Did they produce a compression release head?

Pablo

Pablo

Master Bike Builder & Forum Sponsor
I swear I saw a picture of a leetle compression release gizmo valve in a head....is there one for the 70cc china chick engine?
 
I had an old 360cc Yamaha endoro way back in the 70s that had this. It also had two sparkplugs over the one piston so that you always had a spair spark plug. If you did not use the compression release and that motor "kicked back", you could lose your leg.
For our "china chick" engines, you would have to make it yourself but why?
 
toytime said:
For our "china chick" engines, you would have to make it yourself but why?
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When I rig mine with the super Chinese grandma hill climber gears, the beast is a bear to start with pedals. Man it feels like an 800cc single cylinder with 16:1 CR!
 
I would have thought that the larger sprocket would make it easier but we will agree to agree.
You could do it IF you found a spot on the head that would allow you to drill a hole and tap it for the valves threads. Would I do it? No.
 
toytime said:
I would have thought that the larger sprocket would make it easier but we will agree to agree.
You could do it IF you found a spot on the head that would allow you to drill a hole and tap it for the valves threads. Would I do it? No.
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With a front freewheel whatever ratio makes it "easier" for the engine to spin really fast and have lots of torque, i.e. tiny engine sprocket driving a much larger sprocket - will make it much harder to pedal start for the operator - it's the same direction as the engine - just now the rider has tall gears to fight against (but the engine will turn over at higher RPM!!).

I'm for sure not going to do it unless I find a bolt on head. I just won't be running the ultra granny ratio that often. This is not a problem with the standard jackshaft ratio or the highspeed ratio.
 
If you have a friend who has a heliarc you can weld up an area on the head then machine it to mount the comp. release. Lot of work but it can be done you will maybe need to resurface the head as it might warp.
 
Pablo said:
With a front freewheel whatever ratio makes it "easier" for the engine to spin really fast and have lots of torque, i.e. tiny engine sprocket driving a much larger sprocket - will make it much harder to pedal start for the operator - it's the same direction as the engine - just now the rider has tall gears to fight against (but the engine will turn over at higher RPM!!).

I'm for sure not going to do it unless I find a bolt on head. I just won't be running the ultra granny ratio that often. This is not a problem with the standard jackshaft ratio or the highspeed ratio.
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Pablo are you guys still running the freewheel sprocket in the back? If so weld it to stop the freewheel and you should get the ease of starting back up. With the Schwinn I bought that had the free wheel crank the rear gears are fixed. When I put it on my other bike and the rear is free wheeled also when you coast nothing moves not rear gear no crank and of course my feet. So yes its going to be all up to your thighs to start it and with the extra gears Im sure its not an easy deal. At least if you weld the rear gear to the bearing and make it fixed you can go back to pretty much the old way of starting.
Well at least ya can get a nice hill to coast down and fire up with out killing yourself.
Terry (needs a jackshaft) Jonz
 
jezusjonz said:
Pablo are you guys still running the freewheel sprocket in the back? If so weld it to stop the freewheel and you should get the ease of starting back up. With the Schwinn I bought that had the free wheel crank the rear gears are fixed. When I put it on my other bike and the rear is free wheeled also when you coast nothing moves not rear gear no crank and of course my feet. So yes its going to be all up to your thighs to start it and with the extra gears Im sure its not an easy deal. At least if you weld the rear gear to the bearing and make it fixed you can go back to pretty much the old way of starting.
Well at least ya can get a nice hill to coast down and fire up with out killing yourself.
Terry (needs a jackshaft) Jonz
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It doesn't work that way. Think about it. It still freewheels, even if we "weld" the rear freewheel.
 
Pablo said:
It doesn't work that way. Think about it. It still freewheels, even if we "weld" the rear freewheel.
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Ok Im confused on your problem then. I thought you were wanting to have the ease of start like we do normally with the gear on the left side. When you run a front free wheel and a rear free wheel you have to constanly pedal to be able to start the motor so if your going down a hill and you want to start the motor you have to pedal to start it because there is no movement of any of the drive line. If you have a fixed rear gear then when your going down that same hill you have movement of the drive line your pedals are not moving but everything else is just like it normally would if you are running a regular setup. Then you can just pop the clutch and go.
The schwinn system was made so that the rider could change gears when they were not pedaling with the fixed rear gear because the chain line was still moving but the rider didnt have to pedal.
So by welding the rear we just fliped the system that we use now. So with your setup and a fixed rear gear when you just push the bike the rear gear moves with the wheel it turns the crank and turns the jackshaft and motor just like it does on any other happy time setup. With the two free wheels that you have now its like turning over a model t.
 
