Drouin supercharger

Classic Norton Commando Motorcycles.

Drouin supercharger

Postby baz » Sun Dec 16, 2012 1:17 pm

Hi,i have just bought a drouin supercharger for my 750 commando i will be looking for some help with this unit it hasnt arrived yet ,but i know it needs new bearings and a drive belt i think its a late version anyone with first hand knowledge of this unit would be a great help,i have read a lot about them on this site and others it looks like the bearings are going to be very dear especialy the ceramic version does anyone know where i can buy these at a reasonable cost? or an alternitive? cheers baz
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Re: Drouin supercharger

Postby Torontonian » Sun Dec 16, 2012 3:53 pm

baz , Barry Huron knows a ton on this and actually drives about-towns regularly with the Drouin. He talked with me alot about the bearing replacement issues but we were drinking and the sucking back the Nitrous around the tailgate near the campfire ,at least that I can remember.
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Re: Drouin supercharger

Postby hobot » Sun Dec 16, 2012 4:04 pm

Throw yourself at the ground and miss!
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Re: Drouin supercharger

Postby Bruce Mac » Tue Dec 18, 2012 11:15 am

Hi
Don't waste your time trying to get the built in Fuel Injector to work. plan on getting a new Lectron Carb for it. Its pretty easy to make a mounting for it .
I will fill you in with the details later after we see what you have.
You should be able to get it to work out quite well. Good Luck
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Re: Drouin supercharger

Postby hobot » Tue Dec 18, 2012 1:44 pm

Once I get rear end sorted on Trixie Combat I'm going to try the Drouin + Lake 'Injector' on it and be carefull on how harsh I snap throttle for drive train and wheelie damage. The fly boys like the Lake and have details of how to profile the needle, very very tediously. Peel has issues that prevent Lectron size carb w/o wierd manifolding, so not suggesting any reatain the Lake ESPECIALLY d/t the deadly sticking mostly open ACCELERATING hard. I'll adapt 2nd pull open cable though. Here's the 2002 feed back of Drouin + factory 850 rider in UK with dual belt version...................................................


>> I just took the bike out for it's first run around the block. It runs great! I have to wait for colder plugs or I would have never come home. It takes a bit getting use to working the fuel shut off but I am getting the hang of it. Other than a little bit of fuel spill now and then it is a great mod. The sound of the blower can be heard inside my fullface Shoie helmet and over the boom of the Dunstall silencers. I still have to do some polishing and replace one of my original leaking petcocks but this thing is awesome. I have always wanted an 850 Commando and I never would have even imagined I could have a supercharged one. I will send photos when it is completed to my satisfaction but let me tell you this. I ride a nitrous injected Honda 996 Superhawk as a daily ride and I have a few GP race bikes but nothing, I repeat NOTHING!! stirs my soul like this setup. The only other mod will be a steering damper because the bike lifts up in every gear now and it upsets the steering and a gunfighter seat from Corbin to keep me from sliding off the back of the bike when I twist the throttle. In closing all I can say is YEEEEEHAWWWWWWWW!!!!
>> I'll keep you posted.
>> Mike
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Re: Drouin supercharger

Postby baz » Wed Dec 19, 2012 11:45 am

Ok i am going to need new bearings on this unit i am thinking of using ceramic angular contact bearins on the impellor shaft they are rated up to 50,000 rpm in grease, they are 28 od 12 id 8 width the originals are 11.5 width so a spacer will be needed or maybe a modification to the housing to pair them up? also i need to find a suitable flat drive belt (this is for the doulble belt setup)Barry has kindly told me they are 14 .1/2" long by 11/4 wide but he thinks the original belt may have been 1. 7/16" wide? any thoughts on this bearing idea much apreciated regards baz
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Re: Drouin supercharger

Postby baz » Wed Dec 19, 2012 12:03 pm

The lake injector on my drouin has parts missing so i will try and run it with a 40mm CV that i have spare ,the lectron looks good but pricey, regards baz
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Re: Drouin supercharger

Postby hobot » Wed Dec 19, 2012 9:34 pm

I'm collecting Lake Injector parts if they are not use to others. Flat belts in incremental lengths in proper widths can be found at McMasters supply. Sticking open Lake's and slipping belts shot down Drouins more that the bearings of the era. Ceramic turbocharger bearings would be the cat's meow. Go look in DynoDave's site again it has Bruces upgrade details on spring loaded bearing spacer and support to take up the heat expansion. Bruce and i decided to just buy modern steel turbo bearings. Drouins I know about are driven 7x's faster than crank. Centrifual blowers are not compressor pumps and don't make a set pressure per rpm, but they can spike boost over sales rated level if pilot dares to snap throttle open to load it up and pack it in.
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Re: Drouin supercharger

Postby Bruce Mac » Thu Dec 20, 2012 6:44 am

Hi,
The 40 MM Harley CV will not work well on the Drouin. I spent a couple of years screwing around with one before I went to the Lectron.
If you want your Norton to run like a Parade Float then use a Parade Float CV carb.
Also you don't need the ceramic bearings and most likely can not get them. Get the Barden bearings listed on Dyno Daves web site. I have been running the same ones since 2003 with no problem.
The most important thing you need to do is modify the bearing spacers to accept a spring washer as in the drawings to allow the bearing to move a little as the rotating assembly heats up and grows. I also suggest that after you do that , you get the assembly balanced. I recommend getting Total Seal rings to reduce blow by.
Belts from Belt corp. #400 panther 29 x 3/4" about $6.00 ea., one will last all season, Assuming you have a late model Drouin and the pulleys are aligned properly.
McMaster Carr belts will not work!
I frequently see 15 psi of boost on my stock 850, especially in 3 & 4 gear. Also expect your pipes to blue for about 20 inches.

