Honda Spree and Elite 50 Forums

So I've been chasing a problem on my scoot for just over a week now and for the life of me can't figure it out.

My Dio has developed a problem where it starts and idles fine, but anywhere from no throttle to somewhere between 1/4 - 1/3 throttle it is super rich, bogs, smokes and generally runs worse than a bag of rubbish. Once it gets past this(say up around 20 km/h)it 'clears it's throat' and runs just as well as it ever did, right up to top speed. Oddly enough I only noticed this happen after installing a new drive belt(654x18x30)

Initially I thought it was caused by a broken bystarter wire causing things to stay in the enriched position, therefore making it run richer. I have fitted a spare bystarter(tested and working), pulled and cleaned the carb about as thoroughly as I can but to no real avail.

I dropped a main jet size last night and went for a run. It ran a whole lot better and was barely noticeably boggy off idle(nothing of concern)but I wasnt watching my temps and rather annoyingly soft seized it for the first time, not happy!

Honda Dio AF18
50mm bore
Stock PB carb. #35 pilot, #90 main. Needle clip in lowest notch.
Stock exhaust and airbox. Airbox restrictor pipe removed.

Any pointers on this would be greatly appreciated. Starting to drive me nuts!!

Also I would have thought if the bystarter was stuck in the enrich position it would stay rich throughout the whole rpm range, and not just the first 1/4 - 1/3?!

The 3mm wider belt has you taking off from a stop in higher gear. Try switching back to the oem sized belt (654x15x30), or, keep the 18mm width belt and change the variator boss to a 3mm wider one (zx) but you may have to shim out your kicker cover to clear drive face/starter gear. I don't know if you are running rich but try that oem belt first.

Thank you bones, after putting the original belt back on the problem seems to be mostly cured!

Annoyingly I saw the broken bystarter wire after my initial run with the wider belt, and as the guy who sold it to me swore black and blue that the 18 was the standard Dio belt, even when I queried it, has lead me down the rabbit hole a bit looking for a rich problem that didn't exist...

Thanks again!

Greetings:

Technically the seller is correct; 18mm was the standard belt for most Dio models - just maybe not the early ones.

I'm guessing the bystarter was causing the rich running, did you try the 18mm belt back on? From a 2013 Dayco catalogue, the DIO belt is 18mm standard from 1991 onwards (p/n 7173). Just curious how that affects your top speed.

Looks like the DIO uses the AF18E motor?
https://en.wikipedia.org/wiki/Honda_Dio

Correct. Replacing the bystarter with my only working one has cured the rich running and has my scoot back up and running as it was before.

Yes correct the Dio uses the AF18E motor. Pretty much the same as the 16 bar a few minor details... There is a post on here somewhere that outlines all of them

Further testing with the 18mm wide belt will continue when weather permits, can't wait!