Not again . . . . . .

[Johnny5]

Rattler woes have no mercy with me. I was performing a plug chop topped out at 55 mph in front of my home. As I let of the throttle to "chop" it, the bike chopped itself for me. It soft seized conveniently in front of my garage.

Now I want you guys to look carefully at the stock airbox design and tell me what you think about it. You can see on the throat of the filter that the actual filter is only a 1/2 inch from the edge of the carburetor. My theory is that with the increased demand from the modifications the air is becoming turbulent and not passing by the needle properly thus creating a fast lean condition.

I don't know why else this d*** thing keeps giving me a fast lean condition.

Does soft seizing do any damage? Can you hear detonation? I'm pretty sure I can but I'm not sure.

I ordered a UNI style filter a while back but it's still on the slow boat from China.

My temps while cruising with a few moments of wot never exceeded 270.





Here you can see the filter moved slightly aside from its housing to give an idea of how close the filter element is from the carburetor.

That's a plug with 1 mile on it.

[bakaracer]

did you change the main jet after you installed the big bore kit? why are you doing plug chops at 55mph for? thats asking for it to blow up doing it like that.

[Wheelman-111]

Greetings:

Regarding damage: Soft seizes can be survived without apparent harm, but they always result from momentary excessive heat. Sometimes it causes minimal damage, but it's never a good thing.

For yours: Look closely at that ghastly-white plug: The flecks of metal welded to the threaded edge probably once belonged to your piston. For a street ride I'm with Baka: Any new build break-in should start with a stupid-fat jet. If it runs reasonably well, take that one out and go bigger! Only with a few miles' observation should you start dropping, one size at a time, until you can live with it. Don't forget to oversize the Pilot also. Off-throttle, the engine depends on the cool mist from the Pilot (if possible) to keep from overheating as it coasts down.

Swappiing to a UNI filter will admit even more air to the mixture, making things worse. 386 is evidently more than your bore could sustain.

[Trafficjamz]

What scooter is this?

2 stroke or 4?

[fastplastic]

that has to be a razz

[Bear45-70]

Quit looking for things to blame for your too small of a main jet. You screwed up. Accept it and learn from your mistake.

[eliteguy50]

What scooter is this?

2 stroke or 4?

It is a 2T. A long block PGO version of the H. Minarelli (what they run in a modern Zuma).

[Johnny5]

Baka; I thought that's how you did a plug chop. Run at wot for a short bit and kill it. She runs up to top speed pretty quick (no gears) and of course I re-jetted! The kit came with a 90 & 95 so I installed the 95. It blew up the first bbk cause the stock 80 was still in it. So I'm going jet hunting at my store today where I'll pick up a few bigger sizes and throw in a 105, or the like, and see what happens.

Wheelman! Thanks for the info on soft seizes! Makes me feel a ton better. As for the pilot. I can still adjust the pilot so it 4 strokes out like no other so I'm pretty sure the pilot is sufficient. As for the filter, I gotta try it. It runs so much better without the air filter clogging up the carb's pathway of air. It's like putting the palm of your hand across your mouth leaving some space to breath with on one side......can't be good.

Bear . . . . I'm sorry. Would you like to use the ruler or the belt?

Eliteguy; Nice guess! I thought nobody knew about these.

[Wheelman-111]

Greetings:

Further thoughts on that plug pic. Nice job photy-graffying it, BTW. If that was a new plug a mile ago, why's the tip of the ground strap oxidized? From turning itself into a Glow-Plug, methinks? If so that was pre-ignition and perhaps the immediate cause of the overheat.

If the jetting is rich enough to four-stroke in the low-midrange, then clearly either the Main is still too small, or there's a vacuum leak that opens up only at high RPM. Vibration can do this sometimes. I know, I ride a Harley... Insufficient cooling or insufficient oil (?) are other, more remote possibilities.

[bakaracer]

Baka; I thought that's how you did a plug chop. Run at wot for a short bit and kill it. She runs up to top speed pretty quick (no gears) and of course I re-jetted! The kit came with a 90 & 95 so I installed the 95. It blew up the first bbk cause the stock 80 was still in it. So I'm going jet hunting at my store today where I'll pick up a few bigger sizes and throw in a 105, or the like, and see what happens.

Wheelman! Thanks for the info on soft seizes! Makes me feel a ton better. As for the pilot. I can still adjust the pilot so it 4 strokes out like no other so I'm pretty sure the pilot is sufficient. As for the filter, I gotta try it. It runs so much better without the air filter clogging up the carb's pathway of air. It's like putting the palm of your hand across your mouth leaving some space to breath with on one side......can't be good.

Bear . . . . I'm sorry. Would you like to use the ruler or the belt?

Eliteguy; Nice guess! I thought nobody knew about these.

not at 55mph!! from dead stop get the bike up to where it hits high rpm and then hold for 4to5 seconds. the most you would get up to is maybe 40mph +/- 3mph. if youyr going faster then that to hold wot for plug chops,thats asking for trouble. are you using a pod airfilter on your bike? or stock airbox?

[Johnny5]

Stock airbox. As soon as my pod comes in I'll give it another go........ at 40mph this time.

[bakaracer]

Stock airbox. As soon as my pod comes in I'll give it another go........ at 40mph this time.

before you do that,check for either an exhaust leak or intake leak.if your running a 95 jet with the airbox,that thing should be either running just right or a little rich. Did you mod the airbox in any way?