Jetting and Temps

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exokinetic

New Member
Mar 18, 2016
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Lake Forest, CA
Tires, yeah, I know, I have some cheap slick ones that I am planning to use at Willow Springs, they are 26x2.10. When the ones I have on right now are bald I plan on getting Kevlar tires, at least for the back. I was going to get THIS ONE
I was worried about the chain hitting the tire with the 2.5" ones. I'm already using a BMX chain because the 415 was hitting the tire, also I found that the thinner BMX chain seemed to go through the engine sprocket smoother and with less drag. I got a really strong BMX chain with reinforced links and a breaking load of 12,500 Newton. I haven't had any twisting issues with it at all. But even with that chain, I've only got about a 1/2" clearance with the tire. The 2.10" tires on now have no trouble with the chain scuffing the tire.

Well I will have extra CST's at the track if you want to see if they will fit.

And if they don't fit, or you want to get something decent before the race, and also just for everyday use (I cringed when I opened the tire you linked, hehe) check out this Schwalbe Big Apple:



It's a Schwalbe, so you can trust the rubber compound, and it has a much better tread profile than the tire you were lookin' at, and its a Kevlar tire too. It comes in 26 x 2.15. It is a "touring" tire so it will last a good long time, and provide good puncture protection. It is used by a HUGE segment of the cycling community, so its what you might call a "known good". And it is not that much more expensive at around $40 with shipping.

http://www.ebay.com/itm/SCHWALBE-Big-Apple-RaceGuard-RLX-Wire-Bead-Bike-Bicycle-Tire-Black-26-x-2-15-/381604660573
 

Tyler6357

Well-Known Member
Mar 15, 2012
1,293
294
83
Santa Barbara, CA
Well I will have extra CST's at the track if you want to see if they will fit.

And if they don't fit, or you want to get something decent before the race, and also just for everyday use (I cringed when I opened the tire you linked, hehe) check out this Schwalbe Big Apple:



It's a Schwalbe, so you can trust the rubber compound, and it has a much better tread profile than the tire you were lookin' at, and its a Kevlar tire too. It comes in 26 x 2.15. It is a "touring" tire so it will last a good long time, and provide good puncture protection. It is used by a HUGE segment of the cycling community, so its what you might call a "known good". And it is not that much more expensive at around $40 with shipping.

http://www.ebay.com/itm/SCHWALBE-Big-Apple-RaceGuard-RLX-Wire-Bead-Bike-Bicycle-Tire-Black-26-x-2-15-/381604660573
Thanks for the link. That looks like what I should get. I would like to see if the 2.5" will fit before I buy them though. Stop by my motorhome at the race and say hi, it will be nice to meet you. My RV is a 34ft Class A Fleetwood Bounder, older model, ugly light brown color with faded stripes. I should be there as early as possible on Friday for the practice. I will need all the practice I can get, haha. Anyhow, thanks for all the great info!! You covered a lot of topics, are you a mechanic or something?
 

exokinetic

New Member
Mar 18, 2016
108
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Lake Forest, CA
I'm already using a BMX chain because the 415 was hitting the tire, also I found that the thinner BMX chain seemed to go through the engine sprocket smoother and with less drag. I got a really strong BMX chain with reinforced links and a breaking load of 12,500 Newton. I haven't had any twisting issues with it at all. But even with that chain, I've only got about a 1/2" clearance with the tire. The 2.10" tires on now have no trouble with the chain scuffing the tire.

I run standard KMC BMX Chains on my race bikes, and I have to agree they feel a lot smoother through the engine.

They are also LOT lighter than the the giant chains that come in the kit. This means less parasitic power loss going to spin the chain around, more power gets to the ground.

And I have never broken a BMX chain, running in heavily modified race engine builds at racing speeds reaching 50 MPH. But most stressful on the chain is the constant on-off-on of the torque through the corners.

So I say cheers, you are doing exactly what I would recommend with the chain.
 

Tyler6357

Well-Known Member
Mar 15, 2012
1,293
294
83
Santa Barbara, CA
It's good to know that you have never broken one under heavier loads, my chain is a Wippermann ConneX 1R8, It's nickle plated with straight side plates. It's a perfect chain for this application, although, I kinda lose that cool motorcycle look you get with the 415. However, after comparing it to the Wippermann, I would say that the 415 is bulky and drags.

