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I picked up my 'new' pre-loved AN400 Burgman yesterday and had a splendid 134 mile drive home.

The bike was first registered in July 2001, has 3400 miles on the clock and has a fully dealer service history, most recently on 15 April 04. The bike has had little use in the last 12 months.

The max power achieved on a Dynojet 150 dynamometer is 16.1 (DIN corrected horsepower) which is a disappointing shortfall to what I believe is the 'norm' of 24.5 (Dchp) - a whopping 34% deficit.The dyno run was done before my trip home - I was hoping the journey would blow away the 'cobwebs' but the fact that

I rarely achieved 90 mph (indicated) and never exceeded it, which would seem to confirm the shortfall.

I would value suggestions as to where to start hunting for the 34% and what to suspect.

NormanB
 

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You said the bike didnt get much use lately. So I ask , How old was the fuel and what octane reading is it if you know? Also I would check the air filter to see if it is dirty and maybe replace with a K&N filter since its the 400. There's no K&N for the 650 yet :cry: Good luck in your horsepower hunt. Oh yea one other thing.......check your valve clearances.
 

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yeah Allwalk, octane really does make a difference.
Use the highest available NormanB.
There's a lot of waiting with 87 octane and a lot of holding on with 91.

After doing my own valve tappets last week my 400 has get-up-and-jump
at 975 miles.
 

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AJ, you can confirm this. I would have thought that the top speed of the AN400 was about 90-95mph. The Honda Reflex 250 is the fastest (top speed wise) of the 250 big scoots, and it manages an indicated 85mph or so. The AN250 runs to a similar maximum. To my mind, the biggest difference between the AN250 and AN400 is acceleration and the fact that riding with passenger doesn't effect that acceleration so much, as opposed to top speed.
 

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Norm, 16bhp at the rear tyre sounds a bit lean, but it's only a number produced from one specific dyno. As you begin your hunt for lost power, my advice to you would be twofold:
1. Follow the advice that the guys have already given - be patient, clear out the cobwebs, maintain it well, get fresh petrol in there, and look into K&Ns etc.
2. Remember that scooters are not designed for high top speeds. Take your portable CD player next time and cruise along at 80mph in a cocoon of still air, and in the comfort of an armchair. Even the AN650 (the fastest of all 'scooters') only manages 90mph as a speed it can accelerate briskly to, and 108mph or so after a long run up. But that doesn't stop either machine being devastatingly quick and comfortable on A-roads, and B-roads.

Perhaps if you find a 2002 AN400 advertised somewhere you can get a test ride on the premise that you are "thinking of buying the newer model...", a do a back to back comparison. I don't believe that the injection has any performance benefit at all over the carbed model, so it should be a good way for you to feel if your particular machine is down on power or not.

Good luck.
 

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allwalk;
I was told after my dealer made a call to k&N that they did not have a filter for the 400, could you get me the # of the one that fits .
Thanks. :)
 

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Discussion Starter #8
lycheed said:
Norm, 16bhp at the rear tyre sounds a bit lean, but it's only a number produced from one specific dyno. As you begin your hunt for lost power, my advice to you would be twofold:
1. Follow the advice that the guys have already given - be patient, clear out the cobwebs, maintain it well, get fresh petrol in there, and look into K&Ns etc.
2. Remember that scooters are not designed for high top speeds. Take your portable CD player next time and cruise along at 80mph in a cocoon of still air, and in the comfort of an armchair. Even the AN650 (the fastest of all 'scooters') only manages 90mph as a speed it can accelerate briskly to, and 108mph or so after a long run up. But that doesn't stop either machine being devastatingly quick and comfortable on A-roads, and B-roads.

[snipped]
Good luck.
Hi - thanks to you and the others here for sound advice.

I kept my original post short but will now give more details. I used this forum and others prior to buying the Burgman so that I was a better informed consumer.

One of the many useful bits of info was the fact that the Malossi Variator upgrade was the dogs proverbial mod for the Burgman. The bike was located in Newport and it just so happens an outfit called Taffspeed Racinghttp://www.taffspeed.co.uk/frames.htm is also located there and I booked the bike in on day of purchase. The main man there is an acknowledged expert.

