OzVMX Forum
Clubroom => Tech Talk => Topic started by: Ji Gantor on July 29, 2009, 06:28:36 pm
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With the nationals only a few sleeps away there must be a some members that have freshened up their top ends. New piston and rings to give that extra power. The only thing is that the engine should be run in allowing the rings to bed in.
The usual way is to run the bike in a paddock for an hour at a maximum of 3/4 revs. This does not over work the engine but gives some time for all the components to meet each other without grating on each others nerves.
Okay we have new piston and rings in our engine but no time left to rev around on a track.
Is there another way to run in the engine.
Can an engine be run in stationary. Keep the bike on a stand, start the engine, rev it up and let her run for an hour or until the cops get there.
I have spoken to a Pro rider and he does not bother running in the engine at all.
This would be the perfect question for Lozza.
Ji
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That's why they have practice!
(and on a serious side I doubt having an engine free-wheeling for an hour would do it much good.)
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At the Nationals there is no practice, just two sighting laps then ten minutes to post your best lap time for qualifying.
Ji
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One long running and prestigious American magazine once did a story on this. They stated the best way was to start the engine and then knock the carb out of the manifold :o :o...extreme rpm for a short period beds things in just fine apparently. ??? ???
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At the Nationals there is no practice, just two sighting laps then ten minutes to post your best lap time for qualifying.
Ji
That ought to be enough! ::)
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We get two sighting laps and continue for the ten minutes of Hot Lap qualifying (no break).
So this should do the job?
Two, 3 minute laps followed by 3 laps flat out.
Ji
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Ji. Running in bikes is a bit of a personal thing.
Some people go to great pains and lengths to get it just right (waming them up, cooling them down, run around the bike ten times clock-wise, run around the bike ten times anti-clock-wise).
Other people throw a new piston in at the start of a season, do a couple of easy laps and then flog the piz out it untill it starts to rattle all over again.
As I said. Everybody has a different way of doing it.... ;)
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Other people throw a new piston in at the start of a season, do a couple of easy laps and then flog the piz out it untill it starts to rattle all over again.
That's me. Rebore, new piston, rod and mains. Start her up cold at Harrow for the cold start test, Idled her around till she warmed up. Did a "quiet" lap around the main loop then back to the Parc Ferme and changed the jetting (she was a little lean) then strait onto the special test and revved the shit out of her.
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A fresh motor .... warm it up , 10 minutes around the back yard then turn it off .
Next day check jets & pugs ..... then up it .
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Usually do 3 X 5min bursts waiting untill your hand can touch the cylinder without burning yourself in between.Each 5mins riding round gradually increasing rpm untill you go for the doctor on the the third go.Heat cycling it's called as you want to gradually bring the piston up to it's peak operating temp gradually the first time.
As with a few of the above stories the common element is NEVER keep a constant throttle.Flogging it from the get go is OK in an old air cooled engine but in a water cooled nikasil cylinder you will cold seize within a minute if you do not warm up correctly.
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I just warm it up and let it cool down 3 or 4 times then take it out and bulge it. :) Darcy
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bulge it. :)
I like that term. Bulge it Can I use it? :)
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If you want to use it feel free ;D Darcy
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You know, as a kid I always followed the manufacturer's instructions for running my bike in. And they all worked fine. But a mate would just ride it round the block a couple of times and pronounce her ready to go, then proceeded to flog it. His DT400D was always miles faster than anyone elses. To ride it, it felt like an MXer, revved to the moon and braaapbraaap through the gears. I never understood that - was he lucky, or is it better to run them in like that?
I still start mine up, warm it up, a couple easy laps, let it cool, run round the bike 5 times, another few laps, let it cool, do a handstand, a few more laps, call it a day, and do it again the next time I'm out. Then it's RUN IN...
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Thanks Warden,
I have always run engines in as per manufacturers specifications.
It usually takes all day with jetting and pre-mix..........
I will try this weekend to see if I can get onto a track and give my engine its best chance.
Can a bike be run in on the stand.
Does the engine need varying loads.
If on the stand we can set up an evaporative cooler to keep it cool and keep the revs up and down.
Ji
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What's the purpose of a 'run in' on a two stroke? To me it's just a check that every thing is as it should be - tolerances, timing etc.
One heat cycle - careful start up, pick up more and more revs, listening and feeling for any 'locking', fully warm it by progressively putting it more and more under load (more revs, more acceleration). One successful heat cycle - about 10-15minutes - and then go for it.
If it is quality parts put together right it will be right - it's a two stroke - beauty in it simplicity.
Plug chops and tuning after that as per usual for the usual reasons.
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Usually do 3 X 5min bursts waiting untill your hand can touch the cylinder without burning yourself in between.Each 5mins riding round gradually increasing rpm untill you go for the doctor on the the third go.Heat cycling it's called as you want to gradually bring the piston up to it's peak operating temp gradually the first time.
As with a few of the above stories the common element is NEVER keep a constant throttle.Flogging it from the get go is OK in an old air cooled engine but in a water cooled nikasil cylinder you will cold seize within a minute if you do not warm up correctly.
DITTO
Is a sight lap under yellow flag and who is testing the speed ??? ???
cheers
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bulge it. :)
I like that term. Bulge it Can I use it? :)
I prefer teh term bludge it.
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Can a bike be run in on the stand.
Does the engine need varying loads.
Ji
Heat cycling, just get it hot a couple of times on the stand and let it cool down between, all running in is doing is bedding the rings and knocking the high spots off the piston as metal things expand at odd speeds.
Ever wondered why rental cars run so well, they get a good flopgging from day one.... or they do if I am driving ;D
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I've never run a two stroke engine in...ever. One or two cruise laps to make sure it's been put together properly and then hammer the bejesus out of the forking thing. 8)
I've only ever had two sieze ups in 40 years of owning, riding and racing two strokes and they all perform pretty damn well if I don't say so myself. ;)
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assemble the top end dry
then kick over on kickstart
quickly about 30 times (with tounge out Lh side) :P
run in ;)
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team kawasaki drop the oil out of there 4t multi's and fill her up with deisel with a hour city riding for there run in on prodie racers and the advice from the guys was if the motor was going to be fired up that day you assembled it using crc on the piston/ring lands and bore to stop carbon from forming in the ring lands and to help bed in the rings,ive used this method for years with no drammars