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Vespa 150 (VBB2T)
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So now that I've been able to start the old beast, I've noticed that the engine is running a bit rough. What sorts of adjustments to the carb should I consider to correct? If I was guessing, I'd say it's running rich.

Also, I need a new plastic fan that mounts with 4 bolts to the flywheel (has some broken off fins). Where do I find one of these? I can find kits at ScooterMercato or ScooterWorks, but not the individual fan.

After I get the engine running a bit better, I'll begin the complete tear down work to get started on fixing body and paint issues.
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1980 Honda Twinstar and 2004 Yamaha V Star
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1980 Honda Twinstar and 2004 Yamaha V Star
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Here is a procedure for adjusting the carb that I have found useful.

To adjust the mixture from scratch:
Turn the mixture (pilot air) screw clockwise until it lightly seats, then back out 1 and 1/2 turns. This will be close enough to start bike.
Start bike, adjust idle with the screw with spring on it (idle speed screw). Let warm up.
With engine warmed up, open and release the throttle a few times, make sure it returns to its closed position. If necessary, turn engine off and adjust the throttle cable.
With engine idling, adjust idle speed screw for good idle speed.
With engine idling, turn the mixture screw in or out to obtain the highest engine idle speed.
Turn idle speed screw to obtain good idle speed again.
Turn mixture screw in slowly until the engine speed drops just a little.
Turn mixture screw counterclockwise 1/4 turn.
Set idle speed with idle speed screw.
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'60 Allstate VNB1, '60 GS150 VS5, '61 Cushman VBB1, '62 GS160 Mk1 VSB1, '64 GL VLA1, '74 Rally VSE1 200 Euro, '78 P200e VSX, '06 LX150
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@jwilliams avatar
'60 Allstate VNB1, '60 GS150 VS5, '61 Cushman VBB1, '62 GS160 Mk1 VSB1, '64 GL VLA1, '74 Rally VSE1 200 Euro, '78 P200e VSX, '06 LX150
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UTC quote
Whoa! You are saying you have a plastic fan on your VBB2 engine?

Instruct me with pictures, please and thank you. I thought all vintage large frame were aluminum fans. All three VBB engines I have are with aluminum.

Jim
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1965 Vespa SS180, 1963 Lambretta LI150
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@rover_eric avatar
1965 Vespa SS180, 1963 Lambretta LI150
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Location: Detroit, Michigan
UTC quote
jwilliams wrote:
Instruct me with pictures, please and thank you. I thought all vintage large frame were aluminum fans. All three VBB engines I have are with aluminum.

Jim
He has the shitty bajaj 12v CDI kit with the plastic fan on it.

The one scooterworks sells ( Which i think is an absolute turd ).
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Vespa 150 (VBB2T)
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@kslater avatar
Vespa 150 (VBB2T)
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Location: the other side of Mars, PA
UTC quote
jwilliams wrote:
Whoa! You are saying you have a plastic fan on your VBB2 engine?

Instruct me with pictures, please and thank you. I thought all vintage large frame were aluminum fans. All three VBB engines I have are with aluminum.

Jim
I guess I should have been more specific. The machine came with an upgraded (Bajaj?) 12v kit installed. It has a plastic fan that bolts onto the flywheel.
Crappy looking guard with bashed up plastic fan
Crappy looking guard with bashed up plastic fan
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Rover Eric wrote:
He has the shitty bajaj 12v CDI kit with the plastic fan on it.

The one scooterworks sells ( Which i think is an absolute turd ).
Eric, you may have responded earlier and I missed it, but can I buy a Ducati combined CDI / coil and swap that in for the 2 parts I have now? And if so, would it be a simple matter of just matching up the wires correctly? Or is the problem in the parts behind the flywheel as well?
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Vespa 150 (VBB2T)
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UTC quote
Kevin Harrell wrote:
Here is a procedure for adjusting the carb that I have found useful.

<Snip>

Kevin,

I gave your suggestion a try but really didn't make much progress as I was getting a good bit of white smoke, no doubt due to the excessive amount of un-burned fuel that was being pushed thru the exhaust pipe. Looking around for hints it seems to suggest I have an air blockage or stuck choke. I'll give it another try this evening and a shoot a short youtube video. I figure a moving picture is worth a thousand words.
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Vespa 150 (VBB2T)
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Ignition issues
I played around a bit more with the Rat Rod redo project. I had it running for a bit on the street out in front of the house. As it started to warm up, it died. I tried to bump start it on the driveway and noticed a strange and troubling thing: the motor fired a few times and instead of kicking the engine to live it seemed to momentarily lockup the rear wheel. Almost as if it fired way too soon (on the upstroke) and froze the back wheel; in effect trying to push the piston back down and run the wheel backwards.

I'm guessing this is a timing issue and maybe it would explain the rough running and starting problems?

I had a look over on scooterhelp.com and I'm going to look at retarding the timing a bit. As Rover Eric would say, I "(he) has the crappy Bajaj 12v kit that scooterworks sells". I don't know if that makes a difference in how the timing adjustments work or not.
⬆️    About 2 months elapsed    ⬇️
UTC

Member
1979 smallframe, bajaj Priya aka VBB, PX150E Disc Brake
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Posts: 48
Location: Canada
 
Member
1979 smallframe, bajaj Priya aka VBB, PX150E Disc Brake
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Posts: 48
Location: Canada
UTC quote
Have you resolved this? The 12V Bajaj flywheel/stator I have is the same. Did drill new holes in the stator? What was the 'original' timing? 22º?

I have the backwards flywheel issue, and my current solution is to set the idle speed quite high. I'll be going to 17-18º for a Polini kit once I figure out the current timing.

If the timing is indeed 22º as the stator says, then you will need new holes approx. 4mm away from the existing holes, to allow for the stator to be rotated clockwise.
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Vespa 150 (VBB2T)
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UTC quote
stimuli wrote:
Have you resolved this? The 12V Bajaj flywheel/stator I have is the same. Did drill new holes in the stator? What was the 'original' timing? 22º?
I have sort of resolved this. I need to find some time to tear down the engine and replace the most likely leaking oil seal(s). After that, I can get back to finding out how well the timing and carburetor are working.
stimuli wrote:
I have the backwards flywheel issue, and my current solution is to set the idle speed quite high. I'll be going to 17-18º for a Polini kit once I figure out the current timing.
I don't know what the backwards flywheel issue is. Can you enlighten me?
stimuli wrote:
If the timing is indeed 22º as the stator says, then you will need new holes approx. 4mm away from the existing holes, to allow for the stator to be rotated clockwise.
I had a stator with 2 slots and 1 screw hole. To me, this effectively meant I had a fixed stator. So I created a slot where the screw hole was in the 3rd position. Now I can adjust the stator / timing. Like I said above, I need to first replace the seals and I won't be starting that until the school year starts back up and things settle down.
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