not so much.