The British Historic Kart Club

Hi all

I've just tranferred this info from "kart chat" as I think this is more apprpriate for people looking through the website for information. I think it will get lost in kart chat and with the number of members using the TT27 the questions are going to come up again. The info was posted by "Keith - TT27 Crazy".

Hi members
I get most of my seals, bearings and pistons etc from Dartford Karting. They seem to have a reasonable range of old stock 48 series pistons left, up to 48.75. The only thing to note is that their pistons (boxed as Solo but made by Asso Werke) are 20.0mm wide between the little end shoulders. As the commonly available little end bearing is only 17.0mm the bearing can come partially disengaged from the con-rod, so you have to fit shims or use a wider bearing. I found some 20.0mm wide bearings on eBay, which I believe are still available, I’ll find the contact if you need it.

If you have to go above a 48.75 piston into the 49 series range, you’ll need to drop the barrel slightly, as the gudgeon pin to crown height is about 1.7mm less, from memory.

With regards to con-rods, the newer type IAME rods are a different profile across the big end, so if you come to fit one of these be careful that it doesn’t catch the crank cases. In this eventuality, I believe that most people machine a little bit out of the cases to gain the required clearance.
I'm no expert on setup and others may disagree with me, but I set my ignition around 2.2 / 2.4mm BTDC and the squish band clearance between 0.7 / 0.9mm. I’ve also been advised that it’s a good idea to check the combustion chamber volume, which I believe should be around 8cc, as old cylinder heads tend to have been re-profiled a few times.
Hope this helps, regards,
Keith

hi all,

More usfuel info on the TT27.

I’ve been getting my 20.0mm wide small end bearings from Rider Motorcycles, Yeovil Tel: 01935 421681. They are actually NOS Honda MT125 small end bearings, part No. 91009-444-004 and come in boxes of 5 bearings for around £6.00. They are also still available on eBay, item no. 370192648978.

Just for reference, they also have another auction for small end bearing listed to fit the MT125, part no. 91007-444-004 (eBay item no. 370131130012). Essentially the bearings are the same, but the 91009’s seem to run slightly smoother and are also a little cheaper.

It probably seems strange buying them from a motorcycle dealer, but having contacted a number of bearing suppliers, I discovered that this particular size was only supplied directly to the Japanese motorcycle industry.

Keith