Scooterotica

hi mates,

I bought 61mm old Cosa crankshaft with 107 conrod. the plan was to use it on with RT225 BGM kit. However I heard that 61mm with 107 conrod is very hard to set correct timings on. What do you think, please advice do I need to change to 110 conrod? Or should try as is?

Sometimes, short rods on piston ported barrels can lead to excessive inlet timing, but the best way to check is to dry build the engine and measure the port timings. I am sure that your combination of stroke, rod and kit are uncommon, so it would take a clever person who was familiar with the RT kit and a slide rule to give you an answer without some port timings to work with.

Might I suggest you try the dry build this weekend and report back......?

MB recommend a 110 conrod...

Hi, thanks everyone for suggestions. I'll go for 60/110 instead 61/107. If will have some time this week will try dry built and let you know how it looks.