GT250 running-in

[redliner]

Evening all ..

I've just finished a top-end rebuild on my GT250M (with a +0.5 rebore) using NOS pistons, rings, pins, small end bearings, circlips.
Started fine, ticking over very nicely, and its now ready to go out on the road again.

A question for the knowledgeable, if I may:

Running-in a re-bored engine - first time I've ever had to do this - what's the best/recommended way to do this (if there is one)?
With a redline at 8000rpm, I was thinking of doing a couple of hundred miles at max 4000rpm, then upping the ante to 5500 max for another 100 - a good plan or a recipe for disaster?

Thanks

[PaulD738]

No need to be gentle with it, just ride it as normal with the odd run up to the red line. If you mollycoddle it you will glaze the bores up

[asco58]

From the manuals, Suzuki recommend a 1000 mile break in procedure for the T250/T350. Couldn't find GT250 but it's the same configuration and they suggest the same for most of their air cooled 2 strokes.

Up to 500 miles: limit to 4000 rpm

Up to 1000 miles: limit to 5000 rpm

Mechanical components need to wear in slowly so just ride normally whilst observing Suzuki's recommendations and it should be fine.

[redliner]

Thanks for the input - definitely a topic that reveals different opinions!

Have to say, I'm not entirely comfortable with going up to the redline during this period, despite knowing that other 2-stroke machines I have (like my chainsaws) simply thrive on max revs, and actually seem to work most efficiently in that mode. Can't bring myself to wring the neck off my lovely little old bike at any time to be honest, so I'm thinking of going down the 'middle road' route with this one, 250 miles max 4000rpm, and another 250 max 5500rpm.

Lets see how we do with that.

[canaletto5]

From the manuals, Suzuki recommend a 1000 mile break in procedure for the T250/T350. Couldn't find GT250 but it's the same configuration and they suggest the same for most of their air cooled 2 strokes.

Up to 500 miles: limit to 4000 rpm

Up to 1000 miles: limit to 5000 rpm

Mechanical components need to wear in slowly so just ride normally whilst observing Suzuki's recommendations and it should be fine.

+1 on sticking to the original Suzuki running in recommendations

[HootOwl]

I never run anything in I have to say. I never did. Its never presented my with any issues in 40-odd years of doing that. I do use the best oils available but if its built properly, it won't fail. If its not built properly, then it'll let go at some point anyway

[Gary66]

Jurys out on this one i think! So heres my 2 penneth. I re- built my suzuki X7 motor about 5 years ago now and took some advice and of course ignored some too! After the first 100 miles i started to raise the revs a bit at a time until i thought all would be ok. Out in Derbyshire just giving it a little more revs and it suddenly squeeked and stalled the motor, a deffinate seize for sure, i did manage to grab the clutch and coast to a stop.
I gave it a good 15-20 mins to cool down and then fired it back up. I did nothing to it and Its been fine ever since! regularly hitting the red line, so good luck working this one out!

[asco58]

If you don't break in an engine it probably won't present you with any obvious issues. It's just that there's more friction before everything has worn in and manufacturers release guidelines for breaking in to try and minimise excessive wear during this initial period and maximise the life of the engine.

After all, Suzuki did design and manufacture these engines and they've made recommendations for a reason and there's no downside to taking their advice but at the end of the day it is the choice of the owner.

[oldbiker]

I'm on the side of running in. A light load on the engine and slowly increasing the revs to start with. By 500 miles its nearly back to normal and by a 1000 miles its completed. I have not had a problem sofar with this method. Each to their own.

Expensive to fix if the engine packs-up at speed