Honda Spree and Elite 50 Forums

I have an '85 UK Spec Honda Vision that will only do about 32 MPH that I'd like to get up to 40. The UK versions are classed as 'Mopeds' limited to 30 MPH. There are no restrictions in the exhaust or variator & the ramp plate is not restricted, so I think it's held back by the gearing which is about 12.25:1 (turns of the clutch : turns of the wheel) on the final drive. I think the stock US AF05 gearing is a bit higher than that?
From memory, 32MPH is about 7500 rpm on the rev counter, the AF05 engine produces max HP about 5500 rpm, so I'm thinking that some stock (US) AF05 gearing may help? I don't want to over rev the 32 year old engine and at the same time don't want to overload it. Any thoughts welcome.

Thanks

You should be getting 39-40mph out of your stock AF05...even with the 12:1 gears. Put some pen marks on your variator and run it full speed. Then check to make sure your belt is reaching the top of your variator. This condition would indicate a worn (too thin or slipping) belt, flat spotted (or too light) roller weights, a stuck clutch pulley not opening fully or the vari is in need of a ramp plate change or boss adjustment.

Eliminate all possible issues with trans before thinking of a gear change. The US gears are 11:1 and the rare 10:1's. Both of those are not much different than your 12:1's and I wouldnt expect an 8-9mph gain from either one with a stock bore.

I take your point about the ratios, I was hoping to get about 37mph at about 7500rpm. I changed the belt & rollers earlier in the year, I also marked the variator but have not yet taken the covers of to look.
If what I saw in another thread is correct & if I understood it correctly, 40MPH is about 8500 rpm with a 12:1 ratio. Is that high rpm for an AF05?

http://www.hondaspree.net/phpBB3/viewto ... eter+speed

Whatever gear ratio is in your trans (in this case 12:1) is not the actual ratio in relation to RPM's to tire rotations....this is because of the CVT.

The chart or calculators to get these figures would ONLY be accurate when your variator is in the 1:1 position during mid shift variation. The U.S. AF05 variators have a range of roughly 2.4-.08:1. Therefore, during take-off's your ACTUAL rpm-to-tire rotation ratio is lower than your 12:1 gear ratio. When the variator is at its peak the actual ratio is much higher than 12:1. You would ONLY see an actual 12:1 ratio somewhere in the middle while the variator is shifting and giving your belt a 1:1 ratio to front/rear pulleys. All of this is thanks to your variator constantly changing the ratio as it moves.

This is why your 32mph/7500rpm top speed at would make one think your belt is not reaching the top of your variator.

Check this chart to see overall min/max reduction figures. Once you determine your variator's maximum reduction, then you can accurately calculate what speed/rpm you can achieve when the belt reaches the TOP of your variator.

http://hondaspree.net/wiki/index.php5?t ... ion_Ratios

Yes, it's still possible that my drive belt is not getting all the way to the top of the variator. What rpm do you get at 40mph?

right around 7500-8k!!

OK, so taking the higher number you're hitting 40 at 8000 rpm? Looking at this another way, I can't get to 8000 rpm on the flat, the exhaust has no restriction washer so maybe I need a bigger main jet? I think my main jet is #82, I read somewhere else on here that a #90 might be better. Any suggestions for a main jet size on a stock AF05?

Thanks

On some of our early (US) Elites, there was no "removable" exhaust restriction washer. The restriction was the design and the only way to de-restrict was to get an entirely different exhaust. It can easily be seen by the bulge of the header tube below....I honestly dont know about VISION exhaust restrictions, but keep in mind that "no exhaust washer" does not necessarily mean there is no design restrictions.

I suggest you check your variator as mentioned above before you buy gears, exhaust or jets.

To answer your question: I ran every jet through a stock AF05 and it liked the #87....The #90 had zero performance gain over the #87 and was just a waste of fuel. The #92 was simply too fat.

My UK pipe is somehow between the 2 pictures, there's a bulge at the end of the pipe but it's not so long as the unrestricted. I need & want to keep things looking standard on the outside so the exhaust has to stay. Gurtner jets are readily available here so I can get an #88 jet for not much money, worst that'll happen is it won't go any faster but may smoke a bit more.

Be sure to adjust your mixture screw accordingly when upjetting to accommodate the additional fuel. You may run into a situation where the stock airbox wont be able deliver the needed air. Monitor your plug while tuning with the bigger jet to obtain the optimal mixture. Keep in mind, every stock component is designed/tuned to run best with all other factory components/settings. Upgrade one item and all others will struggle to keep up.

A common misconception is that by upgrading an exhaust (for example) would increase performance. However, with keeping other components stock like airbox, carb, intake/reeds, bore, etc..the gains will be small or non-existent. Sometimes performance would actually go down.

Greetings:

Listen to the Ball o' Meat, for he knows that of which he speaks. Your belt isn't maxing out, perhaps due to wear, or even possibly from an easily-removed travel-limiting grease container or a "short" ramp plate. Honda has tons of other tricks to keep their scooters from Being All They Can Be.

You might be able to locate an SP-3 exhaust from LeoVince on a dusty shelf somewhere there on the Scepter'd Isle. I can speak from experience that it handily outperforms any stock Vision/Aero pipe on the AF05 engine. Perhaps even a Malossi Wild Lion, which has become rarer than Unicorns everywhere, is possible?

Plugging in a different pipe - especially on a 2-stroke, means mandatory jetting change as Meatball suggests. I would add that the benefit of a cylinder head temperature gauge is a de rigueur for anyone tuning these things.

Yep, point taken y'all! I do need to check where my variator belt is getting to & I'll do that next. It's a new belt & rollers (maybe 100 miles). The ramp plate as far as I can tell is not a restricted version although it does have 'UK' stamped on it.
All I'm after is the 'stock' US speed which AFAIK is about 38-40 MPH. Since I can't get past about 7500 rpm on the flat, I'm guessing the motor has either run out of fuel (jets), can't suck any faster (airbox) or can't blow any faster (exhaust). I did once rev on the stand and it went to about 9000 for a few seconds before I throttled back. As I mentioned above, the Gurtner jets are easy to find in the UK so I'll probably go up to #86 & #88 to see how things go.

From looking at the parts list on Megazip, it seems that the #82 main jet that I have is standard for the US '86 NB50 vs a #80 for the '85 version so if the US Aeros will go to 38-40 MPH it's back to the gearing, variator and all.

https://www.megazip.net/zapchasti-dlya- ... r-13651449