I just bought a used LT125 it wont start, seller said it needs a carb but it wont start with starting fluid. The compression is about 140lbs, its has spark but its a littkle weak. I removed the stator cover does anyone know what the stator to flywheel gap is? and what normal compression should be?

Thanks

 

No one has any idea how many lbs of compression is normal for a 4 stroke. I hear so many people on this forum say "compression normal", but what is normal?

 

I'll take a guess and say your compression sounds pretty good. I don't know what the gap is but I measured the resistance of my Primary coil wire (BR/B wire coming from bottom of CDI) to ground and it was around 245 ohms. After that I put an O-scope on the output of the primary coil and it had +6Vdc, so I would guess that's good. My LT125 would not start when I got it home on Sat., even starting fluid didn't help. I pulled and clean the tank and filters. (Even if they told you they just put gas in, dump the gas.), new plug, cleaned the petcock, checked the fuel lines for cracks (changed a couple), pulled and cleaned the carb and took the air filter out (for testing). It then started up and ran pretty good for a while, we had to keep adjusting the air/fuel so I have carb kit ($15 on Ebay), choke kit and primer kit coming. I have a manual coming in a few days, if no one answers your question, I'll try to find the info.

 

I ajusted the pickup coil to two matchbooks I couldn't even get one in before, now it has a bright blue consistant spark and kicks over on starting fluid. I have a new carb on order through ebay $69, I hope to sit it by Friday.

I still find it strange that all the search's I do on compression say the same things, either compression is low or compression looks good, I would really like to know what people are basing these statements on. I know on two strokes that anywhere from 120 - 160 lbs is good with 150 lbs being a good avereage, but 4 strokes are a completly different animal.

 

I Installed a new carb yesterday, it tries to start but then putters out I still need to know what the GAP is from teh flywheel to the ignition pickup coil on the outside of the flywheel. Even is its for a non 125 they should be failry consitant on Suzukis, please help.

 

I received my manual today, it's not the full manual but a supplementary service manual for an 87 LT125 (I'll have to order another one). It shows compression @ 142-199 psi with a limit of 114 psi (i assume this is as low as it can be). It does not show a gap but does show the magneto coil resistance, the pickup coil (blue to grd) is 130-200 ohms. The primarty coil (black/red or brown/black coming off CDI to grd) is 350 to 450 ohms and lighting coil (yellow/red or white /red to grd.) is .2 to .8 ohms. Hpoefully someone will answer your gap question because I'll going to order new coils for mine.

 

I believe the pickup coil is fixed no adjustment to be made.

 

The trigger coil is adjustable, I had to bring it out to .50" thats correct 50 thousands, it will only idle and not rev up. It wont even start at anything under .40"

 

Hello, I just received my factory service manual but it does not list the gap (I'll keep looking). I did find a good article that explains the system pretty good and it says the gap should be .005" to .010". Check out the link, hope it helps. The pick-up coil resistance should be 130-200 ohms, if it's out of spec replace it.
Dan's Motorcycle "Electronic Ignition"
P.S. The cheapest place I have found to buy these parts is on the link below, don't know how good they are yet. The pickup coil is $11.19 (mine will be here in about a week, I'll let you know if they are worth buying). 195054 - Pick Up Coil for Suzuki ATV 87-91

 

Follow-up on primary coil I listed above @ 195054 - Pick Up Coil for Suzuki ATV 87-91 . I installed the primary coil after finilly getting it. It ohmed out within specs. It worked good at first but after a couple days of riding it started fouling the plug after riding for about an hour. It kept getting worst untill it wouldn't start. I just checked the coil and it was bad (143 ohms reading), now I'm going to order a good one like I should have done in the first place, but I had to try the cheap one. I wouldn't through your money away on this coil.