First start after rebore

M

macavity99

Full member
Location
Bedfordshire, UK
Ok, I'm nearly ready:

-- filled engine oil
-- no oil leaks
-- engine turns on starter
-- have sparks
-- one dellorto pumps fuel (only one; worry  :-\ ; they both did before strip)
-- have stopped until tomorrow
-- drinking beer
-- listening to Planet Rock

Planning to start SF3 tomorrow, run at 1500rpm for 20 minutes, then set carbs, go to Post Office to Get road tax etc.

Any suggestions or tips for best practice during first start? (Assuming it starts, of course.)

Cheers, Steve in UK

 
Hey good luck Steve but i reckon if you leave it running for 20 mins you wont be able to get near it with the heat . I ran my tripple recently for the first time since rebuild spun on the starter with no plugs in to get the oil round then did a couple of runs  dumped the oil to check for anything nasty and put fresh in .              Tim
 
If it is anything like a triple to fettle buy 1m of fuel line (?3.99 from Halfords if you haven't got a good local guy) cut it in half, throw an old blanket over the seat and place the tank there the wrong way round (tie some string from petcocks to rear pegs just in case). Then push fit the lines between the petcocks and carbs (I'm assuming it has 2 lines like a triple).

That way you can play with the carbs without frustration (especially with balancing).  Make sure you are not on reserve to begin with (as you can start adjusting all sorts when you get low on fuel and don't notice!). Once it is running (green book gives guide on initial settings for the carbs) check ignition timing before going to town on carbs.

If you get it going on one cylinder and think something is gummed up in the other carb you could place your palm over the throat and rev a little (the vacuum can drag fresh fuel through).

Then the change oil/retorque head studs/recheck valve adjustment/check for leaks/drink beer type things that you do after a rebuild..
 
Don't run it 20 min static, ride it.
Start it up leaving a couple of tappet covers off to make sure oil is getting up there, then clean front of bike and ride.

Ciao
Paul
 
Accelerator pumps usually need to be primed. Sometimes they'll self-prime but in most cases not.

I agree with what others have said. Don't run it for 20 mins without any cooling air flowing over it. It's also not good to run a motor on no load for extended periods.

Cheers,
Cam
 
Start,run till warm,get carbs close,ride it, do a few mild pulls[1/2 throttle or so] not heavy load but make it work some to seat the rings,let cool, retorque,check valve lash,run again,set carbs and ride,make it work some more,don't lug or overrev,it will be obvious when it is happy.
 
If you want to bed'em in real good. Get it on the road and hook into it. I reckon that the first few days of operation after a rebuild is the optimum performance you'll get from it, 'cause it will drop off. And if it pulls a wheelie you'll have 'that' pleasure to remember, it may never happen again.

C'mon, the worst that can happen is that it breaks. That's OK, you know how to fix it now!

So, fang it and come back, check and retension, whilst smiling like a Tom Cat that just fucked the guts out of the Queens Cheshire cat.
 
Whats been done to my 3C is,get it started and give it a couple of reasonable good revs on the stand.Maybe 4 to 5k.Let it cool.Then go for a 10 minute ride again 4 to 5k varying the revs and no lugging or really big hills.Let it cool.Repeat a few times,don't baby it,don't let it lug in the higher gears.You need to seat the rings,it takes revs and pressure to hold them hard to the bore so they take off the high spots and seal as apposed to polishing,glazing.What scares me is if you overdo it maybe you brake a ring.So varring the revs,not too gentle,no lugging and not revving the ring out of it.That's what I do.There are other braver sole who do the ride it like you stole it,I think Piet said that works for race motors built with bigger clearances,to risky for all that work to me.
 
Got it started eventually. Backfiring was the clue -- swapped plug leads and it ran, badly. Can't ride it yet as I'm waiting to get a new road tax disc in August.

Here's the plan: On the road accelerate from 30 to 70 then drop back to 30. Do this ten times then ride normally but avoid max revs for 500 miles.

Re-torque head nuts? How? The two inner rears are impossible to reach and no way am I dropping engine out of frame again.

Cheers

Steve in UK
 
Re-torque head nuts? How? The two inner rears are impossible to reach
Click to expand...

A crow's foot spanner on a torque wrench is suggested by some.  I used a ring spanner on the end of my torque handle....you need to undo the front engine mountings and slacken the rear plus silencers to let the unit pivot down sufficiently (supported on a jack) to gain access.  Watch out for ancillary cables / breather snagging when you do it...there may be other stuff to look out for on an SF3
 
Vince said:
There are other braver sole who do the ride it like you stole it,I think Piet said that works for race motors built with bigger clearances,to risky for all that work to me.
Click to expand...

It usually has to work. :o

Race motors have the strange tendency to blow up at the least-needed moment, spares arrive at the last minute and the engines are finished the night before the race, normally around 2am... Sods' Law.  No other option but to give it all the clearances it needs to spin to the max from the start.  Very often they end up being quite noisy(mechanically) because of this!! :D

I opt to run in road engines carefully over a lengthy period, no lugging, no extended high revs till about 1500kms.  Heads are re-torqued after initial thorough warming, again after about 100kms, again after 500kms, and, if I feel really picky, again at 1000kms.  Usually no difference between the last 2 in terms of head nut tightness, just confirms the gasket has fully seated.

750 heads can be re-torqued with a 3/8" drive 17mm stepped socket used with a "wobble" extension.  Might need a sliver removed from the OD to slip past the frame rail at the rear studs, but spares all the hassle of dropping the donk.

piet
 
Something to bear in mind if using a crows foot spanner or some other kind of horizontal extender with a torque wrench is that it'll affect the torque applied to the nut.
The torque wrench measures torque applied to the 1/2" (3/8" or whatever) socket drive of the wrench itself. If you extend that further away from the wrench handle by using some kind of sideways extension, then the torque applied to the nut will be greater than the reading on the wrench because you've increased the length of the lever arm.

For example, lets consider the hypothetically simple case of a torque wrench with a 1 foot long handle, and an extension of another foot past the end of the wrench. The torque wrench is in effect only measuring the torque half way along the total length of the lever arm. By the time you get to the end of the arm where the nut is, the torque is double the reading on the wrench.

There are a couple of ways to deal with this:

1. Measure the offset in the direction of the torque wrench handle and apply a correction.
2. Arrange the extension so that it's 90o to the wrench handle. That way you're not extending the lever arm of the wrench at all and the torque wrench will measure correctly. This way is easier because it avoids any arithmetic.

If you find this confusing, draw some vector diagrams and it wall all become clear.

Cheers,
Cam
 
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