So all I need is the Fred and good tires and maybe a shock fork (even a cheap one would probably make a difference) and this bike will be done. I know it's not a racing bike but it's the only bike I've got and it's super fun to ride it on the race track so what the heck, Willow Springs sounds like fun, I'll take the rear rack off and I'm there! Plus, I love checking out all the kick azz bikes, go peds, and go carts at the track.
 

Tyler6357

Well-Known Member
Mar 15, 2012
1,293
294
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Santa Barbara, CA
Update: I ordered my 6.0cc Fred Head yesterday. It was kinda expensive ($73.40 with shipping included) but I wanted the real thing and not a cheap imitation. I have not been informed that it has shipped yet. I don't know if I will get it in time for Willow Springs. I will update again when I get it.
 

exokinetic

New Member
Mar 18, 2016
108
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Lake Forest, CA
Sweet!

I'm sure you won't be dissapointed. I'll check back in when you get the head and give a write up on everything I do before installing a new head (surprisingly it involves more than just unbolting the old one and plopping on the new one).

Fred is a great guy, but he is a one man show, so a little patience goes a long way. I too like to support the original creators of these parts when I can and I don't mind spending a bit extra for it, it is almost always worth it.

I like the look of the Jake Head, but his shop is always closed when I need to buy them. I have been able to get 3, and would like to get more, but his shop is closed for the summer...so yea.
 

Tyler6357

Well-Known Member
Mar 15, 2012
1,293
294
83
Santa Barbara, CA
Okay, thanks! I can use all the help I can get. I will update this when it arrives and I can wait. I doubt I will get it before Willow springs but I don't care, I don't want to try to rush it on without getting everything right. I have heard of Jake's but I have never purchased anything from him, it looks like high quality stuff though. Paying extra is often times well worth it.
 

exokinetic

New Member
Mar 18, 2016
108
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Lake Forest, CA
Time to set the squish gap!


Okay, your going to need some soft leaded rosin or acid core solder:

Places to get your test solder

.050" Rosin Core Solder = Radio Shack PN # 64-006 E
.062" Rosin Core Solder = Radio Shack PN # 64-002 E
.093" Rosin Core Solder = NAPA Auto Parts PN # 777-1862
.125" Acid Core Solder = NAPA Auto Parts PN # 777-1857

You may have the right solder laying around, or at your local hardware store.


Basically you cut two small strips of solder about 1" long.

Give them a slight bend so they match the contour of the top of your piston.

Prep the engine so that the head is removed, the cylinder is installed, with the piston installed on the rod and the head gasket you intend to use in place.

Now:

Use some heavy grease and place the two bent 1" pieces of solder on the top of the piston.

Placement is important!

They must be directly in-line with the piston wrist pin, and they must sit on opposite sides of the piston, so that one end of the solder piece goes right to the edge of the cylinder.

Here is an example, I am using plasti-gauge I ordered that is designed for this, but the solder works great and is way easier to find. I also use 2 extra pieces to make a cross instead of just one line. This is not necessary, and solder can be difficult to crush with four pieces. So place your two pieces like these pictures, but only do one line, directly in-line with the piston wrist pin.






Once you have your solder in place, carefully rotate the crankshaft so that the piston is just below top dead center.

Assemble the head onto the engine.

Torque the head to the torque value you use (I use 120" Lbs.).

Use either a hex bolt threaded into the hole for the crank drive gear, or use a 14mm socket on two nuts locked together on the magneto shaft to rotate the crankshaft through top dead center, compressing the solder.

Remove the head, measure the thickness of the compressed solder at its smallest point (usually the edge closest to the edge of the cylinder).

This measurement is the SQUISH GAP.

If it measures over 0.060" then I highly recommend decking the cylinder (removing material from the top of the cylinder to make it shorter).

If you are going to go through the trouble of decking the cylinder, the squish gap you are aiming for is 0.025" 0.035".

If the gap is bigger than 0.060" you might as well not even have a squish band in the head, and you are not going to get the MAIN benefit of the Fred Head, the optimized squish band.


For our engine size and based on all the testing other members and I have done, keeping the squish gap between 0.025" and 0.035" will provide the most power from the squish band, while also providing the best longevity for the wrist pin bearing.


