//ArrowChat Code
Results 1 to 9 of 9

Thread: Need an opinion on TRX70

  1. #1
    Tomcall's Avatar
    Tomcall is offline At The Back Of The Pack Arm chair racerFirst time rider
    Join Date
    Nov 2010
    Location
    Arizona
    --
    215

    Need an opinion on TRX70

    I purchased a 1986 TRX 70. My first quad project. The engine came in pieces in a bucket. It's been a challenge finding out what I have and don't have as I go along. I decided to use an 88cc cylinder (new) I had for another project and a new head. I thought the new head was the upgraded racing head, but not so sure now. Attached are pics of the cam and cam gear. The gear center hole is clearly too small to install on the cam. I have a few used cams from my atc70 projects around and they don't fit either. Can anyone explain what I am dealing with here? Is this a stock cam or an upgraded cam needing a different cam gear?
    Thanks
    Attached Images Attached Images

  2. #2
    Toaster556's Avatar
    Toaster556 is offline At The Back Of The Pack Arm chair racerFirst time rider
    Join Date
    Dec 2010
    Location
    Fraiser Valley, BC, Canada
    --
    176
    That looks like a China "E22" head. They're made to work with a dished or flat top piston, rather than the healthy dome on the old Honda 70 motors, and run 23/20 valves. Most any pit bike shop would be able to get you a cam sprocket, and I might have a spare stashed in my tool box.
    Can you post some additional pictures of the head before I send you on a wild goose chase? If you pull the cam out the head can be positively ID'd

  3. #3
    Tomcall's Avatar
    Tomcall is offline At The Back Of The Pack Arm chair racerFirst time rider
    Join Date
    Nov 2010
    Location
    Arizona
    --
    215
    Toaster 556, I think you are on to something.
    Hmmmmmm, the piston for the 88c cylinder is not flat. I was thinking I purchased another racing head and I purchased the cylinder at a different time vs. getting the whole kit at one time. I think I may have purchased one of those China heads!! This may not work at all if it needs a flat piston. Meanwhile I thought I could swap out the China cam for an oem I have from other projects, but no way as you can see in this pic. I may be better off getting the racing head instead of fooling with this. Thoughts?
    Thanks
    Attached Images Attached Images

  4. #4
    Tomcall's Avatar
    Tomcall is offline At The Back Of The Pack Arm chair racerFirst time rider
    Join Date
    Nov 2010
    Location
    Arizona
    --
    215
    I took a pic of the head that came with the TRX70, on the right and the apparent Chinise head on the left. It appears that the original head has a different configuration where the valves are located. It looks like a deeper cut before the chamber where the valves are. Any thoughts as to how that would or wouldn't make a difference witht the normal upgraded 88cc cylinder kit?
    Thanks
    Attached Images Attached Images

  5. #5
    Toaster556's Avatar
    Toaster556 is offline At The Back Of The Pack Arm chair racerFirst time rider
    Join Date
    Dec 2010
    Location
    Fraiser Valley, BC, Canada
    --
    176
    Yup, thats a classic china E22 head. Most flow poorly, some 90-110 heads are actually clean on the ports. Those have the short 68mm cam and are mostly found on manual clutch pit bikes.
    With the E22 head and a standard piston made for an ATC88 kit, you may have head to piston contact at TDC. The 88 kit's dome is made to work with the larger chamber of the ATC head, rather than the shallow chamber of the newer heads. DR ATV has a good chart on what heads have what size chamber, but dont furnish volume numbers or any other dimension. Unless you can get an 88 cc flat top piston for the 6v crank, you may be SOL on that head. Dr ATV has a nice replacement piece that takes the early CT/SL/XL 70 valves and other stock components for $55, bare. Its a good flowing stock casting.

    This is what a good flowing E22 head looks like cut in half
    20150817_104800.jpg

  6. #6
    Tomcall's Avatar
    Tomcall is offline At The Back Of The Pack Arm chair racerFirst time rider
    Join Date
    Nov 2010
    Location
    Arizona
    --
    215
    Thanks Toaster556,
    I think I must have picked up this head on eBay and thought I was getting a good buy
    I'm tempted to just order the racing head from Spangler and be done with it, or clean up the original head that came with the quad and put new valves and springs in it.
    Anyway, thanks for clearing this up. I was getting myself more and more confused.

    By the way I picked up a 2nd 86 TRX70 over the weekend. I need another project like a hole in the head, but I manged to get it for $125. Needs fenders, front brake cables and probably a ring job with smoke it puts out. I guess that could be valves also. I know there is some way to figure out which it is, but I can't remember right now.
    Thanks again.

  7. #7
    Tomcall's Avatar
    Tomcall is offline At The Back Of The Pack Arm chair racerFirst time rider
    Join Date
    Nov 2010
    Location
    Arizona
    --
    215
    Just an update: I ended up buying a racing head from Spangler A little pricey, but I know it will work nicely.
    I don't think I will take on any future projects when it comes with the engine all in parts in a bucket.

  8. #8
    Join Date
    Mar 2007
    Location
    Texas
    --
    5,046
    Tboltusa.com has a ton of parts. Including cam gears to fit that performance cam.
    The chain needs to be checked too to ensure it is the correct one as well. Talk to Vince at Tbolt and he will help ya.


    Sent from my iPhone using Tapatalk
    ________________
    I'm just a squirrel "Trying" to get a nut!

    Nearly every kind of Honda ATC (plus some custom ones
    several Yami Quads (mostly custom built for MX racing)

    https://www.mikesatvfix.com

    "Freedom is not free...but the U.S. Marine Corps will pay most of your share."

  9. #9
    Tomcall's Avatar
    Tomcall is offline At The Back Of The Pack Arm chair racerFirst time rider
    Join Date
    Nov 2010
    Location
    Arizona
    --
    215
    Thanks for the info.

//ArrowChat Integreation Code //