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428 Conversion- Final verdict

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I realize the topic of the final drive 428 converion has been talked to death,BUT , as far as my extensive research on this goes, I see no clear winner. So, once and for all, is it better to stay 520 or covert to 420 chain?

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The consensus is that it is a wash in most areas, but having said that, the goal of the 428 is rotating mass or drive train weight loss.

IMHO there is absolutely no reason to get rid of a good chain when about the same weight loss can come from a good hardened aluminum rear sprocket, tri-metal rear, or ironman rear.

If your chain is thrashed, spend the $$$ on a very low friction "X" or "T" ring 520 chain and the above rear sprockets. Keep the strength of the 520 and accomplish the weight loss goal at the same time.

You can lose more weight by tire/tube choice than with a chain/sprocket change to a light 520 set-up or a 428 set-up.

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I disagree, have you ever held 2 sprockets and a 520 chain and compared them too 2 sprockets and a 428 chain? There is a big difference, and with the 150 only making around 17hp (if I remember correctly) weight on the drive train means a lot. Changing a tire and tube combo to save weight vs. changing a sprocket/chain to save weight is dumb if you ask me. In all cases you will clearly see an increase of power with a sprocket/chain conversion. I have a built 6.5hp mini bike making about 20hp at the crank and I run a #35 chain. A #35 chain is like a friggin bicycle chain. So choosing to keep the 520 chain over UPGRADING (or downgrading I should say) to a 428 chain is a very good idea. I would go to an even smaller chain is sprockets were readily available. Every little bit counts with these bikes being as heavy as they are so I would take a 428 chain over a 520 (in this case at least) any day.🤣

👍 from Wesley

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I've done the 428 conversion and there was a slight increase (very slight) in low end "snap" but the chain was stretching rather quickly, had a lot of side to side movement, and I had a hard time finding anything other than a 59 or 61 rear sprocket so I went back to the 520 chain and sprockets.

I still have the Renthal 428 sprockets and chain at home. I will weigh the 428 setup and compare it to the 520 chain along with an aluminum rear and steel front sprockets just to see what the weight difference is.

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So is there a company that sells a 520 kit? (I know there is a plethora that sell 428 kits.) I was just wondering there was anyone who sold sprocket/cs sprocket/and chain. Or do you have to buy the seperatly?

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i picked up a 520 X-ring chain and steel sprocket set(13/48)off e-bay $85.00 free shipping. i don't mind the extra weight of the steel sprockets as it should last longer than aluminum and that is more important IMO.

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Alright, I weighed the Renthal 428 Conversion which included a non o-ring chain; steel front sprocket; and aluminum rear sprocket and it was 3lbs 15.7oz.

An equivalent 520 setup (same gear ratio), with the necessary length non o-ring chain; Renthal steel front sprocket and Renthal aluminum rear sprocket weighed 4lbs 6.2oz.

There is a savings of 6.5oz. or 9.3% going with the 428 conversion.

I used the 428 conversion for about a month and the teeth on the front sprocket were already "hooking" and the chain had a lot of side to side play. I used the same 520 front sprocket and chain all of last year except for when I had the 428 setup on the bike and they still looked good at the end of the year.

Hope this helps.

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Interesting. Well I've run a few set ups and my conclusion was the stock o-ring 520 chain has a lot of drag. The difference, however, wasn't that. The difference was changing from a steel rear sprocket to an aluminum one.

Chain stretching? I don't know about that. I just don't believe the chain will stretch from the massive power of our toy bikes. I don't see it.

I will say, however, that I have noticed a lot of chains stretching, but it wasn't because of the motor. Oh no. It was because of chains that were set too tight.

Bottom line? Change the rear sprocket to an aluminum one and you'll save a lot of $$$ and you'll get most of the performance you would from a 428 conversion. There might be an advantage to the smaller chain and non-O-ring, but let's be real; It's not 4 hp like Motocross Action said. That's just silly.

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i am running the 428 on my 150f.. using it for MX and had to adjust the chain 2 times since doing the switch last fall.. these are not easy hours that I am putting on the bike and my DID gold is working just fine. as far as the teeth hooking. who's sprocket were you using? I am using the one that BBR sells and works great..

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Alright, I weighed the Renthal 428 Conversion which included a non o-ring chain; steel front sprocket; and aluminum rear sprocket and it was 3lbs 15.7oz.

An equivalent 520 setup (same gear ratio), with the necessary length non o-ring chain; Renthal steel front sprocket and Renthal aluminum rear sprocket weighed 4lbs 6.2oz.

There is a savings of 6.5oz. or 9.3% going with the 428 conversion.

I used the 428 conversion for about a month and the teeth on the front sprocket were already "hooking" and the chain had a lot of side to side play. I used the same 520 front sprocket and chain all of last year except for when I had the 428 setup on the bike and they still looked good at the end of the year.

Hope this helps.

Interesting. I would have guessed the 428 set up to be over a pound lighter then the 520. I’m also curious as to why you got such short life out of the 428 front sprocket. I’ve had the same 428 kit on my 150F now for 5 solid years with very little wear on the front sprocket or chain. The aluminum rear sprocket is starting to show wear, but I don’t see a need for replacement any time soon. Maybe you ride in sand, or alot more then I do?

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Interesting. I would have guessed the 428 set up to be over a pound lighter then the 520. I’m also curious as to why you got such short life out of the 428 front sprocket. I’ve had the same 428 kit on my 150F now for 5 solid years with very little wear on the front sprocket or chain. The aluminum rear sprocket is starting to show wear, but I don’t see a need for replacement any time soon. Maybe you ride in sand, or alot more then I do?

I ride in the sand a little but not very often. I do weigh 200 lbs but I don't think that would make much of a difference.

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Short life of the 428 is because the pins are smaller in diameter and the chain is narrower than a 520. Using a 520 chain is overkill for strength, a 420 is strong enough, but in the enviroment we ride the 520 provides a much longer life ompared to the 428.

As far as chain friction use a X ot T ring chain instead of O ring for less friction. I lube my T ring chain with a dry teflon chain lube and I can feel the friction drop as I apply the lube.

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