If after you have your measurement you decide you need to deck the cylinder, but have no idea how to go about doing it, I will walk you through a super low budget method I have used. All you need is a reasonabley flat surface, a piece of glass about 1' square or larger, and some varying grit sandpaper.


Let me know how it goes!
 

Tyler6357

Well-Known Member
Mar 15, 2012
1,293
294
83
Santa Barbara, CA
Okay, I understand what you are talking about, haha, I had to read that twice to fully understand what you mean but I think I got it and I'm certain I can do this, it should be easy to check it, I think I have the correct solder and something to measure with.

Thank you for the info. on this. I will let you know what my gap comes out to be.
 

Tyler6357

Well-Known Member
Mar 15, 2012
1,293
294
83
Santa Barbara, CA
Update: Okay, I tried to do this. I made 2, 1" long solder pieces. stuck them to the piston with grease as you showed me and then put the head on. It was a little hard to turn it to the top but I did it slowly with the rear wheel and got it to squish. The smallest portion between both pieces I could measure came out at .0625 but I'm not really sure, it was difficult to get consistent measurement along each piece. .0625 was the smallest measurement I got. I guess my gap is a little big.

I tried running it anyhow. I can't say I noticed much change in speed but I only ran it for a short time up a moderately steep hill to get it hot. I didn't change the jet (using .60) or the plug (NGK B8HS) and it started 4 stroking when I started it up as it usually does until it gets hot, then the 4 stroking went away. I can't say I noticed much difference as far as top speed or acceleration goes but remember that I was already maxing at 33-35 mph on flat ground with the stock head and my expansion chamber gives me lots of low end already. So I didn't notice anything much different from stock, I would say it was no worse and maybe slightly better. Maybe I will notice more after a longer ride. However it is clearly running much cooler! I got it hot enough for the 4 stroking to stop and the head at the base of the spark plug was 136 F. The stock head was at 350 F. Of course, it was late in the afternoon just as the sun was starting to go down so it was much cooler air and I didn't run it very long, but there is no doubt in my mind that I am much cooler with it than with the stock head. I don't know if I want to try decking the cylinder, it makes me a little nervous. Without a mill I'm a little worried I will screw it up and as I said before, I was already very happy with my speed and acceleration. I was wondering if I could try running it without the head gasket for a better squish gap, is that possible?
 
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exokinetic

New Member
Mar 18, 2016
108
4
0
Lake Forest, CA
Couldn't you just use a thinner gasket? I'm thinking about getting a Fred head myself.
Gaskets of varying thickness are not exactly growing on trees for this thing. Most are around 0.025".


The results you achieved are exactly as I would suspect.

The combustion chamber volume is similar to a stock head, so if you don't mill the head, your compression stays the same.

The gap at its narrowest point you reported was just over 0.060"

(the squish gap is tapered in the engines, as the curve of the squish band is a greater radius than the curve of the piston dome. So it will be narrowest at the edge of the cylinder, and progressively gets wider as it gets closer to the center of the head)

This means the squish band is having no effect at all.


So it makes perfect sense that performance has not changed, but it runs cooler.


The advantages of the squish band go alot farther than just improving performance:

It makes the combustion process much more efficient, giving you better fuel economy.

It keeps the combustion event contained in the center of the cylinder. When the squish gap is set properly, the gasses in-between the gap cannot be ignitied so they help cool the cylinder wall and the piston dome, improving piston and cylinder longevity, and helps to prevent piston siezure.

The dynamics of the squish event effectively "squishes" all the gasses into the center of the combustion chamber so they are closer to the spark plug, and can ignite more completely. Rouge patches of unburnt gasses in the cylinder that don't get ignited with the main charge lead to detonation. (Effectively, the rouge patch of gasses ignites late, and the expanding flame front it creates colides with the expanding flame front of the initial ignition event. This is known as "detonation" and is incredibly destructive to engine components)

And on top of all that, it's just free power, everywhere in the power band.


Trust me, you won't ruin your cylinder trying to deck it without accurate cutting tools.

I have done 4 cylinders with the piece of glass figure 8 method. One I removed 0.050" and it took a while, but it turned out great.

