1993 Force 70hp scored cylinder

[kopeck]

The second cylinder on my power head is scored. It ran a little bit funky before the damage was done so I think I cracked the ring earlier then did the wall in over the weekend.<br /><br />Anyway a quick internet search turned up oversized pistons avaiable so I guess that's the direction I'm going ot have to go in.<br /><br />Pretty much I would like to know what I'm getting into, ie how much of a job is it?<br /><br />I need to get a service manual too, any suggestions?<br /><br />Thanks,<br /><br />K

 

[roscoe]

Re: 1993 Force 70hp scored cylinder

Factory service manuals turn up on ebay almost every week.<br />Next I would recommend the Clymer repair manual.<br />Shouldn't be too bad if you follow the manual and have the tools.<br />Let us know how it turns out.

 

[Gary Allen2004]

Re: 1993 Force 70hp scored cylinder

Hi Roscoe,<br /><br /> Last year, when I purchased the boat, I had all three cylinders scored so bad the rings were melted in to the pistons. (I bought the boat at salvage cost)I had comp readings of 5 7 and 12psi respec.I rebuilt the unit,however, you MUST bore out all three cylinders, and replace all three pistons at the same time. This tends to be an expensive proposition with boring the cylinders etc. A reputable shop can (will) charge at least $150.00 to setup and bore the block for you. Most shops shy away from 2 cycle powerheads because of the intake ports causes cheaper boring machines to chatter, so choose a machinist carefully. Also, pay the extra money and have the head decked while they're at it. It will improve your performance noticeably. I used Wiseco pistons with great results. Your biggest problem will be getting the head bolts out without breaking them. I broke four of them flush with the block and had to drill tap etc, which took many days of frustration. I have made all the mistakes already, so if I can spare you some, let me know.

 

[kopeck]

Re: 1993 Force 70hp scored cylinder

Thanks guys.<br /><br />Yeah, I know it need to be bored out. Right now I think I'm looking at around 300 bucks in parts, probably a bit more and what ever the machine shop charges. There's a motercycle race shop down the street, I think I'll go and see who does his machine wokr for him.<br /><br />The head bolts are all out and none of them broke, so there's the first battle...<br /><br />K

 

[Gary Allen2004]

Re: 1993 Force 70hp scored cylinder

Great !!<br /><br />There goes about 1 weeks worth of work you will not have to deal with. BTW, while you have the thing tore down, open up the thermostat passages and the overpressure passages and remove the corrosion if there is any.<br />All the best !!

 

[kopeck]

Re: 1993 Force 70hp scored cylinder

Just curious, but when they bored your block did they have to line the cylinders?<br /><br />I can't tell if what I'm looking at is just the shiny AL or something else?<br /><br />Thanks,<br /><br />K

 

[novicetech]

Re: 1993 Force 70hp scored cylinder

Kopeck, the cylinder walls should be cast iron about three sixteenths of an inch thick. They will not have to line the cylinders. but make sure they know how to champfer the ports.