500R seems underpowered.

Vehicles equipped with the 500 cc Rotax engine

Moderators: DAVID THOMPSON, phlat65

Re: 500R seems underpowered.

Postby MZCountryRider » Thu Jul 17, 2014 8:47 am

Wow. I feel lucky. My Silver Star fires right up with electric start on full choke and once started, the choke can be turned off completely. One of the least "cold-blooded" bikes I've ever owned. My Saxon Country was the same way. Never tried kickstarting, don't feel the need.

The day after I changed to the 16 tooth sprocket on the Silver Star, I had a chance to do a high speed run (at my "secret" test location :wink: ). Achieved an indicated 160 kph/99 mph before I had to start slowing. This was with my small Guzzi windscreen and hard saddlebags fitted.
Charlie
'69 Guzzi Ambassador
'71 Guzzi Ambassador
'72 Benelli 175 Enduro
'73 Guzzi Eldorado
'76 Guzzi I-Convert
'77 Morini 3 1/2 Strada
'81 Ducati 500SL Pantah
'82 Moto Guzzi V50 III
'97 MuZ Skorpion Tour


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Re: 500R seems underpowered.

Postby DAVID THOMPSON » Thu Jul 17, 2014 9:02 am

when they are running correct they can go way faster than anyone really needs to go on 2 wheels
or 4
DAVE
Dave 2002 MZ RT125+1995 Saxon Tour(500cc)
1997 MZ 660 Traveller+6/13/09 WV USA
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Re: 500R seems underpowered.

Postby davegsm82 » Thu Jul 17, 2014 11:28 am

Well I've fitted the 17T and it does seem better, not as 'snatchy' but perhaps that's because the original sprocket wasn't even bolted on properly, the nut was just finger tight and the tab washer hadn't been bent over.

I took it up to about 85 on my long, straight test track, obviously not on a road... no, of course not. While it didn't seem strained, it was definitely out of puff and I was almost at full throttle. Definitely gets to 70 and holds it better with the 17T though.

I think I still might need to invest in a 16T to pull the trailer and the wife comfortably.

What else could I be missing? does anyone have any sort of written procedure for tuning the Del-Orto Carb?

As for starting, it's a pig. I actually managed a first today and got it going on the kicker, albeit with my other leg and after it had already been running.

Dave.
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Re: 500R seems underpowered.

Postby breakwellmz » Thu Jul 17, 2014 2:13 pm

Wife and trailer-i would put a 15t on.What is sidecar gearing on these?
Have you checked plug colour and stripped and cleaned the carb, checked the ignition timing and valve clearances i hope.
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Re: 500R seems underpowered.

Postby davegsm82 » Thu Jul 17, 2014 3:24 pm

Slim-wife and Lightweight trailer I should add 8) the 301 had no bother pulling both.

Last time I checked the plug it was a little dark but not as sooty as it was before I tinkered with the carb when I first got it. As for valve clearances, well, I can't seem to find any information on how to set them up, can someone enlighten me? (this is my first real 4-stroke so I'm a little clueless, i didn't have the FJ long enough to think about valves).

Dave.
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Re: 500R seems underpowered.

Postby breakwellmz » Thu Jul 17, 2014 4:35 pm

C`mon, you just need to try a little harder :roll:-

viewtopic.php?f=26&t=4111
Last edited by breakwellmz on Thu Jul 17, 2014 4:37 pm, edited 1 time in total.
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Re: 500R seems underpowered.

Postby davegsm82 » Thu Jul 17, 2014 5:44 pm

Yep, you're right, I didn't look past the first page! (admittedly I hand't noticed pages 2 and 3!).

I'll have a go at this after the weekend when I get time.

Thanks for the tip-off :smt006

Dave.
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Re: 500R seems underpowered.

Postby davegsm82 » Tue Jul 22, 2014 12:52 pm

I checked the valve clearances today, they were tight so I backed them off to 0.2mm for the Exhaust and 0.1mm for the intake.

Now it sounds VERY tappy which is a little concerning. how noisy should the tappets be? You can hear them over the exhaust note at idle.

On a run it didn't seem substantially better, it started and idled a little easier, so much so I had to turn the carb adjuster out a little as it was idling up at about 4k. There was no blistering improvement in top speed or acceleration.

Dave.
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Re: 500R seems underpowered.

Postby breakwellmz » Wed Jul 23, 2014 7:16 am

If you are sure the gaps have been set correctly then that`s the way it is,they`re not the mechanically quietest of engines as i recall.

The fact it starts and idles better shows that the gaps were too small before, and hopefully no exhaust valve burning has occurred.A compression test might be a good thing to do if you can.I can`t see why your idle speed should have gone up so enormously though.
I wouldn`t expect my Mastiff with its 50bhp to have a`real world` top speed above 95mph to be honest.
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