Let's play "What's the diagnosis?" FIXED!!!

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Post by Skootz Kabootz »

Well... new clutch, new belt, no rubbing, no change. Infact the bogging down/lurching is even more pronounced. Which leads me to the next theory... Eric had asked if I still had the evap system hooked up, which I do. This got me thinking, perhaps perfromance problem is not an issue with lack of fuel delivery as was initially explored, but a lack of oxygen instead.

This lurching and bogging down thing at WOT and higher rpm's bears a few similarities to the dreaded vaccuum lock. I'm thinking that with the engine running more and more efficiently with each improvement we've made, it going to need that much more oxygen to combust properly at higher rpm's. This could explain why it runs great at idle and lower rpm's but the top end is dead - no oxygen for combustion.

So, next up is checking air delivery to the carb etc. Fingers are once again crossed.
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Post by jrsjr »

Skootz Kabootz wrote:Well... new clutch, new belt, no rubbing, no change. Infact the bogging down/lurching is even more pronounced. Which leads me to the next theory... Eric had asked if I still had the evap system hooked up, which I do. This got me thinking, perhaps perfromance problem is not an issue with lack of fuel delivery as was initially explored, but a lack of oxygen instead.
But what changed while you were at work that fateful day?
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Post by Skootz Kabootz »

OK, for those of you playing along at home... I just disconected the evap system and plugged the hole where it connects to the air intake and... the symptoms got 1000 times worse. I barely made it around the block. So we have finally influenced the bogging down/lurching effect at least in some way. Now to figure out what's behind it.
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Post by JHScoot »

^ think you're onto something, there. this is part of the emissions system, yes? i was thinking the same thing b4 logging on. recall reading how problematic it can be, and affect performance. not just on Buddy's, either

just got to thinking about my old cars. if you've ever owned one with a carb, the symptoms are familiar
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Post by jrsjr »

Skootz Kabootz wrote:OK, for those of you playing along at home...
The home version of this game is hard! :(
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Post by JHScoot »

jrsjr wrote:
Skootz Kabootz wrote:OK, for those of you playing along at home...
The home version of this game is hard! :(
yeah because we have nothing to stand around and look at

ever notice how when men folk fix things like this it takes 1 to do it and 5 to stand around staring at the mechanicals going "oh yeah. yup, its that thing there."

this is just like that. only we have no visuals or beer :(
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Post by Skootz Kabootz »

Next clue! The problem only happens under load. Everything appears to work fine when the scooter is on the kickstand. Add a passenger or use the brake to create load, the problem appears.

Are we having fun yet?
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Post by JHScoot »

solution:

ride it without sitting on it

thats all i got atm :P
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Post by jrsjr »

Skootz Kabootz wrote:A new CDI made no difference.
Skootz Kabootz wrote:The problem only happens under load. Everything appears to work fine when the scooter is on the kickstand. Add a passenger or use the brake to create load, the problem appears.
Did you swap out the plug wire and the plug?
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Post by JHScoot »

wheels bearings. something wheel related.
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Post by viney266 »

jrsjr wrote:
Skootz Kabootz wrote:A new CDI made no difference.
Skootz Kabootz wrote:The problem only happens under load. Everything appears to work fine when the scooter is on the kickstand. Add a passenger or use the brake to create load, the problem appears.
Did you swap out the plug wire and the plug?
x2...Check that plug and boot again...just for giggles, crapping out under load is often a bad plug.
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Post by ericalm »

JHScoot wrote:
jrsjr wrote:
Skootz Kabootz wrote:OK, for those of you playing along at home...
The home version of this game is hard! :(
yeah because we have nothing to stand around and look at

ever notice how when men folk fix things like this it takes 1 to do it and 5 to stand around staring at the mechanicals going "oh yeah. yup, its that thing there."

this is just like that. only we have no visuals or beer :(
Untrue. I had one while hovering over the scooter earlier.

I compared it to an episode of House.
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Post by Skootz Kabootz »

Well this is certainly turning into a mystery of epic proportions.
jrsjr wrote:Did you swap out the plug wire and the plug?
We wondered the same thing. So yes, I put in a new plug and new coil/plug wire/cap unit tonight. No change.


The weird thing is that when I removed the evap system and plugged the hole for it, the problem got way way worse. BUT, when I replaced the evap system exactly as it was before, the problem lessened but did not return to the same level of performance as before the evap was removed. Weird. But at least we affected something that seems related.

The funny thing is, the engine is purring like a kitten and really sounds great when at idle. I think when we eventually do find whatever the culprit is (and I bet it ends up being something stupid simple) the scooter is going to be running better than ever.

