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Discussion Starter #1
so after looking at some dynos and some stock trx450r 06+ dynos, our quads like to fall flat on there face after 7-8k rpm. so even with the HRC cam, the quad still seems to fall off at a given RPM before its redline.

what exactly is the reason for the HRC kit wire loom to increase the rev limiter since the quad stops making power even before the factory limiter?

on my friends HRC kit, we never installed the HRC wire loom to keep his powertrain to last longer.
 

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so after looking at some dynos and some stock trx450r 06+ dynos, our quads like to fall flat on there face after 7-8k rpm. so even with the HRC cam, the quad still seems to fall off at a given RPM before its redline.

what exactly is the reason for the HRC kit wire loom to increase the rev limiter since the quad stops making power even before the factory limiter?

on my friends HRC kit, we never installed the HRC wire loom to keep his powertrain to last longer.[/b]
i've never had one fall off that fast

04-06

so some do have a needed for increased limiter

on my personal bike the stock cdi with stock gearing is only good for around 400ft before it hits the limiter
 

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I think Lumi is talking about relatively stock or hrc kitted bikes,all out builds that are making lots of power might use the extra rpms
 

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Having that extra 1000 rpms is very useful in MX racing...hitting the limiter or having to shift just before the lip of a jump can mean the difference in how you approach the race.It can determine what gearing setup you will need for any particular track.It also helps with your holeshot...more forgiving if your wind it out a little too much before shifting.

You are right and it is much kinder to your valvetrain to not use it if your peak power drops off before the stock limiter....but it is awesome to have that ability to increase the rpms by 1000rpms when mods get to the point where it is required.

I wish the 04/05s had it. :yes
 

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Discussion Starter #6
thanks for the reponses
maybe flat on its face wasnt the right term but even riding a stock quad it does feel like it.

i used 7-8k rpm as a example or average from what i have seen. but looks like the hrc cam is much better then stock and peaks its power at about 8k and holds it off until about 9,400k prm before it start to dive, by 10,200k rpm it dives hard?

thanks for the dyno. but doesnt the HRC loom make it limit at 10,850k rpm?
look like u go to about 10,400k, just asking.

but again does that extra 1,000 rpm really help here? since it isnt making much power even up until the stock rev limit? wouldnt it be better for the drivetrain and such to use the stock limit? compare the stock rev limit at 9850 to the 10850, doesnt seem to be much of a advantage.

thanks for bringing that up trx450r14, since the HRC kit is designed a bit after motorcross type riders, and for many types of riding, this can be useuful, for theafter joes,trail riders, occasional trackers and drag racers, how much of a advantage would this 1,000 rpm have, beyond a higher top speed.

wouldnt shifting early before the power start to drop off hard better? or does the theory of gearing and whining each gear out so you are higher in the power range in the next gear, over lap that?
 

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thanks for the reponses

wouldnt shifting early before the power start to drop off hard better? or does the theory of gearing and whining each gear out so you are higher in the power range in the next gear, over lap that?[/b]
i've found that you need a gearing that will allow the engine to rev into the high RPMS FAST

meaning....find a gearing combo that lets your engine not have to work to hard to get in the 8000-9000rpm range.

you don't want gearing that feels like you have to wind every gear out.........find a gearing that allows 5/7 seconds in between shifts

not 10 or more seconds between

hope this is not hard to understand
 

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I have heard that the Green Wire mod also changes the ignition timing? Is this true? If it does change the timing is it a better timing curve?
 

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thanks for the reponses

wouldnt shifting early before the power start to drop off hard better? or does the theory of gearing and whining each gear out so you are higher in the power range in the next gear, over lap that?[/b]
i've found that you need a gearing that will allow the engine to rev into the high RPMS FAST

meaning....find a gearing combo that lets your engine not have to work to hard to get in the 8000-9000rpm range.

you don't want gearing that feels like you have to wind every gear out.........find a gearing that allows 5/7 seconds in between shifts

not 10 or more seconds between

it should take you 5/7seconds to hit the limiter between shifts....stockCDI ONLY


hope this is not hard to understand
[/b]
5-7 seconds??????? just wondering what times you run the 1/8 mile in? you have said hit the rev limit in 5th but that would mean your idea of perfect gearing it take 25 seconds for you to run the 1/8 mile.

my quad is not fast but when i run sand drags im just getting ready to hit 5th in 5.2 seconds.
 

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it is also good just to have the extra rpms just to rev on, it is nice if you can go a little faster, or just rev a gear out longer instead of having to shift right in the middle of a jump, hillclimb etc.
and wouldn't it be better on you power train in general if you didn't rev the engine over 6500 rpms? of course it would, but it would also make things a bit more boring
 

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Discussion Starter #15
im not saying to shift at 6500rpm, but to use and shift at redline with the stock rev limit, instead of using the extra HRC limiter, since it seems you gain no power at that point anymore, and the power begins to taper off even before the stock rev limit.

but like mentioned and stated, some riders might like and need the extra 1,000 rpm.
for more downstated riders and occasional racers like myself who seem to use the midrang alot esp in some XC racing, i think even that extra 1k rpm increase can put additional strain on the powertrain for no reason.

the only reason i can think of which we were talking about would be for gearing purposes,
-using that extra RPM to get higher in the gear and when shifting into the next gear you are higher in the power band in the next gear becuase of the increased rev limit.
- or on the other hand, using the stock limiter would keep you in the meat of the powerband when shifting but lower in the powerband in the next gear due to the the lower rev limit.

i know on my turbo car, i like and the car itself like to perform better when i shorthift to stay on boost and in the powerband, you can feel when it starts to taper off and that when i shift.

not sure what else the wire loom does with timing or the curve tho.
 

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a couple reasons i can see for wanting the extra rmps for a build that is down on power at the stock rev limit are

a mx racer might benifit from the extra rmps on a holeshot or a stright away getting ready for a corner, even though he would be down 3-6 hp from peak it might be better to hold that gear for an extra second rather then shift, then having to down shif right afterwards. it would be better to overrev and be down on power then hit the rev limiter.

another time is whoops, if your are not staying in contact with the ground then with the stock rev limiter your might be bouncing off it while your tires are in the air then be right in the meat of the powerband when they make contact again.

i totaly understand where you are coming from wondering why people want to rev their motor an extra 1000 rpm when they are down 5+hp at the stock limit, add the extra 1000 rpm and they could be down 8hp or more. dyno testing is the only way to know for sure.
 

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Discussion Starter #17
i guess i will need to see a race between a full hrc kit 450r and one that doesnt have the hrc sub harness loom.

and i would need to see a dyno with and without the harness to really tell the difference.

but i think that even with the harness on, it adds to powertrain wear and tear. even if it is a extra 1k rpm, im sure it does wear things down a but more, esp if your at that rpm alot.
 

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it also has a lot to do with personal preference and riding style, you obviously don't ride in that rpm range so don't use the harness, other people prefer/like riding there so they can and in some cases 1000 more rpms can make a world of difference,

i don't understand what you are getting at with this topic, you are going around in circles?
 

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i just looked at my dyno sheet,and my hp just starts to decrease right about 9K.. so i really dont need to the green wire mod except to keep my rpms up for my next gear
 

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OK so it was answered that the timing curve does change. What is the change and how does it affect hp up to that point of the Rev limiter.
 
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