Where to order and what is the best high compression racing head to get? (66cc)

Astraeus

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anyone have a recommendation of a site i can order a good high compression head for my 66cc 2 stroke? i ordered the thunder shark pro racing kit but there was so many things wrong with the kit and the company refused to fix any of the issues so am here asking for some help when i finally got it all put together and warmed it up took it for a ride they i guess used the CNC by like 1/2 a mm to much on the threading for the spark plug i did not over tighten it but now it just pops out of the hole i am using JB-weld to hold it in there atm but really that breaks if i rev it up to high because of the compression in the engine... It has a high compression racing head on it now so i do not want to downgrade to a stndard head id like the same if not a better high compression head so please if anyone has any suggestions let me know
 
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GreasyChris

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you can install new threads into your cnc head by using a helicoil. you can get helicoils from most auto parts stores. essentially you drill out the old threads and retap the hole over sized and then thread the new helicoil threads into it. you now have your orignal size threads that are way stronger than the originals. helicoils come in all sizes so bring your plug with you. although i think its a m14
 

Astraeus

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you can install new threads into your cnc head by using a helicoil. you can get helicoils from most auto parts stores. essentially you drill out the old threads and retap the hole over sized and then thread the new helicoil threads into it. you now have your orignal size threads that are way stronger than the originals. helicoils come in all sizes so bring your plug with you. although i think its a m14
nice i did not know you could rethread and fix a whole that is to big this is good news im sure it will be cheaper than ordering a new head this 1 i havent even finnished the 1st tank of the break in period
 

GreasyChris

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yup if youre not confident in doing it yourself any automotive machine shop can do it. a helicoil kit isnt a cheap kit maybe 50 bucks or so and will come with a some inserts and an installing tool and sometimes the drill bit. sorry to hear you got screwed around on your purchase. motorizedbicycles,ca has good customer service if you need other parts in the future. and there in canada so no duty and all that extra cost
 

Astraeus

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a fred head is probably one of the best heads out there right now. can be found at crmachine.com
i just looked up some the fred head they have 5.5 6 7 and 7.5cc head sizes so i am guessing 5.5 is the highest compression or would i need a 6 on my engine i have the 66cc thunder shark pro racing 5.5 hp kit it is using the iridium spark plug the hottest 1 NGK - BPR6HIX 4085 PLUG
yup if youre not confident in doing it yourself any automotive machine shop can do it. a helicoil kit isnt a cheap kit maybe 50 bucks or so and will come with a some inserts and an installing tool and sometimes the drill bit. sorry to hear you got screwed around on your purchase. motorizedbicycles,ca has good customer service if you need other parts in the future. and there in canada so no duty and all that extrayea im in canada too vancouver area pretty much.... what would u do order the repair kit have a shop do it or just buy a new head?
 

GreasyChris

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i just looked up some the fred head they have 5.5 6 7 and 7.5cc head sizes so i am guessing 5.5 is the highest compression or would i need a 6 on my engine i have the 66cc thunder shark pro racing 5.5 hp kit it is using the iridium spark plug the hottest 1 NGK - BPR6HIX 4085 PLUG
yes 5,5 is the highest compression 5.5 is the volume of the cylinder head in cubic centimeters. you can measure the shark head buy putting the plug in and measuring how many ml of water it holds. 1ml=1cc
i use a ngk b6hs standard plug and a puch/tomos 70cc hi hi moped cylinder head on a heavily modified stroker crank engine.
im curious about the cc on that shark head they look really cool.
i hope you get it going i wanna hear how it goes.
i have 2 bikes, first one i made last winter is a 5 speed shifter bike, it does 85kmh and the second bike is also a shifter bike but just finished it a few weeks ago and havent ridden it yet but it should hit a 100 no problem
 

GreasyChris

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that head looks really cool. id try fixing it first. the kit i linked from princess auto is easy and straight forward to use. it drills and taps the hole at the same time for you. then pick the length of threads you need. and put it in. takes all of 5 minutes tops
 

Astraeus

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Sep 2, 2019
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use loctite on the insert so it doesnt back out
yea i called the store for money wise this i think is my best rout they have 7 in stock at the Langly store which is the closest one to me but yea now u can see why i wanted to fix it or find a cool looking good 1 to replace it with but for 26 bux for that kit cant really go wrong
 
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