Thu Sep 09, 2021 11:22 am

Enthusiast
2005 & 2006 Piaggio Typhoon 50
Joined: 13 Sep 2020
Posts: 58
Location: Calgary, AB, Canada
 
Enthusiast
2005 & 2006 Piaggio Typhoon 50
Joined: 13 Sep 2020
Posts: 58
Location: Calgary, AB, Canada
Thu Sep 09, 2021 11:22 am linkquote
I have been having an issue lately when after riding for 15-20mins every time come to a stop and then go to take off the engine cuts out / misses / lugs 2 or 3 times till it picks up and goes. Really seems like a fuel problem, but strange that I can keep going and it never completely stalls.

I'm wondering if maybe once warm the engine isn't pulling enough of a vacuum at idle (when stopped at an intersection) and it drains the bowl and then when taking off it uses the little fuel that's left and then lugs until it draws a bigger vacuum.

If that is the case I guess I should replace vacuum line first and then maybe the fuel line itself? I did replace the fuel petcock (due to it not shutting fuel off) but the problem existed before doing that.

Any other ideas welcome to hear. If it's vapor lock can I just take out the "filter" on the vent line in case it's causing a blockage?

Thanks,
Lewis


Is it possible this green "filter" gets plugged and causes vapor lock?

Wed Sep 22, 2021 8:02 am

Enthusiast
2005 & 2006 Piaggio Typhoon 50
Joined: 13 Sep 2020
Posts: 58
Location: Calgary, AB, Canada
 
Enthusiast
2005 & 2006 Piaggio Typhoon 50
Joined: 13 Sep 2020
Posts: 58
Location: Calgary, AB, Canada
Wed Sep 22, 2021 8:02 am linkquote
Follow up that I've got it fixed.

Did the following:
1) Replaced the fuel and vacuum line with new lines
2) Removed tank vent line check valve
3) Took carb apart and cleaned thoroughly with carb cleaner and blew out passageways with compressed air.

Ended up with a Yasuni Z exhaust (removed restriction), 75 main jet (we are at ~3300 ft elevation), 5.7 gr rollers, removed brass plate and a Malossi red sponge filter. Runs great, pulls hard.


New hoses, nice that fuel line is transparent so I can confirm fuel flow.


No more sticking check valve. I know this poses a risk in a tip over but I'm ok with that to get a running scoot.

⬆️    About 2 months elapsed between posts    ⬇️
Wed Nov 24, 2021 6:54 am

Enthusiast
2005 & 2006 Piaggio Typhoon 50
Joined: 13 Sep 2020
Posts: 58
Location: Calgary, AB, Canada
 
Enthusiast
2005 & 2006 Piaggio Typhoon 50
Joined: 13 Sep 2020
Posts: 58
Location: Calgary, AB, Canada
Wed Nov 24, 2021 6:54 am linkquote
So this problem has reappeared but slightly different. Now if I'm sitting idling after riding for a while I have to "roll" into the throttle because if I "crack it" open it just bogs.

Also which I think is related, is that if the bike sits for a week or more without starting, it takes 20-30 seconds of cranking to fire up. Its like the float bowl is empty and it needs to refill (acts just like after a carb service when the bowl is drained). Last week I went to start it after sitting and it would crank and crank and not start. Checked spark and all good but plug was dry so figured its not getting fuel. I manually provided vacuum to the petcock and it fired right up.

I then checked (just with my thumb over the hose) if i was getting vacuum from the carb and I was but maybe it's not enough to open the petcock fully.

This is a new (3 months) petcock so I wouldn't think it was the issue.

Is it possible that I'm not getting sufficient vacuum level on cranking and idle to open the petcock fully? Is there a way to test this?

Thanks
Wed Nov 24, 2021 9:39 am

Hooked
2003 Vespa ET2
Joined: 05 Apr 2019
Posts: 446
Location: Cambridge, MA
 
Hooked
2003 Vespa ET2
Joined: 05 Apr 2019
Posts: 446
Location: Cambridge, MA
Wed Nov 24, 2021 9:39 am linkquote
i bet the idle jet is clogged...i would thoroughly clean the carb again

also...check the compression...thats the worst case scenario but that would also explain why its not pulling vacuum
Wed Nov 24, 2021 9:56 am

Enthusiast
2005 & 2006 Piaggio Typhoon 50
Joined: 13 Sep 2020
Posts: 58
Location: Calgary, AB, Canada
 
Enthusiast
2005 & 2006 Piaggio Typhoon 50
Joined: 13 Sep 2020
Posts: 58
Location: Calgary, AB, Canada
Wed Nov 24, 2021 9:56 am linkquote
jixaw wrote:
i bet the idle jet is clogged...i would thoroughly clean the carb again

also...check the compression...thats the worst case scenario but that would also explain why its not pulling vacuum
I took the carb apart and cleaned it really well. Removed both jets and blew out with carb cleaner and then compressed air. Did the same for the passages in the carb body itself so don't think this is the issue.

I will do a compression test ASAP once I find the right equipment. What should be the range on the compression test? Cold versus hot engine?

