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jk9270

engine mods performance vs. durability

30 posts in this topic

I'm thinking about a project for the winter of a new higher compression piston and a Hot Cams stage 1 cam for my 650R. I am curious how big of a power increase I will realize. Is it as big a difference as stock vs. uncorked? Will I win a drag race vs. my brothers crf 450?

My only concern is durability. I'm sure it will decrease, but I havent been able to quantify by how much. I assume valve adjustments and head gaskets will become more frequent. I'm sure someone here has done this. Clue me in!!!

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shouldnt have to go through all that trouble to beat a 450, just make sure youre running right.

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A 450R will probably pull on you until you are solid in 3rd or 4th gear. They are pretty fast but top out somewhere between 70 and 85 depending on their gearing.

If you get a cam, you aren't getting the full benefit until you get a full pipe (header and can) and the side panel cut-out over the air filter. This lets the motor breath. Tuning the carb is a bit of a pain if its your first time. I used a Stage 1 for about 6 months, then stepped up to a HRC cam. I have a Stage 2 in the garage but I haven't tried it yet.

Durability-wise, your bike is pretty much the same. Its more a question of how you ride it. If you ride the bike wide open at high RPM with stock components for long durations, you are doing more damage than modding it up and running it at wide open for a few minutes.

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OK you guys saw right through me. Priority one is beating my brothers bike. The bike is plenty fast now. Certainly fast enough to get me into trouble, but we are talking about beating my older brother here.

I already have a Power core 4 Can and am eyeing a Power bomb header. Would the header and drilling out the side cover make much difference?

I guess I'm looking for the most power and least durability sacrifices for the dollar.

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what kinda HP gains can you get? the increase from stock to uncorked is amazing!

im definatly gona do vented side panel and exhuast, if that doesnt do to much ill think about high comp piston or cam. Im thinking a big bore might be even better, for half the price of the HRC kit you can bore it to 680 or 720 i think?

I would think the 650R would beat the 450 with the right gearing, i've dragged my dad on his stock VFR800, i beat him till 50, even till about 70 then he owns me.

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The XR650R was made to handle much more horsepowr then what showed up on the showroom floor. The bottom end can handle more then 70bhp stock.

The HRC kit was the stock parts till the bike had to pass all the smog laws. The header is major restictive for major flow at any RMP above 3,000.

My point is you are not going to get any less durability out of the engine with a stage two cam but, you can run it harder, longer, and in the end will ride it a lot more making it need fixing more often. It will be just more fun and that makes things wear-out faster........You will need to let the bike flow more in and out of the engine once you go with a stage two cam. A header will be a must to see the full benifit.

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The XR650R was made to handle much more horsepowr then what showed up on the showroom floor. The bottom end can handle more then 70bhp stock.

The HRC kit was the stock parts till the bike had to pass all the smog laws.

This was exactly the info I was looking for. I think you just spent some money for me.:worthy:

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What's your current gearing?

If your bro is red-lining at 75-ish, a super-cheap winning mod would be to gear your R for 85 or so. Factory gearing of 14-48 yields about 107, I think.

Said differently, if your bro geared his bike for 107 top end, you would beat him soundly.

Ok, having said all that, it would still be fun to add more power. Full exhaust system, side-panel venting, re-jetting, will yeild lots of big grins.

I'm running a Pro Circiut T4 system, side-panel, Edlebrock, Uni, and Iridium plug. My son has a semi-uncorked R and recently rode my R and said he was surprised that my bike made only marginally more power. What he didn't account for was my gearing. I run 16-44 with 17" SM rims, which gives me a 114 mph top end, vs his stock gearing.

I like a low-rpm, high-speed cruise.

One guy wrote that the HRC kit was intended to be factory-stock, until they couldn't get it to pass emissions. That's interesting because that implies the HRC would not have a big impact on reliability. Reliability is a big issue for me.

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16-44?

im running 15-45 and my bike doesnt redline? but it does max out around 95, really doesnt go over 7600 RPM's. Its got amazing amounts of torque but it wouldnt even do 107 down hill:excuseme:

i was gona drop the front sprocket to 40-42, would there be an advantage over adding to front or dropping in the rear? 1 front is equivilent to 3 rear am i right?

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If you can't topout with 15-45, switching to higher gearing won't help.

I'm running 16-44 with 17" SM rims and tires. I run 15-45 with factory rims and tires, to give me close to an identical final-drive ratio as with the SM setup.

