newbie HELP

[costa]

Cheers guys. Quite a lot off info out there that seams very year related ect. being a 79 when were these engines produced? ie 78-81 or much more specific. What year 750 pistons fit or is it all 2 valve 750 pistons fit the 2 valve 400 pistons?

well finally got my new phone so got some pitures.

however my photobucket is being awkward so cant upload till this week sometime.

Did find these on the laptop though.
How I bought it



Iv been speaking to a few specialists about the pistons ect from a 750 2 valve ect. still would like to know about hows best to raise the cr and whats a safe raise?

[Mekanix]

Looks good,

Your type of engine is from 77- 79. They changed mid 79 and stayed the same after that.
The only thing that changed after that was the top end.

Your bottom end is a roller bearing type and after 1980 it turned into a plain bearing type.

Your pistons have a 16mm piston pin and most after that have 18mm.

The gs850 is the only one with a 16mm wrist pin that is close enough to your engine bore so that you can use it.

There might be some other pistons that may work from the 750's from 78-79 but I don't know which ones.

[costa]

With the engine apart I have measured the cylinder walls and there a good 3/4" thick. Is it possible to get oversized 400 pistons and just bore the cylinders out to get the same end result? Lots off meat there? Sorry for all the questions but with the engine apart I think I might as well get on with it

[tkent02]

3/4 inch is incorrect. The thickness of the steel sleeve is what is important, not the aluminum casting. You will get an increase in compression ratio by going with bigger bore and pistons, without any head milling. How much? Do the math.
Not sure if the 850 is a higher dome piston then the 400 to start with, but higher compression 850 pistons are available.

Show us a picture or two of the burnt valve?

[costa]

Managed to photobucket to work in the office.







Easy to see and the valve is now on order as well as gasket kit. In theory could have it back up and running this week.

[costa]

sorry for the crap photos . need to mess with my settings

[costa]

Hopefully a guy is getting back to me tomorrow with his findings on pistons he can supply. ill let you know what he says

[pete]

Bike looks good!

And yes I see it has pods and I suspect that exhaust flows better than stock.

Given the valve has burnt I'd really be checking your jetting before getting too carried away, don't want that happening again!

[costa]

Will be getting properly set up with power gains.

[pete]

Cool, sounds like a plan!

[costa]

Ha best laid plans usually do what plans do lol.

[pete]

So true! New tyres planned for my 450 tomorrow and Easter extra long weekend is coming up so what does my 450 do? Drop to 1 cylinder on the way home from work and then miraculously fix itself last night...

[costa]

Ah at least it fixed itself. Wish they all did that I'm currently trying to clean up bird **** welds from po. He's had the right idea just either bodged it together or has little welding skill. I'm certainly checking everything twice

[costa]

pm sent clutchthirty

[Mekanix]

hey costa, you can send pm's but we can't respond to them.
check your settings, might be something disabled about receiving messages or notifications from members