JB Welded Front Sproket Removal

Anthony Lea /

May 07, 2019 08:51AM

Recently brought home a 1978 Cimatti City. Bike as a summer project/commuter and found the sprocket was cracked and held together with what looks like to be JB weld.

I shouldn’t be surprised as one of the rear frame rails is bubblegum tacked together as well.

My question is does anyone have any ideas to get this off without pulling the motor and replacing the whole output shaft assembly?

Also attached photo of rear sprocket to get opinions on if I should swap that out while I’m replacing tires or whether it’s still salvageable.

Re: JB Welded Front Sproket Removal

Moped Lar /

mopedlar

May 07, 2019 09:13AM

Rear sprocket is shot. Replace it!

Re: JB Welded Front Sproket Removal

Dirty30 Dillon /

hydra

May 07, 2019 09:22AM

That's not JB Weld, that is actual Weld.

Re: JB Welded Front Sproket Removal

Anthony Lea /

50ccc OP

May 07, 2019 09:25AM

I figured as much, mine as well as I’m replacing front and rear tires with the SR714 tread!

Re: JB Welded Front Sproket Removal

Anthony Lea /

50ccc OP

May 07, 2019 09:27AM

> Dirty30 Dillon Wrote:

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

> That's not JB Weld, that is actual Weld.

Thank you for the clarification. Sounds like I’m going to have to split the case to replace that output shaft. Any recommendations on what to modestly refresh while I’m in there?

Will eventually be upgrading to 75cc but for now would like to stick to a low budget build to get it on the road comfortably and reliably.

Re: JB Welded Front Sproket Removal

Dirty30 Dillon /

hydra

May 07, 2019 09:49AM

If you are going that far, replace all bearings and seals/gaskets

Re: JB Welded Front Sproket Removal

Anthony Lea /

50ccc OP

May 07, 2019 09:57AM

> Dirty30 Dillon Wrote:

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

> If you are going that far, replace all bearings and seals/gaskets

https://www.treatland.tv/minarelli-V1-complete-engine-rebuild-set-p/minarelli-v1-rebuild-set.htm

This should do the trick!

Re: JB Welded Front Sproket Removal

Anthony Lea /

50ccc OP

May 07, 2019 02:10PM

Rather than posting another thread I’ll just ask here as it still is regarding sprockets.

Knowing I’ll be upgrading to 75cc in the near future is there a gear ratio anyone can suggest to upgrade to now while I am replacing both sprockets? My understanding is 13 for the front sprocket will add top end however I am new to the moped forums and am open to suggestions!

Thanks in advance!

Re: JB Welded Front Sproket Removal

cheetahchrome . /

cheetahchrome

May 07, 2019 03:55PM

If the seal is not pouring out case oil I would just leave it for now. Yes to replacing the rear sprocket now. The n throw on a chain and enjoy the bike till you decide it is necessary to do a full restoration

Re: JB Welded Front Sproket Removal

Anthony Lea /

50ccc OP

May 07, 2019 04:09PM

> cheetahchrome . Wrote:

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

> If the seal is not pouring out case oil I would just leave it for now.

> Yes to replacing the rear sprocket now. The n throw on a chain and enjoy

> the bike till you decide it is necessary to do a full restoration

Not oil pouring out but with that sprocket welded on I don’t know of another way to replace that sprocket without removing the entire output shaft.

Re: JB Welded Front Sproket Removal

cheetahchrome . /

cheetahchrome

May 07, 2019 04:30PM

Well if you dont think the repair is hazardous I would ride the hell out of it for now to see if it is a bike that I want to restore and keep.

Other wise yes to parting the cases and going the full meal deal

Re: JB Welded Front Sproket Removal

Anthony Lea /

50ccc OP

May 07, 2019 05:22PM

> cheetahchrome . Wrote:

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

> Well if you dont think the repair is hazardous I would ride the hell out

> of it for now to see if it is a bike that I want to restore and keep.

>

> Other wise yes to parting the cases and going the full meal deal

I’ve rode it 5+ miles and had a blast, until the chain locked up (sprocket is the culprit) so I feel pretty good rebuilding it. Thanks for the help guys, now it’s time to figure out what sprockets to order from treatland tonight

Re: JB Welded Front Sproket Removal

Brandon Weiss (Detective brandon to you) /

mopedallday

May 07, 2019 05:33PM

Keep in mind that you need clearance between the sprocket and the case, some larger sprockets will require the case to be ground away for clearance. Or so I've heard. Just sold my only minarelli bike, I kept the stock 10 tooth front with a 44 or 45 in the back, did 35mph with 16 inch wheels on the stock lightly ported cylinder with a pipe. Keep in mind I'm 160lbs fully dressed.

With a cylinder kit you can afford taller gearing without losing much low end. But depending on swingarm clearance, it may make more sense to change the rear sprocket to a smaller one than the front to a larger one, to avoid grinding the case.

Seeing as you're replacing both sprockets anyway, I would check and see how much room you have, and report back. You'll probably want to go with somewhere around 10 x 42 gears, just a guess? Dont want to rev too high with a bushing crank if you have one. Keep it under 9k http://toolbox.martysgarage.info

Just my .2 (edited)

Re: JB Welded Front Sproket Removal

pat splat /

ggspeed

May 07, 2019 08:13PM

if u cant tell the difference between jb weld and real metal then... i also say leave it and ride it, just get a new sprocket n chain.

Re: JB Welded Front Sproket Removal

Richard Eberline /

rockettman

May 07, 2019 08:54PM

front sprocket is worn, dremmel it off. The drive sprocket is the main one and heats up must have a very little amount of play.

Re: JB Welded Front Sproket Removal

EH 📣FCC of the QCB /

Go to branch

ericqcb

May 08, 2019 06:15AM

How do you know if the chain or the motor locked up? Does the motor still spin? Just askin.

Re: JB Welded Front Sproket Removal

Anthony Lea /

50ccc OP

May 08, 2019 07:37AM

> Baron Von Hamilton Wrote:

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

> How do you know if the chain or the motor locked up? Does the motor

> still spin? Just askin.

Motor does still spin. Chain jumped off sprocket and locked itself between sprocket and casing.

I figure with the worn front and rear sprocket it is likely to happen again if I do not fix the issue now vs just resetting the chain and considering it a job well done.

Re: JB Welded Front Sproket Removal

Anthony Lea /

50ccc OP

May 08, 2019 07:39AM

> Richard Eberline Wrote:

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

> front sprocket is worn, dremmel it off. The drive sprocket is the main

> one and heats up must have a very little amount of play.

That’s a great idea, thank you for that. Motor is currently detached from the frame however I haven’t started splitting it yet so I may look into dremmeling the sprocket off first.

Re: JB Welded Front Sproket Removal

pat splat /

ggspeed

May 08, 2019 08:17AM

prove me wrong, your never gonna put it back together...

Re: JB Welded Front Sproket Removal

Anthony Lea /

50ccc OP

Jun 10, 2019 12:55AM

Might be better to post a new thread for more relevant responses but I figured I’d reuse my old thread first rather than clog the forum up further....

Came across this today while beginning the rebuild on the V1, didn’t get too far because Treatland didn’t include a piston stop in my recent order with them.

Is this something that will affect my Motors performance or something I should attend to or is this purely an aesthetic part of the case?

*should’ve clarified I’m referring to the missing bit on the inside of that case just north of the sprocket. Found case bits nestled inside that fell out when rotating the engine side to side to remove both covers. (edited)

MOPED ARMY

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