You are correct that if you lock the rear freewheel it will turn the front chainring and assist in starting. The problem is that because in coast mode, rear wheel driving the chainring, as soon as you put a load on it, release the clutch, it will just unwind you rear derailleur and your chain will fall off. On your front freewheel system try riding the bike and put some friction on your front chainring with your foot and you will see what I mean.

Pablo is just having a problem because I screwed up and made an incorrect assumption. He caught my error and things should be good to go once he gets the new sprocket.
 
Yea I could understand that to a point. Have you been having these issues because I could see if there was a heavy bump start you could loosen it some but when the motor goes to power it reapplys the force to it to basically retighten what it just loosened. I really dont think that by applying force to the crank that you should ever be able to unthread the rear sprocket. If so it probably wasnt tight in the first place wouldnt you think.
Im am glad that you are trying to keep us up on whats your going through so that when it comes out we'll all be prepared for what to do and what to watch out for. Ever since I got into motored bikes I have wanted to do this. Jackshafting was always the way but I never knew there were free wheel cranks to you all started talking about it. So now IM like that kid wanting that BB gun...but MOMs not here to tell me Im going to put an eye out. lol
Terry
 
The rear freewheel won't come loose, I don't think. It is the derailleur that will unwind. Currently the derailleur is springloaded to keep chain tension while allowing for varying chain lengths for shifting gears. Using it to drive the front chainring as you suggest will unwind the derailleur causing the top of the chain to loosen and fall off. Try this on your bike. Hold your front freewheel/chainring from spinning, then roll your bike forward. You will see your derailleur unwind. It would continue to do so until it ran out of slack and then it would actually turn the engine over. In the meantime the top of your chain now has all the slack your derailleur was taking up and will probably fall off.
 
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Sure I totally understand what your talking about on that respect. The bike I have my freewheel crank on my front and rear are free and I dont plan on welding it because my crank has a 52 outer and a 39 inner gear on the crank and I plan on connecting to the larger one and working on my thigh muscles. What size are the crank gears that are on the kit that you two have been testing?
Terry
 
Yeah I did have one brain fart - in a perfect world if the rear sprocket was locked then you could use the bike inertia to help start, but it would be quite problematic as Ghost0 points out. I got the gear on the way....
 
Yeah I did have one brain fart - in a perfect world if the rear sprocket was locked then you could use the bike inertia to help start, but it would be quite problematic as Ghost0 points out. I got the gear on the way....
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Please dont think that Im badgering you two...until I can get my hands on the kit Im trying to visually put it all in my head and go through it as if I had one and have been riding everyday with it. Its a bad curse that I aquired when I worked at a printing company that did things that should not have been done with printing presses. BUt I had the ability to take in what they wanted actually see it run in my tiny little brain and work out alot of the bugs before attemting it on press. The guys that ran the presses would come in some night and see some werid thing on there press and hollar...DANG IT JONZ....remember when you got a fed ex shipment and left this thing on your door knob cause you werent home. You can thank me for causing that. lol

SO when Im out riding now I look down at the chain line and imagine what its going to be like when the right chain is turning and there is no left chain and guess what ...............
Its going to be all because of you two...I think thats PRETTY damn COOL(^)

and if you only have one brain fart in a project like this that you two have taken on....I say GREAT JOB...you two are pulling off what takes a year or more and a DAMN many more people.

Terry
 
We've had a couple stinkers - trust me.

No problem, you and the others here keep us driving and make it FUN!! The good to come out of it all this ratio messing is time on the set-up and the different stresses and such the different gears and chains place on the design. It's all GOOD!!:p(^)

MOSTLY I really dislike waiting for stuff at this point and the total lack of response from some suppliers....it's like some of these guys don't want business! I mean really wierd - if times are tough and some guys come along and want to buy 100+ gears, you would think suppliers would be eager to sell. Not so.
 
Could anyone provide a link to what it is you are all talking about. I have no clue, yet this sounds interesting. Would this wheel be the same as a Raleigh with a three speed hub? Is this so that you can use that wheel? I'm going to buy an old Raleigh in a few hours and wondered about that rear wheel. Thanks.
 

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