The building of my vintage racer - Page 6

bmweuro · 06-22-2012, 08:00 AM

Quote:

Originally Posted by mykill

Yes.

Dual plugging is a waste of money and added weight on a 750.

supershaft · 06-22-2012, 01:07 PM

I can think of some race results that would make that a debatable question.

I was just wondering. I don't guess you are having any detonation issues mk? I am still suspecting you could run higher CR dual plugged? Plus making best power at a more retarded ignition timing is always a plus. More torque times rpm.

pommie john · 06-22-2012, 03:20 PM

Quote:

Originally Posted by bmweuro

Dual plugging is a waste of money and added weight on a 750.

All the quickest airheads I've seen have dual plugs. Maybe all these good tuners just do it because someone once said it was a good idea, but I doubt it.

If you have dyno charts for the same engine with and without dual plugs I'd be very interested to see them.

As for the extra weight.. one coil and two spark plugs? Take a piss before the race and you'll save that weight :)

supershaft · 06-22-2012, 03:29 PM

You should always take a piss before each race! Crashing with an empty bladder is safer than crashing with a full one just in case it springs a leak.

When I was a kid our club asked all riders to pee before their race at the rider's meetings. I thought is a nice way of showing they cared.

pommie john · 06-22-2012, 03:47 PM

Quote:

Originally Posted by supershaft

You should always take a piss before each race! Crashing with an empty bladder is safer than crashing with a full one just in case it springs a leak.

When I was a kid our club asked all riders to pee before their race at the rider's meetings. I thought is a nice way of showing they cared.

You can usually tell which race is next up by who's lining up for the bathroom

Renner · 06-22-2012, 05:03 PM

Quote:

Originally Posted by pommie john

All the quickest airheads I've seen have dual plugs.

All the quickest airheads I've seen have the best riders.

bmweuro · 06-23-2012, 10:38 AM

Quote:

Originally Posted by Renner

All the quickest airheads I've seen have the best riders.

Agreed!! When you look at the flash across the piston with a small bore motor a single spark plug is fine. I have been building 750 race motors for over 20 years with results in the 60HP+.

Voltaire · 06-23-2012, 01:52 PM

Does anyone have single/dual plug comparison dyno charts to post up?

Over on the Norton Commando forum there is a guy who has posted up lots of head flow charts...seeing is believing.
Some interesting results on port sizes, lie the standard head flows better than the factory ported one

I twin plugged an R100 20 years ago,as was the fashion but I think it was the lighter flywheel and 40 mm carbs that made it go well,

supershaft · 06-23-2012, 02:40 PM

Dyno and flow charts? The problem with both is that the numbers all depend on the dyno and flow bench and how they are run. Huge differences can be had with both depending on a lot of variables definitely including the test equipment itself. The numbers can be manipulated on purpose too! Making fair and objective comparison runs is a skill and harder do do than most imagine. My advise is don't be a sucker.

Small bore? A 750 is still a short stroke, big bore engine. 82mmx70.6. 1.16:1 bore to stroke ratio. Not nearly as short stroke as our R65's and R100's at a whopping 1.33:1 ratio but . . . . 1.33:1 was considered a REAL short stroke for a long while!

Voltaire · 06-23-2012, 03:27 PM

Quote:

Originally Posted by supershaft

Dyno and flow charts? The problem with both is that the numbers all depend on the dyno and flow bench and how they are run. Huge differences can be had with both depending on a lot of variables definitely including the test equipment itself. The numbers can be manipulated on purpose too! Making fair and objective comparison runs is a skill and harder do do than most imagine. My advise is don't be a sucker.

The Dyno throws up some interesting results. I sometimes race my Sons Bucket Racer, a Suzuki FXR 150 DOHC former commuter bike, the 20 bike field has about 15 of these.

