1995 blaster major running problems

[mikeatchison#1]

hey guys,
i rebuilt and ported my engine with all new parts and, now it hardly wont run. At first start-up it ran great but, after about a couple minutes of running it starts misfiring like crazy and popping out of carb and wont rev up. The reeds valves are fine and the compression is at 135#. I checked the timing and it's at 20 btdc (advance) . One thing happened was when first fire up i forgot to torque the flywheel down and it came loose nearly falling off and, since then the engine has ran awful. By using a timing light the timing looks stable and doesn't jump around. I have tried a different carb that is known to be good, put in new spark plug, and changed fuel. Could be there something on the ignition side that causes conditions like this? I'm open to any ideas!!!!!!!!!! Thanks for any help!

 

[GIXER7502006]

I would check the flywheel key to make sure it didnt shear ...




One thing happened was when first fire up i forgot to torque the flywheel down and it came loose nearly falling off and, since then the engine has ran awfull ,

I would deffently start here^^^

 

[Zwiser]

did you rejet for the porting?

also check the fly wheel key

 

[blasterfreek30]

i would say the flywheel key also...sounds like all the symptoms

 

[mikeatchison#1]

yes we did a rejet for porting is actually on methanol, i dont use a key on the flywheel i just set the timing and torque the crank nut down with an impact the engine was running fine but i descoverd the crank seals were out of it and i installed new berings and seals and now its doing this????

 

[blasterfreek30]

yes we did a rejet for porting is actually on methanol, i dont use a key on the flywheel i just set the timing and torque the crank nut down with an impact the engine was running fine but i descoverd the crank seals were out of it and i installed new berings and seals and now its doing this????

am i getting this right...u dont use a woodruff key to hold the flywheel on??..i just dont see how its possible

 

[Kgibson]

when u dont use the key and just torque it down it's real easy to spin the flyheel and not know it. I also believe the key/timing is your problem. Why not use the key and move the stator...much more percise

 

[Demo4o1]

i agree with every1. woodruff key

 

[Little-J]

I wouldnt be too sure about the flywheel key. Technically you dont need one, but id be weary because the blaster flywheel doesnt have a set reference point where you can be sure of the trigger position.

Which blaster is it your using? pre 2003 or newer than 2003.. I ask because the electronics changed...

but lets be logical for a moment. youve got flames coming back out of the carb..

that means you have spark during the induction stroke or in the case of a two stroke, you have spark when the intake ports are open meaning your tiing is VEEEERY advanced..

With certain porting and running methanol i can see how this can actually run, but its not good...

So timing!!

the only other thing i can think of is that your transfer ports have gotten too big and there isnt enough piston overlapto completely seal the transfers from the exhaust port and your getting a bit of a flame squeezing through and igniting the fuel mix in the transfers...

 

[Demo4o1]

i was gonna say that maybe the transfer port was over ported too but i didnt know the right words to use lol so i 'd have to agree with that one.

 

[mikeatchison#1]

transfer ports were only cleaned up not hogged out, and we did just mild port job on the intake, nothing crazy. got a new flywheel and were gonna try it out today the bore inside the old flywheel was all tore up and it might of been spinning but we dont think it was because the timing was stable and it the rpms never got high enough to spin the flywheel, it would start up and in immediately back fire out if the carb then die the electronics we are using at from a 1990 blaster, could the cdi box cause this proplem?

 

[sicivicdude]

I bet the trigger coil was knocked off it's mounting position by the flywheel "nearly falling off" and is now gapped too wide to get a good clean hall effect signal.

Check the stator plate for damage from the flywheel magnets...

 

[darederek]

idk who told you you dont need a woodruff key, but you do

 

[sicivicdude]

Well, derek, you don't ACTUALLY need a flywheel key as long as you trust your abilities to line the flywheel up with the keyway and torque it down properly.

The interference taper fit is what keeps the flywheel timed to the crankshaft. The keyway only lines them up together to start with and then the taper holds them tight.

If the OP feels comfortable aligning the flywheel and crankshaft keyways without the aid of a keyway, he can do so. I wouldn't run mine without a keyway simply to make sure that the flywheel HASN'T been spinning.

 

[darederek]

i thought of that afterwards how people say its interference fit. idk personally i would run one. is there a benefit of running without?

 

[sicivicdude]

You can set a wild timing advance without moving the stock stator plate or a "degree" key. There isn't a limit to the timing advance if there's no key to align it to start with. It's also not NEARLY as exact a method for setting timing advance as moving the stator plate or a "degree" key...

 

[mikeatchison#1]

I bet the trigger coil was knocked off it's mounting position by the flywheel "nearly falling off" and is now gapped too wide to get a good clean hall effect signal.

Check the stator plate for damage from the flywheel magnets...

i hope your right about the trigger coil, the only thing we have not changed id the cdi box and stator so i guess we can give it a shot. we dont have an extra cdi box so all we can do is change the stator as see if thats our problem

 

[mikeatchison#1]

oh yeah forgot to mention yesterday i put a new flywheel on and set the timing and started it up and it revved it up a few time sounded great, went to take it down the road and all the same symptoms came back