Thanks for the response.
Wed Nov 24, 2021 11:11 am

Ossessionato
73 & 74 Rally, 76 ET3, 80 P200, 06 PX150, 61 Ser 2, 65 Silver Special, 86 Elite 80, 2015 HD Road Glide Special, 2011 Ural Tourist
Joined: 18 Jan 2012
Posts: 4110
Location: Oceanside, CA
 
Ossessionato
73 & 74 Rally, 76 ET3, 80 P200, 06 PX150, 61 Ser 2, 65 Silver Special, 86 Elite 80, 2015 HD Road Glide Special, 2011 Ural Tourist
Joined: 18 Jan 2012
Posts: 4110
Location: Oceanside, CA
Wed Nov 24, 2021 11:11 am linkquote
On the older vespas, we're shooting for 110 psi or higher cold but will settle for low 100s. Anything lower will still run, but either be a bitch to start, or will be gutless at higher rpms. Should be close to the same for the modern reed valve two strokes.
Thu Nov 25, 2021 8:32 pm

Enthusiast
2005 & 2006 Piaggio Typhoon 50
Joined: 13 Sep 2020
Posts: 58
Location: Calgary, AB, Canada
 
Enthusiast
2005 & 2006 Piaggio Typhoon 50
Joined: 13 Sep 2020
Posts: 58
Location: Calgary, AB, Canada
Thu Nov 25, 2021 8:32 pm linkquote
So I was able to borrow a compression tester and tested both the 2006 and the 2005 scooters. Both cold with throttle held open, cranked for 3-5 seconds. Did the multiple times on both and the readings were consistent on both at 70 psi. That seems really low but both seem to run well so am I missing something here?


2005 Typhoon


2006 Typhoon

Thu Nov 25, 2021 9:59 pm

Ossessionato
73 & 74 Rally, 76 ET3, 80 P200, 06 PX150, 61 Ser 2, 65 Silver Special, 86 Elite 80, 2015 HD Road Glide Special, 2011 Ural Tourist
Joined: 18 Jan 2012
Posts: 4110
Location: Oceanside, CA
 
Ossessionato
73 & 74 Rally, 76 ET3, 80 P200, 06 PX150, 61 Ser 2, 65 Silver Special, 86 Elite 80, 2015 HD Road Glide Special, 2011 Ural Tourist
Joined: 18 Jan 2012
Posts: 4110
Location: Oceanside, CA
Thu Nov 25, 2021 9:59 pm linkquote
Happy Thanksgiving from your neighbors to the south! Normally you keep cranking until the needle on your gauge stops moving. Did you notice the needle still moving after your 3-5 second cranks?

If so, and both scooters are running good wide open throttle then I'd say that 70psi is good for the 50cc models.

Focusing elsewhere, I'm thinking jetting. If it's too rich it'll bog hammering the throttle. Can you raise the clip/lower the needle and see if that fixes acceleration?

As far as a petcock issue, can you verify the rubber manifold isn't cracked and leaking anywhere?
Fri Nov 26, 2021 6:02 am

Member
gts 300
Joined: 20 Nov 2020
Posts: 30
Location: west michigan
 
Member
gts 300
Joined: 20 Nov 2020
Posts: 30
Location: west michigan
Fri Nov 26, 2021 6:02 am linkquote
Did you install stiffer springs on the clutch? When you have an aftermarket exhaust the powerband is raised, and there can be lag/bog if the clutch engages at too low of an rpm.

Pretty much a necessary thing to do if you put on an expansion chamber exhaust.

Once you get into engine mods, a lot of things will have a similar symptom. Bogs/lags can be from springs in the clutch and torque convertor, incorrect carb tuning, or variator issues - and you have to determine what is causing the problem.

I had an off-idle lag in one scooter that I chased for a long time. Lots of carb tuning, new carb, roller changes, spring changes, etc. and it still lagged. Finally figured out that the aftermarket variator set-up needed a 1mm spacer between the boss and the drive face. Problem gone. Such a simple thing and yet it took so long to chase, Good luck with the tuning.

Oh, and the compression testing- it seems like with the 50/70 cc engines the compression reads low. Not sure why, but I don't think that they read accurately with the smaller motors. If they fire up and run thru the rpm range you are probably good to go.
Sat Nov 27, 2021 11:31 am

Enthusiast
2005 & 2006 Piaggio Typhoon 50
Joined: 13 Sep 2020
Posts: 58
Location: Calgary, AB, Canada
 
Enthusiast
2005 & 2006 Piaggio Typhoon 50
Joined: 13 Sep 2020
Posts: 58
Location: Calgary, AB, Canada
Sat Nov 27, 2021 11:31 am linkquote
MJRally wrote:
Happy Thanksgiving from your neighbors to the south! Normally you keep cranking until the needle on your gauge stops moving. Did you notice the needle still moving after your 3-5 second cranks?

If so, and both scooters are running good wide open throttle then I'd say that 70psi is good for the 50cc models.
Yes this was the highest point the pressure got, testing multiple times cranking till needle stopped moving. Just referenced the approx time since it didn't take very long to hit the max compression.
MJRally wrote:
Focusing elsewhere, I'm thinking jetting. If it's too rich it'll bog hammering the throttle. Can you raise the clip/lower the needle and see if that fixes acceleration?
Clip is in top spot and it runs great most of the time just every so often it doesn't respond from idle, that's why I was thinking intermittent fueling from petcock.
MJRally wrote:
As far as a petcock issue, can you verify the rubber manifold isn't cracked and leaking anywhere?
Not sure how to do this. There isn't gas/oil staining or anything indicating a leak so nothing obvious.
Dan V. wrote:
Did you install stiffer springs on the clutch?
I have Jasil green springs (+15%) installed when I serviced the clutch.
Dan V. wrote:
Oh, and the compression testing- it seems like with the 50/70 cc engines the compression reads low. Not sure why, but I don't think that they read accurately with the smaller motors. If they fire up and run thru the rpm range you are probably good to go.
They fire up and run good through the rev range, when fuel is flowing properly from petcock haha. Thanks for the confirmation on test numbers being ~ok
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