Big Bore kits??? - Honda TRX Forums: Honda TRX 450R Forum

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Old 03-06-2010, 02:18 AM   #1 (permalink)
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Hey i have a lot of questions about big bore kits!! So how reliable r big bore kits?? 480/490 kits?? do u need to do anything to the head to run a 480 kit? Is a 480 kit more reliable than a high comp piston?? I don't want to run race gas just to ride!! how high can i go with a high comp piston before i have to run race gas?? Is a big bore (480) kit going to give me more power than a high comp piston?? Sorry so many questions thanks for any and all help!!! i really appreciate it thanks!!
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Old 03-06-2010, 03:17 AM   #2 (permalink)
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You can get a pretty reliable bb kit from what I have saw on here but I personally can not recommend a certain one to go with or tell you the power difference over a hi comp piston but I do know they tend to rev a little less and make a little more low end than a smaller bore. 12:5:1 is about the max your going to get on pump gas without issues.
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Old 03-06-2010, 07:45 AM   #3 (permalink)
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about what ^ he ^ said....

yes, as you increase CC's, your gonna rev a little slower than a smaller machine.....but only sitting in Neutral... you will find a big bore to have about +3 HP over a comparable 450 based machine...

no, you dont need to mod the head, but PORTING is always good.....and probably good for another 3-5hp on average....depending on other mods...

12.5:1 is safe....some claim 13:1...but your pushing the limits....

ESR has a 480 kit with 12.5:1 Wiseco piston...a reasonable price and quality....

if it were ME, I would opt for a Venom 12.25:1 big bore piston and send my jug off for bore/plate.... cost a LIL bit more...but you would have a better 'package' IMHO....

at 490 your gonna need an aftermarket cylinder...and the price jumps dramatically..... so keep that in mind...

also....I assume you already have the usual mods.... .Cam (#1), pipe, etc...???

HIGH comp 14:1 or more vs +3mm is gonna act about the same.... same power, same reliability or close to..... the difference is the cost of race gas vs pump fuel....


and yes, they are very reliable in most applications.... jmho....g
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Old 03-06-2010, 09:06 AM   #4 (permalink)
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Thats good to know that they dont slow down the revs while riding greg I dont have experience with a 450 big bore helped build a big bore long rod 430 banshee and big bore 440ex but they both had pretty heavy slugs in them so you could notice a little lslower increase in rpm pulling through the gears but like I say they were heavy heavy pistons and not short skirts like the 450s are
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Old 03-06-2010, 10:21 AM   #5 (permalink)
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Increasing the piston (bore) to stroke ratio should actually increase the revability...espescially with the 04/05s because of the combination of the bore/stroke ratio and using an aftermarket piston that will be lighter than the stock slug....even at a larger size.

As long as you stick with a comp ratio that will allow you to run pump gas(12-12.5:1 normally),why not do a big bore with a higher comp piston. ....there should not be any real decline in reliabilty and will give you nice gains across the board.

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Old 03-06-2010, 10:39 AM   #6 (permalink)
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what r the weakness of the 04/05 motors??? i heard that the stock crank is the weak point??? is this true?? is this a common weak point because if it is the big bore kit would just cause it to go out faster i would think!!?? i may be wrong but my friend said that, so i was wondering if he just talking out his a$$ or he was telling the truth.... thanks!
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04 trx 450r
front razor
22x11x8 10 paddle ultra lights haulers
tks customs Nerf bars
ims foot pegs
pro taper bars
odi grips
moose thumb throttle
stage 2 hot-cam
3way valve bore
spal rad fan upgrade
pro-flow with k&n/ no lid
two brothers full titanium exhaust
13t/38t
6+swing-arm
Regina gold-chain
mod quad billet twin bearing carrier
mod quad inline water cooler with temp gauge
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