atc 70 (power related)

[FTP Star]

i have an 84 atc 70 and was wondering if anyone has a atc 70 with the powroll oversized high compression pistion in it. i am debating on spending the 200.00 to get the cylinder bored and buy the piston and ring set. but i dont know if its worth it. also does anyone know if there is any other place to get pistons for the 70's? i've called quite a bit of places and nobody makes them, they all say to call a honda dealership. and my last question was does anyone know if a atc 110 head will bolt right up to the bottom end of a 70?

thanks,
Chris

[lilatv]

FTP Star

I have been wondering the same thing as yourself.

I have been wondering if the stroker kit and big bore kit are worth the effort as well?

This company offers stock pistons, big bore kits and stroker kits or at least the website says they do:

http://www.dratv.com/atc70honda.html

Good luck with your project

[smokinp]

a modified 70 will sell for less then a orginal 70(good pit bike though),I think that it would be pointless to mod one because you will never get enough power out of a 70 engine and if you switch engines then you still don't have any suspension so you would be better off keeping the 70 orginal and then selling it and using the money to get a bigger trike such as a 200x.a 200x would be a great trike because they have a great aftermarket for them and parts are easy to some by(83-85x)and can be easily modded out to be fast.just my .02

[smokinp]

try www.wiseco.com for the piston kit if you want one they might have one...

[lilatv]

Smokinp


I noticed you added a big bore kit to a scooter..did it make a noticable difference?

[KASEY]

how much do you want to spend??? there are several kool hop up kits for a 70,,,i have one for sale i also have a big valve rollerbearing cam head,,, ,,,,http://www.3wheeler.org/vb/attachment.php?s=&postid=105225 http://www.3wheeler.org/vb/attachment.php?s=&postid=105227

[lilatv]

All I see is red X's.


Could you try a different approach to posting those pictures? Thanks

[smokinp]

the big bore kit made a huge difference,but I sold the scooter.

[lilatv]

Any idea how much of an effect the 70 big bore kit has on the compression ratio, any idea what stock is? Thanks

[FTP Star]

the stock compresion on the 70 is 7.5 to 1 and the powroll bore kit bumps the compression up to 11 to 1.

also wiseco doesnt make pistons for an atc 70 somthing with the way the piston mounts to the crank, i think he said the pin was in a weird spot.

to the person who said i would be better off sellin it and buying somthin else what do you think i could get for the 70? it runs good and everything thing works its just a lil low on power for a 170 pound rider. sorry i keep tryin to post a pic of the bike but i cant get the file small enough.

im looking to spend at the most $200.00 or so. it just needs some more power. i figure if i cant get a lil more power cheap i might just sell it and buy a xr fiddy.

[lilatv]

FTP star

Click on "start", click on "my pictures" find the picture(s) that are too large, right click on it and then click on "open with" then click on "paint". When the picture comes up click on "image" then "stretch/skew" then it will say horizontal % then vertical %. Punch in something like 50% for each. Keep going until the picture appears small enough. If 50 or whatever you use is too much, you can click on "edit" then "undo" then it will take you back one step. Then click on "save as" punch in a new name that you will recognize as the new website friendly picture, and save as type should be jpeg.

I am 200lbs right now and use my 70 to cruise level ground and its a blast IMO, for what it is. I probably look silly but who cares, hell my wife likes it as well, we are enjoying (well I am more than her probably ) and that is all that matters. Don't get me wrong I would love to have a big red but its just not in my near future. The link I gave you in my first post, that company sells their stuff on ebay as well, cams, big bore kits, stroker, etc for the 70. Good luck with your three wheeler

[ATC 70]

Its cheaper to just go to your local motorcycle shop and ask for a atc 90 or 110 cylinder and the piston, pin and rings.Just act like you have a 90 or 110 dont tell them you have a 70.A head off a 110 will bolt up to your 70 motor but it may not clear the front tire.I put a piston and cylinder from a 90 on a 71 Z50 and I cant keep the front tire on the ground.You will have more than enough power for your 70.It may be not have as much power as a 90 or 110 bike if you use your stock carb. :beer