So, to recap...

transmission (variator and clutch): check
carb: check
CDI: check
coil/spark plug wire: check
auto choke: check
check hoses and engine for leaks: check
fuel filter: check
evap system: check
mercury is retrograde: check
bad karma from previous lifetime: check
omnipotent deity with a warped sense of humor: check

I'm wondering now if there is something internal amiss with the engine? Last thing I did before leaving is to begin the process of compression testing the engine. Checked it hot, will check it when cold tomorrow.

Mamma mia. Talk about a crash course in scooter maintenance. With the exception of the engine interior, there is nothing on that scooter I haven't had my hands on.
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Post by JHScoot »

great back to the engine. i may win this whole shebang after all

evap system sounds wonky, though. maybe a component there? how about that charcoal canister thing?
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Post by rajron »

What does your plug say?
Are you running OK, rich, or lean?
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Post by Skootz Kabootz »

rajron wrote:What does your plug say?
Are you running OK, rich, or lean?
Original plug was perfect, new plug is perfect too... and the mix was dialed in again after rebuilding the carb. The engine is purring like a kitten, except under load.

I really can't wait until I do find something wrong! With anything! I am so sick of doing a bunch of work only to saddle up for a test ride and come back with no change whatsoever. I was actually thrilled when disconnecting the evap system made things worse because at least it changed something!
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Post by smithrw »

Check to be absolutly sure that the air filter housing cover is properly seated and good and tight. If it's leaking any air at all it could duplicate your symtoms.
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Post by Skootz Kabootz »

smithrw wrote:Check to be absolutly sure that the air filter housing cover is properly seated and good and tight. If it's leaking any air at all it could duplicate your symtoms.
It's fine, but how do you figure? It's not like the engine is going to get too much air if it is loose, just unfiltered air.
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Post by rajron »

Does the motor sound different when under load?
Is there excessive exhaust, or intake sounds – or does it just purr as normal?
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Post by jrsjr »

Skootz Kabootz wrote:
smithrw wrote:Check to be absolutely sure that the air filter housing cover is properly seated and good and tight. If it's leaking any air at all it could duplicate your symptoms.
It's fine, but how do you figure? It's not like the engine is going to get too much air if it is loose, just unfiltered air.
It's not that simple. Airboxes are sort of a black art all unto themselves. Quick story - I once ran my 1982 BMW R100RT on a dyno at a national BMW rally. The dyno guy had seen a zillion bikes like mine. After the first run, he showed me a distinct "notch" in the HP curve, not good. His suggestion? Modify the airbox by drilling a very small hole in the cover. The lure was that it would get rid of "the notch" and if it didn't work we could just put a piece of black electrical tape over the hole and nobody would ever know. So, we drilled the hole, zipped the airbox back up, and did another dyno run. Result? No more notch. Not really a good idea for the motor and I ended up worrying so much about unfiltered air that I covered the hole back up, but it gives you a feeling for how sensitive motors are to even small changes in the intake. And that was a much bigger motor, two cylinders and 1000 CCs.
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Post by viney266 »

Go over that evap sytem for a crack or a air leak...split hose...spit plastic. The fact that it got worse when unplugged and better but till there when plugged in...

I'd love to ride this bike for 1 minute...this one even has me curious. this is the reason I became a bike mechanic 25 years ago.

I would, just due to milage, go over the motor again. Anything you may have missed...but it still screams air leak or fuel starvation...I still say fuel somewhere...hmmm

wait!!!!...I GOT IT....we are all idiots!!!!

Geez...DID YOU CHECK??? is Mars in retrograde????
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Post by smithrw »

Trust me, if these engines suck any extra air the air fuel mixture gets all screwed up. I say this as a result of having problems myself.
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Post by Skootz Kabootz »

rajron wrote:Does the motor sound different when under load?
Is there excessive exhaust, or intake sounds – or does it just purr as normal?
The sound just deepens as the rpm's lessen. No other sounds or exhaust. I just sounds like it is bogging down.

I totally agree with the fuel/air guesses. Seems so likely. But the fuel delivery system has been gone over soup to nuts including two carb rebuilds. And the airbox and all intake hoses are just fine and have been checked for cracks etc, and it is a new air filter.

But if the engine is somehow being starved for fuel/air, why would it only do it under load?
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Post by viney266 »

smithrw wrote:Trust me, if these engines suck any extra air the air fuel mixture gets all screwed up. I say this as a result of having problems myself.
^^^ Agreed, most small engines are VERY picky to air leaks...

Didja check your air intake boot for carb? make sure it isn't worn out. I have seen some "dryrot" from heat...Yamaha singles were known for it. I've even seen them warp where they join the engine.