Basically:

Materials needed:

1x Flat Surface (reasonably flat table, work bench, concrete floor, etc.)

1x 12" by 12" Flat Piece of Glass (I used the top of a glass table, works awesome because it is so thick. Glass from a picture frame will work as long as it is not super thin)

Multiple Grits of Sandpaper:

120 grit
300/400 grit
600 grit
1200 grit

1x Brush (for sweeping the aluminum shaving off your piece of Sandpaper. As long as you keep the Sandpaper swept off with the brush it will cut surprising well, and won't gal. You run into a problem when aluminum shavings start getting balled up and embedded into the sandpaper, then they start galling -leaving deep gouges- the surface you are trying to sand. Sweep the shavings off the sandpaper before they build up and start getting stuck in the sandpaper)


Now that you have your materials:


Lay the glass onto the flat surface (duh).

If your piece is thick enough that it won't distort, put something rubber underneath it so it won't slide while your trying to sand on it.

If not, tape it down to the surface.


Next, tape the 120 grit sandpaper to the piece of glass to begin.

If you are confident in your ability to measure the small change in height you are going to make (@ 0.0625 your going to need to remove about 0.030" to achieve 0.032", right in the middle of the range) then you can make a few passes, and measure your progress.


If you are not confident in your ability to make this measurement, then you will need to make a few passes (say 10 passes) then re-do the solder crush test. Continue to do passes, and re-measure with the solder crush test until the desired measurement is achieved.


Here is how to do a "pass":

Place the head top down onto the sandpaper (duh)

Note witch part of the head is facing you (exhaust port, intake port, transfer port). I usually start with the exhaust or intake port as it is easier to remember than witch side transfer port.

Lets say you start with the exhaust port facing you.

Take the head in your hands and while maintaining even pressure sweep a figure 8 motion over the sandpaper.

Do a set number of figure 8's, and do that number every time.

I do 10 figure 8's.

Once you do 10 with the exhaust port facing you, rotate the head 90 degrees so one of the transfer ports is now facing you, and do another 10.

Rotate 90 degrees so now the intake port is facing you, do another 10 figure 8's.

Rotate 90 degrees so now the other transfer port is facing you, do another 10 figure 8's.

Rotate 90 degrees so now the exhaust port is facing you again.


YOU JUST DID 1 PASS!!!!!

YYYYAAAAAAYYYYYY


Now do 9 more passes and then measure your progress.

Repeat this process until you achieve your desired measurement.


Once you achieve your desired measurement do 1 pass each at 300/400 grit, 600 grit, then 1200 grit.

NOW YOU HAVE JUST DECKED YOUR CYLINDER!!!

WOOOOOOT!!!


The beauty of the figure 8's, while rotating the cylinder around a 360 as you do them helps to keep everything true, square, and flat.

It just takes a lot more time than a fly cutter on an end mill:



I have faith in you my friend!

If you have any questions let me know.
 

Tyler6357

Well-Known Member
Mar 15, 2012
1,293
294
83
Santa Barbara, CA
Okay, I have faith in me too, haha. I know I can do this and it's probably best for the engine and it's performance to do it, so I will. I think I have all of these things, I will have to check my supply of sandpaper to see what grits I have. I have a large piece of thick glass I can use. I can't thank you enough for spending the time to explain all this to me, it all makes perfect sense.

However, I was thinking that I might wait until after the Willow Springs Race to do this. It would be just like me to break a ring putting the cylinder back on and then needing to go through break in again or some other foolish thing. The race is this Saturday and I am planning on being there for Friday's practice. I'm going with a friend who is bringing his bike too. I don't want to mess up the trip with one big mistake, but rest assured, your knowledge will not go to waste on me, I am going to do this when I get back! Are you still going to the race?
 

exokinetic

New Member
Mar 18, 2016
108
4
0
Lake Forest, CA
Okay, I have faith in me too, haha. I know I can do this and it's probably best for the engine and it's performance to do it, so I will. I think I have all of these things, I will have to check my supply of sandpaper to see what grits I have. I have a large piece of thick glass I can use. I can't thank you enough for spending the time to explain all this to me, it all makes perfect sense.

