Tuning a CR500 for higher rpm

[Nikel]

Have you thought of trying a pipe from a more modern open class bike , that is what I had on the 1962 Greeves MDS I used to race, an early Husky Evo pipe in fact, worked 100%. Much easier to cut and shut than build a new one. You must be very brave to want a Cr500 to go even faster!

Never thought about that.
Good call.

When riding the the bike as a Supermotard it is not the worst thing ever.
But I am quite amazed about you guys who use them on the Mx tracks.
That's insane =)

 

[Bigbill]

I've done around 120mph on the highway here on my 99 husqvarna TE610e I was passing cars but I worried about getting a cross wind as I passed the hills on the side of the highways. I worried about the light weight bike being taller. I hit a cross wind on my 99 Suzuki 1200 bandit once that blew me across two lanes to the left till I put my full body weight on the left peg. The movement stopped in the left shoulder when I was about to cut the grass. Like I said I'm not sure how the lighter, higher bike handles the cross wind on the open highway.

How much horsepower does the 500cr husqvarna actually have?

It has to be more than the 390cr having 43hp at the rear wheel.

 

[Nikel]

I've done around 120mph on the highway here on my 99 husqvarna TE610e I was passing cars but I worried about getting a cross wind as I passed the hills on the side of the highways. I worried about the light weight bike being taller. I hit a cross wind on my 99 Suzuki 1200 bandit once that blew me across two lanes to the left till I put my full body weight on the left peg. The movement stopped in the left shoulder when I was about to cut the grass. Like I said I'm not sure how the lighter, higher bike handles the cross wind on the open highway.

How much horsepower does the 500cr husqvarna actually have?

It has to be more than the 390cr having 43hp at the rear wheel.

Crosswinds have never bothered me, but many of my friends hate them.

I'm not sure really.
In my registration papers it says 50Hp.
I'm a bit slower than my friends Aprilia SXV 550 that has 70 Hp.
So i guess somewhere between 50 and 70 I guess.

I think im going to build my own pipe.
The winter is long here in Sweden and I like to build my own stuff =)

 

[Bigbill]

I built a husqvarna pipe from a Yamaha 490 pipe if I remember correctly.
I had it curling out to the left side, the a U turn 180 degrees to the right side and expanding as it went upward towards the gas tank. I put it on a 250 but it would probably work better on a 500cc engine. I wanted to build a pipe. It was my first one. The front 2/3's of the pipe was Yamaha 490 while the rear section was husqvarna 250.

 

[2premo]

if you do a bit of research on the design, it involves pulse and expansion to extract the exhaust at the correct rate without restricting the overall flow
hence the reason for the power valve, you will give up something in the trade but seems you are not really concerned about the bottom torque so your pipe will need a shorter head pipe and different expansion chamber

 

[Paul P]

All pipes for all bikes made are designed around the stroke length. A rule of thumb check to see whether you have a torque pipe or rev pipe is to measure half way down the rear cone and make a mark. Then measure the distance from the piston to that mark in inches. An example, if your stroke is 80mm, and your measure is 40 inches, you are close to an ideal measure for all around power with good peak rev's. If the measure is over 40, your pipe is getting more towards lower revs.
Diameter and length of the cones and header also come into play and will change RPM's, and where the power hits in the rev scale. I have a 390, and the stock pipe is a very mild tuned pipe, not designed for high RPM. Motocross bikes needed to be rider friendly, so the long torque pipe was what worked best on a variety of conditions.
The Dyno port pipe sounds expensive.

 

[Bigbill]

My 390 cr was a wild machine in its stock form. It was a wick it and hang on. She wasn't for the faint of heart. When wot down the straights while standing up in the race horse position it's the only bike that tried to leave me. I had to keep on pulling it back under me. The wr & or bikes back then we're ported to be mild?
The cr porting wants to fly. But my 79-250 or was a rocket too. With the first three gears being wr and the last three gears being cr in the tranny kept the rpms in the meat of the power band. She didn't bog if you weren't going fast enough like the wr tranny did at times. You couldn't ride it like a four stroke.

So now we can have the pipe tuned were we want the power band to come in at?

My thoughts are with a 500cc close ratio tranny where do you want most of the power to peak at?

 

[Big Timmy]

Bill,

If you are building a few pipes from scratch you should look up "2 stroke wizard". You can download the instructions and the entire program for about $35. bucks or so . If your planning to be building pipes from scratch you just map out the port layout and bore and stroke configuration of the engine and the "2 Stroke Wizard" program will design the entire pipe and cones for you. This program will also tell you how to change the degree of taper of a given cone design taking in consideration the amount of turn in flow in the pipe through that cone ( say 180 degrees) to have the proper volume, working off the center line basically as a straight cone would have.

