28 replies to this topic

[HarrysMini]

As above, as I am currently rebuilding my engine I would quite like to know how everyone would run it in. 

 

It seems there are two options; a hard run in, or a gentle run in. 

 

Hard run in

Self explanatory really, load the engine, use full throttle in all the gears and vary the engine speeds. Some argue that this method allows the rings to bed in better and creates a much better seal. Do this for around 200 miles. It is important to warm the engine up completely before running it hard.

 

Gentle run in

Limit the revs to about 4500 and no full throttle, not letting the engine labour. Others argue that this method allows the rings to bed in better. Do this for around 500 miles.

 

I will be using Halfords Classic 20w50 oil for running in as it isn't particularly good oil and so hopefully will allow the rings to bed in properly. I will change it after about 100 miles of running in.

 

So, what are everybody's thoughts? Lots of people say that it is personal choice, but I can't see how. Surely one method works and the other doesn't. 

 

By the way, I'm not talking about bedding the cam in. I know that you should run it at about 2000 RPM for 20 mins for that. I'm talking about once I've done that.

[danbmini]

I used comma sonic 20/50 mineral oil for running in, not very expensive but has a good zddp content. Ran it in ''Hard'' as you say lots of load ans has been great and made lots of power! Changed oil after 500 miles for more comma and at 1000 changed to millers CTV 20/50.

[Stiggytoo]

I'd really like to know other peoples thoughts on this. I'd imagine you have read that article by the bike guy? He makes a pretty convincing argument.

[IainStallard]

When we run in our race engines on our TVR, they are run on an engine dyno for about 8 hours at varying revs and monitored by computer to make sure the fueling is correct. We've never had any issues doing it like this. This way, you can race it straight away without worrying about running it in on the road

[Stiggytoo]

Although that is the ideal scenario Iain (well that or on a track), most people don't have access to a dyno, or don't want to pay to use one. Your best bet is to find some quiet roads to avoid traffic etc, maybe take the long route to work    

 

Regarding the hard or gentle approach, with my go karts I tend to stick to what the manual says, and drive it with 1/2 to 3/4 throttle, constantly varying the revs etc.

Edited by Stiggytoo, 26 December 2013 - 09:29 PM.

[monster_mini]

Also something very often overlooked is the fuel mixture, it's all well and good a brand new engine, but run the engine in on a rich fuel mixture on the road and all your rings will do is wear those bores away due to bore wash!

[mk1leg]

Dyno run in

[Dolly 89]

I always ran my motocross bikes in by racing, I would rebuild a motor just strike it up, make sure it was all ok, then I would take it to a race meeting, I found the pistons and rings would last longer that way, and it seemed to be a bit quicker to compared to my brothers bike who would never run his in hard

[blackbelt1990]

I did a gentle run in on my 1380, followed all the advice to the letter. Now, I get blue smoke on hard acceleration, so I'll be changing the rings and giving it a good hard run! lol

[mini93]

I did hard run in for around 80 miles or so. That didnt involve revving the engine particually high though, only up to 6,000rpm after that it loved singing upto 7,500

 

I used really piss poor oil, something like Tesco full mineral 15-40 after the oil dump I ran on Valvoline 20-50 Part synthetic stuff

Edited by mini93, 27 December 2013 - 11:43 AM.

[mini13]

I do a kind of mix of both,

 

essentially I do squirts of 3/4 throttle followed by coasting, the idea is to prevent overheating of any of the highspots on the rings/ bores that you are trying to wear in.

 

so maybe a 5 sec squirt in third, then coast for 15 secs repeat ect...

 

the good thing about this method is its fairly compatible with driving on the road.

 

also yes check the mix is ok as you'll have wet feet otherwise. use an AFR guage, check its not going too rich, especially as you get on/ off the throttle,

[HarrysMini]

Well so far, hard run in has easily won. What article was that Stiggytoo? I don't think I have read it. 

 

Very interesting to see how other people run in their engines and what results they've got. 

 

I'm afraid a dyno run is out of the question due to cost and I'm sure I can get the same results on the road/track.

 

I think this topic has and will be very useful for people building an engine as this is probably the most debated topic in that area and it's interesting to see exactly how many people do whichever method and how they do it.

 

Keep the replies and votes coming!

[cian]

Im in the same position dude! Engine will be ready to go in a couple of months and dont know what run in to do

[Stiggytoo]

This is the article: http://www.mototuneu..._in_secrets.htm

My only concern is overheating, but I suppose coasting will help.

[1275GTS]

On both my rebuilt engines I did as my engine builder told me, i.e. gentle to start off with up to 3000rpm for the first 200 miles and then up to 4500 and try not to labour the engine. I have had no problems with either engine the oil was drained out at 1000 miles and I use Valvoline 20/50 oil.