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Re: barlow stage four set ups

Posted: Wed Oct 03, 2012 12:29 am
by Darrell Taylor
the width is adjusted in conjunction with the squish clearance to achieve your desired squish velocity
these are easily measured with readily available pc software and i guess theres freeware available now
the problem with them is they dont take account of the squish changing with operating rpm so a calculated 1mm may drop to 0.6 at 10,000rpm and throw the calcs
the main consideration is obtaining the correct comp ratio and widths and squish clearance are often tools used to adjust the volume unless designing a bespoke head from scratch,std heads often havent meat in the right place or skimming brings the squish area into the plug thread so working limitations exist
tests ive done show little difference narrow med wide and centre or side plug,many years ago i used software by tsr for doing heads but dont bother now,i test what works on the dyno/track/road ,also tested heads in mx from bud/vhm/factory which had a whole manner of designs but the basic c.r. was at the core of what worked
compression also works with or against ignition timing and pipe design particularly stinger size and fuelling which makes for a messy testing regime its like trying to unlock a combination lock trying to find what works and interestingly reveals there are many ways to skin the cat,so id guess harry has dropped on a combination that works for him and his customers are happy with

Re: barlow stage four set ups

Posted: Wed Oct 03, 2012 10:37 am
by C*NTSPEED
[quote="Rosa Bianca"]The head has been reprofiled by Harry, has been built as a high speed tourer, so the large squish is to avoid 'pinking'.

Nearly completed the run in period, and currently spec'd as above but with a 130 main. The main problem at the moment is the new filter is not letting the carb breathe, seems very restrictive. It's new, came in piaggio branded packaging, but not guaranteed to be OEM.
I'm going to try an original air filter and hopefully that will cure the richness.[/quote

ok can you elaborate a bit as there are 3 types of standerd filter
1 has 2 holes in the heart shape indent
1 has 1 hole in the heart shape indent
1 has no hole in the heart shape indent

Re: barlow stage four set ups

Posted: Wed Oct 03, 2012 2:42 pm
by joeythescooterboy
Ooh Joe you're so picky.

Re: barlow stage four set ups

Posted: Wed Oct 03, 2012 6:00 pm
by C*NTSPEED
joeythescooterboy wrote:Ooh Joe you're so picky.
i know but al 3 will act differently wont they :-)

Re: barlow stage four set ups

Posted: Thu Oct 04, 2012 9:19 am
by gaz_powell
its a good point

i`m currently messing around with the different filters

Previously ran a one with two holes in with success (with modified head) for many years (tuned autisa barrel, SIP performer, matched casings and airbox, T5 4th gear, cut crank - 125 mainjet

same engine but changed cylinderhead to a standard disk one recently and used an undrilled filter to IOW (about 350 each way) - no issues but it did seem a bit restricted when going through the gears but nothing adverse on top end - used 122 main jet

will try a drilled filter on way to brid and see what its like

recently did a standard p2 with a taffspeed exhaust - drilled the filter and upjetted - again made a difference going through th egears but nothing on top end

gaz

Re: barlow stage four set ups

Posted: Thu Oct 04, 2012 1:40 pm
by cit205
So, how much are the HB stage 4 kits?

Re: barlow stage four set ups

Posted: Fri Oct 05, 2012 6:56 pm
by cezeta
cit205 wrote:So, how much are the HB stage 4 kits?
200 pound exchange

you supply a barrel and head and get back a 210 kit or 215 or whatever it works out to be if you use a 60mm crank (its a different kit for the 60mm crank)

basically its 100 for the conversion and 100 for his new turbotastic piston

Re: barlow stage four set ups

Posted: Mon Oct 08, 2012 9:56 am
by mickymidas
I run a P200 HB stage 4 . I am definately no expert but 130 main jet seems a bit high to me , the set up Harry advised me was .....

Main jet 122-125, BE3 ( std), AC 160 (std), 60/160 pilot ( drilled), It mark 18*, Plug B7es running in , then B8es after, 4% oil. With Sito+ exhaust.

Re: barlow stage four set ups

Posted: Mon Oct 08, 2012 12:12 pm
by cezeta
i have been told that the hb turbotastic piston is infact an indian beedspeed piston? anyone verify this?

Re: barlow stage four set ups

Posted: Mon Oct 08, 2012 2:03 pm
by cit205
Not to detract from the fact that the kit has a good reputation (and price) as far as i know, what was meant to be 'turbotastic' and new about the piston ,is it not just an oversize piston with a bit of tuning work done to it to match the tuned jacked up barrel and machined/reprofiled head?