If your not a sheet metal man. Look up "projection layout" & "Frustum cone layout". If you can draw a flat view of the actual intersecting cones one at a time, ( height or length + the diameters on each end) with the mitered ends, from the side view it will walk you through the process of projecting that cone out to a 3 dimensional pattern. Its pretty easy actually once you get the hang of it. You can even locate and index the seams to match them or hide them on the back side so they can't be seen. Layout tools needed are a nothing more than a few straight edges, a few squares and a couple pairs of good dividers, compass and a measuring tape. The sheet metal part comes next. A Beverly shear, Treadle shear, slip rolls and a set of Pexto cone mandrels and your good to go.

I've made 2 stroke pipes for many years since the mid 70s, a few hundred at least, for both dirt, street and Quads and some were as many as 35+ individual hand rolled cones and pieces. A few Quads I did years back had to have spring loaded slip joints mid point in the chamber itself that never leaked. I've built Race car headers and pipes for Harleys for years as well so Mandrel U bends for getting the head pipes started are available at many speed shops or available at "Summit racing / Jegs", or the "The Chassis Shop".

 

[Bigbill]

I'm a ways away from needing pipes yet. I'm just gathering my thoughts. I'm not sure to use my original 430cr pipe or go with a brand new tuned pipe.

Down the road I want to build a 390cr and a 500cr. My goal is to have only four husqvarnas this time. A 250wr, a 390cr (my weight loss machine), a 430cr & 500cr. Now my problem is whether to go with the stock pipes or after market pipes.

I can build and port them now it's time to get serious about tuning and tweeting them in. I was a perfectionist when it came to building, jetting,tuning my drag cars. Now I want to get serious with the huskys.

I believe my Yamaha 490 pipe looked good on my 250 but I may have over piped it. Your right I need more info in the education department. Ill checkout that sight on pipes.

 

[justintendo]

dynoport for a lc 500 is $350 factory finish, $450 ceramic coated. they have a side business that does ceramic coating so that is done in house. they are a slightly thicker gauge thickness so they hold up well. i have always liked the look of cone built pipes as well. i think its a pretty reasonable price for a good gain

 

[Nikel]

Good to see al these replies =)

I have calculated my Pipe in Mota, and I have a couple of other programs too.

The stock pipe is waaay long.
Tuned lenght is about 1400 mm.
So it's a Torque pipe indeed.

I'm thinking about matching the pipe to around 7500 rpm.
That would probably work well on the street.
But I wouldn't use it on a dirtrack.

 

[Nikel]

dynoport for a lc 500 is $350 factory finish, $450 ceramic coated. they have a side business that does ceramic coating so that is done in house. they are a slightly thicker gauge thickness so they hold up well. i have always liked the look of cone built pipes as well. i think its a pretty reasonable price for a good gain

Their stock pipes have a good price.
And I'm sure that the mid/high pipe they offered to custom made for me is worth the price.
But still alot of money.

 

[silverstreakNZ]

http://therdbook.com/downloads/2_St...f?phpMyAdmin=d6b6d189e06734965d941db4cadfaedf

 

[silverstreakNZ]

is the cr 500 84 mm stroke ? based on that and sticking to a 4000 fpm mean piston speed limit . u shouldnt rev it much past 7300 . according to gordon jennings
thoughts ?

 

[Nikel]

21M/s shouldn't be a problem.

 

[hva-factory]

We are working on new reed blocks for these (and the earlier 500) that will also work with the 44mm Mikuni. We also have 16 and 17 teeth front sprockets....

Andy.

 

[Nikel]

We are working on new reed blocks for these (and the earlier 500) that will also work with the 44mm Mikuni. We also have 16 and 17 teeth front sprockets....

Andy.

Awzum.

I need that 17 sprocket.
I have been looking for one but haven't found any.

 

[Nikel]

http://therdbook.com/downloads/2_St...f?phpMyAdmin=d6b6d189e06734965d941db4cadfaedf

Well thank you.
I have read it now and it was much appreciated.

And here is a longer one.

http://www.dragonfly75.com/motorbike/2StrokeDesign.pdf

 

[Bigbill]

Andy is a guru. Big front sprocket when we boost the power. There is a big power increase when we reduce the chain wrap on the front sprocket by going to a larger diameter. We also have the option of adjusting the diameter off the rear sprocket. On the street or trail it could also mean less wear by reducing the tighter wrap.

I think my 390cr had a 14t sprocket on it.

I did question my engineering group on what has the most transfer of power the chain drive or shaft drive?
The answer was chain drive.(streetbikes high horsepower)

Since I can advance the port timing as per the husqvarna chainsaw factory rep. I find on my 81 250cr the bike was ballistic on hit and take off through the top end speed. You didn't wait for the rpm to come up it was right there with the response. I advanced the timing with the original pipe.
With a tuned after market pipe it probably would of ran better but I had no complaints. We haven't touched the big bores yet with porting. My 390cr was a screamer stock. But things may change soon. I have two or three big bores to play with. I'd like to built one motor all out.

 

[Nikel]

I actually have a 44 rear sprocket I made at my work.
Its the absolute smallest gear you can fit before the screws hit the chain.

I couldn't fit it of course because my rear sprocket is moved 5mm out to clear the rear tire so the chain touched the brake hold arm.