Pistons Etc.

[shipdamite]

hello all,

ok; dilema is this.

I have a rattly ty ('so do I' you all shout back ;-] ......)

basically, when I got the bike, I looked up the exhaust port and saw blow by. Taking the head off confirmed that the cylinder was on maximum rebore. The piston had a jammy bottom ring, so I put in a cheapo piston and new leb. it sounded rattlier than before, and I changed back to the old leb as the new one was faulty.

Slight improvement, then a bit more improvement jamming up the fins with rubber, but still rattley.

No blow by on new cheapo piston.

So, can I assume that bore is ok and that a nice expensive wossner piston and leb will make it a bit better?

Or, do i get it lined/sleeved and start again at 66mm (stock)?

I know that they all rattle, but mine sounds like a bl**dy woodpecker on steroids.

cheers

[shyted]

Ship , i take it you put new rings in ? The rings would prevent blow by on the cylinder side, and piston side, the new piston will provide a better inner seal to the rings . In other words the ring's are doing one of their job's better ,fuel mixture plays a part on ring seal too . Rattle can be due to quite a few basic engineering and scientific conditions . with the age of the bike i would say measure the bore with an internal mic first before you buy anything other than a gasket set .Don't forget , your bike has a tapered bore so measure above the exhaust port and just below the carbon line at the top of the bore, below the transfer's too. A manual will give you bore dimensions and tolerances . You may have the option of plating these days if need be . Contact Stan Stephens or Mick Abbey and they will tell you whether that's possible ,that's if you need to re sleeve .

A quality piston will be better balanced and with rings quieting things down no end and with a new bore to match , should be silent .I raced and owned loads of Yams from that era and even had a TY 175 when they were new .Oh dear , just seen the grim reaper .

What type of woodpecker ?

Edited May 20, 2013 by shyted

[shipdamite]

Hi Ted

yep; new rings too.

reckon the rattle is probably the yee-hah piston and rings.

spoke to the local 2 stroke tuning place - bdk - and they reckon there are two options; re-line in the conventional manner or re-line and plate. I seem to have read somewhere that plating (nikasil) is not the way to go on these cylinders; not sure why though.

I think I need to find myself another cylinder, get a decent piston and leave it with bdk to do their thing (they are mega busy and will take ages and I dont want the bike sat there with its rod hanging out for weeks [oo-er missus])

I will try your mick and stan as well - se if they can turn things around a bit quicker.

A silent TY? blimey.

Actually, I might have exagerated slightly about the steroids.

Edited May 20, 2013 by shipdamite

[shyted]

Ship , i expect they have them done at Langcourt metal re finishers . Didn't think of that , as none of the tuners can support the cost of the tech involved tooling up so give them a call they can turn around in a week ,(they did with my Fantic ) and the result of plating is a more thermally stable process and less friction on the rings than cast iron .

I think the wossner pistons are better than the rest , Stan Stephens will say Wiesco ,and they are good but not for the money and in two stroke's personally think mitaka may be ok on a road bike ,but in 2 stroke comp bikes not so good .

Or just keep it standard with a new liner . Don't forget that if you go with the plate ,you will need the right rings to run on that . Don't know why plating wouldn't be a wise choice though , that's why every one changed over to it .

Ted .

Edited May 20, 2013 by shyted

[shipdamite]

Hi Ted - Langcourts are good; they have done ktm 4t stuff for me before and did a good job. Reckon I might stick with a standard set up with a new liner and a wossner.... just need to locate another cylinder. thanks for the help.............

[jon v8]

Plated bores may have been slightly better for close tolerances/more power etc.BUT to the owner needing to repair or rebuild that engine it just means more money and hassle - like most other modern non servicable components in engines.Most of the regrindable or rebuildable parts are now single use.Very good for the manufacturers to make money,not good for owners,nor the planet.

Rant over.

[tony27]

Plating an iron liner won't improve the heat transfer as some people seem to think, cylinders that are plated from new are done directly to the aluminium. Personally I'd resleeve it & get it back to standard size which should give it another 35years of life

[woody]

To convert to plated bore, first, don't you need an alloy liner, then plate to that?

So it could cost £150 ? for a liner (based upon replacement cast liner from PJ Engineering for my Bultaco) £130 ish for the plating plus the cost of the piston. Expensive for no gain?

I'd just use a decent piston like a Wiseco and get it bored.

I had a rebore on a 250 Majesty using a pattern piston because it was all that was available at the time and it rattled within minutes of start up. That happened on two bikes and was nothing to with the quality of the rebore as I've had many done by the same person over the years.

[tony27]

If the cylinder is on max oversize like you think it may pay to do some investigating of what is involved in the 200 conversion, someone will know whether it's just a bigger piston or resleeved to a larger size

[shipdamite]

Thanks for the help; looks like the best thing to do is to get it sleeved and pop in a decent piston and leb.

I thought about the 200 conversion, then decided that I would be best keeping the beastie bone-stock.

I have emailed Mick Abbey for a quote on the resleeve but no reply as yet, and Stan Stephens will need a telephone call as he doesnt provide an email address.

also trying to find another cylinder to get this done so the bike isnt laid up.

part of me is tempted to blow some money on a wossner and just put it into the current bore (which is to my eyes ok)and see what that is like. Maybe just too much of a gamble.

thanks again, much appreciated.

[woody]

PJ Engineering in the Midlands did a good job on fitting a new liner and reboring to new piston on my Bultaco. Fired it up last week for the first time and it is as quiet as you can get.

[ausy300pro]

Just as an option, I had an oversize liner fitted and ports cut and bored for my ty and the quality of the work is superb, that was done at SEP in kegworth,

[shipdamite]

PJ Engineering in the Midlands did a good job on fitting a new liner and reboring to new piston on my Bultaco. Fired it up last week for the first time and it is as quiet as you can get.

http://www.pjme.co.uk/acatalog/Job_Packing.html

here? did they ask for your new piston to be sent as well (so they could measure it before doing job) and did they do everything that was required to just fit to the bike?

cheers

[shipdamite]

Just as an option, I had an oversize liner fitted and ports cut and bored for my ty and the quality of the work is superb, that was done at SEP in kegworth,

http://www.sep-kegworth.co.uk/page2.htm

here? did they ask for your new piston to be sent as well (so they could measure it before doing job) and did they do everything that was required to just fit to the bike?

cheers

[shyted]

Plating an iron liner won't improve the heat transfer as some people seem to think, cylinders that are plated from new are done directly to the aluminium. Personally I'd resleeve it & get it back to standard size which should give it another 35years of life

They don't plate it .I certainly don't think putting nikasil over iron would improve thermal transfer and didn't say it would . Also it's only as much hassle getting a re-sleeve as getting re plated . Making sure you don't get someone to cock it up for you is the biggest problem .

Rants accepted ,facts stated .