CR250 ignition for the 500 question (pic)

[Roostius_Maximus]

I'll try the 88 250 setup cuz it cost me 39.00!
And when i asked Danny if that was a good setup, he said thats what he was running, so its atleast different so i'll try it.
It ran fine with an 88 500 system so the analog part isnt really a dealbreaker for me.
I'd tried the 125 setup from an 86, postd the pics on this topic in the other site, but here it is
the 125 stator fits the case with mods, its a full disk shape instead of eliptical. There is no stop for the clutch lifter on a 125 stator.
the flywheel needs to be machined to fit deeper onto the crankshaft, same taper, but shallow.

125


500

[oggo69]

thanks for the info roostius .... 250 iginton it is

[MICK]

I have a question, why does anyone want to use all the old analog 250 and 500 ignitions when you can buy a brand new Digital ignition system with the 2000-2001 CR250 setup.

Price and fitment could be two motivating factors. Andrej gave me his 250 ignition for $90. And the 94-96 systems bolt straight on. Easier than changing a tire...

Seems like everyone is getting hung up on the size of the flywheel also and I just don't see it making much difference on a big 500 with a ton of inertia in the piston, rod, and crank.

I'm not sure if anybody is any too "hung" up on it? But riders might be concerned with a lighter flywheel causing more stalls, difficult starting and abrupt power. Which seem like pretty legit worries to me? As far as making a difference regardless of the crank it does indeed make a difference. Place an object 3" in diameter and 4.1oz in weight on a rod and hold it with both hands. Now turn it 3-6K rpm and tell me you can't feel it? That's how much LESS bullshit I have to deal with changing direction now...Try to remember this is a 230lbs bike. Not a quad. Some of you weigh more than my bike does...

Roostius, do you think you could possibly post any larger pictures?

[100hp honda]

I'll try the 88 250 setup cuz it cost me 39.00!
And when i asked Danny if that was a good setup, he said thats what he was running, so its atleast different so i'll try it.
It ran fine with an 88 500 system so the analog part isnt really a dealbreaker for me.

its all cool man, i wasnt busting your balls but just wondering why the choice of the '88 250 setup. for $39 i can understand why you purchased it. i have a full digital snap-on timing light, soon as i get a chance im going to map out the curve on a '98 500 cdi and ill map a digital 250 cdi.

the 125 stator fits the case with mods, its a full disk shape instead of eliptical. There is no stop for the clutch lifter on a 125 stator.
the flywheel needs to be machined to fit deeper onto the crankshaft, same taper, but shallow.

i wasnt for sure on the 125 but i had a hunch the flywheel inside diameter wasnt a direct bolt on, im glad to know the exact difference . thnx for the info man

[Roostius_Maximus]

Let me know if that timinglight worked for you. My big snapon scatters the light like its on an msd, but a flaming river brand light #1001 or something will work on ANY ignition, has its own power supply, advances, and its cheap. I always stock 2 of them cuz nothing else works as good.

[kball1313]

I have used my MSD timing light on all sorts of stuff and it stays steady. MY snap on adjustable one got sold a long time ago.

[aloha450x]

bump for all the people asking me about it on ebay. i have been sending them here to read up.

[des500mouse]

Well I scored an '01 cr250 flywheel, stator and cdi off of "the bay". Had to remove material from the back plate to clear the ridge on the case around the crank seal. Other than that it's a bolt on affair. As far as wiring it, all I had to do was make a conversion jump wire to connect to the coil. If I like the way it runs after putt'in in some seat time, I'll change the connectors so there's no chance of it coming loose. I haven't found the opportunity to ride the beast yet but fired her off. Dang, it revs like a stink'en Indy motor! Can't wait to roost them 450f's at Cal City come Easter ..............

[hoofarted]

Nice - lemme know how that 01 works out. How difficult was it to start? I've been eyeballin' parts for an 01 off ebay also. Seems to be great variances in price. Anyone know if the flywheels are interchangeable between the years?

[robertg]

The 00-01 flywheels are the same, I have a 97 and it's different. I just put a bike together with an 00 CR250 ignition, it starts first kick every time, hot or cold.

I believe the same Steahly weight will work on 90-01 125 or 250.

[Roostius_Maximus]

Here is what i find with the 3.5" flywheels:

oem 500 flywheel weight 1987-01: 563.9 pickup length .707"
oem 1986 cr500 flywheel weight : 565.8 pickup length .785"
oem 1988 cr250 flywheel weight : 487.5 pickup length .530"

can anybody weigh an '85?

[seanmx57]

so does anyone have some jetting info on the 01 setup with a pwk carb?

[Disturbed]

Ok, my eyes are about crossed from reading threads here and "another" forum on the 250 ignition conversion.

I now have a question.

Seeing as fly wheel weight/DIAMETER must have a lot to do with the different feel of how they ride with the 250 conversion, what about just milling some diameter/weight of the stock 500 flywheel?

Anyone tried it?

Buhler.......

Buhler.......................

[dannygraves]

actually the flywheel weight has little to do with the positive results of running the 250 ignition. most of it is the ignition curve.
Mick proved this with his testing where he swapped things around and ran a 250 flywheel on a 500 ignition and a 500 flywheel on a 250 ignition.