You may have some luck running the engine and spraying brakeclean around the junction parts to see if the idle changes. If it does...you found the leak
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Post by Skootz Kabootz »

viney266 wrote:
smithrw wrote:Trust me, if these engines suck any extra air the air fuel mixture gets all screwed up. I say this as a result of having problems myself.
^^^ Agreed, most small engines are VERY picky to air leaks...

Didja check your air intake boot for carb? make sure it isn't worn out. I have seen some "dryrot" from heat...Yamaha singles were known for it. I've even seen them warp where they join the engine.

You may have some luck running the engine and spraying brakeclean around the junction parts to see if the idle changes. If it does...you found the leak
Done and done. :? But rechecking the air intake boot is now on the agenda. There was a very minor disturbance of the brake fluid around the base on one side but on close inspection it was so minor it was deemed insignificant. Perhaps it is not so minor under load? I will definitely have to recheck that. I do a lot of WOT riding so it wouldn't surprise me at all if engine heat etc has taken a toll on it.
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Post by rajron »

Skoots Kabootz;

I agree with the others who think it is air box related – check the snorkel attachment at the rear of the box, the intake snakes around the outside of the pet carrier the opening is at the rear of the scoot opposite side of the box, any break in that channel may also cause a problem. More so, your symptoms sounds just like when the item #12 baffle is removed from the air box – are you certain that baffle does not come with the 150 air box? Please check with another unmolested scoot.

Your description of the audio nearly confirms, in my mind, the problem is the baffle - I think you are leaning the motor
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Post by Syd »

Look at the bright side, Skootz, when you get burned out at your current career, you can find work as a scooter mechanic's apprentice!
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Post by JHScoot »

NOHO is closed Sun-Mon. game over 'til tuesday, i suppose

doh! just flashed on voices carry and now i have to google aimee mann and see whats up :(
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Post by Skootz Kabootz »

Syd wrote:Look at the bright side, Skootz, when you get burned out at your current career, you can find work as a scooter mechanic's apprentice!
Seriously! And it may just happen sooner that you think. The job I recently started was unexpectedly relocated to NYC from LA which sucks, but that is why I now have all this time to do repair work. Just as well it happened I suppose. I sure couldn't do my daily commute on my scooter as is.
JHScoot wrote:NOHO is closed Sun-Mon. game over 'til tuesday...
Yep. Time to rest the brain and stay in watching movies on a cold, rainy weekend.
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Post by jrsjr »

Skootz Kabootz wrote:
Syd wrote:Look at the bright side, Skootz, when you get burned out at your current career, you can find work as a scooter mechanic's apprentice!
Seriously! And it may just happen sooner that you think. The job I recently started was unexpectedly relocated to NYC from LA which sucks, but that is why I now have all this time to do repair work. Just as well it happened I suppose. I sure couldn't do my daily commute on my scooter as is.
JHScoot wrote:NOHO is closed Sun-Mon. game over 'til tuesday...
Yep. Time to rest the brain and stay in watching movies on a cold, rainy weekend.
My diagnosis is that life has dumped a bushel basket of lemons on you and you are cheerfully making lemonade. Good on you! 8)
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Post by Syd »

Skootz Kabootz wrote:
Syd wrote:Look at the bright side, Skootz, when you get burned out at your current career, you can find work as a scooter mechanic's apprentice!
Seriously! And it may just happen sooner that you think. The job I recently started was unexpectedly relocated to NYC from LA which sucks, but that is why I now have all this time to do repair work. Just as well it happened I suppose. I sure couldn't do my daily commute on my scooter as is.
Just remember, when fate closes one door on you it opens another - and waits in the bushes to lock you outside once you're through it. That sucks, Skootz.
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Post by Skootz Kabootz »

Thanks guys. I have to say, I am certainly very ready for life to ease up a bit so I can relax a little, go for a nice long scooter ride, and enjoy some of that lemonade! I'm all for this character building stuff, but enough is enough! :P
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Post by MWPMWP »

Snooki, have you checked to see if the emergency brake is on?

Just kidding of course. Couldn't resist throwing in a Jersey Shore reference. I'm interested in the outcome of your scooter problem. I just pushed my Buddy 125 home tonight when it sputtered and lost power at about 40mph. I parked it and will deal with it in the morning. I'm thinking.....actually hoping it's just the whole vapor/vacuum thing everyone else seems to experience.

Anyway, can't wait to hear the outcome of your problem. Best of luck to you!
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Post by jijifer »

MWPMWP wrote:Snooki, have you checked to see if the emergency brake is on?

