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Are we having a flood of 3ma4 rebuildings latelly or what?

So here's mine

Bought it from a garage sale,it's been deserted since 1998



First thing was to totally strip it in order to see whats inside..





What a surprise..? New pistons and rings???

Cylinders are in excellent shape.





The right head has some signs of detonation? Any ideas?



Now its time for a deeper look





3ma10 cases







And here we are



The crank looks to be in excellent shape,i'll replace the R and L bearings and seals though just to be 100% sure

A panoramic view



Did some cleaning on the chassis and the fairings





I do believe that it'll hit the streets at the end of next week

Hello Dee,

Looks like you have a good engine.
Seems the previous owner changed some thinks.
The Reeds has been modified, it has no (original) reed stopper looks like you have some tz250 stuff on your reeds.

I do believe that it'll hit the streets at the end of next week

If you manage that, think you have done the fasted rebuild on the forum

Ηahaha yes i know

I've seen all your vids and i've been watching your 3ma "adventure" for a long time now,keep it up bro.

Didnt have a clue about the reeds,thanx Louis

The only thing that troubles me is that the clutch basket looks kinda tired and i'm pretty sure that its impossible to find a new one,i'll check though just to be sure.

Εdit - Found it,its the the same as the TZ250N - Pressure plate with 6 springs - Part number 26J-16351-00-00

looks like the reed stopper has been cut off it looks like there is a rough edge i might be wrong
will be really good when done it looks in really good condition to start with

Great looking SP you got there

The right head has some signs of detonation?

Looks quite bad, Are you planning on replacing the head or using it as is?

Good luck with re-build, you have a small fortune there

Yes i've noticed the sharp edge on the reed stopper,looks like it has been cut off,the funny thing is that the bike is completely stock and unmolested,i mean it still has the rings inside the pipes,untouched snorkels etc

No Luke,i'll stay with this head,unless if you have a spare one to send me

Ι've ordered the pressure plate along with 6 screws/washers and springs,i've noticed that Yamaha is using the same plate on the '87 TZ too.

Lucky guy

I wish I had a spare SP head, I wish I had an SP

Hi Dee , that is not detonation on the head . It looks more like the damage caused by a bearing that has packed up or a piece of ring . Detonation looks more like some has sand blasted the edges . Take some sand paper and clean up the rough edges on that head .

Ι did it Neal,it looks way better now,no rough edges at all.

I'm waiting for the pressure plate,springs and screws in order to finish with the engine

Ready and willin' still not kickin' though

I'll shoot a video from the first kick..cant wait

My buddy did all the hard work,congrats bro

You must be excited!!
Go through your carb thoroughly. Not sure about the SP but I imagine it also has the powerjet inside that gets blocked and whatever mains you have slap one up on rhs.

Looking good

What pistons did you use?

Hi guys

Yes i very excited,cant wait to hear that rattle

The previous owner had 3m1 exhausts with rings and he had lower the mains to 240/250 from 260/270

He told me that back then his goal was for the bike to gain more power at the lower register,well thing is that he achieved nothing more than some sort of a piston damage(i think thats the reason why the right head had these marks,see pic,also thats the reason why before he deserted the bike put new pistons and rings,the stock ones were damaged)

Thank god the barrels didnt suffer any serious damage so we're all good.

I will instal the stock 3ma4 pipes and rejet the carbs with the stock mains,i'll remove the exhaust rings and do the 105 mod at the snorkels for start.

Not sure if the 3ma4 pipes need the 105 mod,they look shorter than the 3ma1 ones,i have to measure them first.

The pipes have been modified in order to be able to instal different end cans,i'll throw some spare dog fight end cans i have.

Shall i need bigger mains with the snorkels mod?

Louis the pistons are stock 3ma,the sp pistons are no longer available from Yamaha,the compression wont be as high as the stock sp because after we measured the heads we saw that they are identical to stock 3ma3 heads,so the difference between the compression of the stock 3ma3 and the sp lies in the fact that the sp piston had a cone shaped top,well sort of.
You may see it at the sp manual.

Well slightly lower compression means slightly better over rev,i might lose a couple of ponnies but what the hell,we'll think of something

PS Last but not least my buddy kept a lot of notes related with the barell's porting etc etc,just to give you an example we measure first the 3ma10s exhaust port from the exhaust's side and we found that the 3ma10 has almost 34 mms port while the sp barrel has 38(the tz 4dp has 41 )

More usefull notes to come

Louis the pistons are stock 3ma,the sp pistons are no longer available from Yamaha

Ok, normally a 3ma piston has one small cut out above the small end (intake side). On the picture it looks like it has a whole cut out.
I Probably seen it wrong.

Yes the 3ma10 has the lowest timing
http://tzr250.webs.com/timing3ma00and3ma10.htm

hmm i am confused now Dee...
I thought the SP models had flat top pistons unlike the other 3MA series...I also thought SP heads are different as well to accommodate the different piston shape.
I know for sure though that my pistons (and the previous ones) had domed crown

I'll check again and get back here for further details Foti

Hi everyone here at the new forum

I am not saying this is for sure but I thought the SP heads had less volume and the pistons are flat top, if you use the standard dome top 3ma pistons you may have trouble.

As Louis says, they do not look like standard pistons.

SP pistons have 3ma20 marked inside them.

My SP never ran right so I popped it open last year and found standard 3ma pistons in there, one of which was starting to melt.

It is hard finding the SP pistons but they are out there.

Hope this helps.

P.S the SP pistons are not as flat top as a TZ piston just less than standard ones.