142 f build

Discussion in '4-Stroke Engines' started by Narkillpunx, Aug 12, 2016.

  1. Narkillpunx

    Narkillpunx New Member

    So I recently purchased a new motor from gas bike. It ran well at first but now it seem to be staving for something at high rpms. Me and my buddy did a compression it test and we only got like 30 pi originaly thought that maybe it was a fuel problem cleaned the gastank ect. At that point o had the oringal carb in stalled and it would not run at half choke poorly no power at night rpms. So I put a nt carb manifold on it and a not carb. Mind you even with the stock carb it ran rich. So no matter what needle setting its on with the not carb it runs rich the plug is super black powdery. Same with exhaust pipe and port. Iam stumped its brand new. What's weird is it only started doing this after it sat for a week. Any ideas?
     

  2. Frankfort MB's

    Frankfort MB's Well-Known Member

    If your only getting 30psi that's your problem. These motors should have 130ish psi
     
  3. Narkillpunx

    Narkillpunx New Member

    New rings?
     
  4. Narkillpunx

    Narkillpunx New Member

    I wonder if they will replace it.
     
  5. Narkillpunx

    Narkillpunx New Member

    When we did it we didn't hold the throttle open could that have been it?
     
  6. Frankfort MB's

    Frankfort MB's Well-Known Member

    Oh I'm sorry I was thinking about a 2 stroke:)

    You'll have to check with others for the exact psi for a 4 stroke
     
  7. Jcs1989

    Jcs1989 New Member

    I'm not sure on the psi of the engine compression. I have this same kit. I've run only 93 octane in it since new. Never had to adjust anything or change anything. I've got 200+ plus miles an have had it on two frames. Check your fuel lines an make sure you have a good free flowing fuel filter. I have all my fuel lines zip tied tight. Make sure your petcock is turned to the on position. Then set the chock on pull a few times to get fuel in the carb. An then turn the chock off. An give it a little throttle when pulling the start. An it should run good. Maybe even try 93 octane.. note I have the stock carb an haven't touched it since out of the box.
     
  8. hazmat

    hazmat New Member

    not sure but would check the valve clearance
     
  9. Narkillpunx

    Narkillpunx New Member

    Yeah I fixed it. I had a older engine laying around.from older build .actually I bought it for100 bucks the whole set up. Poorly maintained other the regular oil changes . He used it for work it ran everyday for 3 years. About 2 hour s a day. Ran good. One exhaust valve bolt hole was stripped. He rode through snow in winter time and once because of the load broke the timing gear. Well while attempting to remove the flywheel magneto . Broke one fin and put two holes in crank case. Well while waiting for the new case. He KB welded the holes. They held and still hold. lol so he sent the new case back. That was about half way into the 3 years of life. Anywho I had that motor for about 3 months ran good just had annoying exhaust leak. One day it just died . I had ordered the mag aluminum wheels from had bike and decided I loved the bike so much that I ordered a back up motor. Walmart frame 4 years old. Now I rode the thing everyday all the way across Philly and I mean all the way .from West Philly to northeast Philly. It lasted like I said 3 months like that the tranmission . ( Hoot dual chain from bike berry) couldn't handle it. Broke two bells and one chain. One day it just died. Timing gear fine carb fine. Just wouldn't start.i stuck a bore scope in it and the cylinder had considerably bad wear. So Iam rebuilding it. Anyway I bought a new mount exhaust and bikeberry dual chain transmission . Didn't know about belt drives and because the one he had lasted him so long I thought they were perfect. So I installed new engine and everything else. The tranmission had a warped shaft so I retuned it for replacment . Up until it was stock ran great. During my wait I installed a Nt carb and NGK plug. Ran awesome forabout two hour then it started the bog thing. Thought it was fuel problem. Changed back to stock carb still same symptom . Installed Stoke everthing still bad. So I finally read a thread about a dude who bought two new motor s and had similar issues. apparently the newer motors have a different could and magneto flywheel. I tried just changing the coil with the one off the older motor. It ran but had no power. Then I did a compression check it was about 30 psi dry then 35 wet. Mind you it was a harbor freight gauge.anywho installed bothers the old flywheel and coil and haven't had a problem since. But I had using old part in new stuff so iam gonna order the old style stuff soon. But runs great . Also another thing that helped me diagnose this was that there was alot of carbon on the plug no matter how leabn I made the mixture it almost looked like it was running extremely rich . The because was all funked up. Well that will happen if your spark isn't strong enough to burn the fuel completely. Hope this helps someone. Because this was a nighmare to figure out. It had all the stones of a fuel problem. And because it was all new . I didn't wanna believe the coil burnt out so fast. The new coils are way different they are bigger the old style. But for whatever reason they won't work with the old style magneto vise versa.
     
  10. hazmat

    hazmat New Member

    sweet i think those double chain trany is suppose to last longer than 2 or 3 months i would contact bikeberry for a replacement i belive warranty is 6 months
     
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