Moby hard to start

matt madden /
bubba54
Mar 02, 2020 04:58PM

been a while since I've asked for help here but I have 3 bikes, pug, puch, moby.

They all run great but the moby 50V takes far more effort than the other 2 (especially if it's sat for a while).

Anyway, runs fine once started and it starts right up after it's been warmed up and running but to get it started initially it takes a good bit of peddling to fire. btw, with the decomp on and the choke pulled in it definitely has a fair amount of resistance on the pedal stroke then the other bikes...almost feels like a heavy handed clutch holding it back at start up but once running it runs just dandy...

timed at 1.3 btdc, good healthy spark, stock vario and starter clutch etc, stock points ignition, good gas flow

what would you think is the most likely reason?

thx!

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Re: Moby hard to start

Richard Eberline /
rockettman
Mar 02, 2020 07:41PM

2.0 btdc

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Re: Moby hard to start

matt madden /
bubba54
Mar 02, 2020 08:22PM

Seriously?

That seems high but maybe give it shot

Thx!

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Re: Moby hard to start

Justin Petraitis /
jayjaypea
Mar 03, 2020 01:39PM

How's your belt? If it's old, it could be slipping as your pedaling, which would require you to pedal more until it finally turns over. But if you're decomp is working, and you're using it as you should, it really doesn't take a lot of effort to turn over. I have a moby that's a bit difficult to start in what sounds to be the same way, but that's because my decomp is disconnected.

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Re: Moby hard to start

matt madden /
bubba54
Mar 03, 2020 01:56PM

put a new belt on when I got it running a couple years ago so I doubt that's it...

I might try and advance the timing a bit but compared to the pug i have this thing feels like i'm peddling a waterwheel or something...i can kick my pug over in one rotation but the moby i just have to stand on it and pedal, pedal, pedal until it pops to life...just weird.

decomp works fine btw

i can live with it but was thinking if it's something others experienced it might be a simple adjustment...like i said once it's warmed up it will kick over with one pedal stroke...

thx!(edited)

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Re: Moby hard to start

Pushrod Fifty /
supercub
Mar 10, 2020 07:11PM

It wont start with the decomp pulled. Try letting it off as soon as the crank starts spinning or about 1/4 pedal turn. Let off if the choke at the same time.

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Re: Moby hard to start

Rebel Moby /
rebelmoby
Mar 14, 2020 10:17AM

NO - 1,5mm BTDC if you are on points - 1,2mm BTDC if you are on CDI.

Unhappy starting - check the exit pipe on the exhause is not carboned up, that tiny exit restriction blocks easy and if the bike is rarely up to temperature the goop builds there rapidly.

If she is 100% stock configuration, the Gurtner carbs idle jet may be blocked - little screw under the carb, remove and run a thin single strand of copper wire straight up into the carb throat. If that wee hole is blocked then it can not get full enrichment. Also check that the choke piston is actually unblocking the little square hole at the union between carb and intake. If the piston does not lift you will not get full fuel enrichment.

> Richard Eberline Wrote:

> -------------------------------------------------------

> 2.0 btdc

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Re: Moby hard to start

Richard Eberline /
rockettman
Mar 15, 2020 08:09AM

My manual clearly states in black and white 2.0 BTDC

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Re: Moby hard to start

pat splat /
ggspeed
Mar 15, 2020 11:28AM

1.5 - 2 doesnt matter. u can test by shooting some premix in the plug hole before startup. if it immediately fires then its fuel, if not its spark, or... im thinking spark plug as ive had hard to start just from a compromised plug alone. gap it too.

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Re: Moby hard to start

Rebel Moby /
rebelmoby
Mar 15, 2020 05:57PM

2.0 BTDC is to restrict the performance of the bike so it complies with all legislation for all three versions 20-25-30mph.

> Richard Eberline Wrote:

> -------------------------------------------------------

> My manual clearly states in black and white 2.0 BTDC

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Re: Moby hard to start

matt madden /
bubba54
Mar 17, 2020 11:01AM

thx all,

points ignition set to 1.5btdc...new engine blocs...dellorto 15 carb...tuned in pretty well...the thing runs great overall just a slow starter...

decomp works fine, seals all replaced, leak down test is good...

Thx for all the helpful info...I do have a cdi I may throw on it...

one thing to note is when I rebuilt this thing the vario was making a horrible racket (scraping sounds and generally sounded like poo)...disassembled and rebuilt but it still sounds noisy but functions just fine

I'm wondering if it could be the starter shoes rubbing or something???

Anyway, not a big deal but thanks for the help...

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Re: Moby hard to start

Rebel Moby /
rebelmoby
Mar 18, 2020 10:13AM

The starter shoes will drag against the cover a bit, they attack at an angle so they work as a override where they will push but the surface they push can override and run faster that the friction pads.

The retarded timing should have taken care of the vacuum signal loss that is more apparent with the larger bore carb. Did you derestrict the intake to have 15mm straight through to where it transitions from round to rectangle? Also you might want to oring the union between the carb and intake, 11/16 X 13/16 X 1/16 oring will suit the 15mm SHA.

If you run a CDI in the future, set the timing at 1,2mm BTDC.

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