New Slant Heads for 80cc's: Compression Boost!?

hi i got some info about how to make a clutch mod that is extremely effective, someone might have thought of this before, but ill talk about iot. first i take off the clutch plate clean it up, now the fun part. i took a 3/8 drill bit and drilled 8 holes in a even design around the clutch pad, at prob 3/8 from the outside of the edge. then i took the plate and counter sunk the holes. filed the lips and sanded it. i installed the plate and i found a extreme difference. the plate grabs alot harder and and without having to get the bike up to speed, i still have stock clutch pads and they wear a whole lot less then they did before. i got the idea from the preformance brake routers on cars, and the 3-stage clutch that Rice burners use. it works real good and it wears alot less. ill get a pic here tomorrow. that my 10cents worth. hope it gives people ideas, it be cool if i was the first to think of it.


P.S. the slant head rocks when you have a 27 tooth sprocket, and perfomance carb and a tuned pipe.
 
Hmmmm.....now I had NOT thought of that. INTERESTING IDEA! Just one question - why bother countersinking the holes?
 
i counter sunk the holes so the the plate and pads dont wear as bad, that and it allows the plate to grab on quicker, and to disapate heat guicker, more heat more wear, less heat, less wear. that what i was told.

also a cold friction has a more lasting grab then a warm friction. it may sound confusing but it really works.
 
joe-craft said:
i counter sunk the holes so the the plate and pads dont wear as bad, that and it allows the plate to grab on quicker, and to disapate heat guicker, more heat more wear, less heat, less wear. that what i was told.

also a cold friction has a more lasting grab then a warm friction. it may sound confusing but it really works.
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Maybe less wear.

Not sure why it would grab quicker with the holes countersunk. I guess with it disengaged it would cool quicker with less mass, it would just get hotter faster. I think with disc brakes the holes are slightly countersunk to prevent crack propagation.

Regardless, I drilled mine, but didn't countersink the holes. I did break the edges. Filed the contact surface and thoroughly degreased it. Really nice now, doesn't slip while riding. I'm still battling the adjustment to get full disengaging with the lever button. (but does fully disengage pulled in all the way) - it's a narrow band.
 
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joe-craft said:
hi i got some info about how to make a clutch mod that is extremely effective, someone might have thought of this before, but ill talk about iot. first i take off the clutch plate clean it up, now the fun part. i took a 3/8 drill bit and drilled 8 holes in a even design around the clutch pad, at prob 3/8 from the outside of the edge. then i took the plate and counter sunk the holes. filed the lips and sanded it. i installed the plate and i found a extreme difference. the plate grabs alot harder and and without having to get the bike up to speed, i still have stock clutch pads and they wear a whole lot less then they did before. i got the idea from the preformance brake routers on cars, and the 3-stage clutch that Rice burners use. it works real good and it wears alot less. ill get a pic here tomorrow. that my 10cents worth. hope it gives people ideas, it be cool if i was the first to think of it.


P.S. the slant head rocks when you have a 27 tooth sprocket, and perfomance carb and a tuned pipe.
Click to expand...


Looking forward to the pics. I think I'm going to order a 2nd motor just to experiment with!
 
So after riding a lot more in areas where I could hold the throttle open for a LONG time, there is now an annoying flat spot at the highest RPM's. The engine does have more power, (as in torque), but the increased power band has shifted down in RPM from what I was used to. It may just be a matter of jet size and expansion chamber adjustment. Stay tuned.

Seems to me I remember increased compression ratio gives more torque. And thinking about the completely different head shape, it should be expected that the previous carb and expansion chamber settings would change.
 
Pablo said:
So after riding a lot more in areas where I could hold the throttle open for a LONG time, there is now an annoying flat spot at the highest RPM's. The engine does have more power, (as in torque), but the increased power band has shifted down in RPM from what I was used to. It may just be a matter of jet size and expansion chamber adjustment. Stay tuned.

Seems to me I remember increased compression ratio gives more torque. And thinking about the completely different head shape, it should be expected that the previous carb and expansion chamber settings would change.
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Pablo

You are right for sure about comp.=torque = power =speed...Play with all that stuff you said and you will come up with the right combo....POPS PS. I'll stayed TUNED and can't wait to here more.
 
Glad it worked for you pablo. I did also experience some clutch issues just figured it was gettin worn out... I had considered drilling holes in the clutch disc but was afraid to take the dive. Cliffhanger read the thread the answers are in there...
 
I ran mine tonight with the new head. Power is for sure more , but with this get up the engine gets way hotter now! I got to question longevity. This could be brutal on a hot july day. I got to start checking with a Inferred thermometer now! Now I really need to re jet and go over my oiling?
 
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I noticed my motor definitely ran hotter but since I abuse mine daily at 10000 rpms I wasnt surprised. Most on this forum dont hit this kind of rpm but I have done this for 1500 miles (750 on this head) and no problems yet... I have power all the way to when I shift but on 80 *F days I do notice some heat soak and then can not go passed 38mph (too bad the fins got smaller on the higher compression head...). (I have considered installing a water sprayer on the head to help with the high temps on those days when im beating it real bad...) If i cruise at a reasonable rpm (w/ shifter kit) at 35mph for a little while the heat soaking subsides and I can hit my usual ~45 mph. So far I am still happy with this head and still recommend it to others :) -Justin
 
I wounder what the before compression was did not check. I don"t really wanna buy a comp gage at the moment what is our new comp at with these heads . I will prob get a new comp checker tomorrow.
 
Europorsche914 How did that walbro HDA treat you? I was considering a WJ series model. It was spec out as 50cc to 100 cc. I noticed the HDA one was spec for 30cc to 60cc. I think I will give up one the reed set up for now. Most folks don't know that a boost bottle with a reed set up rocks! Are you using the reed set up?
 
What if we cut the fin's off the old head and welded them (In some way ,shape ,form) to the new head for extra cooling ? I think it would work. Any thoughts ?...POPS
 
goat herder said:
I wounder what the before compression was did not check. I don"t really wanna buy a comp gage at the moment what is our new comp at with these heads . I will prob get a new comp checker tomorrow.
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Goat

I have a real good comp. tester and I bought the new head, And have a pull start but my motor has never been started before so my #'s would not be realistic as the rings are not broken in yet , But just for giggles I might do it any way and post the results with stock head and slant...POPS
 
Yea I bought the walbro hda based on info from pipelyne and did notice that it was designed for a slightly smaller engine. I do not know if it was just too small or what but I could never get it to tune right... It sits in the garage now. As for the reed setup I tested it out with the factory carb and noticed a little difference but took it off just to see how much of a difference it made. Once the factory intake was back on I discovered my crankcase shaft seal was leaking, causing a lean condition. After that was repaired I haven't had a chance to put the reed kit back on, maybe next week ;).
I had considered welding on larger fins but my welder with aluminum feed wire doesn't get hot enough... Maybe I will take it to someone but I'm not gonna spend more than a couple bucks... -justin
PS I got somethin neat I'm workin on, not performance but cool factor, can anyone say flame thrower exhaust?
 
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