//ArrowChat Code
Results 1 to 3 of 3

Thread: rebuilt atc90 top end with new carb starting problems

  1. #1
    Join Date
    Jun 2021
    Location
    Mt Pleasant , NC
    --
    8

    rebuilt atc90 top end with new carb starting problems

    I have a 77 atc90 engine I just rebuilt the top end. Using a squirt bottle and 3' piece of hose to supply fuel. After 10 or so pulls it will start but runs rough and wont rev very good if at all. New piston rings gaskets hand lapped valves set timing points and valves on the bench. NEw carb from DRATC . Where should I start to correct problems. I cant trust my new harbour freight compression gauge. It shows 30psi on the atc90. It also shows 30psi on my ct90 that I rebuilt, 60 on my atc200m , and 70 on my new Honda grom. Do I need to relap the valves, checdck valves, timing points ....

  2. #2
    Join Date
    Apr 2014
    Location
    Edmond, KS
    --
    2,531
    Maybe you should start with another compression gauge that will let you know how much compression you really have.

  3. #3
    Join Date
    Jun 2021
    Location
    Mt Pleasant , NC
    --
    8
    I think I figured it out and not in a good way. I bought the bike on a pallet board after it had been sitting for 30 years. It has no plug in it so when I was ordering parts from dratv , I ordered a plug. I guess it was late at night and I carelessly didn’t click on the plug I needed. Anyway the plug was too long and hit the intake valve. I tore the engine back apart and put the plug in , said a few select words and ordered some valves and a new head gasket. It’s a wonder it ran at all with a bent valve. I will report back in a couple weeks
    Last edited by Little General; 07-18-2021 at 08:37 PM.

//ArrowChat Integreation Code //