Jump to content
Sign in to follow this  

DRZ500 Concept ...

Recommended Posts

the ice cube uses a forged aluminum sleeve.

so in your opinion are these good?

just the crank and cylinder kit is $2450.

cylinder fill at high rpm becomes a real issue onthese big motors.you can see the effects of that in the dyno graphs they post.

can you cure ?

Share this post


Link to post
Share on other sites

Ed,

Just to let you know, I should be getting my RHC cams back from Ron soon. A local machine shop screwed up big time trying to install adjustable sprocket flanges, ask him about it next time you talk with him. And I sent that ported head up to him for an inspection(the one I got for $100). I was thinking that the intake valves had been cut over 1mm. By the measurments I came up with, .040". Would that give me enough flow to run the bigger bore and stroker more properly?

I already have the FCR 41 running on the 450 and I have the FC2000 on. It's alright, but it takes a while to orient yourself on the mixture. The low idle is pretty hard to get perfectly smooth.

But what do you think?

Share this post


Link to post
Share on other sites
Does anyone remember that Dirtbike Magazine made a DRZ into a 500? It was in the October 2000 issue. They had Thumper Racing bore it out and they put in a steel liner. Total increase was 8.5mm bigger than stock. They did comment that it didnt rev out as far (which was a good thing I guess, so they wouldnt be hitting the revlimiter).

Thumper made two of those in addition to the one tested in Dirt Bike. One was in the shop in Marshall when I picked up a 470 in '2004. Another was still being regularly raced by a local rider.

Thumper spec'd it at 503 cc. It was a '2000 kicker and had more bottom and mid than the 470 that I got. It wouldn't rev out like the 470, but felt more powerful through the mid. Thumper wasn't interested in selling it. Two of the original three are still running as 500's last time I checked.

Share this post


Link to post
Share on other sites
It wouldn't rev out like the 470, but felt more powerful through the mid.

these are revving out better than a stock bike correct? or does it feel anemic at the high RPM's? i'd hate to get a crap load of bottom end and little to no improvement up top.

these have cams and a better ignition i assume also. but the just have a more powerful low or mid making the high end look weak, right?

i hate to sacrifice while having a 500CC air pump.

--keith

Share this post


Link to post
Share on other sites

just using a huge piston doesnt mean the motor is going to make more power everywhere.

this happens all the time with crf 450's.our stock displacement motors out perform the big bore in many cases unless drastic measures are taken to improve high rpm cylinder filling.

Share this post


Link to post
Share on other sites
these are revving out better than a stock bike correct? or does it feel anemic at the high RPM's? i'd hate to get a crap load of bottom end and little to no improvement up top.

these have cams and a better ignition i assume also. but the just have a more powerful low or mid making the high end look weak, right?

i hate to sacrifice while having a 500CC air pump.

--keith

You brought up a good point. The 470 that I'm currently riding has the stock cams, valves and ignition. Only the snorkel has been removed from the air box. Compression was dropped about one point to insure I can get by on premium pump gas on long distance solo rides if I get lost. The engine hasn't been on a dyno, but is probably making 1-3 hp more on top than the stocker. What you really feel is the HP building sooner at lower RPM's versus the stocker.

I was looking for two things; 1.) more HP sooner in the lower rpm's and 2.) long term reliability. To get this we also split the cases and essentially blue printed the engine and cylinder mating surfaces (including the liner). The engine is extremely smooth which probably helps its performance. It will rev out almost as good as the stocker and will still hitting the rev limiter.

One other change is that when you go out fire roading the big bore will let you know it is sucking more air. Depending on how much road noise I'm getting you can hear a loud wistling noise from under the seat as you chop the throttle to decelerate. I've looked at the 3X3 conversion, but I ride a lot of deep water periodically.

If your focus is on top end performance the big bore is probably not the way to go. I would think the stocker or a 440 with appropriate cams, valves and higher compression piston would be more appropriate.

I've ridden a friends 470 that is a big bore only with 13:1 piston, hot cams and upgraded valves and it definitely puts out much more HP. He rides the crap out of it. Were waiting to see if it grenades on him. Also, he can only run VP fuel; I believe the high oxygen content 100 octane variant.

Lot of options to consider.

Share this post


Link to post
Share on other sites
just using a huge piston doesnt mean the motor is going to make more power everywhere.

this happens all the time with crf 450's.our stock displacement motors out perform the big bore in many cases unless drastic measures are taken to improve high rpm cylinder filling.

Seen the same thing when looking at the RMZ450 as a next bike for early next year. It probably has >10 HP on top versus my 470. However, I'd tear it up riding it where I normally ride. The 4 speed didn't help much either.

Share this post


Link to post
Share on other sites

i was looking for just more power everywhere. i figured like a bigger displ. car, the bike would have great torque. but i didn't want it to stop revving sooner. stock limit is ok, higher would be nice to know it'll go, not that i'll put it there often. like the 3x3 and a pipe i want more power all around.

i realize it's a trail bike, not a MX bike. but i will race it and would like to have my friend's YZ450F to not make my bike look slow constantly. we are about the same speed, but his bike is retarded fast. i know it's faster than mine now(3x3, rejet) but i'd like to even it up a bit. (i don't expect my bike to out perform it anywhere really, just not be outperformed at every step of the way). so i think with my susp. set up right, and another 25hp im close(for what i've got) to giving him a fit after the moto is over!

what is the best all around big bore way to go for what i seem to crave?

mild over bore(450-475), with or without stroking, RHC I&E cam(stg1/2?), FCR41(above470cc), yosh Ti, ???

thanks!

--keith

Share this post


Link to post
Share on other sites

stock yzf450 makes 50hp.

to make 50 hp on your sm you need

94mm big bore,rhc cams,41mm fcr and yosh ti pipe.

wanna make him cry?add the 5mm stroke and your in business.

Share this post


Link to post
Share on other sites

i want him to bawl like a little bitch actually! :thumbsup: j/k

that sounds like a plan of attack to follow. im all over it, thanks eddie!

--keith

Share this post


Link to post
Share on other sites

Did I read somewhere RHC can bore your 39FCR larger? 40? 41? This is the limiting factor with my current setup.

Share this post


Link to post
Share on other sites

yes,he can mod any fcr.

your bike is a E correct?if so,i would upgrade to a 41 mm fcr-mx.you can easily sell your stock carb.

Share this post


Link to post
Share on other sites

the store can get it.just tell them you want exactly what on the TT bike.

all the same stuff as 39 kit,just the cabr itself is different.

Share this post


Link to post
Share on other sites

Would it be worth the hassle of ditching my 39mm for a 41mm on a 480cc engine?

Share this post


Link to post
Share on other sites

I'm having Big Gun mod my E motor, (head work,full exh sys, 94.5 overbore,K&N air filt) . This ? is for Eddie, do you think I really need a 41mm FCR carb. Is the perf gain negligable or does it really make that much difference?

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×