just ordered a Fred head. questions before install.

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slayer60973

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Dec 24, 2012
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West Michigan
So I ordered a 6cc Fred head. It's there anything I should know before installing it? My engine is a dax gen 4 "balanced" it's mostly stock with a arrow torquer 2 exhaust speed carb and Stock cdi. Do I need to upgrade the cdi for the higher compression or will a iridium plug suffice? Im unemployed for now and have been making some money fixing small engines. Cheaper is better! :)
 
mapbike

mapbike

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Mar 14, 2010
5,502
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Central Area of Texas
Bolt it on and go, If you haven't done any jug shaving you will have plenty of clearance and you just need to put the head on, torque it down right and run it like you always have and you'll be good to go.

Map
.wee.
 
Tyler6357

Tyler6357

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Mar 15, 2012
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Santa Barbara, CA
Please update this thread after you have run it awhile and tell us what you think of this upgrade. I'm interested to know what perfomance increases you noticed.....thank you
 
mapbike

mapbike

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Mar 14, 2010
5,502
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Central Area of Texas
The Fred heada are nice looking and it only makes sense that the engine will cool better but on most engine I dont think there will be some huge performance increase as far as power and speed are concerned unless the engine is running low compression and then the Fred head or Any other head that increases compression will help with torque and midrange power and possible a couple of MPH if everything else with engine is good like well tuned and a good flowing exhaust, I have a Fred head on one of my engines and I like the way it looks, very nice work.... had thought ai noticed an increase in power until I changed the exhaust back to how it was before and performance had not actually changed in a noticeable way, however it is a great looking head and there isn't anything at all wrong with running one for sure, its a nice addition to other upgrades and may actually add some performance if everything else with engine set up is right.

Fred does great work for sure and has added several new gadgets to our hobby, it's great to put some nice and neat external upgrades on the china girl enines but if the porting isn't clean, if the rotating assembly doesn't have fairly good high rpm balance and the carb isnt tuned properly and the exhaust isn't able to flow good.... changing the head isn't gonna do much for prtformance.

I've found that the biggest gains are seen with clean ports, port timing altared a little, a well tuned carb, and an exhaust that flows good enough not to restrict the upper rpms.

I just built a new engine up two days ago with everything done to it I just described and it is running for now the stock type slant head with a few 0.001" shaved off of it and I posted 45.8 MPH on a GPS yesterday with that engine and it having less than 10 miles on it, it will get a different head strictly for cooling purposessince I ride long high rpm rides between my home and town which is several miles, but I honestly dont expect any noticeable performance gains just better cooling for my long rides.

Map
dnut
 
SuperDave

SuperDave

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Sep 24, 2011
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Theon nailed it, check your squish clearance with wire solder & calipers or a micrometer. Torque your head to 120 inch pounds first(10 foot pounds). Bend the solder into an "L" shape & insert it into the cylinder through the spark plug hole, turn the engine over by hand (might need a wrench or socket on the magnet rotor bolt) until the engine turns over once. You want to squeeze the solder between the squish ring of the head & piston, it may not want to but this is cruicial to determine if you have sufficient clearance. Ideally you want .016" (according to Gordon Jenning's 2 Stroke Tuner's Handbook), but Fred of CR Machine says .010 to .040" is fine. The tighter it is, the more compression it will make, and more power. Less than .010 will result in piston/head collision from heat expansion & we don't want that. If its too tigh,t more gaskets may be needed, either an extra head or jug gasket. If its too loose, hand lap the jug and/or the head.

A Jaguar or Lightning CDI is a good idea, they have better ignition timing curves than stock. Upgrade the spark plug with a NGK, plug wire too if you can. I use an old MSD 8mm plug wire recycled from a tune up I gave my Chevy, definitely improved the starting & ride smoothness. You may find the increased compression a bit harder to grab the clutch, so an adjustment to the internal spring & flower nut may be required. When I upgraded my head to a Puch HiHi head, I went from a NGK BP6HS to a cooler BP7HS plug. I also installed a rocket key under the magnet rotor to retard the timing, made it run smoother & reduced my vibrations a lot. I would upgrade my CDI if I could, but my Super Rat uses a 1 piece magneto, so I have to use old school tricks to tweek my timing.

Other upgrades you might consider are shaving your piston & porting the jug, the only cost is gaskets and an investment on a Dremil. Do your research first, if you remove too much material you can't put it back & you end up with an expensive paperweight.

The best upgrade you can do is knowledge. Here's a link to free downloads of Gordon Jenning's 2stroke Tuner & Graham Bell's Performance Tuning.
http://www.scootershack.co.uk/threa...handbook-by-gordon-jennings-pdf-manual.25450/
 
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slayer60973

New Member
Dec 24, 2012
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West Michigan
SuperDave said:
Theon nailed it, check your squish clearance with wire solder & calipers or a micrometer. Torque your head to 120 inch pounds first(10 foot pounds). Bend the solder into an "L" shape & insert it into the cylinder through the spark plug hole, turn the engine over by hand (might need a wrench or socket on the magnet rotor bolt) until the engine turns over once. You want to squeeze the solder between the squish ring of the head & piston, it may not want to but this is cruicial to determine if you have sufficient clearance. Ideally you want .016" (according to Gordon Jenning's 2 Stroke Tuner's Handbook), but Fred of CR Machine says .010 to .040" is fine. The tighter it is, the more compression it will make, and more power. Less than .010 will result in piston/head collision from heat expansion & we don't want that. If its too tigh,t more gaskets may be needed, either an extra head or jug gasket. If its too loose, hand lap the jug and/or the head.

