Jump to content

Cr500 information

Recommended Posts

Hi guys, about a few weeks ago I traded my 03 crf450 for a done up 1991 cr500! This bike is near mint just had a top and bottom end rebuild from less than 4 hours ago, has v force 3 reeds, fmf fatty and silencer, ported and polished. Anyways I'm sure you guys are more knowledgable than me so I have a few questions about cr500s in general and mine. To start with my bike has a few things done to it. I ride at 4000ft so it's not going to put out the advertised power but if it were to be at sea level what kind of power do you think it would be putting out? Be mindful these bikes put out 56hp stock when people tell me my bike should be 80+ hp I don't think it's true. My other question is I had a friend who had an 98 cr500 and had all the things mine has but without the porting but claimes his was faster and snappier. He had a carb off an 86 with the 98 jets in it and I know the older 500s made more power but no one seems to know why. And the last my bike is geared low but so was my friends with the 98 500. I got spanked by my brother 2016 ktm450 that's geared a little bit lower than stock. Would by bike be faster geared higher... like acceleration wise. Thanks

  • Like 1

Share this post


Link to post
Share on other sites

Your's will be making right around 56 as well. If it's not jetted correctly, it may stumble or bog and not run right.

The 85/86s didn't make more power afaik, they just had an explosive powerband that put you on your ass before you knew it. 

Gearing depends on what you are looking for. It's a 500; torque is everywhere and you gear it for how you want to ride it. You can easily lug it, or you can wind it out in every gear. Going taller would make it easier to lug, shorter would make it wind out and accelerate faster, if that's what you are looking for.

  • Like 5

Share this post


Link to post
Share on other sites

That's cause the 450 is faster sry to say. Why anyone would port a 500 is beyond me no need for it just shift

  • Like 2

Share this post


Link to post
Share on other sites

I know with the fmf exhaust it neede to be jetted a little different but would the reeds make it need to be tuned again due to more air flow? If so how would you tune it as well as possible?

Share this post


Link to post
Share on other sites

wth . That 500 should smoke any stock 450... 14/48 gearing start out in second and short shift don't waist time trying to rev it out and by the way a new back tire helps. Go try that and report back the mighty 500 should win a drag race.

fmf fatty pipe or stock pipe is far better than a gnarly or shityprocircit

i have a few cr500 bikes and to me my 85 rocks compared to my 98 , go roost them 4 strokes

  • Like 3

Share this post


Link to post
Share on other sites

You adjust the low end with the pilot jet; no option there but to try different sizes to find which one gives you the best performance. You will probably need to adjust the air screw also. Mid - top end is the main jet and needle position. Again, due to the modifications to your bike, it will require making a change and test it.

  • Like 1

Share this post


Link to post
Share on other sites

The 1985-1987 Cr500's did make more Power due to different port timings, different cylinder heads with more compression, more aggressive ignition timing.
With a good portwork, cylinder head, suitable pipe made and ignition setup for the application you should be happy if you get 70 hp at the crank.
I dynoed my old 500 with all this done and got 70 hp at the crank at 7500 rpm. Now i have a special built 500 with a 550cc top end making over 90 hp.

  • Like 1

Share this post


Link to post
Share on other sites
On ‎2017‎-‎09‎-‎08 at 8:17 PM, Motox367 said:

That's cause the 450 is faster sry to say. Why anyone would port a 500 is beyond me no need for it just shift

it depends on what you use it for and what type of Engine character you prefer.

  • Like 1

Share this post


Link to post
Share on other sites
On ‎2017‎-‎09‎-‎09 at 4:02 AM, Dusty99 said:

I know with the fmf exhaust it neede to be jetted a little different but would the reeds make it need to be tuned again due to more air flow? If so how would you tune it as well as possible?

I would take out the Vforce3 as they aren't good for the CR500 and use either a stock case, which is good or a Vforce2.

Share this post


Link to post
Share on other sites

you can always tell when a CR500 gets on the pipe....

it's on a wheelie. In ANY GEAR! Ever wheelie'd doing 100 mph - IN DEEP SAND????

This was my former '91 CR500...

cr500.jpg

Eric Gorr motor, 39 PWK...and ...

the secret trick for doing wheelies at 100mph in deep sand?