Now while the dyno recorded horsepower was lower than Terry had seen for other 400 Burgmans, my guess is my trip home (which was brisk) cleared out at least some of the cobwebs - as it now appears that an indicated 90 is not far off spec and probably not achievable with 16 horses.

So, I am going to heed the sage advice and will not be ripping it apart anytime soon to ferret out the missing equines. However, even though it has a recent service I will put in a fuel system cleaner, clean the air filter and maybe extract the plug to view its condition and colour (color!) - just to build up knowledge of the bike.

Any advice on how to clean the air filter - the manual says non flammable cleaning solution -? - washing up liquid??

Thanks for you assistance you are all great people.
Finally - until I replace the stock screen I ain't going to hear very much at all - at 6 foot 1 - it was like sitting on an aircraft wing at anything above 50mph! :wink:
NormanB
AN400 - is it short on horses? - I will let you know.
 

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Any advice on how to clean the air filter - the manual says non flammable cleaning solution -? - washing up liquid?? Norm, I use a bio-degradable product called "Simple Green"...which is a powerful degreaser. Have to let the filter dry thoroughly before reoiling.
Also, I have read that the foam filter is actually better than the K&N for keeping out the finer particles. The K&N, by its very nature, is more porous. I learned this recently, just after buying a new k&N for my ultralight! :roll: And foam is much cheaper.
 

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Discussion Starter #10
Thanks Ted

Simple Green it is then!

I was looking at the K&N site last night - I think you just saved me a wad of cash.

Feel free to pop over for a beer - on me :wink:

NormanB
 

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Norm, as for filter cleaning, any of your household degreasers products will do...all is needed is something to wash away the oil and of course the dirt goes with it.

I like the Green because it will not discolor chrome, or aluminum, on cars or motorcycles as does some of the more caustic products. I use it for degreasing engines as well. But for foam, anything will do. I've even used kerosene or gasoline...but they are more harsh on delicate hands. :lol:
 

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I'm going to be using a cleaned out Stouffers Family Lasagna pan
for the solution tub and I won't forget the cleaning gloves to keep the
solution out of my pores.
 

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Discussion Starter #13
This is an update on current position and to thank all who replied to
the above post offering sound advice.

On that basis I am taking a cautious approach rather than a 'rip the
guts out'. I have not had the opportunity to ride out much since the
above and have only clocked around 35 miles in 2 trips!

I have put a fuel system cleaner in the fuel tank (Redex) and double
dosed it. I have cleaned and re-oiled the filter - it was actually in good
nick and not particularly dirty.

I have noticed the following, acceleration to 70 is reasonably brisk,
70-80 is rather pedestrian (or progressive ;-)) and anything above 80 is achieved in near geological time frames. After a twenty minute ride home today average speed 50mph, with peak of 80 for 4 or 5 mins, I noticed
during the post-ride inspection that the rear tyre and wheel was unexpectedly (no experience ;-))warm. I do not have a digital thermometer but my guess is around 100 deg F (38 deg C) with spec tyre pressures!

Also when grasping the wheel at 12 and 6 o clock and rocking the wheel (push/pull) there is a perceptible bit of play - difficult to judge but best guess is a couple of thou (imperial).

Grateful for you views and comments.

NormanB
 

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NormanB,

"in good nick" - Hey I'm gonna use that phrase here in the States.

You say that there's Play (lash) in the rear wheel bearings?
No more 80mph until you have that checked, okay!
At the least, bad bearings cost horse power.


Lycheed,

I've had my 400 up to 85 for a few seconds at a stretch but haven't
tried to wind it out to 90+ Yet.
The wind noise is roaring up there.
That AN250 sounds like the Power To Weight winner.
 

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AJ, I don't think it's a pwer to weight comparison. Being CVT the gearing will decide top speed, whereas the torque and power will decide acceleration. Comparative power to weight ratios are as follows:

400: weighs 181kgs dry, and 32bhp / 24ft/lbs torque claimed crankshaft output. That gives it a power to weight ratio of 119bhp per ton / 90ft/lbs per ton with one 75kg rider and maximum 10kg load under the seat.

