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@hjarvis avatar
UTC

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1974 GTR w/ '03 Stella engine (166 Malossi upgrade)
Joined: UTC
Posts: 16
Location: Buffalo, NY
 
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@hjarvis avatar
1974 GTR w/ '03 Stella engine (166 Malossi upgrade)
Joined: UTC
Posts: 16
Location: Buffalo, NY
UTC quote
Running a 2003 LML MY engine in my '74 GTR.

Recently replaced my clutch, crank, shift cross, and some seals (original clutch blew open, crank had lousy slot for the key, cross was worn...)

After the rebuild, I had oil dripping on the wheel side (didn't have a chance to nail it down yet)...

Now am running really smoky and significant loss of power. Can drive, but must rev the engine a lot to get momentum to use lower gears.

Wondering if the smoke and loss of power are classic symptoms to get me pointed in the right direction. We're renovating the house just now and zero time to fix the bike, but it's my transport. Frustrating!
@blake7even avatar
UTC

Hooked
1968 Sprint 175, Lambretta Li185S
Joined: UTC
Posts: 289
Location: London
 
Hooked
@blake7even avatar
1968 Sprint 175, Lambretta Li185S
Joined: UTC
Posts: 289
Location: London
UTC quote
Sounds like a seal leak. You're burning gear oil. Smell your gear oil to see if it smells of fuel. Or drain the oil run for a few mins to see if the smoke goes. Don't do this for long (as it will be lean if you do have a leak) & DON'T ride with no oil in the gearbox)

It's not good to have an oil leak. Could mean the case halfs didn't seat and seal properly. But could just be the rear hub seal.

You can split the case in the scoot to retry a new gasket.
OP
@hjarvis avatar
UTC

Member
1974 GTR w/ '03 Stella engine (166 Malossi upgrade)
Joined: UTC
Posts: 16
Location: Buffalo, NY
 
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@hjarvis avatar
1974 GTR w/ '03 Stella engine (166 Malossi upgrade)
Joined: UTC
Posts: 16
Location: Buffalo, NY
UTC quote
Thanks, blake7even.

I did not relace the rear seal, so that could well be it.
(I didn't realize that would allow oil into the combustion chamber.)

I'll have to see where the external oil leak is coming from.

Then I guess resplit the case.

Great suggestions!
@blake7even avatar
UTC

Hooked
1968 Sprint 175, Lambretta Li185S
Joined: UTC
Posts: 289
Location: London
 
Hooked
@blake7even avatar
1968 Sprint 175, Lambretta Li185S
Joined: UTC
Posts: 289
Location: London
UTC quote
hjarvis wrote:
Thanks, blake7even.

I did not relace the rear seal, so that could well be it.
(I didn't realize that would allow oil into the combustion chamber.)

I'll have to see where the external oil leak is coming from.

Then I guess resplit the case.

Great suggestions!
The rear hub seal won't let oil into the combustion chamber. It's just that might be your leak. Could be two seperate things. It could be that the clutch cover is leaking. Again this wont let oil into the combustion chamber.

If you case seal (gasket) is not sealing this would allow oil out and oil in.. If you get me?

There is a good test where you drain the oil, and plug the exhaust. Then take the carb off and fill her up with diesel fuel with the piston at tdc.

If you leave the oil drain plug out diesel should NOT come flowing out! You can drain it all out from the exhaust.

If diesel comes out split the case and hopefully you see a trace from where it was coming.
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@hjarvis avatar
UTC

Member
1974 GTR w/ '03 Stella engine (166 Malossi upgrade)
Joined: UTC
Posts: 16
Location: Buffalo, NY
 
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@hjarvis avatar
1974 GTR w/ '03 Stella engine (166 Malossi upgrade)
Joined: UTC
Posts: 16
Location: Buffalo, NY
UTC quote
Quote:
... drain the oil run for a few mins to see if the smoke goes. Don't do this for long (as it will be lean if you do have a leak) & DON'T ride with no oil in the gearbox)
I'll try this first.

(Not sure I understand the part about filling the top end with diesel...)
@blake7even avatar
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Hooked
1968 Sprint 175, Lambretta Li185S
Joined: UTC
Posts: 289
Location: London
 
Hooked
@blake7even avatar
1968 Sprint 175, Lambretta Li185S
Joined: UTC
Posts: 289
Location: London
UTC quote
hjarvis wrote:
Quote:
... drain the oil run for a few mins to see if the smoke goes. Don't do this for long (as it will be lean if you do have a leak) & DON'T ride with no oil in the gearbox)
I'll try this first.

(Not sure I understand the part about filling the top end with diesel...)
Yeah do that first. The top end is supposed to be sealed from the bottom. And also sealed from the outside.