Just kidding of course. Couldn't resist throwing in a Jersey Shore reference. I'm interested in the outcome of your scooter problem. I just pushed my Buddy 125 home tonight when it sputtered and lost power at about 40mph. I parked it and will deal with it in the morning. I'm thinking.....actually hoping it's just the whole vapor/vacuum thing everyone else seems to experience.

Anyway, can't wait to hear the outcome of your problem. Best of luck to you!
hope it's just a spark plug - super simple fix
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Post by KABarash »

MWPMWP wrote: have you checked to see if the emergency brake is on?
Just to laugh at myself, my Honda has a 'parking' brake that is 'self releasing' situated on the left side, I remember one day shortly after I got it going to pull out of the driveway one day thinking I had something wrong. I braked at the bottom of the slope going to turn back up to see what's wrong, it then just took off on me (for whatever a Met can 'take off') and I realized Duh..... I'm a 'moron'! :fp:
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Post by LunaP »

ericalm wrote: Untrue. I had one while hovering over the scooter earlier.

I compared it to an episode of House.
It's never Lupus.
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Post by ericalm »

LunaP wrote:
ericalm wrote: Untrue. I had one while hovering over the scooter earlier.

I compared it to an episode of House.
It's never Lupus.
Exactly what someone said when I compared it to House the first time!
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Post by PeteH »

All chug when its a sarcoidosis. Or vapor lock.
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Post by jijifer »

well?
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Post by Skootz Kabootz »

jijifer wrote:well?
Heh. Unfortunately no work's been done yet this week. I tried yesterday but the shop was busy and also I've been busy rewriting resumes, updating portfolios, and taking care of other job search joys. I am planning on working on the scooter tomorrow afternoon as soon I get this one job response submitted.

I need a vacation... paid of course... :P
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Post by iMoses »

Skootz Kabootz wrote:
smithrw wrote:Check to be absolutly sure that the air filter housing cover is properly seated and good and tight. If it's leaking any air at all it could duplicate your symtoms.
It's fine, but how do you figure? It's not like the engine is going to get too much air if it is loose, just unfiltered air.
A few years ago I dumped my 125 on it's left side (air box side) which allowed fuel to soak the air filter. I was able to ride it home (3 mile trip). But after it caused all kinds of havoc, when I tried going down the street it bogged down, but while idling it seemed ok. I replaced the air filter and my issue went away.
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Post by jijifer »

Skootz Kabootz wrote:
jijifer wrote:well?
Heh. Unfortunately no work's been done yet this week. I tried yesterday but the shop was busy and also I've been busy rewriting resumes, updating portfolios, and taking care of other job search joys. I am planning on working on the scooter tomorrow afternoon as soon I get this one job response submitted.

I need a vacation... paid of course... :P
also consider you're back to stock and are thinking of it running like it was all pimped out. I don't know that indicating only 55mph is terrible for 150cc.
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Post by Skootz Kabootz »

jijifer wrote:
Skootz Kabootz wrote:
jijifer wrote:well?
Heh. Unfortunately no work's been done yet this week. I tried yesterday but the shop was busy and also I've been busy rewriting resumes, updating portfolios, and taking care of other job search joys. I am planning on working on the scooter tomorrow afternoon as soon I get this one job response submitted.

I need a vacation... paid of course... :P
also consider you're back to stock and are thinking of it running like it was all pimped out. I don't know that indicating only 55mph is terrible for 150cc.
Bogging down under load is the issue. The scooter barely makes it around the block now. And 55mph sucks! Remember, my mods decreased the top end in favor of being able to maintain speed going up hills. Stock should ultimately give me an increase in top end speed. That's if it ever gets running properly again...
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Post by jrsjr »

All along, we've been focused on the intake (knowing that the valves have been freshly adjusted) because it really sounds like that kind of problem, but I'm thinking that it might be time for a compression test. I've been following this thread and comparing it to the troubleshooting list over on Cyclepedia.com and you've really covered a lot of the items on their checklist which is as follows:

Poor Running or No Power at High Speed:

Firing incorrect:
Spark plug dirty, broken, or maladjusted
Spark plug cap shorted or not in good contact
Spark plug incorrect
IC igniter trouble
Pickup coil trouble
Ignition coil trouble

Fuel/air mixture incorrect:
Starter plunger stuck open
Main jet clogged or wrong size
Jet needle or needle jet worn
Air jet clogged
Fuel level in carburetor float bowl too high or too low
Bleed holes of air bleed pipe or needle jet clogged
Air cleaner clogged, poorly sealed, or missing
Air cleaner duct poorly sealed
Water of foreign matter in fuel
Carburetor holder loose
Fuel tank air vent obstructed
Fuel tap clogged
Fuel line clogged

Compression low:
Spark plug loose
Cylinder head not sufficiently tightened down
No valve clearance
Cylinder, piston worn
Piston ring bad (worn, weak, broken, or sticking)
Piston ring/land clearance excessive
Cylinder head gasket damaged
Cylinder head warped
Valve spring broken or weak
Valve not seating properly (valve bent, worn, or carbon accumulation on the seating surface.)

