New to Blasters, have a few problems...

[Vootie]

Hi

I recently bought a 1991 Blaster for 500 bucks. I thought I got a pretty good deal, but maybe not. I knew going in that it was gonna need a little work, but now I'm thinking more than I bargained for.

Problem #1

It starts easy and idles/runs good (other than it seems way too "pipey" for a 200), but the compression is around 90 psi so It's time for a new top end. When I bought it, the kid told me it had a big bore kit in it and that it was a 260. Not knowing anything about blasters, I took his word for it. I don't have a micrometer, so I have no idea what this thing is bored out to. The top of the piston has either "100" or "1.00" engraved on it, but I can't really tell. Anyway, do I want to measure the cylinder, or the piston?

Problem #2

I rode the bike for maybe a total of an hour before I decided to tear it down and go over the whole thing. It sat in my garage for a couple days, and when I came out today to strip it, I noticed a puddle of gear oil underneath it. I pulled the motor out, and visually, I don't see any cracks in the case. The drain plug was tight also. It was a fairly large puddle, and there isn't much oil left in the case, could this much oil have leaked through a bad seal in the case halves? Any where else it could have come from?

It's been a long time since I've owned a two stroke, and for that matter, a long time since I've worked on one. Any help would be greatly appreciated.

Thanks

 

[robert0762]

Yes you want to measure the cylinder. As for the oil if you r sure its oil and not gas or 2 stroke oil then the only place it could come from is the cases

 

[Vootie]

Ok, thanks, I'll see about renting a micrometer or something. And yeah, it's definately transmission oil, just wondering if there was anywhere like an overflow or something other than the seal between the halves that it could have leaked from.

Oh, and the stock bore is 66mm, correct?

Thanks

 

[DUALSTROKE]

66mm is correct.It is 1mm over now.Probably stock not big bore but mic it anyways to find out.Only places tranny oil can come from is the case halves which is just yamabond.Or it can come from clutch cover gasket(right side sitting on bike).Last spot would be under oil pump cover(small cover mounted to clutch cover) could be the oil pump gasket if still running one,block off gasket,and worst case scenario I have seen the nut spin off the crank and blow a hole through the clutch cover.Best bet is to drain it then just use Type F Automatic tranny fluid and watch to see where it might be.Type F is alot cheaper and works very well.Even if you don't want to run that fluid use it to find the leak so you are not wasting the $6-8 on what you normally use.Hope this helps.

 

[LoneWolfNY]

Check the seal on the foot shifter shaft. Mine had a leak there that slithered down to the bottom of the motor then dripped off. Made it look like it came from the bottom but came from that seal. Replaced mine today, leak now gone.

 

[Vootie]

Thanks for the replies guys. I'll have a better look at it tomorrow and check the places you guys mentioned. The bike does have the oil block off, although it looks kinda like a half assed attempt.

So, assuming it is 1mm over stock bore, would that be like .40 over? .60 over? I don't really want to bore this time around as the cylinder wall looks ok, I am hoping just to hone it and drop a piston in. Or is this not a good idea?

Thanks

 

[Braapbraap95]

The better thing to do is to bore it. But honing works too. 1mm would be i think .040. So you are going to need either a .050 piston or a .060. Don't take my word for it, i don't know exactly what I'm talking about. haha,

 

[blasterfreek30]

^ ithink it is .40 over , mine is 60 over and my piston is 67.50mm

 

[pittboss45]

Have the clearance checked and if it is .004" or larger then spend the money and get it done right, bore job with a new piston.

I see this stuff all the time. A customer comes in, orders a piston cause the bore looks good, no scratches. Then after not taking the advice from someone that knows what he is talking about cause his bubby said that he can get away with a hone job, the new piston that he just put in has a broken skirt and I should replace it cause it was defective.

 

[Vootie]

Ok, cool, thanks for the advice guys. Heading to the garage now to play with it. Decided to split the cases because there is some metal shavings in the oil. I ordered some tools: a fly wheel puller, clutch/flywheel holder, and a crank installing tool. I found a tool to split the cases with, but it's 60 bucks. I'd really rather not buy a 60 dollar tool that I'll probably use once, so does anyone have any tricks to splitting the cases?

Thanks

 

[blasterfreek30]

ive used a rubber mallet, and it worked great