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  #7921  
Old 03-31-2015, 04:41 AM
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mapbike mapbike is offline
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Default Re: what did you do to your motorized bicycle today?

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Originally Posted by DRBS View Post
ive been using the timing thing my brother builds them for me, there are like 7 different ones out there mine actually do make it a tad bit more responsive and a little faster like 2-4 M.P.H. but its better than stock!! im ordering a Jake diamond head ice been using the dome top ones think ill try these and see if there any good
ive tried some of the after market cdi units, only found one that performs as good as a stock unit, but never got any of them to outperform the stock unit on my fastest build which GPS'd 52mph on a bike with 24" wheels and a 30T sprocket.

If youve got them that actually do add performance over a stock unit thats great.

I have a Jake's Diamond head and I really like it, you'll need to find an extra long reach spark plug for it, i'm using an E3 3.22 in mine and it could actually use one a bit longer.

the combustion chamber design of the diamond head is different than all the others, the squish ring in head is actually roughly 47mm, it doesn't have a flat surface for the head gasket to seal on like the other heads but instead the head gaskets bore diameter actually matches the squish areas diameter so the squish band is actually the exact height of the jug deck when a standard thickness head gasket is used and if a thin .016 gasket was used the heads squish band will actually sit down in the bore just a few thousands since the squish band is the same diameter as the bore and is beveled from the outer edge all the way in until it ends and the actual combustion chamber starts.

this design is gonna make it easier for those who want higher compression to get it without having to shave the deck height down as much or none at all if they have a 40mm stroke engine, all they will have to do is order a .016 head gasket from juicemotors and they will get a higher compression ratio than they will with any of the other 6cc chamber heads ive seen.

The diamond head is taller and a little heavier that the others, but I kinda like the looks myself, and I really like the squish band design, this head should really wick heat away from the jug also, only downside is that builds with tight space for the engine may not be able to run the taller head, but most all 26" cruiser frames and any full size fixie or mnt bike diamond type from will have plenty of room.
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I dont always ride WOT, but when I do..I do my best to keep the rubber side down..Ride safely my friends!

Last edited by mapbike; 03-31-2015 at 04:48 AM.
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  #7922  
Old 03-31-2015, 08:45 AM
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Davezilla Davezilla is offline
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Default Re: what did you do to your motorized bicycle today?

I've been considering the jake's Diamond head for my next build too since it has the different combustion chamber design to see how that works out. Another one I'm keeping a close eye on is VMB's Shark head he's still designing and perfecting at the moment.
I just picked up a Super Rat bottom end from BGF Motors on ebay last night that I'll do my next build on. I know these have ignition issues but I got a few ideas to hopefully work around that issue, and now that I can get those ignitions fairly easily I'll take the risk. First thing I'll need to do with it is check the geometry and change out all the bearings for the good stuff. I'll also check, true, and balance the crank while I got it apart since it could just as easily be engine vibes that's killing the CDI units in these as well as the heat with not enough opening in the covers to let it escape out quick enough. My other thoughts here are that other magnetos might work better with the type of rotor this engine uses.... We'll soon find out.
I also saw that the same seller has the jugs with the straight intakes installed on them so I bought one of his to see if it has the bigger flat transfers, if so that'll be great, but if not, I got other sources for these jugs. The Super Rat bottom ends he sells also come with a piston installed so that'll take the initial guess work out of piston selection too.

I'm hoping I can get one of these to work reliably because these will make for a very clean looking install on future builds.
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  #7923  
Old 03-31-2015, 09:18 AM
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Default Re: what did you do to your motorized bicycle today?

I have looked at a few different heads there basically the same. There are a ton of the ignition boxes some work better than the others I really like the one I bought last its a no name one and it has better mid-high rpm range my brother made me one last month and it works great
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  #7924  
Old 03-31-2015, 09:28 AM
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Default Re: what did you do to your motorized bicycle today?

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Originally Posted by Davezilla View Post
I've been considering the jake's Diamond head for my next build too since it has the different combustion chamber design to see how that works out. Another one I'm keeping a close eye on is VMB's Shark head he's still designing and perfecting at the moment.
I just picked up a Super Rat bottom end from BGF Motors on ebay last night that I'll do my next build on. I know these have ignition issues but I got a few ideas to hopefully work around that issue, and now that I can get those ignitions fairly easily I'll take the risk. First thing I'll need to do with it is check the geometry and change out all the bearings for the good stuff. I'll also check, true, and balance the crank while I got it apart since it could just as easily be engine vibes that's killing the CDI units in these as well as the heat with not enough opening in the covers to let it escape out quick enough. My other thoughts here are that other magnetos might work better with the type of rotor this engine uses.... We'll soon find out.
I also saw that the same seller has the jugs with the straight intakes installed on them so I bought one of his to see if it has the bigger flat transfers, if so that'll be great, but if not, I got other sources for these jugs. The Super Rat bottom ends he sells also come with a piston installed so that'll take the initial guess work out of piston selection too.

