Won't start after top end rebuild...Help please.

[nathanastone]

At the end of my rope here. I've checked and rechecked everything I can think of. I have good spark. It does have compression but a bit low at just over 90 lbs. I sprayed ether and didn't get anything except the kickstart kicked back a little bit. Grounds should be good if I have spark, right? I had the TORS unhooked and tried it with it hooked bak up too. Oil injection is removed and I'm mixing 32/1 - 33/1. I cleaned the carb and checked reeds before I put it back together. One thing though. Is the throttle stop screw under the seat supposed to be seated and backed out like the pilot screw? It seemed to just keep spinning. The carb is my weak point so I'm hoping this could be the problem. I kicked the sh%! out of it for an hour. Help please and thank you.

 

[stephen12091985]

you suspossed to have like 120psi

 

[nathanastone]

I know. I checked the manual. Not sure why it's so low but wouldn't it still start at 90-100?

 

[fioz600r]

I have read that you have to cut and attach the tors wires that are from the harness plug.

But I am not sure, when I removed my Tors i took the entire system from mine, wires from the harness and all.

 

[mr_3_0_5]

I know. I checked the manual. Not sure why it's so low but wouldn't it still start at 90-100?

are you sure you did the compression test right?
kicking it wide open throttle till the guage stops..
with that low compression it might fire if you pulled it with a car or something but on a new top end you should have at least 120 psi.

 

[fioz600r]

Did you put the head gasket on right?

 

[nathanastone]

OK. I did the test again, no choke and throttle WFO. 120+ psi. Sprayed a little ether and kicked the sh*t out of it. The plug came out wet with ether. I have great spark and compression. Possible stator/timing problem?

 

[fioz600r]

is it backfiring at all.

I dont know if this has been asked but have you checked to see if you getting fuel to the carb.

 

[sc0r1a]

I'm having a similar problem. I talked to a guy and he sad my carb was set up for just gas running through the jets so it might need to be up jetted b/c the gas is thicker now with the oil mixed in.
I haven't tried it yet. just somewhere else to look.

 

[fioz600r]

I'm having a similar problem. I talked to a guy and he sad my carb was set up for just gas running through the jets so it might need to be up jetted b/c the gas is thicker now with the oil mixed in.
I haven't tried it yet. just somewhere else to look.

I dont see how that could be true. Since your oil and gas mix in the carb before it goes to the reed cage.

 

[Blaster200boy]

It's probably a timing issue....That or your jetted incorrectly....

 

[Braaaptor]

I'd check your timing, indeed. All the spark in the world won't do any good if it doesn't occur when the piston reaches TDC. Just take the flywheel (ignition rotor) off using a puller, and make sure that the small woodruff key in the crankshaft is in place and intact. I bet its sheared.

If the flywheel key is OK, reassemble it and go check your spark again by resting the plug on the cylinder head and kicking it over with the spark plug outside the engine. You can also set the spark plug gap (temporarily) out to .040". This will put a load on the ignition coil and simulate the conditions the spark plug must fire under while inside the engine. Furthermore, try a new spark plug if you haven't already done so. They do develop shorts from time to time. A wet spark plug means that you are at least getting fuel to the cylinder.

If the igntion checks out OK and you are SURE that it is in-time, pull apart your reed cage and have a look inside. Broken, damaged, or poorly-seating reeds can cause the symptoms you are describing. OH! While you have that flywheel off, go ahead and unbolt the stator plate to be sure that the LH main crankshaft seal is still in place and intact.

Good Luck!!

 

[nathanastone]

I don't know if it's backfiring b/c it won't turn over whatsoever. I kicked the sh*t out of it and the only sound i get is a grumble with full throttle wiht the air box off. Like I said, I'm definately no expert but timing is the only thing I haven't checked. One more...The trottle stop screw just keeps turning. Don't know if it's supposed to be seated and backed out like the pilot but it doesn't seat. Not sure what else to troubleshoot.

 

[Blaster200boy]

The little bronze screw on the SIDE of the carb that is flat tip should be turned in all the way, and then backed out 1.5 turns....What Are you mods???

 

[sr5bidder]

I don't know if it's backfiring b/c it won't turn over whatsoever. I kicked the sh*t out of it and the only sound i get is a grumble with full throttle wiht the air box off. Like I said, I'm definately no expert but timing is the only thing I haven't checked. One more...The trottle stop screw just keeps turning. Don't know if it's supposed to be seated and backed out like the pilot but it doesn't seat. Not sure what else to troubleshoot.

if you have the throttle stop screw turned in to much the slide will be open too far and the idle circuit wont be able to deliver fuel. ...adjust the throttle stop screw out till there is only a 1/8th to 3/16th gap between the bottom of the carb bore and the throttle slide....this will give the proper velocity/vaccum of air when kicking the engine over to suck fuel through the idle crcuit

other than that you can put your hand over the back side of the carb and kick it twice then see if it starts on the next few kicks with hand removed ( for this you would need to remove the seat and air box)

 

[brandoz28]

why did you rebuild the top end in the first place? was there a problem?

 

[nathanastone]

I have 120psi, good spark, no fuel problem. Next step is to pull the flywheel cover and see if the wodruff key is sheared. I think it's a timing problem beacause the plug came out with ether still on it. I suppose that would mean it isn't firing at TDC? All this troubleshooting sure is a pain in my ass. lol I just wanna ride my new toy.

 

[nathanastone]

I rebuilt the top end because there was a hole melted in the top of the piston because the oil ijection was bad. I bought it like that and the first thing I did was the block off kit. The only other mod is tors removal. I hooked it back up just to see if it might start like that. Also the reeds are good and carb adjustments are done according to the factory manual. 1 1/2 turns out. I'm on my way out to the garage to pull the flywheel off and check the keay to see if it's sheared. I'm almost sure this is the problem seing as I've eliminated pretty much everything else.

 

[fioz600r]

so was it the key since I see you are looking for one?

 

[Nick1994]

I'd check your timing, indeed. All the spark in the world won't do any good if it doesn't occur when the piston reaches TDC. Just take the flywheel (ignition rotor) off using a puller, and make sure that the small woodruff key in the crankshaft is in place and intact. I bet its sheared.

If the flywheel key is OK, reassemble it and go check your spark again by resting the plug on the cylinder head and kicking it over with the spark plug outside the engine. You can also set the spark plug gap (temporarily) out to .040". This will put a load on the ignition coil and simulate the conditions the spark plug must fire under while inside the engine. Furthermore, try a new spark plug if you haven't already done so. They do develop shorts from time to time. A wet spark plug means that you are at least getting fuel to the cylinder.

If the igntion checks out OK and you are SURE that it is in-time, pull apart your reed cage and have a look inside. Broken, damaged, or poorly-seating reeds can cause the symptoms you are describing. OH! While you have that flywheel off, go ahead and unbolt the stator plate to be sure that the LH main crankshaft seal is still in place and intact.

Good Luck!!

im having a similar problem. I have an 03 blaster I rebuilt once or twice before, some years later (now) I rebuilt it again, it refuses to start unless I chain it to a car and it runs if you pull it but when the car stops so does my blaster . I cleaned the carb, got all new gaskets, new rings, it was recently rejetted, I have no idea what else to do. please help if anyone has ideas..... Mods: fmf powercore2, 240 vitos bigbore topend kit, wiseco bottom end crank, boysen reeds, oil block off kit. I run 32-1 premix