250: weighs 166kgs dry, and 23bhp / 18ft/lbs torque claimed crankshaft output. That gives it a power to weight ratio of 92bhp per ton / 71ft/lbs per ton with one 75kg rider and maximum 10kg load under the seat.

On the road, although the 250 will be almost able to match the 400 in still air for top speed, acceleration from a standing start, or from any speed to any will see the superior torque and power of the 400 quickly distance itself from the 250. Over here, 250s are exempt from the extremely tough vehicle inspections (a failure will walk the actually quite strict British vehicle inspection MOT) which makes them by far the cheapest machines to run on the road. Pulling power vs reasonable performance and economy. That's the major difference.
 

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Discussion Starter #16
RESULT!! LOST HORSES FOUND

Hi - thanks all those who took an interest in my
problem and offered advice.

I had an interesting couple of hours, following the workshop manual
and removing bits and pieces from the Burgman to allow me best access
to the carburettor and even more fun (not) replacing them all, the
underseat box being the only difficult bit for some strange reason.
The funny thing is most of what I removed was totally unnecessary - (
I never did find the throttle position sensor lead wire coupler -
page 4.9) - and now I know what I am it doing will be a 15 min job at
most in future. :)

The throttle cables moved from the idle stop to full fuel position
with no restrictions. The carb slide (or throttle valve) only lifted
about (this is very approx) 10-12mm (there is a small indention on
the carb slide and it moved up so that this was almost covered.

I removed the top cover - boing! Sh*t - but managed to catch the
spring and retrieve the cover (embarrased or what), removed the slide
and inspected. There was evidence of polishing where it had contacted
the matching surfaces in the body, but no ridges. It was clean enough
but i gave it a thorough clean, inspected the diaphragm - all looked
well.

Reassembled and for reasons unknown to me was now able to lift the
slide completely so it left the throat completely unobstructed, a
lift of around (again vey approx)22mm, my guess is the spring
retainer had not been sitting correctly and had bound up the spring
(but it is only a guess).

After reassembly took it out for a short test run up and down a
private road ;-)

It was like a completely different machine and I am chuffed to bits.
I did not have the road space to fully explore but it roared up to 85
with almost turbine like smoothness. :) :) :) I fully expect the
performance above 85 to be to spec.

Thanks once again :) The lost horses have been found!!


NormanB

PS: Can anyone tell me how you actually remove the throttle cables at
the carb end - I could not find it in the manual, nor could I figure
it out :-(
 

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:lol: It was rather fun reading this whole story and how with enough time and work(and hands on knowledge) such a tiny thing could make a difference.
If you are using a dyno, you will be upgrading your scoot a little.
There is an aftermarket foam filter that is 2 stage and allows more air to reach the carb. Also the smaller header and muffler restricts the exhaust flow and can be fixed by a leo vince(4-road series)exhaust. These exhausts are a higher grade of steal and won't rust like the factory unit(a real problem in England). Oh! And run a little more air in the back tire(tyre)...otherwise you get cupping and they wear much faster.
Everything else has been mentioned. Ta and good luck!
Scooterjockey in dallas texas
 

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Discussion Starter #18
scooterjockey said:
:lol: snipped
If you are using a dyno, you will be upgrading your scoot a little.
There is an aftermarket foam filter that is 2 stage and allows more air to reach the carb. Also the smaller header and muffler restricts the exhaust flow and can be fixed by a leo vince(4-road series)exhaust. These exhausts are a higher grade of steal and won't rust like the factory unit(a real problem in England). Oh! And run a little more air in the back tire(tyre)...otherwise you get cupping and they wear much faster.
Everything else has been mentioned. Ta and good luck!
Scooterjockey in dallas texas
Hi Scooterjockey.

It was on a dyno for the Malossi variator upgrade - which as they say over here is the 'dogs bollocks' of a mod.

I will stick with the stock air filter as I am not convinced of the merits of a K&N in this application.

English weather is hard on exhausts (and me!), I think mine may have a year or two left in yet - so I will research at that time. The stock exhaust on the later Burgmans looks pretty neat though - don't you think?

Regards
 
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