Moster pull start struggles to retract

[JP Tulo]

Hey all, I’ve been having more and more trouble with my pull-start cord not retracting back on the spool after a few pulls. The symptoms seem to get worse the colder it is. I had a lot of trouble with this early in the engines life(less than 10 hours) but it progressively went away. Now it’s starting to be an issue again. After the motor starts sometimes I’ll pull it out a little to try and build up some momentum to pull it back in and it makes a high pitched unhealthy sort of sound. I’m unsure of the inner workings of the Moster/starter but I understand the concept. I assume there’s a one-way bearing in there somewhere. Are those common wear items? How often do pull-start springs need replaced? The motor has about 90 hours on it.

On a somewhat related note, it is REALLY difficult to turn over sometimes. Feels like it has an unnatural amount of compression going on in the combustion chamber. I remember reading somewhere about a pressure relief valve or port or something like that that can get gummed up. Does anyone have any insight? Thanks in advance for any light you can shed on these issues for me!

-JP

[Hann__]

I`ve had that pull start not retracting thing on my Moster over the years and have had the start mechanism off a few times to fettle it...

How old is your motor - classic or more modern?

Like you, i`ve had to do that jiggle where you pull the pull start handle out a tad (and get that noise) then release quickly to try and encourage the cord to get pulled back.

Back in the early days Vittorazi issued a kit to fix this problem consisting of a plastic/ptfe washer which fitted between the cord drum and starter cage and which was designed to reduce the friction of the cord drum  against the cage. This worked on mine for a while until the vibration and fretting from the engine vibration wore the washers` diameter down and it caused more friction/sticking when it slid out of position.

I finally cured it by actually screwing the plastic washer in place (to the starter cage) and it`s been fine for a couple of years now.

Also, don`t be tempted to oil the recoil spring - it just causes stiction and exacerbates the problem. Unwind the spring, clean it but install it back with no lube.

Basically, just do everything necessary to eliminate all sources of friction in the starter system - does the cord have a straight a pull out of the starter as possible? Is your frame pulley in good shape? Cord not catching on harness etc?

 

The `decompressor` is simply a drilling in the cylinder wall half way up between the exhaust port and the top of the cylinder and exits in the exhaust port itself. In effect it bleeds off compression pressure to the exhaust when starting (when the engine is turning over slowly) but has little to no effect when the engine fires and is at normal running speeds.

Maintenence just involves making sure that it is clear - use a steel rod or suitably-sized drill bit and poke it through the hole..

If your engine exhibits unusually high compression only occasionally then it`s probably not this decomp. drilling - they would tend to be either blocked....or not.

[JP Tulo]

Thanks for the reply! I think I got it figured out. There were three shims underneath the clip holding the drum on. The top one was kind of bent and they were binding pretty badly. I removed two of the shims and lubed the shaft going through the drum and put back together and the difference is night and day. I imagine its been binding for the majority of it's life as this has always been somewhat of an issue, however just recently it got so bad that I needed to investigate. I haven't reinstalled the starter yet, but i'm pretty confident I've got'er figured out! 

On a side note: Do WHATEVER you can to avoid pulling the starter cord while the engine is running. I can tell that my paws are slightly damaged from coming into contact with the flywheel from doing that. Difficult to explain, but the damage it's doing is even worse than it sounds in reference to the sound we both described.