GL with p200 motor running badly...help?
Post Reply    Forum -> Not-So-Modern
Author Message
Evil
86 T5, 71 Sprint, 63 GL
Joined: 30 Oct 2014
Posts: 666
Location: Oak Brook, Illinois
Thu Apr 29, 2021 4:14 pm quote
I have a 1963 GL with a freshly rebuilt P200 motor and sip road 3 exhaust in it. Iím having a hard time getting to run right.
First the symptoms...
It will start right up
The idle is choppy but it will continue to on the stand
Throttle response on the center stand is good.
When I ride the scooter, it accelerates well but it will buck and hesitate when I back off the throttle.
Once this starts, I can pull in the clutch lever but the scooter still wants to cut out and die, unless I go to past half throttle and basically rev the motor.
By the time I get the scooter back home, it wonít stay running anymore..
What Iíve tried so far...
New spaco 24-24 carb, main stack 160-BE3-118, idle jet 55/160
Set the mixture screw 3 turns out, and 2 turns, etc, etc
Set the timing with a timing wheel and gun, scooter fires at 24 degrees before TDC
Spark plug looks black
Tried a different idle jet
Checked compression, itís only 90 psi
Ran w/o air filter
The scooter has a scored rotary pad, but I donít think thatís the problem.
Running out of ideas, not sure what to try next.
Video to follow.




Addicted
GL, PK, PE200 with hack, Sears Rust Badge
Joined: 24 Apr 2012
Posts: 995
Location: Deep in the heart of Texas
Thu Apr 29, 2021 4:27 pm quote
From my limited observation, 1st check is the choke cable at the carb. Is it all the way in or is it pulled out a little bit? To me, on the video it seems a lil out but I could be wrong.


It seems the choke arm is pulled out and s/b more toward the float bowl



Last edited by rowdyc on Thu Apr 29, 2021 5:09 pm; edited 1 time in total
Ossessionato
VSX, Stella 177, VNX1T, V9B1T
Joined: 20 Jul 2018
Posts: 2990
Location: Staten Island, NY
Thu Apr 29, 2021 4:42 pm quote
What's your plug look like?

The dying on idle after warm sounds like mine when I'm rich on idle and fouling plugs fast.i also have to slightly hold throttle at lights to keep it from dying when idle is very rich. But your other symptom of bucking when letting off throttle sounds like a lean idle. So check your plug after using on stand and it dies. Also try turning af screw in half a turn to see if it stops the dying at lights.
Ossessionato
62 VBB1T Round Tail W/ leaner sidecar
Joined: 26 Jan 2019
Posts: 2241
Location: california
Thu Apr 29, 2021 5:01 pm quote
I'm with them.
Sounds rich at bottom end to me.
Perhaps start by running the mixture screw in a bit - and see if it moves you in the right direction.

You could also run at low throttle for a few minutes and then pull the plug to see if it looks wet - I suspect it will.
Enthusiast
Vespa 125 VMA, Vespa SS 180
Joined: 14 Feb 2018
Posts: 75
Location: Minneapolis, MN
Thu Apr 29, 2021 5:37 pm quote
You mention 90 psi compression. You might want to check that the head nuts are torqued and that you have a good seal at the head and cylinder base. This has caused me issues like you describe.
Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: 21 Oct 2005
Posts: 8701
Location: The state of insanity, SoCal
Thu Apr 29, 2021 6:00 pm quote
90 is low and Iím thinking air leak. Or something along those lines.

Also, bump that idle up. At three turns youíre nearly into the main.

Double check all connections and make sure youíre not sucking air.
bodgemaster
63 GL, 76 Super (x 2), 74 Primavera (x 2), 06 Fly 150
Joined: 26 Sep 2013
Posts: 5830
Location: So Cal
Fri Apr 30, 2021 7:14 am quote
Concur with rowdy & greasy ...

1. Check that choke is closed all the way.

2. Idle sounds too low. Twist it up a couple hundred rpm.
Evil
86 T5, 71 Sprint, 63 GL
Joined: 30 Oct 2014
Posts: 666
Location: Oak Brook, Illinois
Fri Apr 30, 2021 11:20 am quote
I checked the choke cable itís okay, also replaced carb and carb box gaskets, and correctly torqued cylinder head. I want to spray around the cylinder while itís running to check for air leaks but the type of spark plug lead that I have arc all over the place with the cylinder shroud removed. Iím going to see if I can find an NGK spark plug lead today.
The scooter is running even worse today, jerky, idle speeds up then slows down, for no apparent reason.
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: 14 Jun 2017
Posts: 2755
Location: London UK
Fri Apr 30, 2021 11:36 am quote
There seems to be a bit of white smoke when revved. Before running too much check the gear oil level is still there. If the main seal has fell out it will be making a mess of the casing.