Piccy from last weeks meet.
Lots of mods are done and tried on ONE dyno by the same guys and they have tried almost everything to make these things faster...cams, carbs, pipes etc.
Latest one is the Ignitech programmable ignition that you can adjust while the motor is running, Ignition, flat slide carb and exhaust with no other mods turned out 18 HP. More than the bikes with fancy cams and pistons on the same dyno.
The guys who own the dyno do it free. Then the bikes are tried on the track measured with transponders.
I'll mention next month that their dyno is for suckers....

supershaft · 06-23-2012, 04:59 PM

You need to read my words again. IF you come to understand them, run them by your friends. I am sure they would agree. Now that I think about it, you had better just have them read what I wrote. You are getting a pretty long history now of turning what I write on its head. You are still putting some pretty stupid words in my mouth but at least you aren't using quotation marks while you're doing it!

What is with you guys?

pommie john · 06-25-2012, 02:02 AM

Quote:

Originally Posted by bmweuro

Agreed!! When you look at the flash across the piston with a small bore motor a single spark plug is fine. I have been building 750 race motors for over 20 years with results in the 60HP+.

I'm not disputing your power outputs, I'm asking if you have direct comparison dyno charts for single and dual plugs.

pommie john · 06-25-2012, 02:15 AM

Quote:

Originally Posted by Renner

All the quickest airheads I've seen have the best riders.

And how may plugs do these bikes have?

Renner · 06-25-2012, 04:42 AM

Quote:

Originally Posted by pommie john

And how may plugs do these bikes have?

some single, some dual: it varies

FreeTheBeast · 06-25-2012, 04:57 AM

Quote:

Originally Posted by bmweuro

I have been building 750 race motors for over 20 years with results in the 60HP+.

I'd like that kind of power... :~)

06-23-2012, 02:40 PM	#84
supershaft because I can Joined: Sep 2010 Location: San Francisco Bay area Oddometer: 6,073	Dyno and flow charts? The problem with both is that the numbers all depend on the dyno and flow bench and how they are run. Huge differences can be had with both depending on a lot of variables definitely including the test equipment itself. The numbers can be manipulated on purpose too! Making fair and objective comparison runs is a skill and harder do do than most imagine. My advise is don't be a sucker. Small bore? A 750 is still a short stroke, big bore engine. 82mmx70.6. 1.16:1 bore to stroke ratio. Not nearly as short stroke as our R65's and R100's at a whopping 1.33:1 ratio but . . . . 1.33:1 was considered a REAL short stroke for a long while! supershaft screwed with this post 06-23-2012 at 03:04 PM

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06-22-2012, 01:07 PM	#77
supershaft because I can Joined: Sep 2010 Location: San Francisco Bay area Oddometer: 6,073	I can think of some race results that would make that a debatable question. I was just wondering. I don't guess you are having any detonation issues mk? I am still suspecting you could run higher CR dual plugged? Plus making best power at a more retarded ignition timing is always a plus. More torque times rpm.

06-22-2012, 03:29 PM	#79
supershaft because I can Joined: Sep 2010 Location: San Francisco Bay area Oddometer: 6,073	You should always take a piss before each race! Crashing with an empty bladder is safer than crashing with a full one just in case it springs a leak. When I was a kid our club asked all riders to pee before their race at the rider's meetings. I thought is a nice way of showing they cared.

06-23-2012, 01:52 PM	#83
Voltaire Studly Adventurer Joined: Jun 2011 Location: New Zealand Oddometer: 718	Does anyone have single/dual plug comparison dyno charts to post up? Over on the Norton Commando forum there is a guy who has posted up lots of head flow charts...seeing is believing. Some interesting results on port sizes, lie the standard head flows better than the factory ported one I twin plugged an R100 20 years ago,as was the fashion but I think it was the lighter flywheel and 40 mm carbs that made it go well,

06-23-2012, 04:59 PM	#86
supershaft because I can Joined: Sep 2010 Location: San Francisco Bay area Oddometer: 6,073	You need to read my words again. IF you come to understand them, run them by your friends. I am sure they would agree. Now that I think about it, you had better just have them read what I wrote. You are getting a pretty long history now of turning what I write on its head. You are still putting some pretty stupid words in my mouth but at least you aren't using quotation marks while you're doing it! What is with you guys?