If you fill this chamber that is higher than the gear chamber up with diesel it shouldn't go anywhere. If it does you can see where. Simples
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@hjarvis avatar
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1974 GTR w/ '03 Stella engine (166 Malossi upgrade)
Joined: UTC
Posts: 16
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@hjarvis avatar
1974 GTR w/ '03 Stella engine (166 Malossi upgrade)
Joined: UTC
Posts: 16
Location: Buffalo, NY
UTC quote
Quote:
If you fill this chamber that is higher than the gear chamber up with diesel it shouldn't go anywhere. If it does you can see where.
Sorry to be anal, but this sounds like an flood waiting to happen if I don't do this right!

1. drain the crank oil
2. leave drain plug out
3. disconnect exhaust
4. plug exhaust port (with cloth..?)
4. remove carb
5. piston at TDC
6. pour oil into top end (until flush with carb opening..?)

Then see if oil works its way down to drain plug..?

Anything else..?

Thanks!
@blake7even avatar
UTC

Hooked
1968 Sprint 175, Lambretta Li185S
Joined: UTC
Posts: 289
Location: London
 
Hooked
@blake7even avatar
1968 Sprint 175, Lambretta Li185S
Joined: UTC
Posts: 289
Location: London
UTC quote
hjarvis wrote:
Quote:
If you fill this chamber that is higher than the gear chamber up with diesel it shouldn't go anywhere. If it does you can see where.
Sorry to be anal, but this sounds like an flood waiting to happen if I don't do this right!

1. drain the crank oil
2. leave drain plug out
3. disconnect exhaust
4. plug exhaust port (with cloth..?)
4. remove carb
5. piston at TDC
6. pour oil into top end (until flush with carb opening..?)

Then see if oil works its way down to drain plug..?

Anything else..?

Thanks!
Do the smoke test first but yeah.... that would have been a flood with that list!

1. drain the crank oil
2. leave drain plug out
3. disconnect exhaust
4. plug exhaust port with rubber bung, cork old inner tube and cable ties. anything liquid proof.
4. remove carb
5. piston at TDC
6. pour diesel into top end (until flush with carb opening..?)

Then see if Diesel works its way down to drain plug through the seals. Or even works it's way outside the case.

If it starts trickling out the drain plug then drain the upper crank chamber from the exhaust. You may have to tip the scooter to get it all out. Split the cases and hopefully there will be a trace of where the diesel came from. You could use petrol too but it wants to be thin and not damage the seals if they are good.
@v_oodoo avatar
UTC

Style Maven
'74 50s x3 '87 PK125XL '92 PK50XLS Plurimatic - & - '58 AllState '68 Sprint '66(?) Super125 and '72 DanMotor Super150
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Location: seattle/athens
 
Style Maven
@v_oodoo avatar
'74 50s x3 '87 PK125XL '92 PK50XLS Plurimatic - & - '58 AllState '68 Sprint '66(?) Super125 and '72 DanMotor Super150
Joined: UTC
Posts: 9541
Location: seattle/athens
UTC quote
Good plan. I first learned how to do this in an old Scooterworks catalog.

External inline image provided by member with no explanatory text

Scanned it, added Adastra's guide to checking the seal on the rotary pad and posted it on page 3 of 'tips & tricks' so I can find it online whenever I need to.
⬆️    About 1 year elapsed    ⬇️
@bigben avatar
UTC

Evil
p2, jet2, lml166
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Posts: 666
Location: Philadelphia, United States
 
Evil
@bigben avatar
p2, jet2, lml166
Joined: UTC
Posts: 666
Location: Philadelphia, United States
UTC quote
bump: just did a diesel test today. took off the carb and the carb box, rotated the piston to TDC and filled the engine with diesel: nothing came out of the drain plug so it looks like the seal is ok in that reguard.

my main question is how to best get all the diesel out of the engine. for clarification, a bunch came out of the exhaust stub but it still feels like theres some in there, so should I just keep the exhaust stub clear from the exhaust cover the cylinder shroud with a rag, put the panel on and just kick for an hour until all the small bits vaporize out of the intake and plug hole?
@ginch avatar
UTC

Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and '66 Blue Badge Smallframe
Joined: UTC
Posts: 8619
Location: Victoria, Australia
 
Veni, Vidi, Posti
@ginch avatar
74 Super, 75 Super, PX project, LML off-roader and '66 Blue Badge Smallframe
Joined: UTC
Posts: 8619
Location: Victoria, Australia
UTC quote
bigben wrote:
...and just kick for an hour until all the small bits vaporize out of the intake and plug hole?
Try this. It takes out the hard work... which is like Christmas for a lazy man like me.

https://modernvespa.com/forum/post1548049#1548049
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