A Jaguar or Lightning CDI is a good idea, they have better ignition timing curves than stock. Upgrade the spark plug with a NGK, plug wire too if you can. I use an old MSD 8mm plug wire recycled from a tune up I gave my Chevy, definitely improved the starting & ride smoothness. You may find the increased compression a bit harder to grab the clutch, so an adjustment to the internal spring & flower nut may be required. When I upgraded my head to a Puch HiHi head, I went from a NGK BP6HS to a cooler BP7HS plug. I also installed a rocket key under the magnet rotor to retard the timing, made it run smoother & reduced my vibrations a lot. I would upgrade my CDI if I could, but my Super Rat uses a 1 piece magneto, so I have to use old school tricks to tweek my timing.

Other upgrades you might consider are shaving your piston & porting the jug, the only cost is gaskets and an investment on a Dremil. Do your research first, if you remove too much material you can't put it back & you end up with an expensive paperweight.

The best upgrade you can do is knowledge. Here's a link to free downloads of Gordon Jenning's 2stroke Tuner & Graham Bell's Performance Tuning.
http://www.scootershack.co.uk/threa...handbook-by-gordon-jennings-pdf-manual.25450/
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I have smoothed the transfer ports to the best of my ability, a flat head screwdriver and light tapping with a hammer. Kinda chiseled the rough casting edges. They are no where near perfect but its better than stock, my head is supposed to be here tomorrow, I'll ride up to the junkyard that's amile away and get a non resistor plug wire. Took the black paint off the jug with brake cleaner. Looks cool with a black low end and silver jug. I have to save up to get a dremel. Then I cleaned all the carbon off the piston. Oiled up the piston and jug and reassembled. Can't wait to rip up the dirt road tomorrow
 
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slayer60973

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Dec 24, 2012
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West Michigan
Alright, I received the head today. I put it on and snapped a head stud. Great.... but wait I have an extra engine laying around. Success! The bolt was just barley sticking out puff the case but I managed to twist it out with pliers. Thank God. Put the new used stud in and reassembled everything.Put the head back on making sure not to over torque It this time. Put the carb and exhaust on and started her up. Runs good but bogs down at full throttle. Lots of smoke out of the exhaust. Just bought a new spark plug.letting the engine cool off.Then I'll do a plug chop
 
Tyler6357

Tyler6357

Well-Known Member
Mar 15, 2012
1,293
294
83
Santa Barbara, CA
Map: Oh, I didn't expect huge increases in speed or anything. But if it runs the engine cooler or makes a better sealed combustion chamber than it is increasing the performance of the engine. That's all I meant, I mean, can you notice the engine running slightly cooler? Does the engine cool down faster after shut off? Does it just run better?? Less chance developing air leaks?
 
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slayer60973

New Member
Dec 24, 2012
96
0
0
West Michigan
Tyler6357 said:
Map: Oh, I didn't expect huge increases in speed or anything. But if it runs the engine cooler or makes a better sealed combustion chamber than it is increasing the performance of the engine. That's all I meant, I mean, can you notice the engine running slightly cooler? Does the engine cool down faster after shut off? Does it just run better?? Less chance developing air leaks?
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I always warm up my engine before I ride. The cylinder gets hot way before the head even gets warm. And that's sitting still with no airflow. I still have to tune the carb a little so I don't know about performance gains just yet. It does run a lot smoother after stealing a NON SUPPRESSIVE (no resistor) spark plug wire off a JEEP at the junkyard a mile away. He said I could have it for free lol. Much better throttle response. It definitely runs cooler. That's a given. This head is HUGE
 
mapbike

mapbike

Well-Known Member
Mar 14, 2010
5,502
109
63
Central Area of Texas
Tyler6357 said:
Map: Oh, I didn't expect huge increases in speed or anything. But if it runs the engine cooler or makes a better sealed combustion chamber than it is increasing the performance of the engine. That's all I meant, I mean, can you notice the engine running slightly cooler? Does the engine cool down faster after shut off? Does it just run better?? Less chance developing air leaks?
Click to expand...
I agree with all you said here, if the engine is running cooler it is gonna perform better as far as less chance of seal failure, less chance of preignition issues and by running cooler odds are the engine will last longer.

I run a Fred Head on one bike a Puch Head on two other bikes and a stock head on my oldest engine that none of the after market or Puch heads will work on because the bolt pettern is different.

I just replaced the stock head on my newest dax build because I kept blowing the head gasket, may have been the gasket more than anything because they were very thin gaskets, I have one of the thin gaskets on now along with the Puch hi hi 70cc head and so far so good, the engine runs better with the Puch head also, picked up 1 mph top speed and toque increase is noticeable on the hills I ride up around here, the china girl engine run good and for a long time with the atock heads but I like the look and extra cooling of the Puch heads, the Fred heads, the Fred heads are actually designed to give the best performance on the china girl engines when the squish is set correctly between 0.025-0.040, I dont go to the tdouble of even checking for squish clearance and Im sure Im loosing some performance because of it but I dont get that serious about performance tuning on my engines, I concentrate mainly on a wel tuned carb, a good flowing exhaust that gives me good torque and still allows my engine to breathe good for a good top speed, and lately I've done some piston mods that has helped with the overall balance of the engine at medium and high rpms, at some point I may dive into working to get the squish where it has been recommended to be and just see what difference it makes.

Map
.wee.
 
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