TZ spec o ringed heads

mj43 · Post by **mj43** » Tue Feb 06, 2007 7:11 pm

Whilst my billet heads are slowly plodding along here is another set I am trying

O ringed machined to same spec as TZ '97 unleaded so motor will be on 4DP pistons.

mgtkr1 · Post by **mgtkr1** » Tue Apr 24, 2007 10:32 pm

do the barrels need boring/replating for 4dp pistons as there were some on ebay recently stating they were intended for a kr1 s but had to big a bore? always thought machinig head to suit deck height/profile was only required. i understand that 26j are nla so will resort to 4dp if more appropriate? are the 4dp easiest to come by/the most straightforward mod? heads look trick btw, and there just the modded stock ones! cant wait to see the one off items your having done fitted to the bike! cheers matt.

mj43 · Post by **mj43** » Tue Apr 24, 2007 10:51 pm

Matt

To run 4DP or 4AK or 3TC pistons the barrels need to be shortened by 2mm (need to check that figure so don't go cutting just yet).

Then I advise strengthening the barrel - rather strengthen it first then shorten it - takes out the distortion put in by the welding.

If you don't then the barrel will fail - will show piccies of what I have done and how they crack

If you run 3TC or 4AK then the head just needs re-profiling.

If you run 4DP - ideally it needs welding but you can just skim and re-profile keeping a hemi-head. There is a spreadsheet on my website (which I know is falling apart) which allows you calculate volumes etc.

The head in the piccy wasn't a success - compression to high and lost overrev. I have a reworked one to test but need to get some barrels sorted. Mean time I will be racing on a set of old 26J pistons

mgtkr1 · Post by **mgtkr1** » Tue Apr 24, 2007 11:33 pm

there is some pistons on ebay atm (59w) do these pistons fit,are they same bore/stroke as 26j etc? desperate for some so will give padgetts/dennis trollope a bell,unless you know of some were cheaper? if there no good then will get a set of what you already mentioned once you post specs. info was helpful cheers matt

mj43 · Post by **mj43** » Wed Apr 25, 2007 5:29 am

Try this https://rscycles.com/images/price_sheet ... Prices.xls

They are half the UK price - even after Tax and shipping will be cheaper.

Order piston 26J size 96, piston ring and circlips. Use standard KR-1S piston Pin and little end bearing.

mgtkr1 · Post by **mgtkr1** » Sat Apr 28, 2007 6:56 pm

mark, ive sourced some 4dp pistons and have a good supply. just about to get the bracing/machining done, could you post me a piccy of were to weld and how much to remove? i think you sent the specs so ill have a look to check, any other tips/things to look out for would be greatly appreciated, cheers matt. p.s, good luck at mallory!

mgtkr1 · Post by **mgtkr1** » Sat Jul 07, 2007 11:02 pm

mark, could you give a ballpark figure on the price of oneoff heads to be made with inserts ala rs h***a etc and also bigger cooling capacity like a ''coolhead'' type design? i understand you have put your billet heads on hold for now but im intrestred in the idea of better cooling potential aswell as o ring and been able to alter the combustion spec, not to mention det rings. another good thing would be getting rid of that horrid step near the gasket between the head/barrel. i know the rgv boys have modifyed std heads with great sucsess but seems the powervalves location makes the kr heads awkward to do the same mod.

mj43 · Post by **mj43** » Tue Jul 10, 2007 7:06 am

Matt - sorry will post piccies tonight

I have two sets of heads made so could probably let you have a set. If you want to try finishing the development. I can't see myself getting round to doing it as I have another much bigger project I am starting after Bonneville

If you are up at Cadwell 28/29 I will bring the billet heads up.

mgtkr1 · Post by **mgtkr1** » Tue Jul 10, 2007 6:47 pm

i will be at cadwell to see the strokers in action in the form of f250, i would happily try and finish developing the heads mark, could you pm me? i am looking forward to finding out what your up to, sounds intresting if the heads are been cast aside, almost like there smallfry compared to your future project!

mgtkr1 · Post by **mgtkr1** » Sun Jul 15, 2007 9:06 pm

mark, i think ive seen a pic of the heads somewere before but cant seem to find it anymore, were did you post it, was it on team sparrow?

mgtkr1 · Post by **mgtkr1** » Tue Sep 04, 2007 8:06 pm

mj, just wondered what ignition system you run? have you bothered with the zeeltronic at all?