My 2000 scrammy is letting me down can someone help me find this problem. It is very rich on the bottom but not on top(maybe lean). i have a digatron gauge and it tells me that it reaches 1250 degrees( i know its high).The quad runs great in the middle but when i increase speed from 1/2 throttle to full it poops out, it starts poping and breaking up. Just like if your gap on your spark plug was open too much and the spark was being blowen out.or if your plug cap was loose,or even to rich. Heres the kicker--- the plug is black(too rich?) the egt is reading 1250(too lean?) the carb is clean but 3 years old. the reeds are new, the rings are 5 hours old. it run great from the bottom to mid just like it should but when it climbs to top that is where it is wrong. has anyone of you had this happen. I have a new coil to put in and i'll try that. Could It be that maybe my flywheel spun Agian( but this never happend). or could my timing plate have turned? could the pick up coil be going bad? WHO KNOWS But At least I have My Pred. I still need to fix it for my friend who has been using it while his cRaptor is getting fixed AGAIN?

Thanks
Matt Spears
Team Bricktucky

 

Needs more air first. 1250 is OK. 1300-1350 is max 6" from exhaust bolt up at engine.
Running right fuel for compression?
Water in fuel? Drain some into a glass jar and look for water.
Plug gap. bad plug.
fuel filter plugged up?
the list goes on
Try these first! Good Luck

 

You could be rich on the pilot and needle jet and lean on the main jet. Toss a new plug in it and ride in the low to part throttle range, no WOT, and check your plug. If it's black you're going to need to work on those circuits. You can then do plug chop for the top end. There's a lot of info on the how to tune a carb do a plug chop. Sudco has a great tuning manual as well. Always start with the pilot and work your way up. Each circuit contributes to some degree on the top side, and the reason you need to start from the bottom. Your description on the main sounds like a lean condition. You didn't say what carb you were using, but I'd go up a couple of sizes on the main jet, just to be safe. If it's surging after that, don't stay on the gas. Go up another size or two on the main jet until the surging is no longer present. It would seem that HPD should be able to give you some jetting recommendations.

 

Yeah,which carb are you running ?

 

i had one that sounded the same get a load on it and it poped and sputtered turn out to be a bad plug and it looked good so i did not think it was that

 

Go more by the plug color than the EGT reading. I used to worship EGT....use it to augment your testing, not as a base.

Are you running ES8 plugs?

Do you have the mod sparkplug wire end?

Changed your fuel filter lately? LH side of tank just under plastic.

 

It really sounds like you are lean at WOT. The plug could be black from idle to half. You need a fresh plug to check WOT plug color. Go up on the main until the breakup stops then go 1/2- 1 size bigger just to be safe. Better to be a little rich then a little lean.

 

thank you everyone, Heres a update and some of the things that are on the quad.
The scrammy has almost 200 psi of compression, I'm running a pwk 39mm carb with a 35 pilot jet and a 178 main with a dail-a-jet in the richest spot.(No change in having the dail a jet or not) . I used a spark tester and it seem fine too, very constaint spark. I,m starting to believe that mybe it is just rich on the bottom and lean on top or that something is wrong with the carb.

Has anyone ever had this HPD race kit with the 15:1 head run out of gas on the top end?
I just bought a fuel pump to see if that may fix the problem.
Are anyone of you running a smaller pilot jet with a bigger main and could the needle jet be a factor even if the problem is at WOT

Heres what i,ve see so far----I cleaned out the stator cover and cleaned the mags and coils
I did find a wire that broke off causing me to have no lights or any 12volt to work other than the cdi/spark,although i have a simpleflied wiring harness.
No dirt in the carb,200psi,good spark pug,cap and overall spark
THE PROBLEM IS ONLY AT WOT IN GEAR BUT,NOT IN NEUTRAL WITH WOT!!!
Who Knows Flooding, carb maybe?This thing goes though gas very fast!!
HELP
Any Ideas Now?

Thank you much
Matt
Team Bricktucky

 

not sure if this will help but check this info search for "ATTN" 39 pwk owners by x_scrambler3

 

You shouldnt need a pump for this carb to perform right.Make sure you dont have the brass pin in the bowl,if you have it pull it out.This carb will pass alot of fuel thru it,it's normal.The 35 is the smallest pilot for this carb , i believe.Also what needle do you have ,you should have an EEG needl.The newer carbs use a different needle.