New Big Block Gran Turismo Kit 200-245cc

[Lambrettatastic]

What's a good starting point for jets etc with the 30mm please. Got my carb just need to buy the kit...

[Rich_T]

from the manual:
Dellorto PHBH30 (caution standard version of this carb has restricted access to air screw and idle stop adjustment when fitted) Cable choke conversion Part number: 53003. Settings for open mouth with JL3 or KRP3 expansion chamber. Suggested jetting between 115 -125 main jet, AV268 atomiser, X13 (or X7) needle, 40 slide, 55 idle jet, Timing set at 17 degrees BTDC.

[Lambrettatastic]

from the manual:
Dellorto PHBH30 (caution standard version of this carb has restricted access to air screw and idle stop adjustment when fitted) Cable choke conversion Part number: 53003. Settings for open mouth with JL3 or KRP3 expansion chamber. Suggested jetting between 115 -125 main jet, AV268 atomiser, X13 (or X7) needle, 40 slide, 55 idle jet, Timing set at 17 degrees BTDC.

sorry mate...when you say standard version of this carb,how can i tell the difference,the one i was going to order has phbh30 bs stamped on it.

[storkfoot]

He means that when carb is fitted to the TS1 right side, the adjusters are on the left as you look at the carb when fitted. This means they are fairly tight to the engine mount and hard to get at

[Lambrettatastic]

Now I have re read it ,yes that makes sense..but I'm right in saying you can fit a 30mm on the standard side,are there pros and cons to which side the carb goes.i have a dl200, so no battery tray.

[Rich_T]

Well pointed out, there was a bit of copy and paste. There is a new manifold for 30mm on the L/H side so there is no problem with access to the adjustment screws.

[Dryballs]

Hi rich, I haven't been on for a while so I've missed a few developments... Are you saying this won't work with a varitronic? I'm keen to put one in my series 1 which has a 61mm crank with 115 rod. Are there no low crown pistons at all?

[Rich_T]

Dryballs, there is good news and bad. If you have that crank arrangement you could make an 8mm packing plate or you could use a DT175 piston and 5.5mm worth of packers (I have 2.5mm packers so easiest option would be two of those plus the gaskets). Because the GT cylinders and Porcupine heads are shorter than stock you don't end up with a head cowl problem, in actual fact a 5.5mm packer will bring it back to stock or there about.

I experienced lots of problems with the IDM ignitions (Varitronic/Parmakit). These problems manifest themselves as erratic running to which most people associate jetting/air leaks etc. Consequently they spend ££££ & months messing around with carbs and jets. When ever the ignition is changed to fixed timing AF/Indian/Ducatti or the RS125 conversion everything works fine.

[mickjr]

is 245cc the highest you go?could you go 250cc/260cc torque tourer or is the alloy kit with liner better for the higher cc and longer touring

[Rich_T]

is 245cc the highest you go?could you go 250cc/260cc torque tourer or is the alloy kit with liner better for the higher cc and longer touring

You can go as big as you want to but I wouldn't see any benefit in doing so as the problems far outweigh the benefits. The limitation is the skirt diameter, practically speaking the max bore is 71mm, depending on what you do with crank you could achieve 72 x 62 which is 252cc.

However, once you are at this configuration there is so much work to be done and modifications to make you might as well just jump in with a liquid cooled Blair Witch at 75 x 60 = 265cc and 35bhp out of the box all day long.