'86 Spree piston and cylinder are toast...

[Jam-bro]

Was riding it on a long straight doing about 31mph. If I close the throttle a bit, it accelerates to 35mph. This day, it went close to 40mph. I was BUWOW, then it bogged down. I made a u turn it went up to 25mph and then died. The pics show why it died. The cylinder cracked as well. You can see it on the pic. Prev owner honed it to fit a 48mm piston. It was paper thin.

[paulpauly7]

the 48 mm kit is different to a stock cylinder as you have found out you cant hone the stock cylinder to 48mm

[patthesoundguy]

Wow that's cooked :'(

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[Jam-bro]

Emailed Taz and he is out of BBKs til mid July. Should I go with a 44mm or a 48mm? I will run it with a stock carb, stock exhaust and uni pod filter.

[JJ Joseph]

Emailed Taz and he is out of BBKs til mid July. Should I go with a 44mm or a 48mm? I will run it with a stock carb, stock exhaust and uni pod filter.

Go big, or go home, as they say. Go for the biggest bore that you can afford. A bigger bore doesn't usually cost much more. Bigger bores sometimes require a bigger exhaust pipe. Check before you buy. Stay with the stock carb, but upjet about 20% (from 65 to 80, for example). You can muck around with bigger carb etc AFTER you get it running because carburetors can really mess with your mind - and your wallet

[Jam-bro]

Thnx JJ... I was leaning towards the 48mm BBK. My plan is to keep the stock pipe, Uni filter and stock carb. I will install whatever jet Taz includes and hopefully he guides me in the right direction to set it up correctly. Before the piston and jug got shredded, it ran pretty well. It was lean at WOT and that is something I will have to deal with. I spun the crankshaft by hand after I removed the pston and cylinder and it felt really smooth. Looked inside and did not see any debris in there. What do you think caused all the scoring on the piston?

[paulpauly7]

somthing that will probably do the same again unless you split the cases and clean it properly

[Jam-bro]

Is it a pain to split the cases? Any special tools required?

[patthesoundguy]

There is a good thing about splitting the cases, two actually. You can clean up the intake nicely And you will be sure that there is nothing inside to ruin the new big bore kit

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[swimmingfree]

i wood split the case it look like you are missing a piece of the jug ... all it take is a small piece it mess up your new top end or the crank .... i use a chicken foot stile steering wheel puller to pull the case apart as well as the fly wheel off .. if your going to go with a 44 or 48 new top end i wood get a hold of tazland001 on here he sell the bbk on eBay and make sure you tell him what air filter your going to use so he can send you the right jet for the carb ... i feel the you were running leen and not anuff oil you need to add a oz of oil in the tank ... look at the spark plug ill bet its lite in color... when you get the new top end you shood start the motor let it idle for 10 min then shot it off for a hour do this about 5 to 8 time ... then go for a short ride but not a full wot till you have about 200 miles on the new top end the do as you please it shood take ...
swimmingfree

ps
like patthesoundguy said You can clean up the intake on the case at this time

[noiseguy]

Splitting the cases is a major job and requires special tools. I try to avoid this when possible.

You can alternately flush out the bottom end with premix gasoline (remove engine, fill and dump).

[Jam-bro]

Thnx for all of your input. It's great to find an enthusiastic group like this one.
I think I going to go the easy/cheap route here. I got this Spree for $150. Splitting the cases is complicated and expensive. If it craps out again, oh well! it was fun whole it ran;-)

Pat, JJ Joe and Noise, I am gonna go with your suggestions. Clean up with a flush, comp air and vacuum.

Noise, how much gas/oil should I use per flush and how many flushes should I do? Is the gas/oil mix be the same Used to run a two stroke?

Thnx again to all of you for taking the time to help me with this. I really can't say it enough. I will keep y'all posted.