I'm hoping I can get one of these to work reliably because these will make for a very clean looking install on future builds.
I think you'll like the design of the diamond head Dave, Im not gonna claim it to do a better job than the Fred head or similar, but a.016 gasket used on each one will cleary raise compressjon more if the Jakes diamond head is on that same engine because of how the squish band area will actually be down in the hole just a little, the lack of me considering this fact is how I ended up with a tight squish than I was aiming for on the newest "Taffy" build, I was looking for twice the squish that I ended up with, so Its possible that I will need add a thin base gasket to what I already have or make me a thicker head gasket or just make a thin one from some of the 8mil aluminum I have, Im concerned about not having but slightly over 1/4 of a mm squish clearance, compression is gonna be through the roof with that setup and may just be way to high, but of course I have to try it first to see how it acts.

Im a little concerned about continued gasket compression as the engine runs a while, I sure dont want it getting to the point that the piston starts to strike the head.


Ive looked at those SR engine BGF has listed, if the engine atually is a SR it will be 40mm stroke and use the low pin piston, best wishes on the build, Im looking forward to hearing about it and how well it runs.
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  #7925  
Old 03-31-2015, 09:37 AM
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Davezilla Davezilla is offline
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Default Re: what did you do to your motorized bicycle today?

So on the Diamond head the combustion chamber protrudes into the bore? that'll be nice since it can save time shaving the top of the jug down for sure. I'd use the copper gaskets from Juice to prevent gasket compression and get the squish clearance just above 1/4mm just to be sure the piston can't hit the head. the .016" thick gaskets he sells come out to about 0.4mm so by adding one of these at the base or at the head you'll end up with about a .65mm squish clearance which would put the compression ratio at a more reasonable level and prevent the piston from hitting after the engine warms up etc... As long as you keep the squish below 1mm you'll be in the acceptable range where it can still work to prevent detonation really well.

I know on my current running engine it has a 0.75mm squish clearance and the compression ratio came out to 12.7:1 so I run 93 octane premium and have no issues with detonation, of course, that's the static compression ratio and the actual is measured from the top of the exhaust port up making the effective compression ratio closer to around 8:1 or so.
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  #7926  
Old 03-31-2015, 12:25 PM
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bluegoatwoods bluegoatwoods is offline
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Default Re: what did you do to your motorized bicycle today?

Okay. Here's a better view of my handlebar choke adjuster.

I actually did not want to use that rather ugly greenish cable sheath. I've got plenty of black sheath on hand. But the green one was long enough for the job and I guess I didn't want to see it go to waste. Being a bit of a miser? I guess so.

But it also worked out well, in a way. In these pics there's now no doubt about which cable to pay attention to.
choke plus L bracket.JPG

A home-made L bracket fastened to the seat tube forms the cable stop. Then loop the cable over and run it along the top tube up to the twist shifter on the left hand grip.

cable run.JPG

I took her out this morning when it was about 50 deg F or so. That's not all that cold. But it's enough that the engine wants some choke. The results were very good. I was able to 'feather' the choke on and off with a good deal of accuracy.

No more 'too much' or 'too little'. Yay!

By the way, my pics 'zoom' quite well. You can get a close look at it.
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  #7927  
Old 03-31-2015, 12:50 PM
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bluegoatwoods bluegoatwoods is offline
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Default Re: what did you do to your motorized bicycle today?

Maybe I ought to add one word of caution:

You can not mount the cable out at the end of the choke lever. Out there where you find the little 'nubs' for your fingers.

The reason for this is that your shifter does not have enough 'throw' to get that choke fully closed. Or fully open, if you adjust things from the other end.

The cable must be mounted closer to the fulcrum. So this means that you need to fab up a little tab that you'll attach to the choke lever. Giving you a decent spot, closer to the axis to attach the cable.

But that's not hard. Mine only cost 25 cents.
quarter.jpg
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  #7928  
Old 03-31-2015, 05:13 PM
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mapbike mapbike is offline
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Default Re: what did you do to your motorized bicycle today?

