Recumbent Honda 90

[sendler]

Originally Posted by Ironside

and look into the feasability of fitting an Innova or similar fuel injector.

Fitting the Innova F.I. might not work well. Even if the Honda donor F.I. has an O2 sensor, the computer has a limited range to adapt the mixture. And only in a few global operational ranges. The mixtures for any given operating conditions of throttle angle, load, temp, and rpm ect. are mapped by wide band measurement at the factory for a particular engine design. The mixture is computed by inference of throttle angle, absolute manifold pressure, and intake air temp. There is no air mass sensor. Different displacement and cam tunings ect. will throw the mixture off of the map. If someone makes a wide band, logging, piggyback fuel controller for the Innova, it might be made to work really well. Offering you complete control over the final mixture for all conditions.

[Ironside]

renault-megane-dci wrote:-

Ironside, I understand your bike redlines downhill somewhere around 75mph and probably around 9K and that you were usually around 65 which sounds very much like 8K so the engine might have been used in waste mode.

Have you been looking over my shoulder ?, spookily accurate. I'm not sure what you mean by 'waste mode'.

My point is that streamlining works better if at all with a big gear reduction to cruise a little below peak torque with the throttle at 75% and basically no potential for extra acceleration unless dropping a gear.

I'm currently using the highest gearing I can find off the shelf, 14 x 36. I can't go smaller on the rear sprocket without going larger on the front because the chain has no clearance over the swing arm. The gearbox sprocket has un unusual design and without cutting and welding, is only available in 14t from the USA at $40 + shipping + import duty +VAT (ask me how I know). So I'm kinda stuck with it for the moment.

Peak tourqe for an unmodified engine is 5,500 rpm. which equates to 45 mph. and a quarter throttle. I should try a run at this speed to see what happens.

Although the fuel economy is important, the bike has to remain useable, having only 4 gears means that I dont have a spare gear to use as overdrive.
I've read somewhere that there is a vehicle called the TRX 125, which shares a similar motor but has 5 gears, if I could get one of those engines things might be different. Unfortunately it was never imported into the UK.

Different displacement and cam tunings ect. will throw the mixture off of the map.

Thanks sendler, I don't think I'll bother with that then, time and money would be better spent on an AFR meter to set up the carb properly. Even at today's fuel prices, the payback time won't be too long.

Thanks for the feedback
Ironside.

[PeterS]

Do you have any idea of the hp output is at around 5000 rpm Pete? That 45 mph is on you current bike as set up ?

Is there room for a larger than 14 tooth sprocket on the front ( an hour on the lathe would see the centre bored out of a larger one ready to weld on .... I know you've thought of that) but is there room?

Originally Posted by Ironside

renault-megane-dci wrote:-


Have you been looking over my shoulder ?, spookily accurate. I'm not sure what you mean by 'waste mode'.



I'm currently using the highest gearing I can find off the shelf, 14 x 36. I can't go smaller on the rear sprocket without going larger on the front because the chain has no clearance over the swing arm. The gearbox sprocket has un unusual design and without cutting and welding, is only available in 14t from the USA at $40 + shipping + import duty +VAT (ask me how I know). So I'm kinda stuck with it for the moment.

Peak tourqe for an unmodified engine is 5,500 rpm. which equates to 45 mph. and a quarter throttle. I should try a run at this speed to see what happens.

Although the fuel economy is important, the bike has to remain useable, having only 4 gears means that I dont have a spare gear to use as overdrive.
I've read somewhere that there is a vehicle called the TRX 125, which shares a similar motor but has 5 gears, if I could get one of those engines things might be different. Unfortunately it was never imported into the UK.



Thanks sendler, I don't think I'll bother with that then, time and money would be better spent on an AFR meter to set up the carb properly. Even at today's fuel prices, the payback time won't be too long.

Thanks for the feedback
Ironside.

[renault_megane_dci]

What about machining a standard used sprocket to become a sprocket holder ?
Obviously your rear sprocket needs to be spaced the same.

Best economy is around peak torque AND at 75% throttle.

I would not fear about that 75% throttle thing because you still have 25% if needs be.

Waste mode is a personal naming that I give but basically it's away from peak torque and incidentally bikes are usually set up on the rich side at either side of the rpm for safety reasons.

[PeterS]

I fed an approximation of Ironside's Honda specs into the calculator at the top of the page,
180 kg
rolling resistance .018
cd .4
frontal area 5.5 squ ft
engine efficiency .22

Assuming that is correct I get a requirement for 3.56 hp at 55 mph or 2.84 hp at 50 mph.
It sees logical to match the engine output to the aero power requirements.... so what rpm at 50 mph?

[renault_megane_dci]

The calculator is not really bike friendly because we have a pretty lame drive train with higher than standard (read car) transmission loss.
Yes a brand new chain is good but is only brand new for 1/20 of its life.

Big digression to say that the setup you entered should hit the peak power of the engine at its top speed, namely 8,5 K at 70 mph.
As for its peak power, I don't know.
If it's a 90, 7hp sounds realistic.

If the stall point is not that, then some coefficient need to be tweaked.
Engine efficiency, drive train loss, Cd or S.

I would happily play with the calculator bit I'm on my phone ...

[PeterS]

IIRC there is a real difference between O ring and non O ring chain but the main difference is a clean , preferably unworn chain . The old Honda chain guards made a BIG difference to chain condition and life.

[cRiPpLe_rOoStEr]

Originally Posted by Ironside

Although the fuel economy is important, the bike has to remain useable, having only 4 gears means that I dont have a spare gear to use as overdrive.
I've read somewhere that there is a vehicle called the TRX 125, which shares a similar motor but has 5 gears, if I could get one of those engines things might be different. Unfortunately it was never imported into the UK.

That was a 4-wheel ATV. Some had the Cub-type slant engine and others had a vertical-cylinder engine. Not sure if the slant-engine ones were ever available with a 5-speed transmission...

[renault_megane_dci]

How is starting up with the 14x36 sprocket ?
Does it require a lot of clutch slip ?

The way I see it, the number of gears is of least importance than the ability to take off.

Is gear spacing already an issue ?

[PeterS]

Originally Posted by cRiPpLe_rOoStEr

That was a 4-wheel ATV. Some had the Cub-type slant engine and others had a vertical-cylinder engine. Not sure if the slant-engine ones were ever available with a 5-speed transmission...

Google finds a 125 cc Honda style tilted engine called a Loncin with a 5 speed box.