Running in after a rebuild

[oldguy]

Just picked up my engine this afternoon, had the bottom end done, I have just finished putting the top end on, new piston rings and bearings, all torqued down and ready to go back into the frame.
I forgot to ask how do I go about running the engine in.

Help/advice appreciated

Cheers John

Thanks to Scott :niceone:and Mr Motorcycles, :first:

[oldguy]

:doh:Forgot to mention the engine is a KX65 2smoker

[cheese]

How old?

Personally I take it easy first start, warm it up properly then only give it a little bit for teh first 10 mins then after that. pretty much good to go.

[telliman]

:doh:Forgot to mention the engine is a KX65 2smoker

RAPE IT!!!!!!!!!

[tnarg]

My 2cents. Just the basics really. Dont labour it,dont over rev it.
Keep changing through the gears without staying at one constant rev for too long. Basically dont thrash the poo out of it. Being a 65cc not sure how long to run it in. Change oil then go play.

[oldguy]

How old?

Personally I take it easy first start, warm it up properly then only give it a little bit for teh first 10 mins then after that. pretty much good to go.


RAPE IT!!!!!!!!!


My 2cents. Just the basics really. Dont labour it,dont over rev it.
Keep changing through the gears without staying at one constant rev for too long. Basically dont thrash the poo out of it. Being a 65cc not sure how long to run it in. Change oil then go play.

Its an 07....so which is it, this confusing

[Squiggles]

Tis a matter of great debate

[Taz]

Doesn't really matter as you're only scrubbing in a new piston and rings in an already run in bore. Main thing is to check all is in order after a few minutes running. You wouldn't want to do an hours ride only to find that you'd lost all your coolant on the way. Being a 65 it probably would be hard not to rev it anyway. It'll be fine. Just warm it up a little first.

[Reckless]

Read this my man. http://www.mototuneusa.com/break_in_secrets.htm
I have used this method on every kart racing engine I had in the last 20 years. First few years simply by accident because i was impatient. Did two laps then, went fast. Then deliberatly. Always had fast engines.
Anthrax is correct a 2 smoker already has pre oiled petrol, and a nikasel bore, so you need to bed the new ring in to the the wear and tear already in the bore. To get good ring seal and therefore good compression. Just as an aside, every article and experiance I have ever had; More oil = more horsepower, in my opinion runnning lean has no HP gain and just creates to much heat. Anyway, start it in the garage, using your normal mix, to make sure you have put everything together ok. Don't idle it warm. Start it, sounds ok, turn it off, check the water level for air locks. That just means you know it will go when you get it to the track. You checked things like ring end gap when assembling I suppose? Its the first heat cycle that is important I rekon. Then take it to a ride, warm it up, check the water level again, and run it as normal. Dont thrash the shit outa it, but ride it like you want it to go well. And it will!
Only way you can damage a 2 smoker is by puting it together wrong or if your jetting is so lean it would have blown up anyway. Than change the oil after the first ride, to get rid of any crap in there during assembly or break in!!

[Reckless]

OK I've just had a thought! To all you guys out there assembling your 2 smokers. Here's some hints.
Air caught in the engine (an air lock) when you reassemble it is a common way of stuffing your new engine. When you fill a 2smoker do it slowly and listen the the water going in and the bubbles coming out. Secondly leave the bleed screw that most have, out of the head until you see water coming out. If you don't have a bleed screw leave the top hose off. this means the engine is full. Then put it on and fill the remaining.
Make sure you get the correct piston for the bore. Usually A or B size in a nikasil bore or in 10 thou jumps or so in a cast iron bore.
Make sure you put it in the correct way around. Usually the window (if it has one) faces the carb and the arrow on the top faces the forward. but look at the manual for the arrow bit.
Make sure you slip the ring into the bore B4 you put it on the piston and measure, then file (if necessary) the correct ring end gap.
Make sure the gudgeon pin cir-clip, clip gaps are in the groove opposite the little indentation area where you can remove them.
Use a smear of clean 2smoke oil on all surfaces when you assemble needle rollers, pins and rings.
When you put the barrel on make sure the ring ends are correctly each side of the pin in the ring groove.
Save your self some parts. I seldom take the head off the barrel and always put a little smear of silicone on each side of the base gasket so I can remove the barrel and head without tearing the base gasket every time.
Clean you power valve up each time, make sure it works OK. Make sure you assemble it correctly during putting the barrel back on. and leave the cover of till you start it to make sure it opens and closes correctly. The power valve is very important on a 2 smoker.
lesson over gotta go pick up my daughter. Hope the above helps a little.

[Danger]

All pretty good advice. I do it like this, similar as mentioned above.
Start engine, bleed air of head and top up radiator, warm it up gently but play with the thottle slightly so its not just idling the same revs constantly. Just enough to check things out and get the engine warm.
Let it cool down totally.
Start it up again and run it through the rev range, often I will ride it down the road and back without loading the engine too heavilly with low rpm or high rpm, the important thing is to vary the revs without loading the engine components.
Let it cool totally.
Then next ride is at the track, warm it up normally, then just ride it easilly for a half hour with different throttle settings using the entire rev range without loading it up then ride it as per normal.
That might all be a little excessive for the KX65. Probably just warm it up, check things out, take it to the track and tell the kid to take it easy for a bit then ride it normal.
I'm just due to do my top end on my RM250. Fitting a Wiseco Prolite piston. Its done about 200 hours on the last piston which was fitted after 30 hours (For its first 40 hours it was used mainly for MX where a slight drop in power is more noticable than in off road use where it is used mostly now).
My KTM 200 did over 400 hours before it needed its first topend.