Quote:
Originally Posted by Davezilla View Post
So on the Diamond head the combustion chamber protrudes into the bore? that'll be nice since it can save time shaving the top of the jug down for sure. I'd use the copper gaskets from Juice to prevent gasket compression and get the squish clearance just above 1/4mm just to be sure the piston can't hit the head. the .016" thick gaskets he sells come out to about 0.4mm so by adding one of these at the base or at the head you'll end up with about a .65mm squish clearance which would put the compression ratio at a more reasonable level and prevent the piston from hitting after the engine warms up etc... As long as you keep the squish below 1mm you'll be in the acceptable range where it can still work to prevent detonation really well.

I know on my current running engine it has a 0.75mm squish clearance and the compression ratio came out to 12.7:1 so I run 93 octane premium and have no issues with detonation, of course, that's the static compression ratio and the actual is measured from the top of the exhaust port up making the effective compression ratio closer to around 8:1 or so.
Yes with the right gasket that is thinner than a stock kit thickness gasket the outer edge of the squish band will be slightly down into the cylinder bore, the head gasket actually seats around the squish band rather than the edge of the combustion chamber sitting on the head gasket like it does with all the other stock and after market heads.

Not only could this increasing compression on an engine that hasn't had any deck material removed but its also going to help prevent blowing a head gasket possibly, of course if the head gets loose none of this will matter since it will leak no matter what, but the way Jake had them design this head it actually sorta interlocks with/in the cylinder bore when a thinner .016 etc... gasket is used, this also puts the combustion chamber perfectly centered over the bore since the outer edge of the combustion chamber closely fits inside the cylinder bore just slightly.

I'm using a stock thickness head gasket with mine since thats what i have on hand, i shaved the deck height for use with this thicker gasket, the next engine I build with the Jake head design will likely get a thinner gasket, next engine to get this head used on it will be one of my dax GT5 type engines.

I'm not trying to start a debate over which head is best or anything like that, and really this is kinda the wrong place to talk to much about it, but I do like the design of the Diamond head even though its big and tall compared to all the others, I am gonna go down to my local motorcycle shop and see if I can find a longer reach NGK plug for them, the E3 3.22 will work,but even as long as it is it could stand to be 1/8-3/16" longer reach to use all the threads in the head.

Once I find out which plug is the ideal length I'll post it in the correct location so others who may be interested in running one of these heads will know what plug they need to get for it.
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  #7929  
Old 03-31-2015, 11:00 PM
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Panhead Panhead is offline
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Default Re: what did you do to your motorized bicycle today?

After seeing a photo of another bike with a velocity stack I decided to try the unrestricted route with my own ride & pulled the outside cover & filter. Rather amazed at the difference just this small change made. In the cool, damp spring air that baby wanted to run!
I've just ordered an angled intake from another of the members here, a man named Brad, & will soon be looking to replace the Ruixing carburetor with something a bit less temperamental.
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  #7930  
Old 04-01-2015, 08:11 AM
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bluegoatwoods bluegoatwoods is offline
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Default Re: what did you do to your motorized bicycle today?

I had pretty much decided a week or so ago to convert my bike from multi-speed, derraileur type to single speed coaster brake type. Just for the simplicity of it. But since that means a fair amount of retro-fitting, I figured I'd wait until I had a good, solid few free days.

Then yesterday at about noon I walked on out to the bike, to run a short errand, and found a flat rear tire. So I figure I might as well go ahead and do the conversion if I have to pull that rear wheel anyway.

So it took me the rest of the afternoon to pull the rim brakes and clean up the cables and handlebars and install the new rear wheel. That wasn't really so bad. But I felt a bit crabby about it because I had other plans for the day. But...no big deal.

I got it all together as the supper hour was approaching. Took it out for a test run and toasted a wheel bearing. The one on the brake lever side of the wheel. That particular one seems to be a bit problematic; I've had trouble with those before.

So I replaced that bearing. I have one more as a backup. I'd better order some more. By that time the Sun had just about set.

So now it's morning and I'm waking up with a couple of cups of coffee. Then I go out and try to make sure that my bike is road-worthy. I've got a couple of hours before my work week starts. If I can't trust the bike, then it's a week of commuting by car. (Though I suppose my pedal bike could be ready without much trouble.) That's not the worst thing in the world. But I'd rather just have a working bike.

So wish me luck, eh?
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