[lilatv]

ATC 70

I have a couple questions if you don't mind. About how much do the 110 cylinder/piston kit and 110 heads run? Do you reuse the 70 cam/rockers/valves or would a person need the 110 cam as well? Can you reuse the 70 head with the 110 piston/cylinder? Thanks

[ATC 70]

the heads might run about 200 you would nave to use 110 vavles cam and rockers because its bigger.If you could get a used head it would be cheaper.It would probably be cheaper to just buy a 110 cylinder then to get your 70 cylinder bored out.

[lilatv]

Do you mean get a 110 piston and bore the 70 cylinder?
So the 70 head can be reused if I went with a 110 piston without having to worry about any interference? What size valve does the 110 use and 70 use?

I did a quick search.

110 parts
complete head $148
rings $32
piston $35
retainer $11
cyclinder $281

*ouch*

I suppose the 70 cylinder head could be ported. Don't mean to drop all the questions on ya but you seem like a source of information and right now I am trying to soak up all the information I can. Thank you for your time

[ATC 70]

So maybe its cheaper to just get your cylinder bored out to 110cc's but your going to have to get a sleeve put in it.
You could just put on

.Your old cylinder bored out to 110 with steel sleeve
.110 rings
.110 piston and pin
.port your cylinder

That should give you enough power to pull a Geo metro.

[lilatv]

That sounds like a plan...or I will keep my eye out for a 110 piston and cylinder.

So were does the 110 piston put the cubic cm of the 70 engine. I am assuming the stroke is different so obvioulsy the cubic cm would be less?

So if stock is 7.5:1 compression will it run 11:1 on 92 octane?

[lilatv]

Well with a little looking I found the specs on a 110 atc and a 70 atc. Adding the 52 cc piston/cylinder would put the atc 70 at almost 90 cubic cm. I suppose that is where the big bore kits that I see everywhere originated, off the 110 parts shelf.

So how do these air cooled 4 strokes respond to a 11:1 compresson ratio? I know an automobile would require aluminum heads and / or some high octane fuel.

[FTP Star]

kasey what hop-ups do you have for the 70 and how much are you lookin to get for them?

[lilatv]

FTP Star

Hope you saw my other thread, seems some of the info given by ATC70 may have been inaccurate. later

[martyrsxblood]

hey lilaty i could sell you a 110 cylinder for way cheaper then 281 dollers how about it you just need to hone it or bore it (its about $ 60 to bore it)

[lilatv]

martyrsxblood


Well that would be part of the inaccurate information. The 110 cylinder will not bolt in place of the 70's, so that isn't a real option. I would need to replace the entire engine/tranny. Thanks for the offer though.

[FTP Star]

yea the 110 head wont bolt onto the 70 but i was wondering if anyone has a atc 70 cylinder head because a couple days ago i went to go change the plug and noticed the plug that was in there isnt the stock one it was a ngk type d6ha. i had found out my cousin stripped the threads out like 10 years ago so they just had new ones heala-coiled in. that plug is a b*tch to try and find. the closest i could find was a b8ha and its too hot of a plug to be run in the 70.

[lilatv]

I couldn't find a ngk locally for mine either...went with an autolite 4194, Might wanna try it, I have had no problems so far. If they used the heli-coil for the original plug threads it should work fine.

[FTP Star]

thats the problem though they didnt leave it the old size, they enlarged the spark plug hole thats why its got a different plug. anyone have a 70 cylinder head laying around they want to get rid of?

[lilatv]

I see.


The equivalent of a ngk d6ha would be:

autolite 4173
champion 888
denso 4078

cheaper than a head, good luck finding an atc70 cylinder head, if you find more than one and they are in good shape and priced right, feel free to let me know.

[Arlo]

How about just getting a complete 110 cc motor from lifan they are around 300 bucks and all your problems are solved. Just a thought.