Just got my Scrammy completly rebuilt from top tobottom. New rod kit,bearings,piston and rings and RCR porting. Broke it in real slow and today took it for it maiden voyge. Was running real good and stopped to take a beaverage break. Started it up and noticed no power at all. EGT jumped up to 12-13000 degrees in no time. Even running hot ideling.Never seized but turned my pipe blue. Took my time getting back to the truck and started playing. Changed jets both ways and still nothing. Took silencer off thinking clogged up still the same. Remixed the fuel and still the same. Changed plug and still nothing. Brought her home and checked compression and that was ok. Checked spark and its definantly there. Even put another battery on and still the same. Cannot start it at the house. It tries but it will backfire and the plug comes out all wet. Starting to think electrical. Maybe timing jumped. Got a polaris mechanic coming over with ohm meter to check stator. Any body have any ideas? If you do send em my way cause I go on vacation Tuesday to ride. Also put my original reeds back in and looked in the exhaust and intake port and the piston just looks normal.

thanks

 

sounds like a air leak, could be a crankseal, maybe not installed right.

 

The polaris mechanic around the corner came by and put the ohm meter on all electric stuff. All that checked good. Wouldn't it still start with a leaking crank seal. Never seen one try to backfire while starting with a leaking crank seal. He said my float was off and could have dumped a lot of fuel in crankcase. I took the drain off and some came out not much. Have the reed cage off now and blowing air in the crankcase. Will try again in a couple of hours. Still have counterbalancer fluid.

 

when EGT goes up you are lean. If the bike went hog ritch then the exaust temp goes down. was it smoking a lot with no power? how did it idle? turning pipe blue is sure saying it is running hot. EGT guage tells all. Out on the trail you were lean. now that it is home it sounds ritch. shut the gas off and let it dry out and start over. and watch the exaust guage. the stator may have moved or the flywheel nut wasn.t tight enough and the key is half sheered off. if you do get it running again spray all intake seams with some starting fluid to make sure you don't have a air leak. 1300 on the temp is to high.. gook luck

 

That has what has thrown me for a loop. When I was firsr riding it the EGT temp never even got hot. I rode this thing around the house for 2 days just breaking it in. I ride fir a hour this morning watching the EGT and then shut it off to take a break. The minute I started it back up I could tell something was wrong. I went up and down all sizes on the jets and still could not get the temp down and even played with the needle. Just had a polaris mech over and we put a ohm meter on everything and all electical stuff is OK. Also did another compression test and it is the same as it was day one. My float was off on the carb and he told me to take reed cage off and spin motor about every hour to see if the crankcase might be loaded up. I have rebuilt my own topend on all my motors and never had this problem. The flywheel is next if drying the motor out doesn,t help. Still cannot figure out why it backfires cause I just checked the spark and got bit again. At least at the riding spot it would run I have not even got it to start at home yet.

 

take this info for what it is worth..probably not much. But I had a 91 Honda TRX 250x-a four stroke. Ihad it bored .40 over...got it home would start...done about the same thing sounds like yours is doing. Pulled my hair out for weeks working on it. Come to find out, took it to a dealer mechanic, and the Valves were shot. It was blowing back in the carb.

 

Snoopy61,

It sounds like you seized it. That backfiring and the fact that it won't start is the indicator. You might have melted the piston, or got some aluminum deposits on the cylinder wall that jammed the rings open. BTDT (been there done that). The only way you'll know is to remove the cylinerd head on your machine.

Sorry I had to be the bearer of bad news.[img]i/expressions/face-icon-small-sad.gif[/img]

 

Just went through this with my 400 , when you took a compression
test what was your psi and is the gauge good .

 

It seemed low when I put it together. It only had 125 but when I did it again last night it still showed 125. Will not start this morning either. The gaude has only been used a couple of times.

 

maybe it blew a cylinder base gasket, have your mechanic friend perform a leak test on the motor, if you have a leak you will then find it. If it doesn't leak then pull it apart, you may have burnt the piston at the exhaust port and seized the rings but with that you would have very low compression. It should run with 125 psi. Also make sure the exhaust is not plugged and the throttle switch is functioning ok.