Paul's Yamaha 3MA track bike

[Paul]

i bought a bike last year from a lad in cape town,



i asked he deliver it to graham cokers workshop and i'll pay him if graham says it is pretty sound. so i had it off him for R15000. i immediately comissioned graham to make it TZ like as a track bike, to look into engine design and overheating issues on RHS and flooding on low down (not that this is a major issue on a track bike but wanted a little progress here anyway). he used modern software and the way i understand it because, i have had images off him for my 3XV



is that he creates a digital model of the engine and runs it overnight to destruction on his PC, he then gets all the hotspots and changes the model until it improves by re-running. part of the requirements is this damn expensive headgasket which is getting more expensive and lesser in numbers, i wanted o-rings fitted.
a lot of machining is involved and jigs etc.











casings are finished, cylinders to and pipes are nearly there.
more news as i go

ps, it is nearly a year now but don't tell anyone

[Neal]

How do the water jackets seal ? Gasket maker etc ?

[Paul]

How do the water jackets seal ? Gasket maker etc ?

apparently neal. i would like to know more as i have seen it done this way before.
if anyone can testify to using this method please boost my confidence.

[KeLeYTiS]

Iam thinking of this mod too because gaskets are expensive (especially when you setup your bike and i might need a lot of these

It should although have 2 orings ,one for the chamber and one for the water , in your case you should use some kind of gasket sealant to prevent water come out of the head

Here is an ebay ad with a photo ,I think i will send it there as soon as yamaha lets me raise some money (expensive oem stuff)

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&_trksid=p4340.l2557&item=380459407107&nma=true&rt=nc&si=KvSSXpF4JUhBKRjAOPMFclR3lnk%253D&sspagename=STRK%3AMEWAX%3AIT&orig_cvip=true&rt=nc

[Paul]

Threebond Yamaha gasket maker. I managed to speak to graham yesterday. I've ordered a tube.
That machining looks good. There is not much room on the 3ma to get around the studs so I agreed to go this route.
My engine is assembled and bolted back in the bike. Finishing the exhausts is next.

[Paul]

[KeLeYTiS]

The cylinders look sweet did you have them sandblasted ?

[Neal]

Progress at last , you must be happy !

Umm - you looking for a test rider for that baby ?

[Crank]

Do both cylinders have the same crank rotation on 3MA?

[Paul]

180 deg

[Neal]

The easiest way to clean them is with blasting soda , it does not damage anything and is easy to clean off .

[casal-fan]

How do the water jackets seal ? Gasket maker etc ?

apparently neal. i would like to know more as i have seen it done this way before.
if anyone can testify to using this method please boost my confidence.

Go for it.
I have been using that setup (O-ring combined with sealant) for years, without any problems.
As long as the machining of the groove and ring type choice is done correctly, it is in my experience a great mod.

[Paul]

Cheers casual fan and welcome back!!

[Louis]

Hello Paul,


I have studied your 3ma head pictures and it kept me thinking

What I see is that Graham have made the squish equal to each other (with is a good thing as oem they have slightly different readings between L en R)
He has worked the squish band width to (it looks a bit wider then stock now) and have set the squish on a (estimated) 0,8 a 0,9mm??


But what I now is that a stock 3ma head has already a tight head volume around 10,5cc.
If you just skim the head and make the squish correct ,you will be way, way down the 10cc.
I see this du the marks on the combustion shape (where he have tighten the head on to the milling machine) this indicates to me that he perhaps not have opened the bowl.
Also the aria where the thermostat sits is equal to the rest off the head, with indicates that there probably is takeoff quit a bid


This could give you troubles with setting up the ignition.
(like the 3xv with the changed heads )


Can you ask him if he has measured the head volume?

The O-ring mod looks good, and with use off sealent it wont leak.

[Paul]

Hi Louis
He has re machined the heads, his opinion is their design is susceptible to detonation.
He has redesigned the whole motor by measuring and applying filler or machining. New porting etc.
He is also doing me race fuel and pump gas heads. The one head was warped and had bad detonation damage, that is why he machined it right down.
He measured the heads on the engine by sealing piston edge, then he uses Perspex I understand as its quicker.
I am afraid we'll have to wait and I'm pretty excited. I'll set this one up on the Dyno. Hope I don't battle like the 3xv, I really had a rough time with that bike but it is a whopper now and I still have new heads to try.