Maniac Mechanic came out with a new head

[Ratchetbirds]

Just ordered my Gen II head the other night along with an adjustable magnet. I love the looks of the new head versus the old head and am sure that the fins will cool better than the stock head. Thicker fins and all. I found the price to be low in my estimation for the amount of time machining and the quality of what you get. Always remember, you get what you pay for. His gen I head was a very interesting design but I just didn't like the look of it. Fickle me. Beauty is in the eye of the beholder. Now as for the magnet and that guy who's buddy found his performance best set at the original keyway: Every one of these engines is loaded with tolerances to the positive and the negative side. What this means is that every engine is different in many aspects. 3 degrees of advance is what has been found to be the norm on stock engines, but this can vary by as much as 5 degrees in either direction. I would rather buy this magnet, experiment and find that my engine performs best at original keyway setting than to not know for sure that I have tried my best to get the best performance from it. Again, fickle me.

 

[impression]

Just a thought. I think the cooling fins should run parallel with the bike. As the bike is moving forward you want good airflow thru the fins to pull away heat. That head design looks cool but may not be the most affective for cooling. It may be more prone to warping.

actually the fin design is really good. go study up on some thermo/fluid dynamics

 

[Ratchetbirds]

Oh baby, I got my head 2 days ago and it is now on my engine. Very nice fit and finish. I have no complaints whatsoever. The only thing is, and this is NOT a complaint, is the sharp edges on the cooling fins were not taken down, or had the edge broken. It took me all of 10 minutes with some 100 grit emery to break the edges. No sweat at all. The fit was a truly machined fit. Nice and snug, no sloppiness. This Manic Mechanic guy takes pride in his work. I should be able to have my bike back together next week and I will give a report on how she performs.

 

[Ratchetbirds]

Okay, fired her up today and man she has some compression now. I have to pedal harder to get her started but well worth it. I run an Iridium 7 NGK plug and after I decked my cylinder by .0625 my piston tapped my plug a touch and closed the gap almost all the way. Added a copper washer under my plug for clearance and voila, runs like a champ. I should have checked my plug in the head before installing, but I was anxious and forgot to. I was lucky. Learn from my minor mistake here. Even if I had checked first I still would have decked the cylinder the same amount. I wanted the full benefit of the crompression increase. I HIGHLY recommend this head.

 

[mission moped service]

Okay, fired her up today and man she has some compression now. I have to pedal harder to get her started but well worth it. I run an Iridium 7 NGK plug and after I decked my cylinder by .0625 my piston tapped my plug a touch and closed the gap almost all the way. Added a copper washer under my plug for clearance and voila, runs like a champ. I should have checked my plug in the head before installing, but I was anxious and forgot to. I was lucky. Learn from my minor mistake here. Even if I had checked first I still would have decked the cylinder the same amount. I wanted the full benefit of the crompression increase. I HIGHLY recommend this head.

was the plug a NGK BPR7HIX?

 

[Ratchetbirds]

That is the plug I use. I love that plug and feel very lucky I didn't mess up my engine, or my plug.

 

[mission moped service]

That is the plug I use. I love that plug and feel very lucky I didn't mess up my engine, or my plug.

yeah i have a br6hix but correct me if im wrong but i think the bpr7hix is a bit longer than the br7hix

 

[impression]

The cooling fins on this new chinagirl head being perpendicular as opposed to parallel with the bicycle's length likely have no difference whatsoever in cooling performance.

incorrect.

 

[The_Aleman]

Nice response /sarcasm. No source? I'm ready to debate if you are, but it doesn't look like you have much to say.

Edit: also, you claimed the cooling fin design was just fine in a previous post. Have you changed your mind or just bumped your head?

incorrect.

 

[impression]

i'm saying the new head has a great fin design.

 

[Ratchetbirds]

Heya,

Found this chart on NGK's web site. Hard to navigate and find anything of value there until I found this. The "H" is the length designation and H = 1/2".

http://www.ngksparkplugs.com/docs/tech/design_symbols_plugs.pdf

 

[bandito]

The reason for fins is to increase surface area to dissapate the heat more efficiently. Airflow helps lawn mowers, weed eaters, generators by how much?

 

[riff44raff]

i dont want to jump in and change the subject but the quesgion is about the new head . the M M page said the piston crown has to be .160 and the deck hight .03 i think check it out well my raw motor has a .100 crown piston so the question is can I take a piston with a .160 crown and use it in my raw motor ? I guess the gt5 and pk80 motors have the .160 crown or does anyone know if this will work where I can buy a .160 crown piston ?or how about a pk80 motor ? thank you guys

 

[richirich]

i have a silver jet 66/80 motor from piston bikes that i put the mm head on ,it has the .160 piston. also the pistons they sell are the 1.60 pistons. i dont know if it wold work in your motor though

 

[riff44raff]

hay thank you for the info I e mailed the people at piston and a few other places and no responce probaly because they dont know so again thank you I think it will work if I use the M M head if it fits same dimanter did you have to sand down your cylinder ? on the M M page it shows that the deck hight is a certian size check it out but I guess the M M head is a fit for most motors I just got one that is not again thank you

 

[riff44raff]

I just had another idea would you happen to know the size in diamanter / bore of the piston with the .160 crown that piston bikes sales I was going to call or email them but ... they dont reply all the time again thank you

 

[richirich]

the cylinder is a 47mm bore. piston bikes does not seem to answer e-mails. you just need to call their 800 number. they are open from 11am to 7. i have always called between 11am to 12 and they have always answered the phone.
Good luck..

 

[riff44raff]

your the man you dont know what a pain it was just to get a litt info so thank you so very much Its people like you that make this form rock !!!

 

[richirich]

your welcome, ive leaerned alot on here and always try to help with anything i can.
RIDE ON>>>>

 

[Ratchetbirds]

After installing the head on my Grubee GT5, I feel that you can install it on your motor as is....you just won't have as much compression as you would with the .160 domed piston. I also followed MM's instructions for measuring my cylinder height. Turns out I needed to have .062 removed from my cyl so as to get the best possible compression. Any small machine shop can do this operation for you, as long as you know how much you want removed. I am not a machinist but I was able to do that job in well under 30 minutes, so the cost for this job should be minimal. When you are all done, no matter which way you go, be sure to double check your spark plug clearance. I had to add a copper washer under my plug or it would crash into the piston dome.