As said 90psi is way too low, if it has been measured with a 2 stroke pressure gauge. If its a 4 stroke pressure gauge its probably more than 90psi in reality.
Evil
86 T5, 71 Sprint, 63 GL
Joined: 30 Oct 2014
Posts: 666
Location: Oak Brook, Illinois
Fri Apr 30, 2021 12:07 pm quote
Jack221 wrote:
There seems to be a bit of white smoke when revved. Before running too much check the gear oil level is still there. If the main seal has fell out it will be making a mess of the casing.

As said 90psi is way too low, if it has been measured with a 2 stroke pressure gauge. If its a 4 stroke pressure gauge its probably more than 90psi in reality.
Jack. I think you may be onto something, the scooter took 5 ounces of gear oil, and I havenít noticed any oil on the garage floor.



Ossessionato
76 Sprint V, 63 GL, 62 VBB, 05 Stella
Joined: 16 Jun 2011
Posts: 3201
Location: Nashville
Fri Apr 30, 2021 12:31 pm quote
That motor sounds all kinds of off. Also, it sounds like like it's misfiring, not just idling poorly, so you could have electrical issues clouding the issue further.
Evil
86 T5, 71 Sprint, 63 GL
Joined: 30 Oct 2014
Posts: 666
Location: Oak Brook, Illinois
Fri Apr 30, 2021 1:36 pm quote
From what I understand, the top end sucks in the gear oil until thereís basically none left, and from that point the motor is sucking air, and then it is air leak. I think thatís what happened between yesterday and today.
I donít mind pulling out the motor, splitting the cases and installing new seals, I hope the clutch seal is intact and hasnít damaged the cases.
Jet Eye Master
PX221 MHR, O tuned PX200, PX125 and some motorbikes
Joined: 14 Jun 2017
Posts: 2755
Location: London UK
Fri Apr 30, 2021 2:44 pm quote
Vpfalcon wrote:
Jack221 wrote:
There seems to be a bit of white smoke when revved. Before running too much check the gear oil level is still there. If the main seal has fell out it will be making a mess of the casing.

As said 90psi is way too low, if it has been measured with a 2 stroke pressure gauge. If its a 4 stroke pressure gauge its probably more than 90psi in reality.
Jack. I think you may be onto something, the scooter took 5 ounces of gear oil, and I havenít noticed any oil on the garage floor.
White smoke and missing oil are big clues. As it's just been rebuilt there are two possibilities, seal fell out ( less bad if full rubber ridged type) or too much gasket sealer, causing to oil sucker issue (fingers crossed it's that).
Be sure to pressure test it after.
Evil
86 T5, 71 Sprint, 63 GL
Joined: 30 Oct 2014
Posts: 666
Location: Oak Brook, Illinois
Mon May 03, 2021 2:09 pm quote
I pulled the motor and opened the cases to see what was up with the clutch side seal. The seal looked okay, not only that but when I drained the gear oil, before pulling the motor, to my surprise, nearly 12 ounces came out.
But I did spot a possible problem. The circlip holding the clutch side bearing in place was not seated all the way into the groove. Even when I tried to pop it in.
I know Iím grasping at straws here, but is it possible that actuating the clutch lever was moving that bearing? Causing problems?
In other news, I ordered a new piaggio 200 top end. And Iím planning to pressure test the motor before I install it this time.



Ossessionato
1979 P150X, 1983 P200E, 1988 T5, 1995 PX200E, 2011 Yamaha Fazer 600 S2
Joined: 02 Aug 2015
Posts: 2261
Location: Veria, Greece
Mon May 03, 2021 2:17 pm quote
That's definitely your problem. Crank moves a bit when clutch is pulled so having the circlip out of place probably moved the bearing along with the seal...
  DoubleGood Vespa T-Shirts  
Post Reply    Forum -> Not-So-Modern
[ Time: 0.0400s ][ Queries: 25 (0.0203s) ][ Debug on ][ Thing Two ]