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Gg Engine Rebuild


magicmat
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Make some good pictures, preferable not with yr mobile phone, and show us the pitting. I had two barrels done and there is no pitting when done proper, but the pictures must give me a good idea about that.

The piston with no window won't blow any gaskets or damage the small-end. My bike runs with no window so no sweat there.

However when the barrel was designed for a window piston, chances are that you will loose some performance, as the flow will change. Time will tell, maybe you find the performance oke anyway B) You can ask the shop what they think about it, maybe they have experience with the no window piston and will tell you not to worry about it.

Show us the pictures of the barrel ..... fast.

I am interrested :)

Edited by gasgas
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ok, going home this weekend for my 21st !! which i already had on valentines day !! B)

the pitting its....it wasnt there before but its been acid dipped etc, and its chromed over piston,

ill talk to the shop. and find out,

will take pictures and post on monday :)

i JUST want to finish it now !!

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My bike runs with no window so no sweat there.

gasgas I'm presuming your bike is a pro going by your atavar if so this has crank case induction Magicmat bike is cylinder induction so needs the windows in the piston. It might run without the windows but it's not worth using a brand new piston to try it, get it changed for the proper one.

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EXACTLY !

ill go and talk to the shop who got me the stuff, there a well established place, but i wonder if they have overlooked this,

there is a bit missing out of the skirt on one side, but im at uni now, so cant sneek a peek.

PROBLEM

the bore has just been plated and matched to this piston !! is its wrong is not my fault surely !! ??

can the piston be machined ?? to have a window put in ?

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Right a quick question on this side while i look into the piston and a picture of bore pitting

here is a picture of the casing, there is a plug directly under the area of the crank and the main bearing

WHY ?? B)

there is no oil there is there? the gearbox oil is seperate and its a wet clutch

So its a drain plug ?

why and when would i use it ? im abit confused :)

Edited by Magicmat
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The drain plug is for when you either drown your bike & the crankcase fills with water or when your float needle starts leaking and fills the crankcase with fuel (no overflow on a Delorto).

The window in the piston is needed to ensure that the inlet port timing is not controlled by the piston skirt, the port stays open for a full 360 degrees and inlet timing is controlled only by the reeds.

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Actually that was my first thought then i looked at it,

NOT that i want to steal any of your thunder grib :)

Im getting worried about this piston now, this one does have abit missing out of the skirt but no windows, and there is the pitting in the bore.

My dad is going to a chroming plant to get some advice, then to talk to the shop.

Hopefully will all work out alright :PB)

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UPDATE

BORE

had a chat with a a chroming place, they say that the pitting is normal, the more you take out of the bore the more pitting you will come across, think its to do with the casting process, and theres nowt you can do about it

anyway, he says, that its not that bad, and it will run fine. BUT i should put an additive in my petrol to line the bore, because i dont want a build up of carbon in these pits as that will score the piston.

THEN WHAT THE HELL DO I RUN THE PETROL AT AND WITH WHEN I RUN IT IN ???

PISTON

apparently the bike isnt a 1993, its a 1992, the headstock lies !! anyway, they can't get the piston i need anymore :P

So ..... i have to drill the windows into the piston !! putting the same template as the old piston, but not to make the holes as big as there is abit missing out of the skirt at the bottom, round holes will work but i should really make square ones, with rounded edges inside ... :)

..now..... i dont think i trust myself to do it, if i cock it up, the piston will split, :P

Back to the shop me thinks !! B)

the windows are for the intake port opening, as grib says,

was told to do this by White bro's, gasgasuk pointed me to him, cos hes been around since the year DOT ;)

Edited by Magicmat
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  • 3 weeks later...

Hello,

Had a bit of a breack from the engine, as i got my new bike ! what a surprise ! :chairfall:

Anyway,

Ive put the main bearings in, i heated the casing up with a blowtorch, and then used a threaded bar and a socket to pull the bearing in, with alittle loctite on to make sure the bearing wont spin in the casing,

CONFUSION :chairfall: One bearing spins fine, the other is stiffer and doesnt spin as well, i took it to <mention of this company is not permitted on Trials Central> (who have really helped me out) incase i hadnt put it in square or the bearing was knackered, and they said it was fine,

Could be that the hole in that casing is smaller than the other restricting it slightly, should be fine apparently,

Also

Got the gearbox in now too !! :chairfall: Went in quite well and easily actually :chairfall: , my dad lost the charger for his camera, so i couldnt get the pics for where the selector forks went on the shifting drum, but i worked it out :P

So now all i need is, my base gaskets to come, and the new studs to hold the barrel on !! hehe

Just got to stick the crank in now and aline about 8 different things !! lol,

Anymore advice or comments peeps ?

post-1852-1141644936.jpg

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LOOK HOW BIG IT IS !!

Ive been looking at the insides of the pro engine and the old GG engine is massive !!

the shifting drum is twice the size !!

and so many gears !!

lol ... my new bike is ace, but i will also love this one when its done :chairfall:

Edited by Magicmat
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  • 3 months later...

Hey guys,

I put the casings together last night. I put the crank in the freezer for about 4 hours !! :thumbup::thumbup:

Casings went together fine, put the crank seals in and the front sproket seal. I'll post some pics soon.

Engine just needs painting now. :wub::wub:

Just waitging for seals and other bits now...

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  • 4 months later...

Hello !!

im going to post the pics so far now, and the ones of the bore for you gasgas...(sorry for the wait)

Ive painted the engine casings, with hamarite metal paint a **** load of coats and a long time to dry... and i dont think its as hard as i want it to be so im abit gutted about that

Bore has been clear laqured with clear high temp paint !! :blink:

I recon in a couple of years ill have to take the engine out and paint it again ( properly ?? )

Well here are acouple of pics,

Ive fitted the bore and piston (drilled a hole in the side for the timing) and i also changed the mains bearings, front sproket bearing, crank seals, con rod kit, coil rewire, whole gasket set,

Anway, ive got to put the head on now, and rebuild the otherside of the casing, and then laquer the frame.

My dads advised that i just paint it on nice and thick...lol ??? :chairfall:

ok im getting this error when trying to upload,

The requested file upload failed because suitable permissions have not been enabled on the 'uploads' directory. Please contact the board administrator and inform them of this error.

pic, think i sorted the upload

pic of the barrel, this is the worst part of the pitting and in honestly looks worse than it is

barrel

post-1852-1161642456.jpg

post-1852-1161642792.jpg

Edited by Magicmat
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Dont know if it has been mentioned but check the water pup impelar shaft for wear as the rubber oil seal wears a groove in it. from what i remember the shaft is about 20 qiud ish i had problems with mine dumping water into the gear box and overheating turned out that was the cause

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