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Showing posts from December, 2011

Steering Head Bearings

A nice modification on the steering stem of most motorcycles, is to replace the stock ball bearings with taper roller bearings. E.g check the lower part of the photo below with the Nsr250 steering head bearings. Bearing assy consist of a cup and a cone ball bearing with the balls held in place by a suitable cage. Even though this method was even used on later racers, they are considered old-fashioned. On the other hand, taper roller bearings give excellent results and a smooth steering (less head shaking) as they kind of act as a soft steering damper. Only drawback is that installation procedure takes a little bit more time as alignment isn't as easy as using the stock ball bearings. 
Nsr250 ball bearings, stock and taper roller on top.  Part numbers are Koyo 32006JR (lower bearing) & NTN 4T-CR-0574(top bearing).

Hellenic Road Racing - The Old Days

A Facebook group about old era Hellenic-Road-Racing.
Pass by and have a look at the pics... Cheers!

MC16 port layout

A cylinder port map out of a Nsr250 mc16 model. Timings are very racy and quite similar to early Rs125 nf4 cylinders but port lengths are narrower. This cylinder will seriously benefit from slightly bigger transfer timings while keeping the exhaust port as it is.

Total length of the cylinder is 86.3mm and it's a straight swap to all Nsr250 crankcases. Water jackets could have been bigger so upgrading your cooling system would be a good idea. 
I really like the straight roofs of the exhaust ports...  *Numbers are in mm increments.

Oil Blank Plugs for Nsr250

Spyros(GR) aka Bismarck, made some quick and dirty blank plugs for a Nsr250 mc21/28 crankcase.
Oil pump plug on the left, GPS plug on the right
... looks sweet.

2Τ Oil PreMix Chart

My favorite oil measuring tube is made by a UK based company called Apico. A really nice graduated tube with a detachable base and a lid to keep the inside clean and leak-free.

Crm250 AR PGM units

I haven't posted any pics of PGM units lately, so here is a couple of AR units for Des(UK) and Andy(UK). Repaired, tested and ready to be posted back.

PowerJet Kits are now SOLD OUT!

Adjustable power jet kits are now sold out.  Big thanks to everyone for your interest so far, more two stroke stuff are around the corner!

Blitzkrieg Tools

...or how to remove the Nsr250 mc28 swingarm axle in a couple minutes without having the proper tools.
I used a -not anymore- 32mm socket for the castle nut and a BR9ECM spark plug with a lock nut for the pivot bolt. To construct such precision and special tools, you will have to make use of some other delicate tools such as an angle grinder and a file. Believe or not, no CNC machines were involved during all the steps of this construction... LOL