But my main question back to you is, how is your bike setup, engine wise: inatke, exhaust , etc. Seems you should be able to take it to redline in 5th. If you can't it sounds like your bike is either not fully uncorked or has some other power-robbing problem, like bad jetting, clogged filter. Something is holding your bike back.

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I have 14/48 gears on my bike. I never take it on the freeway, so maybe I should look into a 50 on the rear. Friday I ordered a powerbomb header to go with the existing powercore 4 can that I have. I also got a Hot cams stage 2 cam and an 11:1 piston. I think that ought to do the trick. I'll put a new high flow air filter and drill out my side cover when I install the new parts.

Now to get that suspension set up........

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Do the suspension first cause...you'll need it with the other stuff.

Brakes too maybe.

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Somebody help me here.

A properly uncorked and tuned R with factory gearing should redline in 5th gear, shouldn't it? Mine does.

Okay maybe I've also got an Edlebrock and vented side panel but that doesn't add all that much, I don't think.

JK, make your mods to your engine, but first I'd figure out what's holding your bike back right now. Something just isn't right, in my opinion.

Ride safe.

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JK let us know all the specs on your bike so as someone here will get it sorted.

Is it completely uncorked,holes in sidecover, and such,what jetting and so on.

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My bike is stock right now except for being uncorked and rejetted according to Honda 's uncorking directions. Instead of the HRC tip I put on a FMF powercore 4 slip-on, because it was about the same price as the HRC tip.

I have no complaints with the bike as it is, and I haven't even raced big bro yet. We just talk a lot of shit over the phone, and I want to be sure I can back it up next weekend when we finally ride together.

Haven't vented the side cover yet, but that is on my list for when I get a minute.

As far as what is holding the bike back, I don't think anything is. It goes real fast and wheelies with just a little goose.

Internalcombustion, I think you are looking at my post and hondacrf150f1 and thinking we are the same person.

As far as the suspension I have in my garage a set of forks from a CRF 450. I'm debating an Emig racing triple clamp to hook those up. Any suggestions for a 185 lb guy who mixes woods riding and fire roads with some back roads? Also for the rear?

Finally, I realize I don't have the riding skills to even come close to maxing this bike out, but It is just how I am with everything from mountain bikes to my lawnmower. I just like working on stuff to make it better.( My wife calls it fixing things that aren't broke. What does she know?) I guess it is a good thing I never got into drugs.

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16-44?

im running 15-45 and my bike doesnt redline? but it does max out around 95, really doesnt go over 7600 RPM's. Its got amazing amounts of torque but it wouldnt even do 107 down hill:excuseme:

Something is not right with your bike, in my opinion. A fully uncorked and properly jetted 650R with factory gearing should be able to redline in 5th gear on more-or-less level ground.

Please give us the specifics of how your bike is set up, uncorked mods you've made, current jetting, air filter, etc. We can help you figure out what's holding back your bike.

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Internalcombustion, I think you are looking at my post and hondacrf150f1 and thinking we are the same person.

.

Indeed I did, jk, sorry about that. Sounds like your bike is rocking-and-rolling just fine.

I just posted an inquiry to hondacrf to see if we can't help him sort out his bike.

Thanks for steering me straight. .

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Indeed I did, jk, sorry about that. Sounds like your bike is rocking-and-rolling just fine.

I just posted an inquiry to hondacrf to see if we can't help him sort out his bike.

Thanks for steering me straight. .

ok here's the deal, the bike runs awsome its fully uncorked,

I open'd up the carb booty going into the cylinder 175 main jet, 68S pilot, 3rd needle clip pos, HRC exhuast tip, both baffels outa the airbox, uni filter, and less restrictive airbox screen. Ive never heald it wide open for more than 5-6 seconds i quess but its never gone over 97 and around 7800 RPM's, according to my vapor? i suppose the vapor could be off? but by 500 RPM's?

It definetly feels uncorked, i can be cruising at 80 and be at 95 in under 3 seconds, ive been told a vented panel and larger exhuast headers will give it more top end, so thats what im evenchually gona do.

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ok here's the deal, the bike runs awsome its fully uncorked, Ive never heald it wide open for more than 5-6 seconds i quess but its never gone over 97 and around 7800 RPM's, according to my vapor? It definetly feels uncorked, i can be cruising at 80 and be at 95 in under 3 seconds,.

I'm confused. You say the bike feels awesome and will do a roll-on from 80 to 95 in no time. And you say youve never had it above about 97 but have never held it at full throttle for more than 5-6 seconds?

When you did hold the throttle wide open for 5-6 seconds in 5th, was the bike still accelerating when you let off?

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