Running in

[Stuart Jenkins]

Hello there,

I'd like some advice for running in my 41' G3L after an engine rebuild.
I've read in the single & twins 'instruction book' it recommends that the "throttle or twist grip is not opened in excess of one-third of its total movement for the first 1,000 miles"
This is fine and i've marked up the throttle with markers. The Burman gearbox is WD, so it has the low first three gears and then a noticable gap to forth where the revs drop, my question is in certain situations like going up a hill is it better to rev a bit more in third gear or have it in forth where it feels like it is labouring, what is the lesser evil for running in?
Unfortunately living in Sussex I cant really get away from hills!
Many thanks
Stuart

[Rob Harknett]

Use gears never let the engine labour.

[ianw1]

What was done to the engine in the rebuild Stuart?

[Mick D]

Use gears never let the engine labour.

Spot on Rob

Regards Mick

[56G80S]

+1 for Rob H and Mick D's comment.

Johnny B

[alanjennings]

A light touch on the throttle and an "ear" for the engine note and all will be well!

[Stuart Jenkins]

Great, thanks everyone!
Believe it or not it's the first engine i've had to run in as all of my previous bikes have been pre-owned!!
Hi Ian, these where replaced drive bearings, timing bush, cam bushes, small end bush, NOS barrel & piston, valve guides and valves.
Thanks
Stuart

[ianw1]

Sounds like nearly a full rebuild Stuart, follow Rob's advice & you can't go wrong.

[Rob Harknett]

Sounds like nearly a full rebuild Stuart, follow Rob's advice & you can't go wrong.

Just one more note. When you have done the 1,000 miles or what ever is stated, do not consider the engine run in. Gradually increase speed in stages and number of miles.

I have run in well over 10 new cars. One in particular I felt was no where near run in after the miles required. I mentioned this to an older engineer friend. He came round and started the engine then turned it off. He did this a few this a few times. He then said, the engine was no where near run in ????? He tuned the engine on and off again, said, notice the engine stopped dead when turned off. It never ran on a bit at all. You have a tight bore there. So you could do that test with a coil ignition bike. With mag. ign. perhaps if you close the throttle and the engine soon stops, that could mean a tight bore.

[clanger9]

I'd say running-in properly is more about feel, rather than following a precise mathematical formula.

Each time you push the engine a bit harder than before, you are stressing it. Do this too much and it will feel tight/hot. Ignore this and it'll seize. Alternatively, if you are too gentle, it'll never get run in properly. Some of the worst "oil burners" are engines that have been run in too gently.

The trick is to gently give it progressively more revs/throttle as you rack up the miles, varying the engine load and speed as much as possible. Never let it labor or slog, never hold the throttle wide, try to avoid constant engine speed. Use the gears a lot.

You should soon get a feel of when it's happy (and when it isn't). As Rob says, you can tell straight away if an engine is still "tight" by the way it stops.

Hope this helps!