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mex087
50cc nipper
Joined: 12 Jan 2008
Posts: 48
Location: seaham
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 Posted: Mon Feb 18, 2008 7:18 pm Post subject: help with info on 86 250r |
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hi guys wonderin couple of things. first off im about 2 do a bottom end on my trike and tony was telllin me bout this long rod conversion.. qhuick questions but..
is there a noticeable power increase> i jus cant see how as its only a bit more crankcase volume? and the port timing and stroke shouldnt change should they? jus wonderin coz the pipe wont fit barrel as neat then and less room round sparkplug.
also with mains do u guys just use ones from bearing shop? they wud probably just be 63/28? but do they have same number of rollers as genuine? jus curious as i know that with bikes some aftermaket ktm bearings have differnt number of rollers then genuine and last only couple of rides!!!!! im a motorbike mech so i can do it all myself but havnt done much experimenting wid trike motors power! any info would be great! need 2 get it goin before easter |
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Sponsor
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greenhuman
Roostin Away
Joined: 12 Feb 2006
Posts: 980
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| Posted: Mon Feb 18, 2008 7:54 pm Post subject: |
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You have to remember that both Tony's here are extremely well educated gentlemen.
I would rebuild it with stock rod length and make sure the main bearings from the bearing shop are C3's with the extra clearance . |
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Jamie
Moderator
Joined: 27 Aug 2006
Posts: 749
Location: somewhere
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| Posted: Mon Feb 18, 2008 8:13 pm Post subject: |
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I wouldnt bother with the long rod set up.i think BC has a long rod motor in his trike its quick but not that quick my stock 85R with just a pipe seems to keep up with him for a short while  ,his brothers i think just has had port work and a bigger carb and that shits all over bc's trike  |
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PC
Joined: 20 Dec 2006
Posts: 565
Location: Newcastle
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| Posted: Mon Feb 18, 2008 8:56 pm Post subject: |
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| Jamie wrote: | | I wouldnt bother with the long rod set up.i think BC has a long rod motor in his trike its quick but not that quick my stock 85R with just a pipe seems to keep up with him for a short while ,his brothers i think just has had port work and a bigger carb and that shits all over bc's trike |
Dont get him started!
His is quicker than mine at the moment, I think I have killed mine. |
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greenhuman
Roostin Away
Joined: 12 Feb 2006
Posts: 980
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| Posted: Mon Feb 18, 2008 11:30 pm Post subject: |
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| greenhuman wrote: | You have to remember that both Tony's here are extremely well educated gentlemen.
I would rebuild it with stock rod length and make sure the main bearings from the bearing shop are C3's with the extra clearance . |
I hate you Clare. |
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ashnery
Moderator
Joined: 03 Jul 2006
Posts: 927
Location: www.dn.eng.com.au
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| Posted: Tue Feb 19, 2008 9:50 am Post subject: |
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| Jamie wrote: | | that shits all over bc's trike |
Your introuble now jamie ,,you may just have open a bag of worms...lol
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OH "profanity removed" I SAID "profanity removed".......OH "profanity removed" I SAID "profanity removed" |
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JASE.71
90cc 2 stroke / 110 4 stroke
Joined: 04 Nov 2007
Posts: 96
Location: Newcastle
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| Posted: Tue Feb 19, 2008 11:46 am Post subject: |
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Mine has the long rod & spacer in it. Same speed as any other 250R that its been near. (except PC's) More cost for no gain if you ask me.
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85 HONDA 250R
85 HONDA 125M |
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4stroker
Joined: 15 Jan 2007
Posts: 1420
Location: North Queensland
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| Posted: Tue Feb 19, 2008 2:03 pm Post subject: |
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yooz are missing the point of the long rod
the long rod will not make any more power, but it will decrease front/rear loading on the piston and bore, which will help them last longer
if the motor needs a new rod, do the long rod conversion
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2002 SE Banshee
Last edited by 4stroker on Tue Feb 19, 2008 2:21 pm; edited 1 time in total |
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4stroker
Joined: 15 Jan 2007
Posts: 1420
Location: North Queensland
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| Posted: Tue Feb 19, 2008 2:21 pm Post subject: |
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just spent 5 minutes on google search and i can see why a long rod is reccomended for the 250r's...
they have a stroke of 72mm and a rod length of 125.3mm, giving a poor rod/stroke ratio of 1.74:1
2:1 is considered the norm for a reliable rod/stroke ratio
just as a comparison a standard banshee has a stroke of 54mm and a 110mm rod length, giving a 2.04:1 ratio, and it is a common mod when rebuilding banshee's to go to a longer rod again, 115mm, giving 2.13:1 ratio.
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2002 SE Banshee |
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4stroker
Joined: 15 Jan 2007
Posts: 1420
Location: North Queensland
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| Posted: Tue Feb 19, 2008 3:35 pm Post subject: |
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it looks like you can also use the piston from a 1987+ TRX, which has it's gudgeon pin located 5mm higher (because they had the londer rod standard), which negates the need for the spacer plate, which in turn fixes your ill fitting pipe and spark plug clearance issues...
i would look into this some more though, try and get some info on people who really know their 250r's...
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2002 SE Banshee |
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BC250R
Joined: 23 Jan 2007
Posts: 375
Location: Stockton Dunes if i'm lucky
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| Posted: Tue Feb 19, 2008 4:42 pm Post subject: |
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Check out the the thread link under my signature photo's. There is a full explaination of the advantages and disadvantages of the long rod motor.
4stroker is correct, it is not about power its about increasing engine life.
Less severe angles at half top dead centre reduces the force with which the piston gets jammed into the side of the bore, therefore reducing wear.
Another point is that the piston hangs around TDC and BDC longer (dwell) allowing the intake charge slightly more time to flow in and out. The down side of this is it reduces the revability of the motor.
As for main bearings, CR500 has 3 extra balls. Biker Chicks LTD on ebay do mains that have 3 more balls than CR500 with nice thick race, good quality and come with seals. Quiet easy to purchase and even with freight are cheaper than OZ. These guys also do full rebuild bearing kits for about $100US. I'll find a link and post it.
Yes Ash and Paul, they got me started.
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Technical info thread
http://www.ozatv.com/forum/viewtopic.php?t=4425 |
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BC250R
Joined: 23 Jan 2007
Posts: 375
Location: Stockton Dunes if i'm lucky
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