hello all just bought a gas gas pro in bits for £500 quid built it back up put new piston and rings in new gaskets kicked it up it started 2nd kick with choke knocked choke off put it in gear sets off but soon as you put it under load its like it choking its self

I put another a new plug in run abit better but still missing abit

can someone help me out

Jason

congratulations for one of the longest sentences ive seen recently

First thing in diagnosis is... When / what went wrong when it was last working correctly (before you got it?)

If this is reason is unconnected, it sounds very much like the following potential issues:-

• A carb problem, needing a thorough clean?
  
• Incorrect float height?
  
• Incorrect carb needle clip setting?
  
• Choke not fully turning off?
  
• Wrong petrol / oil mix ratio?
  
• Exhaust bunged up?
  
• Clutch side crank seal gone?
  
• Poor compression?
  
• Coolant leaking into the combustion chamber? (Cyl head o-rings?)
  

Just a starter for 10.... first thing though is to find out why it was in bits in the first place.

Dom

The kid i got it off said he was riding it and it lost power it kept juddering when riding so i have replaced the piston and rings put new cylinder o ring seals on new base gasket and put it back togethher thats it

If you post a picture of the old piston it might give some info.

Looks to me like it's picked up or seized at some point. Did you check the barrel for damage ?

Jason

The fact that the piston has seize streaks in multiple radial positions tends to indicate that it is or is similar to a "4 corner seizure". Also two other symptoms also point at this. The ring land has melted / broken up in one place, and the piston crown has a grey/white colour.. this also points at the same issue.

A multi point seizure is normally a sign of overheating of the piston which has caused the piston to expand more or faster than the barrel that surrounds it.

This is usually caused by one of the following:-

• Over advanced ignition timing.
  
• Lack of engine cooling
  
• Blocked or restricted exhaust
  
• Overly lean jetting
  
• Extreme load placed on the engine from cold.
  

So, I would check out these failure modes. Notice that some of these causes are similar to potential issues already identified before we knew this detail. I would check these first, especially the ignition timing, jetting of the carb (vs. standard) and blocked exhaust.

Hope this helps

Dom

Edited May 22, 201313 yr by dombush

hello all the barrel did have marks on it and a little score of the nickel plating b and b road and trails local bike shop told me to get some henry cloth and sand it out and id get away with it.

i started the bike up yesterday and took it up garden path when you rev it its not letting enough gasses out of the exhaust and spitting white stuff out of the exhaust does this help anymore i dont wanna be throwing loads of money at it as im out of work at the minute

someone suggested that it may be the crank seals that have gone the fan is kicking in when riding the bike

how do i unblock the exhaust

Jason

the most likely cause of a blocked exhaust is something blocking the bore of the silencer section.

I don't want to jump at shadows but I would make sure that the silencer "mesh" hasn't collapsed and is blocking the gas path.

This would cause increased back pressure, poor scavenging and therefore overheating of the piston,

If your bike is a Pro model you need to remove the M6 bolt and 2 M5 screws that connect the silencer to the "centre" section.

You can then look up the bore of the silencer and although its slightly kinked you should see daylight if all is well.

Dom

P.S. re cost of repairs..nothing discussed so far involves anything but your time to investigate.

right peeps been into garage today and the bikes been leant at side of bench there is coolant all under the bike

its not leaking from any of hoses or from radiator can anyone help what would i get for as it is

Coolant Leak.

The cooling systems on Gassers are pretty simple. Radiator, cap, hoses, hose nipples, water pump, thermoswitch and head o-rings are all there are to leak. If the leak is not visually dripping, you can use paper to help find it. You can use newsprint, paper towels or even toilet tissue. Refill the system with water, dry off any spillage, then push the edges of the paper against any place that might be leaking. A little water will be very visible as the paper soaks in the water.

White exhaust smoke

Is the white stuff smoke or steam? Steam will disappear quickly while smoke will hang around longer. If you use anti-freeze in your radiator and it is steam, you will smell a very sweet odor. 99% chance that would be from bad o-rings under the head.

If it looks and smells like 2 stroke oil burning, it is most likely a plugged exhaust baffle or spark arrestor. Those are usually located on or in the end of the exhaust system. This will cause smoking and choking of the engine. Remove and clean the screen.

Good luck. Let us know how you get on.

cant suggest where its coming from the coolant it looks like it from bottom of engine is there a specific order the hoses go on and the o rings are brand new on cylinder head

checked coolant level it hasnt dropped no leaks as of yet took the exhaust off and its blocked i cant see daylight through it so how do i go about unblocking the exhaust