[marks]

I'm just due to do my top end on my RM250. Fitting a Wiseco Prolite piston. Its done about 200 hours on the last piston which was fitted after 30 hours (For its first 40 hours it was used mainly for MX where a slight drop in power is more noticable than in off road use where it is used mostly now).
My KTM 200 did over 400 hours before it needed its first topend.

Not to hijack the thread but does that imply I should be able to get 200hrs out of my wr450 piston (Ive got 100 on it now)?

[oldguy]

Wish I had of posted this thread before I had assembled the top end, now I'm not sure, did I do this, did I check that, Should be fine.
I just realised Ive left the gear shifter behind when I picked up the motor.
oh well, I'm away Saturday, Jean's of to a birthday party on Sunday so no rush
now.

thanks to all for the advice/ help.

John

[Danger]

Not to hijack the thread but does that imply I should be able to get 200hrs out of my wr450 piston (Ive got 100 on it now)?

I don't think a WR450 would be very hard on pistons. Not like most 4 $trokes these days.

[Reckless]

Not to hijack the thread but does that imply I should be able to get 200hrs out of my wr450 piston (Ive got 100 on it now)?


I'm a fiddler. I just have to know its good. There's no way I could hold myself back from leaving a engine for 400 hrs. I couldn't help pulling it down and having a measure. But thats just me! They are some big figures Danger is quoting. I'm not saying he is wrong at all, but the longer you leave it the more chance you have of a skirt breaking off or a top needle bearing shitting itself or a pin clip loosing its tension. Dangers figures do make the manufacturers 20 or so hours look bloody silly. My CR250 did 50 hours on trails at 40:1 with richish jetting for enduro. I stripped it measured the piston it was a little shinny on one side but measured fine so I put a ring on it $32-00 and it did another 30 hours. But we are talking 2 smokers here a piston kit is $180-00 and its do it yourself not like 4smoker. They have valves and all sorts of ugly stuff.
With your WR most would be thinking of a freshen up at 100hrs but its up to you based on your riding, oil change frequencies, feel of the bike (does it seem underpowered), how does it sound(any rattles) and your budget. Most I have spoken to have done 100 hrs ok in their 450 4smokers. But I am a 2stroke man!!

Shit 400 hours Danger! I think I'll put off stripping the KTM for a few more rides. What I don't know don't hurt me aye!

[Danger]

The 02 KTM had a good quality piston. I think they changed it in '03. Apparantly once your replace the original with what they now give you over the parts counter your in for more frequent rebuilds.
I only did the topend because the bottom end needed rebuilding. Silly not to do it while its apart.

[camchain]

Wow, nice work reckless. I was just about to dig out the same link. I read that article a few months back and liked/saved it. This principle about getting enough combustion pressure going to force the rings to the bore and bed in properly made a lot of sense to me. Before that I was in the run it in like a granny camp. I think the warm up cool down thing seems reasonable as well.

Running in used to be a lot more important in the old days of sloppy tolerances/machining/surface finishes and shaky engines. Thanks, Japan.

[Reckless]

yes I agree. The two main things that have changed are the metals we now use are much much harder. i.e. Niksel and crome molloy rings etc. Nikasel aimed to never wear out and the ring and piston aimed to be the bit that is replaced. And the tolerances are much better as you say. So you don't need to be so careful.
Added to that, are the oils are so much much better, with synthetics etc. We used to run in all our engines in on castor based old castrol R. But if your using say a Motul 800 or a fully synthetic 2smoke oil you need to give it a bit of shit to get it to bed in properly because the oil is so much better.

[camchain]

I still remember the sweet smell of that castor oil. 'Chase and Sniff' when gunning down modern two strokes isn't as rewarding as it once was (sigh).

Good point on modern harder bore materials. It seems to me that without hone marks to help bed the rings (on well used engine) running in can't be as critical or possibly even very effective when replacing rings? Do the modern bores even have hone marks in them?

[cheese]

Crikey mr CR has done 50 and I'm about to rebuild it.

[Danger]

Yeah my mates '05 CR250 has had about 3-4 pistons replaced in the time I've had my RM. And he does not ride as much as me.

[oldguy]

Ok guys thanks for all the advice, got it sorted and back together, ran the engine as advised, check over all OK.
Just the other day, I noticed an oil leak, on close inspection I find its coming from the seal around the front sprocket.
How easy is it to replace.????
Is it just a matter of hooking it out the old seal with a screwdriver and pushing the new one into place or is there more to it.

cheers John.

[Buddy L]

what type of work did the bike shop do? if they split the motor , maybe it might be under warrenty?

[Danger]

No need to split the motor to do a front sprocket seal. Might be a seal and an oring that need replacing and possibly a bush. Depends on bike.
Some bikes don't like aftermarket front sprockets which can be slightly thinner and these place less pressure on the oring and thus they leak. Anyway east to replace these parts and cheap. Check circlip if it has one and if its notched flip it over, this might preload the oring so that it does not leak. Again depends on bike. Quite common for some bikes to leak here.

[oldguy]

what type of work did the bike shop do? if they split the motor , maybe it might be under warrenty?I got them to split the bottom end, I had supplied bearings, and gasket set, got them to replace what was need and put it back together for me, I just had to put the top end back together with new piston and rings.
got the seal out so I guess its just a matter of sliding the new seal on.

[oldguy]

sweet as all done.