I tend to ride more on my Ducati ST3S ABS more now, but the Norton with the Drouin is pretty close acceleration wise up to 100 mph.
Do it Right and you will enjoy it!

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Re: Drouin supercharger

Postby Dances with Shrapnel » Thu Dec 20, 2012 9:59 am

@Bruce Mac - 15psig boost from a Drouin, that is impressive. Are you running that later single belt or earlier dual belt? I was only good for about 10psig boost back in the day with the earlier (two belt) version of the Drouin; maybe the cam I was running back then had something to do with it.

I ran the flat slide that came with the unit back then but a double pull cable was necessary; I was in the process of converting over to something to replace the Drouin flat slide.

The bike was very accomodating with regards to mixture setting; there was never a stumble so a CV carb would seem to be a waste or overcomplication. Your approach of a Lectron sounds solid.

My hunch on the engines responsiveness with the Drouin is (unlike a straight carb through manifold through port), the air/fuel mixture must go through an impellor (blender) first on a Drouin. The air/fuel reaching the combustion chamber must have been way more uniform and homogeneous than with a naturally aspirated carb set up. Maybe increased heat of the air/fuel mixture also helped here although not something one really wants in a spark ignition IC engine.

Another thing on the drawing board "back in the day" was sorting out some sort of intercooler.

@baz - good luck and keep us posted.
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Re: Drouin supercharger

Postby Bruce Mac » Thu Dec 20, 2012 11:46 am

Hi,Dances,
It's the last model single belt, Drouin on a basically stock 850 except for total seal piston rings.
Idles well and runs well with the Lectron carb connected to an Alum,6061 tube, T6,1.75" od. .083 wall pressed into an Alum 1/4 ' plate. The tube protrudes into the eye of the impeller about 3/8 '' and is flared outwards to help direct flow towards the ouside of the impeller.
It's interesting to note that once started it will run fine with out the belt. It will spin right up just on air/fuel mix flow. No boost but it will run quite well and even idle. The Drouin acts like a super fuel/air Mixer. The boost only builds up to max in 3rd & 4th under full load. Most of the time under normal driving there is hardly any boost.
The Lectron connects right up to one the stock carb cables from the splitter. I think I had to cut the cable outer cover back about 3/8 " to get near full throttle.
It makes it easy to go back to the stock carbs as I only need to replace the modified cable with a stock one @the splitter. The stock throttle will not open a 40 mm carb more than 80% so I have motion Pro throttle that gives 100%
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Re: Drouin supercharger

Postby Nortiboy » Thu Dec 20, 2012 1:28 pm

Bruce Mac wrote:Lectron carb connected to an Alum,6061 tube, T6,1.75" od. .083 wall pressed into an Alum 1/4 ' plate. The tube protrudes into the eye of the impeller about 3/8 '' and is flared outwards to help direct flow towards the ouside of the impeller.


Hi Bruce,

Do you have a drawing / sketch / photo of the carby mount and the Lectron specs ?.

Anything appreciated.

Cheers
In My Shed - 1973 750 MKV - 74 920 MKII - 1974 750 Shortstroke - 1973 850 Yellow Peril Replica - MKIII 850 - Aprilia RST1000 - GasGas 450 FSE - KTM540
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Re: Drouin supercharger

Postby baz » Thu Dec 20, 2012 2:28 pm

Bruce Mac wrote:Hi,
The 40 MM Harley CV will not work well on the Drouin. I spent a couple of years screwing around with one before I went to the Lectron.
If you want your Norton to run like a Parade Float then use a Parade Float CV carb.
Also you don't need the ceramic bearings and most likely can not get them. Get the Barden bearings listed on Dyno Daves web site. I have been running the same ones since 2003 with no problem.
The most important thing you need to do is modify the bearing spacers to accept a spring washer as in the drawings to allow the bearing to move a little as the rotating assembly heats up and grows. I also suggest that after you do that , you get the assembly balanced. I recommend getting Total Seal rings to reduce blow by.
Belts from Belt corp. #400 panther 29 x 3/4" about $6.00 ea., one will last all season, Assuming you have a late model Drouin and the pulleys are aligned properly.
McMaster Carr belts will not work!
I frequently see 15 psi of boost on my stock 850, especially in 3 & 4 gear. Also expect your pipes to blue for about 20 inches.

I tend to ride more on my Ducati ST3S ABS more now, but the Norton with the Drouin is pretty close acceleration wise up to 100 mph.
Do it Right and you will enjoy it!

Bruce MacGregor
Hi,my drouin is the 2 belt type it is very different on the bearing set up,it has 1 bearing in the impellor housing and 1 bearing in the outer drive belt housing cheers baz
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Re: Drouin supercharger

Postby baz » Thu Dec 20, 2012 2:43 pm

Could someone tell me the diameter of the pulley wheel on the impellor of the single belt drouin? as i am thinking about maybe converting my twin belt setup to a single belt cheers baz
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Re: Drouin supercharger

Postby hobot » Thu Dec 20, 2012 3:39 pm

Impeller pulley is 1 inch OD and the crank pulley is 7" OD with a slightly crowned profile to keep belt centered. The last and best Drouins were the single belt type with a belt tensioner provision. The crank pulley snout is threaded so takes the place of the alternator crank end nut. Btw can any Drouin rider tell me about where they find the wheelie balance point?
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