Update on the t35 misfire/ bad barrels saga.

[george sutton]

  For those of you who followed the sad story of my bike, I was hopeing to come up with some good news. Especially as good old Brian in Angus kindly donated two genny barrels  to me for xmas, but alas, it goes on !   Have just had these barrels Lightly honed to rid them of pitting, but no, they wont do. so now i've got a pair of brand new std pistons, and still no useable cylinders.      Am hoping to try JP piston makers in austalia for a quote on .010" domed  over size pistons. Has anyone had any luck with this firm please?      PS,having complained bitterly to the classic co. i bought it from, they reckon they have just aquired two genny barrels themselves which dont look too bad, PLUS, a refund for parts ive had to buy so far. so here we go again..     i'll beleave in the good fairy when i see her fly in with a good barrel on each arm.   Denis Sutton

[David H]

HI

As far as I know JP only supply flat top pistons for Mk3 onward and dragonfly. 2 year ago when I was in the same position that was all they made. I have dealt with them for other things and they have had good service and the products are of good quality.

I ended up putting very thin wall sleeves in my worst barrels and then boaring them to the old pistons, I know that this is not the accepted practice but touch wood it is holding together so far.
I actually made the sleeves just a tight push fit and with a small shoulder at the top to hold them. They are only .025inch wall thickness after sizing and the finished bore is 0.010 under size. I felt the few cc's I lost in the process were insignificant.

The other process I investigated was to have the barrels built up with Nickasil (nickel-silicon carbide plating) There is a firm in Melbourne which will do the job and guarantee the finish up to 0.020inch But the price was too much for me $1000 for both barrels if I remember correctly, That included dressing up the old pistons and sizing the barrels to them.

Hope this helps a little
David H (Melbourne)

[aggettd]

What was it about the generator barrels which made them not acceptable? Was it a flaw with the specific barrels you got or an intrinsic incompatibility problem? I had always thought that I would pick up generator barrels as a backup for my MK1 if I ever came across them (not likely), but not if they won't work.

[george sutton]

david, thank you for shareing your experiences on this.    ref: the liners, presumably you made them much thicker for fitting, then bored back to .025",  am supprised though that they are still ok with running temperature differences.  What iron? mehanite? cheers Denis.s



Quote removed - Dave, 31st Jan 2010

[george sutton]

hello again aggetta, it would seem  from my own limited experience of genny barrels, that you just have to get yourself some good ones that have had little use but more importantly, ones that have been kept in warmer drier climes.   condensation forms in the bores and eats into the metal forming rust scarring,   alas, my problem,   causes too much oil  to get up into the heads.  If some thoughtful manufacturer  produced up to + .020" pistons for mk1 bikes, many old genny barrels could be saved.  MK1 bikes too. hope this helps, Denis.S



Quote removed - Dave, 31st Jan 2010

[aggettd]

I have Hepolite +.030 domed-top pistons in mine now. I don't know if they are still available, but they certainly were at some time in the past to someone who had my bike before me. I don't know what compression ratio they would give, but I have seen high compression Honda CB750 pistons that could  have a bit turned off the outside and piston lands, that could easily be made to fit with modified wrist pins. Don't give up.

[george sutton]

Hi aggettd. the +.030" pistons you say you have now, Is that in generator barrels ,or motorcycle cyl.barrels ?? As for giving up !  no way !  the support i've had from club members  has been marvellous. so there is always hope .Denis s



Quote of previous post removed - Dave, 31st Jan 2010

[richson]

Probably difficult to get sorted but there are some Mk looking barrels up on the Argentine e-bay site. Maybe a Spanish speaking member could help - there's always hope!: http://articulo.mercadolibre.com.ar/MLA-77472967-2-tapas-de-cilindro-douglas-moto-antigua-_JM


Quote of previous post removed - Dave, 31st Jan 2010

[graeme]

These appear to be heads rather than barrels - unless the barrels aren't pictured.

[aggettd]

George:

The +.030 pistons I have are in motorcycle barrels. I don't know the history of the bike, and who did what to it over the years. It's taken lots of effort (and help from this forum) to get it to the point where it is reliable transportation. Although I am a member of the LDMCC, as a North American I am not permitted to buy parts from the club, so I'm getting better at finding alternatives and making parts. I'll be retiring within the next month, so hopefully will have  more time to assemble a database on suitable alternatives to genuine parts and what modifications are necessary. Perhaps it's something that could be tracked on the forum. I'll have to consider that. There are dribs and drabs in the forum, such as bearing references, and various drawings and descriptions of homemade parts, but they aren't all in one place.

[george sutton]

thank you for the info. aggettd, sorry for late reply, have been away. Denis. s



Quote of previous post removed - Dave, 31st Jan 2010