Greg Brillus Racer

[nkt267]

but at least I'm going to have an absolute blast and a lot of fun. Cheers......Greg.

That is the MOST important thing in racing..I was never any good,but didn't come last all the time,but I had bags of FUN.
A well known Bultaco racer had a shop in Barnes , if I remember correctly, and he told me that only a few people really make it in the racing world. His advice was to have FUN, and if that lead to success then GREAT.
There is usally better racing in the middle of the field than at the front..John

 

[davidd]

Tim, Ed or anybody,

I have never run methanol. What would the difference in ignition timing be between petrol and methanol? Any idea how a twin plug set-up might also differ?

David

 

[vibrac]

I got my pistons made by Venolia in USA I sent them a piston with a plasticine head shape moulded on top before I sent it I made the plasticene hard by soaking it in..... (Im almost ashamed to say) Castrol R.!
The new one came back an exact replica and the cost was very reasonable

 

[BigEd]

Tim, Ed or anybody,

I have never run methanol. What would the difference in ignition timing be between petrol and methanol? Any idea how a twin plug set-up might also differ?

David

The Sunbeam engine we used is a very old fashioned design compared even to a Comet. The engine has an iron head and barrel and it was difficult to get a high compression ratio. The main benefit for us was probably the cooling effect of meths. As a rule of thumb you usually need a bit more ignition advance with meths compared to the same compression ratio with petrol. Jetting is not so critical as long as you keep on the rich side. We once ran so rich when experimenting that you could see meths in the oil! In theory twin plugs should require less ignition advance as you will have already found on your racer so as with a single plug try a bit more advance.
Is methanol as a fuel easily available in the USA? Is it already used in racing?

 

[davidd]

I

The Sunbeam engine we used is a very old fashioned design compared even to a Comet. The engine has an iron head and barrel and it was difficult to get a high compression ratio. The main benefit for us was probably the cooling effect of meths. As a rule of thumb you usually need a bit more ignition advance with meths compared to the same compression ratio with petrol. Jetting is not so critical as long as you keep on the rich side. We once ran so rich when experimenting that you could see meths in the oil! In theory twin plugs should require less ignition advance as you will have already found on your racer so as with a single plug try a bit more advance.
Is methanol as a fuel easily available in the USA? Is it already used in racing?

I have never seen it used in vintage road racing over here. I all the years of racing the subject has never come up. When I helped out Stuart Hooper at Bonneville in 2011 I snapped this photo. It was supplied locally in Ogden, Utah in a 5 gallon container:

David

 

[bmetcalf]

These guys sell it, alcohol drag racers use it.

http://www.vpracingfuels.com/vp-drag-racing

Indy cars used to use it, but it is E85 "petrol" now.

 

[greg brillus]

A good friend of mine runs methanol in his fuel injected Vincent ex speedway outfit with the same pistons I am running. He uses 34 degrees of timing, which is the same as the timing I set most of the road bikes I do. I think you could run higher than this, like David said, if you test and adjust on the dyno. But with fixed ignition, I am a bit worried about it kicking back. I will be starting using electric rollers, but what if I need to bump start if I stall it. I cant run the original decompression set up due to big cams.....maybe I should use the ones that go in each cylinder head.? My fiends outfit starts easily on the rollers at that timing setting. I have a choice of ignitions....the brand new Joe Hunt magneto which is fixed.....or a rebuilt Scintilla with a manual cable advance..? This will be with single spark plugs. What about the push button decompressors like they use in the big cubic inch Harley chopper engines. Or am I worrying about nothing......I think re starting, there are 2 issues, one is the high comp, and the other is the relatively high ignition timing. Can any of you share any experience. Thanks for now...........Greg.

 

[ksbundy]

A good friend of mine runs methanol in his fuel injected Vincent ex speedway outfit with the same pistons I am running. He uses 34 degrees of timing, which is the same as the timing I set most of the road bikes I do. I think you could run higher than this, like David said, if you test and adjust on the dyno. But with fixed ignition, I am a bit worried about it kicking back. I will be starting using electric rollers, but what if I need to bump start if I stall it. I cant run the original decompression set up due to big cams.....maybe I should use the ones that go in each cylinder head.? My fiends outfit starts easily on the rollers at that timing setting. I have a choice of ignitions....the brand new Joe Hunt magneto which is fixed.....or a rebuilt Scintilla with a manual cable advance..? This will be with single spark plugs. What about the push button decompressors like they use in the big cubic inch Harley chopper engines. Or am I worrying about nothing......I think re starting, there are 2 issues, one is the high comp, and the other is the relatively high ignition timing. Can any of you share any experience. Thanks for now...........Greg.

Greg,

 

[ksbundy]

Greg,

Greg, When I run on speedway I run Shell A Methanol. I had 12.5 : 1 compression and used both Amap GP 1 3/8" and 38 mm Concentrics. Jetting was 1200 or 1300 depending on the conditions. Timing was 38 deg. I used to push start in second gear with a 72 tooth rear sprocket, no problems. My Ignition was a total loss battery and coils system I made up using a triumph twin points set and Yamaha Coils. Regards Ken.

 

[Magnetoman]

You don't mention what carburetor you will use but you show a GP in several of the photos. Assuming that's what you will be using, I made some measurements on Amal main jets that could be of interest to you (the old, "original" Amal jets, not ones made in recent history). I searched the Forum to see if I had posted some of this information before but couldn't find it. But, in case I have, I'll make a long story short to avoid repeating.

I have hundreds of Amal jets in sizes up to 1700. Again, long story short, but I measured twelve "500" jets on my Superflow flow bench. Of these 75% of them were within +/- one size of where they should be (i.e. between 490 and 510). However, 25% of them were as much as +/- 3-1/2 sizes too small or too large. For someone trying to tune a single-carb bike, let alone one with two carbs, this would be somewhat frustrating. My suggestion to you is to go to the track with a box with paired, calibrated jets. If you find a, say 1200 is too lean and you put in a 1300, you want to be sure it flows like a 1300, not like a 1000.

The second point that could be of interest is that when I plot actual flow rate vs. marked number (ignoring outliers and averaging over the others), there is a clear straight line behavior, as there should be. However, there is a quite obvious change in slope at 1000. My data clearly shows Amal used a different machine to calibrate the jets smaller than 1000 than larger than 1000. If I extrapolate the "low flow" data to high flows a "1500" jet should flow ~20% more than it does. Again, because you will be using jets in this range the issue of calibration, and change in calibration, will affect you.