However, I was thinking that I might wait until after the Willow Springs Race to do this. It would be just like me to break a ring putting the cylinder back on and then needing to go through break in again or some other foolish thing. The race is this Saturday and I am planning on being there for Friday's practice. I'm going with a friend who is bringing his bike too. I don't want to mess up the trip with one big mistake, but rest assured, your knowledge will not go to waste on me, I am going to do this when I get back! Are you still going to the race?

I completely agree with this line of reasoning!

Yea buddy, that's for sure!

I just finished putting a backup rear wheel in my dad's race bike. Destroyed the hub on a carbon race wheel doing some testing.... Balls.


See you there on Friday for sure!

White F-250 4x4, Shade cannopy with brown tarp walls will be us.

Bikes #124 and #154
 
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Tyler6357

Well-Known Member
Mar 15, 2012
1,293
294
83
Santa Barbara, CA
I completely agree with this line of reasoning!

Yea buddy, that's for sure!

I just finished putting a backup rear wheel in my dad's race bike. Destroyed the hub on a carbon race wheel doing some testing.... Balls.


See you there on Friday for sure!

White F-250 4x4, Shade cannopy with brown tarp walls will be us.

Bikes #124 and #154
Sweet! It will be nice to meet you! I will be in my 34' older model "Bounder" motorhome, ugly faded brown on the outside, comfy on the inside. We have to talk to Neil about getting race numbers...see you at the track!
brnot
 
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Tyler6357

Well-Known Member
Mar 15, 2012
1,293
294
83
Santa Barbara, CA
Update:
Okay, I finally got around to decking the cylinder. I ran 10 passes with 10 figure 8 patterns per side with the 120 grit sandpaper as described, I didn't push down or put any pressure on it at all, after which I rechecked the gap and it read .039". I then removed it again and ran 1 more pass on each of the 120/400/600/1500 grit sandpaper. I couldn't find any 1200 so I used 1500, meh.... Anyhow, put it all back together and went for a test ride. It did increase my top speed, by probably 3-5 mph, I only took a short test ride but I could feel a stronger top end, not much change on the low end though. But it was revving higher and louder and was running slightly hotter too with more vibration, so much that it kept resetting my speedometer so it was difficult to know exactly how fast I was going. I need to figure out how to keep that from happening. Anyhow, I'm considering jetting up to a .61 or .62 although it did 4 stroke until it got warmed up. Hmmmm, I wonder if I should try that? I might just need to adjust the carb settings to get it to go into low idle faster. I will run a longer test tomorrow on flat ground.

Thanks for your help with this!

brnot
 
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exokinetic

New Member
Mar 18, 2016
108
4
0
Lake Forest, CA
Glad to hear it went well for you!

The tuning process seems to never end ;)

If nothing else, it keeps you learning, and it can NEVER be a bad thing to know more about your bike.

To me, it sounds like jetting needs adjustment.


Play around with both directions on the main jet(I always recommend going rich first, and then leaning things out, it is the safest way).

Definitely try different clip positions.

And if you still can't get the throttle response dialed in to your liking, post back with some description of what you are experiencing, and what you have tried jetting wise, and I will try and help you out.
 

Tyler6357

Well-Known Member
Mar 15, 2012
1,293
294
83
Santa Barbara, CA
Glad to hear it went well for you!

The tuning process seems to never end ;)

If nothing else, it keeps you learning, and it can NEVER be a bad thing to know more about your bike.

To me, it sounds like jetting needs adjustment.


Play around with both directions on the main jet(I always recommend going rich first, and then leaning things out, it is the safest way).

Definitely try different clip positions.

And if you still can't get the throttle response dialed in to your liking, post back with some description of what you are experiencing, and what you have tried jetting wise, and I will try and help you out.
Well I'm using an RT carb, I had jetted it with a .65" but it was 4 stroking and missing so I went for the .60" and it seemed perfectly dialed in. Now, after decking it, it seems maybe a little lean. .60" is the smallest jet I have unless I drill one myself. But I'm thinking maybe a .61" or .62" might give me a little more cooling effect without the 4 stroking. Also, I think I have it set a little too far open, the RT doesn't use a clip, you just tighten or loosen the throttle cable to set it, it has a screw that holds the cable where screwing it out will open it up and screwing it in will bring down the idle. I'm sure I need to fine tune it. It should be no problem. I'll know more after a good ride!

brnot