Author Topic: Flywheel wieght on CR 250 ignition (Read 8440 times)

rablack21 · « **on:** August 19, 2014, 04:38:53 PM »

My setup:
88 TRX set up for MX
ESR 310 pv
38mm cast Smart Carb
ESR TRX 5 pipe and silencer
Vforce 3 reed cage
CR 250 ignition

I am doing some testing on my race quad to see if the flywheel weight is helpful or hurtful. I thought I would share this information with anyone who might also be interested. I bought and installed a Steahly flywheel weight 10 oz. So far, I have only taken it down the road and around my subdivision, but was able to pull a couple of full stretch runs on it. So far, I have not noticed a great deal. The engine still revs up pretty quick. It might be just a tad slower on revving up when going through the gears, but if it is, it is not by much. So far this is all I have noticed. I've only ridden offroad once and it wasn't in any area that I could tell much. It does seem to keep it centrifugal momentum up a little better and doesn't slow down the revs as fast. The real test will be when I get it to the track and see how traction is affected and how cornering is affected. Right now, I am running 14/38 gearing. I'm gonna run it on the track with what I have on first and see how it does. Then I will probably switch to 14/37 and see how it likes that. These are just a couple initial impressions that I have of the flywheel weights. As of the moment, I can't tell you whether there is a benefit to running the weight or not. I hope to go to the track Friday and do some tested. Stay tuned!

aberegg05 · « **Reply #1 on:** August 19, 2014, 05:15:23 PM »

Thanks for the report. I haven't got around to buying one for mine yet. Keep us updated.

Allison#51 · « **Reply #2 on:** August 19, 2014, 09:36:21 PM »

Be cool if you could run a couple laps without it come in put the weight on and run a couple more and compare lap times

Jerry Hall · « **Reply #3 on:** August 20, 2014, 10:37:25 AM »

Quote from: rablack21;41247

My setup:
88 TRX set up for MX
ESR 310 pv
38mm cast Smart Carb
ESR TRX 5 pipe and silencer
Vforce 3 reed cage
CR 250 ignition

I am doing some testing on my race quad to see if the flywheel weight is helpful or hurtful. I thought I would share this information with anyone who might also be interested. I bought and installed a Steahly flywheel weight 10 oz. So far, I have only taken it down the road and around my subdivision, but was able to pull a couple of full stretch runs on it. So far, I have not noticed a great deal. The engine still revs up pretty quick. It might be just a tad slower on revving up when going through the gears, but if it is, it is not by much. So far this is all I have noticed. I've only ridden offroad once and it wasn't in any area that I could tell much. It does seem to keep it centrifugal momentum up a little better and doesn't slow down the revs as fast. The real test will be when I get it to the track and see how traction is affected and how cornering is affected. Right now, I am running 14/38 gearing. I'm gonna run it on the track with what I have on first and see how it does. Then I will probably switch to 14/37 and see how it likes that. These are just a couple initial impressions that I have of the flywheel weights. As of the moment, I can't tell you whether there is a benefit to running the weight or not. I hope to go to the track Friday and do some tested. Stay tuned!

10 oz is not much weight if the weight is a disk and will not change the moment of the crankshaft very much. 10 oz added to the outside circumference of the flywheel would make a noticeable difference. The majority of the kits that add weight to the flywheel have a constant thickness disk whose center of mass is located at a much smaller radius than where the outside of the fly is located.

rablack21 · « **Reply #4 on:** August 20, 2014, 12:06:31 PM »

Flywheel weight would be rather pointless if the weight wasn't added to the outside circumference of the flywheel. Both Steahly and MSR flywheel weights are set up on a larger radius. Compared to the weight of the cr 250 flywheel and the trx 250r flywheel, a 10 ounce change ( 283.49 grams) is quite significant.

rsss396 · « **Reply #5 on:** August 20, 2014, 01:16:40 PM »

I think the 16oz made a noticable positive differance in idle quality and honestly for the guys that want the somewhat stock feel that is the weight to go with.

rablack21 · « **Reply #6 on:** October 14, 2014, 01:21:33 PM »

Update:

So I tried my weight this weekend at a mx race. I honestly can't say that I noticed much difference to not having it. It's hard to say with only two motos of opportunity. I will say that it may have played a role at the starting gate. It was a loose sandy track and the starting gate was such as well. I figured that I would get alot of wheel spin off the line, but that was not the case. I was launching in 2nd gear, throttle at 3/4, dumping the clutch at take off, weight leaned forward over the gas tank. On the first gate drop, I come out of the gate wheels high. I had to let of the gas, quickly clutch it, and then take off again. On the 2nd gate drop I made sure I was far enough forward; with my crotch basically up to the gas cap with my head leaning over the handlebars. Same take off procedure as before. Again, on the gate drop, I come out of the gate doing a huge wheelie having to clutch it and go again. I can't say with all certainty that my ridiculous amount of traction was due to this flywheel weight, but it is possible.

fx4pitrone · « **Reply #7 on:** October 14, 2014, 02:47:49 PM »

Good report... I'm also looking into one of these for my build.....

Burns363R · « **Reply #8 on:** October 14, 2014, 03:36:14 PM »

I run a flywheel weight on both my MX and XC CR250 Ignitions. It made a noticeable difference for me. I was never happy with the CR ignition untill having the weight added.

rablack21 · « **Reply #9 on:** October 14, 2014, 03:47:27 PM »

Quote from: Burns363R;44536

I run a flywheel weight on both my MX and XC CR250 Ignitions. It made a noticeable difference for me. I was never happy with the CR ignition untill having the weight added.

Kyle, What was it that you noticed about it? I'm curious. Again, I have only gotten to run this for a short bit on the track, so I am still keeping my ear to the ground, so to speak, to see if I notice anything different from before. What amount of weight are you running?

Burns363R · « **Reply #10 on:** October 14, 2014, 04:55:20 PM »

15 ounce weight. IT has more bottom end coming out the of the corners. Or should i say more resistance to stall. I can drive a corner harder, slide the rear end and roll on the throttle with less likeliness to bog. It also smooths out the power.

rablack21 · « **Reply #11 on:** October 14, 2014, 07:55:15 PM »

Hmm. Maybe I just don't have enough weight to see quite as much difference.

rablack21 · « **Reply #12 on:** October 15, 2014, 07:52:36 AM »

Quote from: rsss396;41343

I think the 16oz made a noticable positive differance in idle quality and honestly for the guys that want the somewhat stock feel that is the weight to go with.

Quote from: Burns363R;44538

15 ounce weight. IT has more bottom end coming out the of the corners. Or should i say more resistance to stall. I can drive a corner harder, slide the rear end and roll on the throttle with less likeliness to bog. It also smooths out the power.

Where did you guys find a 15oz or 16oz flywheel weight? What brand are you running? The biggest size that I have found so far for a cr250 is 14oz.

Burns363R · « **Reply #13 on:** October 15, 2014, 08:12:42 AM »

You wont like where I get them at. They make them in house.

rablack21 · « **Reply #14 on:** October 15, 2014, 08:26:59 AM »

Quote from: Burns363R;44579

You wont like where I get them at. They make them in house.

I understand. Thank you for replying back anyway. How did you decide what weight to go with or did you just experiment with several different weights?