Faster after top end rebuild, or after run-in

[Snorty]

I've just rebuilt the top end of my engine, 1.5 O/S piston, rebore etc.

Is it now at the fastest it will be, or will it be faster after being run-in properly?

I seem to remember reading something about compression being higher after being run-in?

[MarJay]

[Snorty]

Haha. I've only had a quick blast on it, by that I mean I haven't been over 30mph, just making sure it runs after the rebuild in the car park.

I just mean it feels really responsive on the throttle when I pull it, the pressure comes off the front forks when I do.

It's only a TZR 125 (closed powervalve so doesn't rev past 8k, never has since I bought it). I imagine I shouldn't go above about 6k rpms?

[Teflon-Mike]

I'm confused.
First why were you doing a rebuild in a car park?
Wouldn't it have been warmer in a shed?
Second, if he ran it in, keeping to the book, like 1/3 throttle & 40mph for first fifty miles upping five mph and a nadgers more max throttle every fifty after, until full throttle & full speed reached after 250 miles or so..... it would quite obviousely be faster after run in?
Or is that what you mean marjay?
If he DOESNT run it in, he'll know how fast it is now, but not after running in, becouse it wont have been......
Err..... I give up.... my logic is too cunning even for me now!?!
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My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
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[Rogerborg]

LOOK OUT! The following advice applies to 4 stroke, not the 2 stroke that was belatedly revealed as the subject of the inquiry.
vvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvvv

If you're interested in performance ON A 4 STROKE, and thinking of doing a gentle run-in then I suggest that you read this.

Then ask yourself who told you to run a new or rebuilt engine in gently, and why, and what evidence they provided. Note carefully that "everybody says" isn't evidence, it's blind faith.
____________________
Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

[Snorty]

Ah no I've been rebuilding it at my work (factory unit) then took it outside once it had been rebuilt.

Putting the new float valve needle in the carb today and I should be good to go.

Last time I had a rebuild I gave it a good thrashing, it survived a fair amount of trips over to the east coast but heat seized on me...

I suspect it was due to me being a doylem and filling up the coolant expansion chamber instead of the radiator when topping up...

Going to treat it a bit gentler this time round as I've had enough bus trips to work to last me a lifetime, with the spluttering diseased scummy public.

[Kickstart]

[DrDonnyBrago]

[Frost]

I always think about people who race 2 strokes, like at the TT and stuff. You don't see then covering hundreds of miles at low revs to run the engine in. They just stick it together and rag it to the limit.

[Kickstart]

Hi

True, but they are probably running single ring pistons (not much to run in) which they replace every race.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Teflon-Mike]

[MarJay]

[0l0dom0l0]

There is a fair few different opinions.

I think the picture did it for me:

https://www.mototuneusa.com/BreakInF3Pistons.jpg

The piston on the right was broken in via the 'running it hard' method. The one of the left, the 'normal' method!
____________________
CBT Passed: 30/08/2009, Theory Passed: 31/08/2010, Mod 1 Passed: 6/9/2010, Mod 2 Passed: 13/09/2010. Restriction ended 13/09/2012.

Bikes: 2007 Derbi GPR 50, 1998 Yamaha Fazer 600 (written off), 2002 Yamaha Fazer 600, 1994 CBR 600F, 2003 Triumph Daytona 600, Kawasaki ZX6R J1.....Current: 2006 Yamaha FZ6, 1998 Suzuki TL1000R and a Honda VFR 400 NC30.

[Kickstart]

Hi

Bit that would stop me taking that at face value is the total lack of any carbon build up ABOVE the rings.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Blau Zedong]

[Frost]

[Rogerborg]

Calm down, dears. The type of engine was disclosed while I was off searching for that link. Yes, yes, always read the intervening posts, measure twice, look before you leap, i before e except when the sun's over the yard-arm.

INSUFFICIENT DATA FOR MEANINGFUL ANSWER.
____________________
Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

[0l0dom0l0]

[Snorty]

So I finally got the bastard carburettor to stop leaking... fitted the rebuild kit all the parts, jets throttle pin, needle seat etc.

Still leaked, took 3 attempts but third time lucky after bending the float "frame" part that sits on the needle valve.

Took it out for a test run, plenty of power behind the throttle (for a 125!)

Nearly binned it when I braked on some slate some c**t had left in the road.

Still... all is well now, got it home, tucked it in, ready for work tomorrow, I am no longer a bus wanker!

How *should* a 2T be run in? What's the general consensus? I'm sticking below 5000 revs, once I get to that, I shift up, until I am in final gear.

[Teflon-Mike]

Roger, this wouldn't be sort of pent up angst at having faithfully run the 125 in to an archaic run in procedure, keeping speeds to 25mph or so for a few hundred miles, incrementing it by 5mph every decade, whilst doing oil changes with every fuel fillup, and then feeling a bit conned by it all, would it?

If it makes you feel better, your running in regime wass actually pretty close to ideal for that motorcycle...... must confess it has bog all to do with reliability or power or limiting warranty claims, though.....

Its more to do with making you REALLY appreciate life in the slow lane, so that when you HAVE got it fully run in, your so bludy relieved that you can actually keep up with some traffic, you don't grumble about how slow it is!

While also giving you some hope that it might actually prove reliable, paddling about for a thousand miles, without it making enough power to actually shake anything loose!
____________________
My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?'

[Frost]

I think run in procedures are secretly there to stop people getting a new car or bike then ragging it to the limit first chance they get and ruining the cars reputation, or more likely making use of the warrenty

Personally i think there is no finer feeling in life than picking up a hire car to find it's got 20 miles on the clock. You know you can treat the tires and clutch how you like and they'll still be working fine when you give the car back