Help! polini/phbg/hpi GURUS!

I call upon the power of the Guru universe to help this possible brainfart...


the bike has

polini 64

polini 4p reeds

hpi cdi



This bike ran and ran and ran well. Its a push start, and i had to push real fast, and had to have the clutch cable set to very hard, so push fast pull choke hard.

I took a few things apart and made a few changes. now I don't have a working ped.


when i push now, and look at the hpi while holding the clutch, it really doesn't spin much. I've tried to tighten and loosen clutch cable giving different grab strengths but to no avail. If i hold lightly and push slow, it turns quite a bit, but as soon as i run and hop on the spinning becomes intermittent (even at different clutch cable tightness')?

When i push and pull clutch, it just slows to a stop, im not even really getting glug glugs glugs.

I counter checked to make sure im not crazy against other mopeds, and when holding the clutch and pushing/pedaling the flywheel/ or spinning mass was spinning consistently

bike has compression, i took the head off and made sure the piston/ rings weren't broke. all good there

I took the phbg off, all clean. After trying a few pushstarts, the inside of the intake is all wet.

I drained oil, and refilled to make sure it was fresh and had correct levels.

bike has spark. when i hold the plug to the side of the head and can see little sparks.

as for the hpi, when I've changed the setting btdc. however its a range of 2mm btdc to 4 btdc. runs at about three, and that's where i had it when everything was reliable.

help me trouble shoot please!

I really want to think this thing is have a clutch issue but I don't understand how or what.


Re: Help! polini/phbg/hpi GURUS!

"I took a few things apart and made a few changes."

elaborate please.

Re: Help! polini/phbg/hpi GURUS!

the changes include, but mostly shouldn't matter?

changed intake from one i fabricated (used when the bike was working, to the stoke one that the polini 4p comes with.

i loosened my clutch springs:

3 shoe clutch, paz springs.

the bike originally ran with the spring tension i set, then i tightened the springs all another half turn each to try and get higher rpms. rode like this the entire time. I turned back that 1/2 turn hoping i wouldn't have to push start as hard to get them to engage like i had been.

the oil changed and put in atf type f

Re: Help! polini/phbg/hpi GURUS!

sorry for bumping so fast, trying to get it done.

dismantled entire engine to see the inside.

everything is in good shape.

having a real hard time getting clutch off of the crank.

another question to pose as well: before when it was running, should I have had to push start it very fast and have the clutch cable set tight to grab super hard?

Re: Help! polini/phbg/hpi GURUS!

got any pics of the start clutch being pulled??? you mite not be getting the right angle and so the cable is not pulling the right direction, making it impossible... we had the same problem w/ a magnum, the guide for the cable on the frame broke and the guy had it running kinda stiright at the starter clutch puller thingy, wich in turn just kinda pulled it dhwn towards the case more then stright at it..

Re: Help! polini/phbg/hpi GURUS!

i tore the entire engine apart to check everything, hey why not haha...

if you can post pics or links to the correct way anyways let me know?

as far as i know, when you install onto the ped, the lever should make 90 degrees with the bike, and when pulled it should move towards the front of the bike. on the inside the piece (flat / rounded piece) should sit flat in front of the clutch assembly?

then when pulled, the flat part should rotate to make contact?.

Re: Help! polini/phbg/hpi GURUS!

sorry late night bump:

this thread from last year, basically states

3 shoe clutch + top racing crank = no woodruff key

this thread was saying the starter plate wasn't the problem but the clutch itself was slipping on the crank.

I'm pretty sure I torqued that baby in there, but I meet these same requirements:

top racing crank

3 shoe clutch

have to have cluch cable tightened realy tight, and pull the shit out of it....

so my question before i trouble shoot later today, is any fixes found, the thread dies off. . .

Re: Help! polini/phbg/hpi GURUS!

sounds like it wouldnt be your drive clutch slipping, it sounds more like a starter clutch issue. maybe move the starter lever a spline or two?

Re: Help! polini/phbg/hpi GURUS!

after checking over everything and reading, I agree it's a starter clutch / plate issue and not the clutch slipping on the top crank.

what are my options to make this grab better? I have the correct washers/circlips before and after on the crank.

Re: Help! polini/phbg/hpi GURUS!

what mike said. rotate the starter arm a spline or two clockwise.

Re: Help! polini/phbg/hpi GURUS!

explain why clockwise though so I can make sure I fully undertand why I'd be doing that?

Re: Help! polini/phbg/hpi GURUS!

sorry CCW if you're looking at it from the top. so it pushes the starter plate harder with the same amount of pull.

Re: Help! polini/phbg/hpi GURUS!

yeah that's what I was thinking.

question though, before i took the engine apart to check everything. i had the lever at "stock position" but the cable was adjusted to the max and when I pulled it was extremely tight, adjusting the arm ccw should relieve some of that force needed?

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