Modern Vespa

New longer bolts will be here tomorrow so I can bang them out then.

Today I rigged up a choke cable pull. Since I'm going with a bench seat on a VNA I needed to rig something up. So I just took a piece of one of the many throttle cables I messed up and made a choke cable pull.

And one more question about the spark plug/cht.

There's a small leak from under the CHT tab. Should I put copper seal or something like that on the bottom of the CHT ring to keep it from leaking? Or would it be more prudent to drill a hole into the cylinder head to just attach it like that?
If yes to drilling how deep should I drill into the head? I'd prefer not to drill just so I don't mess the head up but if it's not a stressful situation I could do the drilling I think. I have the bits anyways. Would I need to remove the head? I'm thinking yes then I can just use my drill press and get a nice straight hole drilled and tapped.

Reason I checked the plug was to see if maybe that was the issue with the speedo and I think it may be. Plug that was in wasn't a resistor plug. Just need some guidance on the CHT ring so I can button that up and check if it cured the speedo resetting a million times

Will the CHT lead fit on one of the cyl studs? thats what I do on my smallie. Not as accurate as under the plug, but close enough for me; and dont have to mess with it each time removing the plug

The CHT lead is a bit larger than the cylinder studs. Do you got a pic of how yours is?

CM2 tapped a hole into one of those two openings around the CHT for a M10x1.0 CHT sensor just a few days (so, like...five pages ) ago, if you want to see how he did it.

I just added one to my BGM that I homemade with an M6 and a K-type sensor. You need to be able to drill and tap about 6-8mm, I think. I have a spare sensor I can go measure if need be. You want it to be shallow enough that the tip ground out at the bottom of the hole to get a good contact for measuring, but it works even better than the plug ring, plus no annoying leaks.

I dont have a good pic. My lead is a bit larger than the stud as well; so I used an extra washer on top. Torqued to spec, and all is well; so far

Doing the same. Broke my 14mm after a few plug changes. 10mm in the mail.

Do you have a general idea re what to expect as far as bolt temp differences to expect on a cast iron cylinder?
I remember a thread here about this. Can't find it via a search.

You'd probably be okay using a fresh crush washer with every plug install. But those b9es plugs...$$

I imagine with an aluminum head a bolt cht would be pretty accurate. Just no experience doing so.

I have no clue the difference between bolt / plug. You are right, there is a discussion on that somewhere...

I am running the 10mm lead, on alum head, on a iron cylinder polini 130.
One of these days I'll get a plug lead, and do test runs with both to see the difference.

I use my gauge just as a guideline. regardless of the #, if my normal temps jump; I know to pull that clutch lever! So far good to go

Going with a head bolt will give you lower readings - and reportedly a bit more delay in temp change in the cylinder.
Ray - there was a discussion - but quick search didn't turn up for me either.

As long as you stay consistent (with where you have it), you can get to know that scoot's safe operating temp through experience.
It just might not be the same number you get at the plug.

FM - I have a similar head on my build.
I have a fancy mill to drill holes with - but a careful job with a hand drill could do the same.
Just make sure if you go this route to have the head nicely clamped do a bench so it stays still for you.
On the head - there are areas next to the plug with lots of meat in them.
I decided to drill and tap a hole for the 10mm sending unit for my CHT.
Pics below if you haven't seen previously.

Nice n Clean, CM

I think I can swing this. Thanks!
Was it difficult getting the nut on the sensor tight in that small space?

It just needs to be finger tight, really. If you have a deep 3/8" drive 10mm socket, you can feed the sensor through the top and use that to tighten it down by hand. Otherwise, it's a PITA. I added a screwdriver slot to my homemade sensor for the same basic reason.

So - at some point - just before you do this - you will realize that you can't use a socket - 'cause the connector wire comes out of the top of the unit and it cant go through your socket with a socket wrench it...

If you look at where I placed mine - I cheated it toward the spark plug - on purpose.
Then I just used some needle nose pliers to snug it. Was more than enough.
The sensor has a point on it the pokes into the bottom of the hole its screwed into - there are no bonus points for getting all the threads in either.

Put a few drops of locktite on - and snug it lightly with needle nose.
It will be there for the life of that head.

But you can feed the sensor lead through the hole in the top of the socket and now you have the whole socket to hold on to while you screw it in by hand. Much easier than trying to do it with the sensor lead or pliers.

^ smart!

Good news, resistor plug allows the speedo to work!

Didn't end up putting the cht probe in the cylinder head yet. Planning on doing it eventually but I was tired last night and decided to just put some copper gasket on the ring of the cht for now so I could at least check the speedo.

I need the damn kill switch though. The sound of the engine speeding up when the gas is turned off gives me so much anxiety. It's probably all in my head.

Good news on the resistor plug!

When my kill switches aren't working (it happens), I just put it in 1st, grab the brake, and stall it by letting the clutch out at idle, then back to neutral.

stalling in a higher gear = less lurch, use 2nd or more. it's hard on your cush drive.

