Gain going to disk style from shoe style clutch (1/8 mile)

[durandbagwell86]

Ran my mbx10 at the 1/8 mile track and only ran a 12.4 @55.xx. I know I'm heavy (250+lbs) but my bike doesn't launch real hard with my mongrel clutch, it really feels like it needs to engage at a higher rpm. I was wanting to know if it would probably knock some time off if I switched to a disk style clutch like a bully, tomar, or norm? I'm running a 13" rear tire and 14/75 sprockets now. The mongrel engages at 3100 RPMs and I think my motor would do better leaving at a higher rpm. I'm looking at a quality 3disk because I'll be running a wet kit on this bike in the near future. Any help and 1/8 mile times with clutch change will be much appreciated.


The specs are
-non hemi predator 212
-billet rod and flywheel.
-nrracing ported 18cc Honda head milled .050
-SS valves and 26lb springs
-cm push rods
-champion rocker arms
-.016 copper head gasket
-lash caps
-black mamba sr. cam
-head and side cover studs
-22mm mikuni with long intake and k&n style filter
-Robertson torque tube 3 stage header

 

[bdomit01]

I prefer to use drum type clutches. They work just as well when set up properly and there are less parts that could break on them.

 

[CarPlayLB]

Is there springs for the Mongrel that will give you a higher stall? I'd try that first.

 

[cheezy1]

Yes you will...race proven at the track. 3 disc for your weight would be best. Drum clutches are for the slow kids.....no offense.

 

[DBMonster85]

Ran my mbx10 at the 1/8 mile track and only ran a 12.4 @55.xx. I know I'm heavy (250+lbs) but my bike doesn't launch real hard with my mongrel clutch, it really feels like it needs to engage at a higher rpm. I was wanting to know if it would probably knock some time off if I switched to a disk style clutch like a bully, tomar, or norm? I'm running a 13" rear tire and 14/75 sprockets now. The mongrel engages at 3100 RPMs and I think my motor would do better leaving at a higher rpm. I'm looking at a quality 3disk because I'll be running a wet kit on this bike in the near future. Any help and 1/8 mile times with clutch change will be much appreciated.


The specs are
-non hemi predator 212
-billet rod and flywheel.
-nrracing ported 18cc Honda head milled .050
-SS valves and 26lb springs
-cm push rods
-champion rocker arms
-.016 copper head gasket
-lash caps
-black mamba sr. cam
-head and side cover studs
-22mm mikuni with long intake and k&n style filter
-Robertson torque tube 3 stage header

Is your bike reving out at the end of the 1/8th or is it still picking up speed past the 1/8th? If it's still picking up speed then try dropping 1 clutch gear. That will get you out of the hole better and hopefully have enough gear to make the full 18th. I run a 13 and 64 and it's just about right but I also have a bully 2 disk clutch. Also what is your rpm at the finish line?

 

[bdomit01]

Is your bike reving out at the end of the 1/8th or is it still picking up speed past the 1/8th? If it's still picking up speed then try dropping 1 clutch gear. That will get you out of the hole better and hopefully have enough gear to make the full 18th. I run a 13 and 64 and it's just about right but I also have a bully 2 disk clutch. Also what is your rpm at the finish line?

Agreed try dropping one tooth on the driver before dumping the money on a clutch. If you're coming through the 1/8 at 55 with that tire and gearing then you should be turning just over 7500. Black mamba sr will pull well above that. I've had a mamba jr spin to 8000. So dropping a tooth on the clutch should get your out of the hole faster with you running out of the top end.

 

[durandbagwell86]

Yes, but 3600rpms is the max you can make it stall.

 

[durandbagwell86]

I don't gain any speed past 3/4 of the track. I'd say 7500 if the clutch wasn't slipping any, I think it might be. I don't have a tach yet though. 60ft is a 3 flat and 330ft is 8.10.

 

[durandbagwell86]

I've ran this bike flat out for a mile and it runs 55, between 1/2 and 3/4 track I'm running 55. I don't know if I have some slippage with the clutch on topend.

 

[massacre]

I have drilled out the weights before to raise stall speed

 

[durandbagwell86]

I prefer to use drum type clutches. They work just as well when set up properly and there are less parts that could break on them.

What type of times do you run with a drum style?

 

[durandbagwell86]

I have drilled out the weights before to raise stall speed

When you get it to stall higher with a drum clutch does it slip more at the higher rpms? Does the rpm's match up with the speed for your gear ratio? I don't want to spend time or money on this clutch of it won't perform, or spend money on a clutch style if it won't help. I'll be spraying this motor soon and won't something to hold up (maybe a 3 disk bully).

 

[durandbagwell86]

Agreed try dropping one tooth on the driver before dumping the money on a clutch. If you're coming through the 1/8 at 55 with that tire and gearing then you should be turning just over 7500. Black mamba sr will pull well above that. I've had a mamba jr spin to 8000. So dropping a tooth on the clutch should get your out of the hole faster with you running out of the top end.

Yeah, I should be turning a little over 7500 if the clutch is fully engaged with no slippage. Has anyone experienced slippage with a drum clutch (RPMs higher than it should for the speed)?

 

[bdomit01]

I don't drag race I do trail riding. But after climbing a big dirt hill my clutch is cool enough that I can hold my hand on it, so it's not slipping much if any... Draggin skin is a drum clutch that they advertise with a stall adjustable up to 5000 rpm. But really any drum clutch can be set up to do that with the right combination of shoes and springs. Are parts avavilible for your clutch? Even if they aren't l, just measure you spring and find a matching one on McMaster in a thicker wire diameter.

 

[durandbagwell86]

I talked to the guy that I've been told was the best in the country on these clutches and he said anything over 3600 stall it will be inefficient and not work good. I'm new to minibikes, but I've dragraced for years and do have a drag car that I run now. I just want to get the most out of my setup. I might just order a clutch style, I'd just like to hear some positives from someone swapping to one first.

 

[CJdoodlebug90]

we have similar setups. i have the same problem with take off and ive install the black spring in a max torque clutch. i ran like a 13.00... my gear ratio is 15/70. think i need to go down in rear sprocket...was think about a tav

 

[durandbagwell86]

If a tav would hold up to my RPMs I'd have one for sure.

 

[deesel]

Get a disk clutch, you won't regret it.

 

[isaiah3g]

I stacked black springs on my hilliard extreme duty. Major pain gettin them on, I'm engaging about 4100, at least that's where I'm able to read until my neck snaps back.

I have a 10" rear wheel (unsure total height with tire) and running 12/90