Are you sure it needs a rebuild? What's wrong with it?

 

As I say, it's slow as hell. Doesn't feel responsive on the throttle.

 

First thing I'd look at would be the carbs.

How many miles has the engine got on it?

 

Carbs seem OK, needles seem to have been shimmed at some point. No idea or record of the milage.

 

Check the valve clearance and then check compression. That will tell you if you need a rebuild.

 

It's running on all cylinders isn't it? You should destroy your friend's sportster.

 

Yeah running on all cylinders. It's frankly embarrassing being burnt off by a Harley. Will book the bike in for a valve and compression check.

 

Other items to look at: air filter, spark plugs, valve clearance, synchronize carbs, throttle cable (is it opening the carbs completely?). Does your bike have a fuel filter (I've put in-line filters on past bikes) and if so, is it clogged?

Of course if you have a compression check done and find low/inconsistent cylinder to cylinder readings you do have some internal work to do.

 

Aside from the valves all been done recently. I'll get them checked and the compression. Thanks for the advice folks.