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i would bet you could use 350 aircooled headpipes with the stock mufflers and probably use the repro 359 baffles in there

Thats something I had considered, thanks.

Here is bike as I got it.

it would help if you mentioned what country you are located in and picture or 2 of the bike you're talking about.

The bike is in UK but I spend my time between Florida and UK. Will try and post a picture of how it was when I bought it.

It's totally different, different height and angle. I guess I'll be having a set of chambers made to fit. I was hoping somebody here may have found an alternative.

What are guys who have put 350 top end onto later RD250s using for exhausts? Will 350B front pipes go into later pipes/chambers? What are my options, bike is a '79 250E with 350 cylinders.
Thanks.

chambers are more related to stroke, so go for250/350 ones.

as far as carbs..  depends its sort of a Hodge podge. id baseline wirh 250 jetting but up the main by 3 or 4 sizes from there.

Good info, thanks.

I am putting the 350 top end on my 79 250E, the bike had 2R8 barrels but 1A0 carbs, I assume that makes no difference as I'm changing the top end? is it worth putting 2R8 slides in and where should I start with jetting? its got standard airbox currently with all snorkels but wonder if they should be removed??
Second question, I want to get expansion chambers, so should I be looking for 250 or 400 ones? will there be much difference in performance with one over the other? Thanks.

assuming you know about length difference between RD250 & RD350 cylinder studs

Yes, thanks, I have already changed them.

That looks on par with the set of US/UK spec repros I got.  They are a rougher casting than the India spec repros, but the ports are in the right spot, and the lining is thicker. 

Clean them up and run them!

Thanks.

i mean, not really bad, you need to chamfer the ports as everyone knows, but thats about on par with most stock factory rd cylinders

 

Fair enough, I'll get some pistons, chamfer the ports and give them a go.

Here's some more pics, they do look pretty poor quality

I'll take some more later. I have emailed the seller so will see what he says too.

3 sets ive had in my posession and they all looked fantastic

Thats a worry...

I have 2 sets and they also look fantastic. There's great info in this thread if anyone has read it from post #1.

Only concerns I have seen is from people who bought the cheapest set they could find in a hurry.

You get what you pay for 

Mine are the ones as shown in this post, but I wonder if he had changed what he's selling now.

So you guys who have got these cylinders, are the casings nice and smooth like the pictures on the listing, I recently got a set and the casting is awful, also, whilst I wasn't going to use the pistons its worrying to see the pistons dont have a full circlip groove machined into them, I'm worried the seller is now selling the cheap ones. The other thing is the transfer ports, they seem to be hardly open at the top, there is a load of aluminium residue blocking them. I think I need to get them off to somebody to do some porting if I am going to use them.