sweetness
so i just tell the guy to bore it out +.080"? im new to the whole measurments game
edit : sorry the pistons are held with circlips to the gudgeon pins.
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| honing my 998 block (NEED TO KNOW BEARING SIZES NOW) https://www.ausmini.com/forums/viewtopic.php?f=2&t=55159 |
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| Author: | meeni [ Wed Jul 15, 2009 8:41 pm ] |
| Post subject: | honing my 998 block (NEED TO KNOW BEARING SIZES NOW) |
ive pulled my block apart on the little 998 i had sitting around and it looks like it was rebuilt fairly recently, the crank has been balanced and the rods and bearings look pretty good.. i want to put it together just to use while i build a good big bore engine. i can still see the previous hone marks.. can i get away with just having it honed and putting it together again with new rings.. i dont really see the point in spending the extra money on a motor that is just going to be used inbetween engines if its not required |
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| Author: | drmini in aust [ Wed Jul 15, 2009 8:56 pm ] |
| Post subject: | |
Get somebody to measure the bores, top and bottom. If only worn .001" or so a hone job and rings will work. For a while. Not as good as a rebore and new oversize pistons. |
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| Author: | meeni [ Thu Jul 16, 2009 7:33 pm ] |
| Post subject: | |
ok, so if i was to rebore and everything, what sort of specs should i be telling my machinest to bore it to. also what pistons should i fit, flat tops? ive been allowed to build this engine so its fairly nice, so let me know what to get to get a 998 going nicely on the road.. cheers sean |
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| Author: | drmini in aust [ Thu Jul 16, 2009 7:52 pm ] |
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meeni wrote: ok, so if i was to rebore and everything, what sort of specs should i be telling my machinest to bore it to. also what pistons should i fit, flat tops?
ive been allowed to build this engine so its fairly nice, so let me know what to get to get a 998 going nicely on the road.. cheers sean I would definitely use flat tops, it's hard to get decent compression in a smallbore (with a reshaped combustion chamber) otherwise. Hypatec +.080" pistons are good value, and you can still bore to +.100" or +.120" later. http://www.minisport.com.au/prod1092.htm |
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| Author: | meeni [ Thu Jul 16, 2009 7:56 pm ] |
| Post subject: | |
sweetness so i just tell the guy to bore it out +.080"? im new to the whole measurments game
edit : sorry the pistons are held with circlips to the gudgeon pins. |
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| Author: | drmini in aust [ Thu Jul 16, 2009 7:58 pm ] |
| Post subject: | |
These Hypatec smallbore pistons all have circlips. If you don't like them or want to rev it hard, any decent engine builder can make you up some PTFE buttons instead. These have to be made to suit the piston and pin, so they are a nice neat fit. If you use circlips, always fit them with their sharp edges OUTWARDS. |
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| Author: | mini_mad_matt [ Thu Jul 16, 2009 8:01 pm ] |
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Isn't the way to do it normally to give the machinist the piston and say make it fit? instead of them boring it out to a dimension and hoping its all sweet? You should probably also give them the rings so they can check the gap. Or do people just chuck the rings in out of the box usually? |
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| Author: | meeni [ Thu Jul 16, 2009 8:02 pm ] |
| Post subject: | |
im not going to be revving the guts out of it.. nothing more the prolly 5 grand at a serious push otherwise just the normal 2-3500rpm.. |
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| Author: | sgc [ Thu Jul 16, 2009 8:05 pm ] |
| Post subject: | |
meeni wrote: im not going to be revving the guts out of it.. nothing more the prolly 5 grand at a serious push otherwise just the normal 2-3500rpm..
Yes you will, it's a 998  They spin so sweetly, you'll be at 7 grand before you know it 
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| Author: | drmini in aust [ Thu Jul 16, 2009 8:07 pm ] |
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mini_mad_matt wrote: Isn't the way to do it normally to give the machinist the piston and say make it fit? instead of them boring it out to a dimension and hoping its all sweet? You should probably also give them the rings so they can check the gap. Or do people just chuck the rings in out of the box usually?
Yep, you are right on both counts. |
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| Author: | meeni [ Thu Jul 16, 2009 8:08 pm ] |
| Post subject: | |
im a p plater so 5000 rpm probably means 7 lol, just like when you tell the police your speedo said you were doing 100 when you were doing 130..  
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| Author: | meeni [ Thu Jul 16, 2009 8:17 pm ] |
| Post subject: | |
drmini in aust wrote: mini_mad_matt wrote: Isn't the way to do it normally to give the machinist the piston and say make it fit? instead of them boring it out to a dimension and hoping its all sweet? You should probably also give them the rings so they can check the gap. Or do people just chuck the rings in out of the box usually? Yep, you are right on both counts. ah ok, seems like the logical option, obviously why i didnt think of it
cheers for your help everyone |
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| Author: | BALLISTIC [ Thu Jul 16, 2009 8:23 pm ] |
| Post subject: | |
Go the 100" ups , get a fun grind cam, get a 202 head and put some slightly bigger valves.....blah blah blah.....it will sing  we have the technology
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| Author: | meeni [ Thu Jul 16, 2009 8:25 pm ] |
| Post subject: | |
yes but how far do i want to go for a motor between motors if that makes sense, i want to keep all the extra money that doesnt have to be spent for a twin cam engine later on. id be happy with a nice reliable little 998 to keep me going for 6 months or so |
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| Author: | BALLISTIC [ Thu Jul 16, 2009 8:30 pm ] |
| Post subject: | |
build a boggo +20" 998 then.....or go the whole hog now and bolt on the new head later. |
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