Miscellaneous:
Throttle valve will not fully open
Vacuum piston does not slide smoothly
Brake dragging
Clutch slipping
Overheating
Engine oil level too high
Engine oil viscosity too high
Drive train trouble

(P.S. I deleted their section on "knocking" since that wasn't a symptom)

At this point, if it were up to me, I'd want to do a compression test, and I'd also like to verify spark under load, however the heck you do that. :roll: If those two items were eliminated, there's almost nothing left on the list to check. :shock:
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Post by Skootz Kabootz »

jrsjr wrote:All along, we've been focused on the intake (knowing that the valves have been freshly adjusted) because it really sounds like that kind of problem, but I'm thinking that it might be time for a compression test. I've been following this thread and comparing it to the troubleshooting list over on Cyclepedia.com and you've really covered a lot of the items on their checklist which is as follows:

Poor Running or No Power at High Speed:

Firing incorrect:
Spark plug dirty, broken, or maladjusted...

...

...Drive train trouble

(P.S. I deleted their section on "knocking" since that wasn't a symptom)

At this point, if it were up to me, I'd want to do a compression test, and I'd also like to verify spark under load, however the heck you do that. :roll: If those two items were eliminated, there's almost nothing left on the list to check. :shock:
Awesome check list jrsjr! Thank you! I will be going through it one by one for sure. I hope to be back working on the scooter tomorrow. I finally finished rewriting my resumé (one of my least favorite things to do) and updating my portfolio so by tomorrow afternoon I should have time again.

The last thing I did on the scooter was to compression test when warm. Next up is to test it again when cold. I hope that gives some kind of clue. I really am hoping this is not piston/ring related. I'd rather not to have to open up the engine. Then again, that is the only thing I have yet to do. Tackle that, and my training will be complete... :P
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Post by jrsjr »

Skootz Kabootz wrote:I'd rather not to have to open up the engine. Then again, that is the only thing I have yet to do. Tackle that, and my training will be complete... :P
"Splitting the cases" is a time-honored rite of passage in the vintage world. Think of the street cred you'd have, especially if you actually found the problem and fixed it! :wink:
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Post by Skootz Kabootz »

jrsjr wrote:
Skootz Kabootz wrote:I'd rather not to have to open up the engine. Then again, that is the only thing I have yet to do. Tackle that, and my training will be complete... :P
"Splitting the cases" is a time-honored rite of passage in the vintage world. Think of the street cred you'd have, especially if you actually found the problem and fixed it! :wink:
Do I get a patch or something? Maybe a tattoo? Inside info on a secret handshake? :lol:
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Post by jrsjr »

Skootz Kabootz wrote:
jrsjr wrote:
Skootz Kabootz wrote:I'd rather not to have to open up the engine. Then again, that is the only thing I have yet to do. Tackle that, and my training will be complete... :P
"Splitting the cases" is a time-honored rite of passage in the vintage world. Think of the street cred you'd have, especially if you actually found the problem and fixed it! :wink:
Do I get a patch or something? Maybe a tattoo? Inside info on a secret handshake? :lol:
This is a tough crowd we're talking about. You'll be lucky if you get The Nod. :wink:
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Post by Skootz Kabootz »

jrsjr wrote:
Skootz Kabootz wrote:
jrsjr wrote: "Splitting the cases" is a time-honored rite of passage in the vintage world. Think of the street cred you'd have, especially if you actually found the problem and fixed it! :wink:
Do I get a patch or something? Maybe a tattoo? Inside info on a secret handshake? :lol:
This is a tough crowd we're talking about. You'll be lucky if you get The Nod. :wink:
Ooooooo... "The Nod"! What will be left to strive for after that? :lol:
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Post by Syd »

jrsjr wrote:
Skootz Kabootz wrote:
jrsjr wrote: "Splitting the cases" is a time-honored rite of passage in the vintage world. Think of the street cred you'd have, especially if you actually found the problem and fixed it! :wink:
Do I get a patch or something? Maybe a tattoo? Inside info on a secret handshake? :lol:
This is a tough crowd we're talking about. You'll be lucky if you get The Nod. :wink:
I heard somewhere that you got a lip ring, sorta like sailors who have crossed the equator.
The majority is always sane - Nessus
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