I don't disagree that it's not the best thing you can ever do for your cush drive, but compared to how I treat mine running through the gears, I'd say it's a rounding error in its overall service life ,

Also, wouldn't it be the opposite? Since the cush sits between the crank and the gear stack, if the scooter lurches less, that means the cush is absorbing more of the stall. Thus, you want more lurch, not less, because in that case, the mass of the scooter is absorbing the force of the motor rather than the transmission.

it definitely feels softer to stall in the higher gear. the speed change will be faster the bigger the gear ratio. the lurch is when bad things are likely to happen. witness that cush drive I just took apart - that factured tooth inside had to be from a fast speed change. since the clutch was also imploded, one of them caused the other to fail, most likely.

agreed, probably not too important but I'd not make it a habit. still, who wants to wait for the fuel to run out?

Pulling the choke is a much less violent way to kill the engine. With an SI carb, you're actually gently flooding it.

Awesome.
Where did you pick up that sensor?

Inspired by your choke pull!

Tried many things there! For now I have a $10 generic choke that works well.

I'm thinking a side-draft carb adapter there, a hole through the front of the bench seat with a brass grommet, and a tether like yours. Pull the choke without having to lift the seat.

I bought these a few years ago. I was putting lock nuts on all thread in limited space. The inside is hollow, works good for spark plugs also.

https://www.homedepot.com/p/Husky-3-8-in-Drive-6-Point-Pass-Thru-Ratchet-and-Socket-Set-28-Piece-H6PTTHRU28PC/303046171?source=shoppingads&locale=en-US&&mtc=Shopping-VF-F_D25T-G-D25T-025_001_HAND_TOOLS-HUSKY-NA-Feed-SMART-2231655-WF-Apex_HandTools_Q4_D25T_Paid_Search&cm_mmc=Shopping-VF-F_D25T-G-D25T-025_001_HAND_TOOLS-HUSKY-NA-Feed-SMART-2231655-WF-Apex_HandTools_Q4_D25T_Paid_Search-71700000088409703-58700007477940396-92700067211800391&gclid=CjwKCAiA866PBhAYEiwANkIneJ82Eqx88364-5ufhxk4mSv-xk5x21o3cLrwktTyVWTTBlXHhfINNxoCGcwQAvD_BwE&gclsrc=aw.ds#overlay

I hadn't seen those before, but it's a socket set designed to do what I do.

Nice!

Dremmeling the ring out a little also helps with the ring catching the spark plug threads. Along with that fancy socket and a slightly larger ring should help with spark plug off and on.

Lots of good stuff here.
Like the dremeled heat sensor ring.
Choke is pretty slick as well Ray.
FM - I assume you were removing the spark plugs original washer when using the CHT? It acts as you washer.
Should have asked if you had done that in prior posts.

Yeah I took the crush washer off. I sprayed some copper gasket on the CHT sensor ring figured that's better than nothing.

I did manage to kick her over to test the speedo in a 44° shop without the choke. First kick no less. So I'm not sure I'll ever need to use the choke pull I made! I do like the dremel the ring tip. It gets caught up just enough to be annoying. Gonna do that next time I pull the plug out.

Greetings:

My (Honda/Polini 72cc) experience is that the head bolt reads about 15 degrees cooler than a spark plug ring. And it's a LOT less hassle to remove and reinstall the plug.

Question for the gurus:

Drilled air filter or no air filter?

I have the VMC177 in there with the following jetting:

60/160 pilot
160/BE3/116 for the stack

Trying to tidy up before spring so I can actually ride this thing.

Just put a shorter rear shock spacer. When I'd lift the bike up to work on it I noticed the carb box was getting pushed by the frame. It was also tight getting the carb box top back on and off. Much better now. No rubbing at all. And put longer nuts on the split rims with blue lock tite.
Speaking of wheels, does anyone make a drum with longer studs on them? I'm worried the nuts ain't on there enough. I could be over thinking that though. See below.

It's a got danged heat wave! Gonna pop out on Saturday for my first ride. Can't wait!!!

Dont forget the sunblock and shades

Hot DAMN!

Do you even have any idea how long I have been waiting for this moment and nearly gave up?

And I hope you have an official videographer lined up to document the moment so you can share it all with us!

From way back LAST YEAR when you got it running nicely, but no lites:

Boy did I ever fiddle a fuss with them damn lights! Funny how it's always the simplest solution. Going to have to run a new kill wire but that can wait till after the first ride!

She made her way outside today! I did cheat and rode her around to the side of the house but no video of that sorry.

First ride is tomorrow. Here she is basking in the heat and sun!

That's sounding great! Idles like a top

Is the sunblock for me or the scoot? She ain't seen the sun in decades! I at least left the house a week or so ago…

Sounds good!
Nice little purr.

Dig it!!!

correct!