LCGB Forums

by **mainstand** » Tue Jan 27, 2015 5:45 pm

Look by the gudgeon pin..

as used on millions of racing 2 strokes since the 70's...

by **Wack** » Tue Jan 27, 2015 6:05 pm

They're for bridged exhaust port lubrication.

by **Scooterlam** » Tue Jan 27, 2015 6:35 pm

An old boy, brit bike mechanic. Told me yearrs ago that when he had a nip he would Clean it up then drill a 1mm hole T that point.
Holds oil in the same way as an oiler ring does on a four stroke.

by **Knowledge** » Tue Jan 27, 2015 8:32 pm

Ian Frankland recommends drilling such lubrication holes either side of the exhaust port on the old iron barrelled 240cc conversion.

It is a simple and virtually risk free.

by **Adam_Winstone** » Tue Jan 27, 2015 8:55 pm

I don't know how much communication you want between the exhaust port and the crankcase though (I really don't know)? Obviously, the exhaust bridge would normally form a barrier to the exhaust pressure pushing burning fuel into the crankcase through these holes. Without the bridge/barrier it could be an issue... or perhaps not.

Adam

by **rossclark** » Tue Jan 27, 2015 8:59 pm

When knowledge said 'either side' did he mean out side the width of the port on either side?

by **phil23fair** » Tue Jan 27, 2015 9:26 pm

Harry Barlow drilled two holes, one either side of my Rapido 250 piston between the piston crown and gudgeon pin. I can't remember the exact size but they were in the order of 4mm. I think this was more about improving big end lubrication though but may be wrong, it was about 4 years ago.

by **rexton270s** » Wed Jan 28, 2015 8:03 pm

rapido 250 phil23fair how have you found the kit? torquey ......peaky......thursty.......??? wat setup av u got am thinking of a 250 race? :?:

by **phil23fair** » Wed Jan 28, 2015 9:32 pm

rexton270s wrote:rapido 250 phil23fair how have you found the kit? torquey ......peaky......thursty.......??? wat setup av u got am thinking of a 250 race?

I'm very please with mine but it has been tuned by Harry Barlow. It is very torquey and I don't think overly thirsty for the way I ride it. I probably get about 40mpg. It can cruise quite comfortably at 65 mph plus and get there quickly. I'm guessing the top speed is probably low 80's but the speedo is not that reliable at the top end, but it will keep up with a well kitted out TS1. I'm running it with a 30mm Dellorto and Taffy copy exhaust. Li150 gearbox with 46/17 sprockets giving a final drive ratio of 4.6. I live in Devon and we have got a fair few hills around here and the 250 makes easy going of them.

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Who else drills holes in their piston?

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