New Build Problem

[fouchis]

So I just finished up my son's blaster today and took it out to go through some heat cycles and had a very bad experience. BTW, here is the build and set up. NEw Wiseco crank and piston, bored to 66.50, DG exhaust system, carb- 290 main and air screw out 1.5 turns. Fuel 32:1, new boyesen reeds. New seals all the way around and air leak tested. K&N filter. Tors and oil injection delete. PUT A CHEAP $40 adjustable STATOR ON IT FROM EBAY (set to 0). I'm guessing that is where a problem may lie.

After going through one heat cycle and cool down, I started it up for another one, I was adjusting the idle at the throttle body screw when it started revving very high as if it were WOT. So I immediately, hit the kill switch and key, but it still kept going, meanwhile I thought it was doomed and it was going to blow. Anyway, I hit the throttle to the Wide open position really quick and it stalled.

However, during the first run I did hear a couple of unusual knocks seem to be coming from the jug. Was this Piston Detonation or is there another problem somewhere?

This is my second build on a blaster. The first one was almost the same, except new FMF exhaust and no cheap stator. No problems with that one. Really, don't want to fire it up again until I hear something. Chris

 

[Larry's Shee]

You didn't turn the bars causing the runaway? Sure fuel was on, didn't run carb dry ?
Double check throttle is working well. Should hear slide snap closed when letting off throttle quickly. Even tho you've done leak test, might consider another. Re-torque head & base nuts.

Future FYI , best way to kill a runaway is hold brake, shift to second , let clutch out.

 

[fouchis]

Fuel was on. I probably caused the runaway when I was adjusting throttle. I adjusted it so I can hear the slap /metal on metal now. It still doesn't seem right though.

 

[82cutty]

Take the fuel line off the carb and turn the gas on to see if you have a good stream of fuel . Also check your float height . Sounds like you were lean on fuel or have a big air leak . Check the carb cap also...make sure gasket is good and tight

 

[jus_me]

The knock noise could be piston slap. Did you have cylinder bored and honed to the size of the new piston?

 

[fouchis]

The knock noise could be piston slap. Did you have cylinder bored and honed to the size of the new piston?

Yes, Advanced Machining in MT. Carmel, PA did it. He bores to the size of the piston. It was ok on the third heat cycle. Not like my other machine I did though without any problems??

 

[jus_me]

As mentioned before, did you re torque head a base nuts after heat cycle? Sounds like you may have gotten it real lean to rev like it did.

Are you using fresh gas?

An ignition prob wouldn't have you reving to the moon. If anything it would backfire or run like crap. Is the K@N sealed well? I have to grease the rubber gasket in order to get my K&N to seal correctly.

 

[fouchis]

I did re-install the air filter box lid because we do a lot of riding in muddy mud mud and water. Maybe I should take that back off. Oops.

 

[jus_me]

What's your mods and what is your current jetting, temps, altitude etc??

 

[fouchis]

What's your mods and what is your current jetting, temps, altitude etc??

NEw Wiseco crank and piston, bored to 66.50, DG exhaust system, carb- 290 main and air screw out 1.5 turns. Fuel 32:1, new boyesen reeds. New seals all the way around and air leak tested. K&N filter. Tors and oil injection delete. PUT A CHEAP $40 adjustable STATOR ON IT FROM EBAY (set to 0). Altitude-sea level to 2000' - 40 degrees


Read more: http://www.blasterforum.com/threads/new-build-problem.63632/#ixzz3zNtwDV5H

 

[fouchis]

It was the carb float height. It was at 12mm. Set it back to stock 20mm. Thank you very much.

 

[Blaaster]

How long did it hold 7psi for when it was leak tested.

Where did you pressurise the engine.

 

[fouchis]

How long did it hold 7psi for when it was leak tested.

Where did you pressurise the engine.

I did 6 PSI for 4 minutes and pressurized it at the intake. (used one of AWK's setup) I know people say 7psi or even 8psi, but I'm a little leery for seal reasons plus the manual says 6psi for 3-5mins.

 

[Blaaster]

Your symptoms scream air leak somewhere, or something restricting the fuel flow.

 

[fouchis]

Your symptoms scream air leak somewhere, or something restricting the fuel flow.

It's absolutely---positively not an airleak problem. I just checked it for a third time. I even checked the fuel by opening the valve at the tank and letting it run into a coke bottle. I cleaned the carb good and blew it out last night and reset the float level. We'll try it again today and see what happens. I went to a 310 main jet too.

 

[jus_me]

Just make sure you have pluged the oil line on the carb that used to be for the oil injection.

 

[Charles hoffman]

Ive experienced this problem before on mine. If you pull your choke out does the symptoms go away? If so as the others say you are probably running lean. My problem turned out being that even though I cleaned the carb several times lol I was getting crap pulled in from the gas tank which was clogging the main jet causing it to me lean. Make sure when you clean the carb you can see daylight clearly through your pilot jet and your main jet if you already haven't. If you don't already have one i would get a fuel filter as well. Just my .02

 

[BlasterPat]

Ive experienced this problem before on mine. If you pull your choke out does the symptoms go away? If so as the others say you are probably running lean. My problem turned out being that even though I cleaned the carb several times lol I was getting crap pulled in from the gas tank which was clogging the main jet causing it to me lean. Make sure when you clean the carb you can see daylight clearly through your pilot jet and your main jet if you already haven't. If you don't already have one i would get a fuel filter as well. Just my .02

I am against using fuel filters I feel they hinder fuel flow but if you have gunk in ur gas tank I would def use one then until I got to take the tank off and flush it out.

 

[Zbskater400]

I has this problem before. Check your stator side crank seal. You may think it's in correct but that could be the problem. My seal was bad and made it go wot without even touching the throttle.