VP C12! and the 5th gear is overdrive.

The dude I bought it from set it up to race in the Baja 1000. Damn thing wanted to KILL me!

  • Like 2

Share this post


Link to post
Share on other sites

How much HP, simple answer is more than you can put to the ground :thumbsup:

Racing 450's, you should be able to get them in the short run if you can get the traction, but once you start running out of gears and revs it's all over.  

With 500's a little bit of tuning/jetting ect... goes a long way.  

I had an Eric Gorr spec head on my 91 for a couple years.  The bike was easy enough to ride, i liked it for woods riding and even in some gnarly stuff, would still power wheelie easy in 4th if you could find the traction.  With my last rebuild i switch the head to one of the squish adjusted heads from Roosti on the 500 forum set to run on race fuel or 50/50.  Switching to this head and running 50/50 93/vp110 woke my 500 up and made it way more snappy, it's definitely harder to ride in the tight stuff now but man that POWAA!! 

My suggestion is try and tune the bike to your riding, who cares if it isn't the fastest 500 out there, as long as you can ride it and ride it well that's all that matters, you will have more fun that way too.

She has looked better.... she has also looked worse ;)

20170402_114742.jpeg

  • Like 1

Share this post


Link to post
Share on other sites

Dusty, jet your bike for smooth usable power and then develop your riding skills. On my last CR5(90) I lowered the pilot one step, added a 16oz fww and it was perfect for all round woods use. I get the feeling all your buddies are just drag racing down dirt roads, don't be one of those guys.

  • Like 2

Share this post


Link to post
Share on other sites

Ditch the stock PJ carb if it has one and look for a 39mm Air Stryker off a kx250.

Or go aftermarket with a smart carb or Lectron.

 

 

Share this post


Link to post
Share on other sites

39 pwks also came stock on 2003-2006 KTM 125sx & 200sx. The KTM 39PWK brand came w/ the 1469G needle (Honda needle, IIRC), a triple taper needle ideal for open class  outdoor MX, all mid and top performance. If you want to win drag races, this is the carb setup.

 

  • Like 1

Share this post


Link to post
Share on other sites

For your issue you are likely spinning away your drag race win, normally the open class 2T's let all the ponies out of the barn at the same time causing some major rear end spin. Remedy that with taller gearing if you want or start off in 3rd and use the clutch to keep some the ponies back until you get moving. You can/should also play with the jetting to see what you can find, who knows what the previous guy was after. I always found my 84 CR500 (air cooled) could dig a trench in almost anything and destroy any and all contestants I put on as a rear tire fairly quickly.

Regardless of drag race results the 500's, red or green will always bring a smile of fear to your face, and skid marks in your pants.

The dudes who raced these things fast were masters of throttle control and clutching. It was always a coin toss as to what was about to happen when you hit the throttle on it, spin, loop out, or you get the right hook up/spin to actually rocket away.

84(air cooled) 85-86 had the short stroke engine which in turn gave them the murdering power band hit. The issue with them now is you can no longer get cranks and will have to have a spacer made for under the jug to accommodate the long rod crank. I also believe 85-86 also have a longer reed housing as well which is a mod some add to the later models (reed spacer). 

From 87 on I think Honda kept removing power from the engine and the last generations 98 and up (guessing) were the least powerful with changes to the ports (see port windows in pic) to aid in starting. Get a decomp valve installed in the head regardless of year, will kick like a 125. 

I currently have an 86 engine that is hopefully going to marry a 2005 crf250 frame this winter. I am back to 2 strokes with a vengeance this year, just traded my 450f for a yz250 and am going to be selling the 250f engine and start the 500 install. 

 

 

CR500bore.jpg

Edited by scootersbikes
Bad writing
  • Like 3

Share this post


Link to post
Share on other sites

As much as I like the 500 hit, over the winter I plan to make the power more useable. I want to put a heavier flywheel since there supposed smooth the power and let the bike get better traction. I would like to put a bigger carb and what I think what was wrong with that race was the tuning and a small crack in the pipe. I looked into one of those cr250 ignition swaps they're supposed to smooth the power and allow the bike the rev higher but I'm not to sure if I like the idea of

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:


×