[Disturbed]

I thought I read where the bike would get into turns better [MX] due to the lower rotating mass.......

[seanmx57]

In order to make the stock 500 flywheel smaller the pickup area would have to be rebuilt or she would vibe worse. I like my 250 set up because cornering is easier with the smaller flwheel, I'm not fighting the inertia of the 500 flywheel, there is much less tendancy for it to want to stand up in a corner. Handles more like my 250 now.

[Disturbed]

So I know it's buried on page 137 or somewhere but what year 250 ignition/flywheel would bolt on to an 87?

Would that same ignition bolt on to a 97?

What are the crossover years that would do either?

My CR500 information bookmarks are beyond out of control to the point where I can't locate what I need anymore.......

[dannygraves]

really, in all honest the cr500 changed VERY little from '85-'01. The 250 setup will directly bolt on ANY cr500.
I find it hard to believe that a an ounce or two off the flywheel makes a cr500 corner like a 250... the cr500 crank is a massive heavy beast weighing in over 2lbs easily.
the 250 ignition setup improves engine performance through a more agressive timing curve. period. Ask Mick how his 500 ignition performed w/ the 250 flywheel.

[CR500R7]

I am not going to say what difference in handling the flywheel weight makes, because that is hard to quantify.

I do know that the lighter something is, the easier and the faster it is to more it.
Taking static weight off of a vehicle is one thing, but when you take rotating weight away it makes more of a difference.

The closer that rotating weight is to the engine the bigger that differnce is, when I say closer I mean if it is running through gearboxes, diffs and chains.

I once read an article in Circle Track mag, that said if you take 15 pounds off of static weight in the car, it makes very little differnce in accleration.
Then if you took 15 pounds of rotating weight from the wheels you would make an even bigger difference.
If you took 15 pounds out of the diff it would be even greater.
Then the tailshaft, the gearbox.

The single biggest gain you could get was losing that 15 pounds from the engine where there is no gearing involved.

Simply put weight drains useable horsepower, less weight faster acceleration and decceleration.
Which means the engine doesn't have to work as hard or the brakes to slow the bike down.

Add in a better ignition system as well and you gain a $h!tload of performance.

I am sure someone will disagree with me but that is the FACTS!

So it is a combination of the two things together that give you the gain, which one does the most, I am not getting into that one.

[Roostius_Maximus]

at the circle track the difference of running a crank with 2.100 pin and a 6" h beam rod or running a 1.88 crank pin and a 6" rod (about 150 grams a hole) is the difference of letting off at the flag stand to get int the corner, or letting off 1/4 of the strait away further, and when you get back on the pedal the car better be setup for running low and tight so its almost on the inside rail cuz shes gonna grab,hook and lift the front left where the heavier assembly would having to run high and wide in the corner to spool up longer.
I'm not going to say lighter is always the way, but i'll build the engine to suit my customer, not to make him re-learn how to use it, but probably do some chassis work to bring it in.
i've got one guy who runs deep+low, that engine is light and light, did i mention light. hes the only guy i know who pitches the car into the corner to the mat before the end of the strait, engine loads VERY hard, usually he's out front by a ways so you can hear it on its own, has a charachteristic "ACK-ACk-ACk" loaded in the corner but is holding over 9000

this is stil a 2.100 pin Crower crank, but you can see what it looks like compared to the standard stuff.

[dannygraves]

I'm not doubting how big of a difference a lighter rotating assembly will make... rotating mass in huge. the thing I'm arguing is that taking an ounce of flywheel off a 500 will not make it handle likea 250, hell a 500 with no flywheel with still have more gyros than any 250. I do believe a lighter flywheel will improve handling, but with that massive crank spinning in there, it will always turn like a 500.

[Roostius_Maximus]

no disputing that

i'm looking at the pics of the crank from sean with the mallory slugs in it, IF i balance this next one i'm working on, its not going to see weight added, it looks like theres plenty of meat in the rod pin, i'd rather lick material from inside it, and radius the holes outer edges, drill beside the pin like micks pic + grind weight from the piston where able, and possibly lathe the entire crank wheel down on the sides to lighten it further

[seanmx57]

Did I say 250 I mean CR85

I think it's quite a bit more than an ounce, the smaller diameter really makes a difference. I have 2 identical gen 2's a SH 500AF and a stocker CR250, same supension revalve, rear wheels in the same location (foward) and forks in the same location. I ride em back to back at the same track regularly. They handle about the same really. the 500 motor of course has more gyro, but it's a lot better than it was with the big FW.

[Roostius_Maximus]

exactly, even if there is an identical mass to a+b in this scetch i stole from google, it stil takes longer for A to reach an identical peak rpm and decline to as stop than it does b

[CR500R7]

Danny, I don't disagree with what you have posted, I was just trying to elaborate on what you had already posted.

It is not one or the other making it better, it is both.

1 being CR250 ignition.
2 being lighter flywheel.

Which makes the most difference.

As for handling like a 250 , You are right a 500 crank still has a lot of rotating mass.
I can't see it, but I could be wrong.