magento plate wobbles

[dalliance]

hi all
i have a problem with the magento plate. it wobbles and hits the magnets on the fly wheel. the timing screw is frozen. i have tried penetrating oil and heating it up but it wont move. any other suggestions before it go after it with the impact ?

how do i correct the wobble ? i had thought that perhaps the fly wheel wasn't all the way down on the shaft so i tightened it up, but that didn't do anything.

my last question is the little screw on the bottom of the magento plate what does it do ?

thanks for all your previous assistance rebuilding this 40 +, hopefully i can get this last problem solved

safe boating
dalliance

[Double Dutch]

Be careful with flywheel magnets hitting the coils.
The pictures explain what happened with my 200CC Villiers motorcycle engine.

[Charles uk]

The most common cause of flywheel wobble, is wear in the top main bearing.
If you hold the flywheel firmly on the rim with both hands & rattle it sideways, any sideways movement is 99% of the time, tired main bearings, the cure is replace them, a job that requires considerable engineering expertise & a special reamer.
More often than not the most cost effective cure is a new crankcase, so in your case talk to Sean in San-Francisco! I am told he has a vast array of British Seagull spares, he recommends you telephone him on 415-861-6124, between 8 and 4 his time, his web site address is www.britishseagulls.com.

A very nice man well worth a call.

[dalliance]

thanks charles for your reply
the fly wheel is ok its pretty solid. its the magneto base plate that's the problem
i took a bold step and hit the locking screw with an impact. eventually the screw broke loose. looked inside the hole and can see where the screw goes.if i hold the base plate up with some clamps and put the screw in and tighten it down it will hold the the base plate but the screw isn't in all the way so therefore its biting just above the hole. what ever it is that has the hole in it has to go up about a 1/8-1/4 inch. i looked thru the manual that i downloaded from this site and i couldn't find a picture of whatever it is that has the hole in it.

thanks again charles

safe boating

dalliance

[chris]

I replaced a wobbly magneto base plate on an old century that belonged to a friend of mine, the motor had done a real lot of hard work, the job was an easy one, the hole that screw goes into is a locating hole for the proper ignition timing, If the base plate is worn this screw will make little to no difference to the rigidity of the base plate as that isn't the purpose of the screw, if the plate is not worn it shouldn't wobble with or without the screw, replacing the plate should fix it

[dalliance]

hi chris

thanks for your response.

it puzzles me that something stationary can wear out. i am guessing that the hole for the locking screw is in the crank shaft bushing. i wonder if it has possibly moved. i would have to take the motor apart to have a look. another thought is if i shim the base plate and tighten the locking screw which would be a little over the
hole,it would stay put.

thanks again chris

dalliance

[Horsley-Anarak]

I would say look at Service sheet No. 5

"RE-TIGHTENING THE MAGNETO BASE"

Looks like there was problem with the screws holding the magneto base.

Not sure if I can post the pictures from the manual.

H-A

[StephenRT]

The procedure mentioned in Service Sheet No 5 is this:

Remove flywheel.

Slacken timing fixing screw in magneto baseplate and remove baseplate.

Accurately countersink the hole in the crankcase spigot to accomodate a Brass 3BA washer ( the simplest way of doing this is to use an 11/32” drill ),reboring the hole to the correct depth …..a good guide is to allow the point of the drill to just commence cutting the bronze top main bearing bush.

Insert the 3BA washer in the recess and hold in place with grease.

Refit the baseplate and screw the timing fixing screw back tightly….it will depress the washer and lock the mechanism and can be re-tightened at any time.

I've never had to resort to this but it may be worth a try.

Steve

[Todd]

I had some luck fixing a loose mag plate on my CPC by removing it and dimpling the crankcase mating surface with a prick punch. Many, many dimples. This raises the surface enough to fill the gap between the crankcase bearing flange and the mag plate. Try a few then test the fit to judge how many and how heavily you want to dimple the surface. As an added measure I applied Loctite green (permanant, gap filling) to insure it doesn't loosen again, but some consider such practice as being un workman-like.

I suspect the mag plate loosens over the years as a result of a less-than-tight locating screw combined with vibration, being used to lift the motor, etc.
Just a word of caution: It is possible to overtighten the locating screw in an attempt to secure the mag plate to the point that the crnakshaft bushing becomes distorted, thus binding the crank.

Todd

[dalliance]

hi all

went out and bought a 11/32 drill bit and a few lock washers. removed the base plate and drilled into it until it just started into the brass. inserted 2 washers into the hole and tightened it up. the base plate is solid now and the magnets are running free

thanks for all your help once again
safe boating
dalliance