Thumper Club Forum

Technical => Bike Problems/Questions => Topic started by: crackedhead on June 21, 2009, 09:36:34 AM

Title: Spare XBR engine - bench testing ?
Post by: crackedhead on June 21, 2009, 09:36:34 AM

I've picked up a 'spare' XBR engine from Tony in Haxby and would like to start it, before I get around (to the hassle) of swapping the engines around .....any maybe back again, should the 'new' one have problems.

There should be enough spare parts in the garage to setup a test rig, except for a frame to put the thing in. Has anyone tried this before ... suggestions would be welcome.

Title: Re: Spare XBR engine - bench testing ?
Post by: bullet350 on June 22, 2009, 05:53:05 PM

 i'd get the head and barrel off it and have a look inside. this sould let you know the condition of all of the main parts which wear, and give you a good idea of the parts you can't see.

 the only other probelms come from electrics and carburation, both of whcih can be taken from the 'old' engine (if good) and swapped over.

 bullet350

Title: Re: Spare XBR engine - bench testing ?
Post by: KungFooBob on June 23, 2009, 01:01:32 PM

I saw your engine, I picked mine up a couple of days before you were due!

it's probably quicker to just swap the thing than faff around setting up a test rig.  If you're really worried, but don't want to take the head off, then get it compression tested (testers are pretty cheap on eblag).

Title: Re: Spare XBR engine - bench testing ?
Post by: guest564 on June 23, 2009, 03:08:34 PM

A compression test should be done with the engine at normal operating temperature, cold it may not show up a cracked head. I'd pull the head off, it really doesn't take long.

Title: Re: Spare XBR engine - bench testing ?
Post by: guest18 on June 23, 2009, 04:33:27 PM

Tbh I wouldn't worry in the least about a cracked head unless you're going to modify it and tune it. In my experience the failure point it the rocker pad wearing through and the cam hardening flaking off, but even then they seem to keep on running...
Hmmm, wonder if an XBR lump would fit into swmbo's nrs chassis....  ;D

All opinions expressed are of course mine and your mileage or opinions may vary....  ;)

Edited to add, the NSR has about 9.25cm across the frame rails, anyone know the width of an XBR head...?

Title: Re: Spare XBR engine - bench testing ?
Post by: xbruby on June 26, 2009, 04:33:32 PM

If the engines in question have been purchased from Tony there is every chance he has had the top end off them anyway. I doubt very much Tony would sell an engine if the cylinder head was cracked as he usually sends them to Service Exchange Parts in Kegworth to have them re-worked if they are cracked.

Andy