BUILDING A NEW 750 RACE BIKE.

Hello all!
I am into building a Seeley Norton, see www.myseeley.net, and as I have now switched from a NRE engine that never arrived, to a 750 Commando engine I have tons of questions and would appreciate all help I can get.
The basics for the Norton engine are:
750 cc, bore 77 and stroke 83 ( if I remember correctly.
Maney cases and cylinder.
270 degree modified Triumph T140 crank.
270 degree ( obviously ) JS2 cam and his radiused BSA style lifters. JS pushrods.
JS 11:1 CR pistons for long con rods.
R&R aluminium connecting rods.
Fullauto 850 head to be ported and valved by Jim Comstock ( delivery in first quarter 2017 if I am lucky).
Gardner 35 mm carbs.
RTE Ignition
I think that sums it up. I am open for suggestions. In my ignorance I am hoping for a 8500+ red line and
as much horsepower as this will produce.

First question I have is: Do I secure all studs ( cylinder, head, oil pump et cetera with Loctite ? If yes,
how much do I tighten the studs down ( torque ) and which grade Loctite to use??

The 750 short stroke crank is usually 80.4mm

Be careful with that loctite...it is not normally used most places you mentioned....better to get the best bolt set you can....and torque where you can easily, which is not everywhere...

You might do better to sacrifice a bit of top end power and unreliability, to increase the midrange power of the engine and then concentrate on getting the bike to handle.

moppedog said:

Hello all!
I am into building a Seeley Norton, see http://www.myseeley.net, and as I have now switched from a NRE engine that never arrived, to a 750 Commando engine I have tons of questions and would appreciate all help I can get.
The basics for the Norton engine are:
750 cc, bore 77 and stroke 83 ( if I remember correctly.
Maney cases and cylinder.
270 degree modified Triumph T140 crank.
270 degree ( obviously ) JS2 cam and his radiused BSA style lifters. JS pushrods.
JS 11:1 CR pistons for long con rods.
R&R aluminium connecting rods.
Fullauto 850 head to be ported and valved by Jim Comstock ( delivery in first quarter 2017 if I am lucky).
Gardner 35 mm carbs.
RTE Ignition
I think that sums it up. I am open for suggestions. In my ignorance I am hoping for a 8500+ red line and
as much horsepower as this will produce.

First question I have is: Do I secure all studs ( cylinder, head, oil pump et cetera with Loctite ? If yes,
how much do I tighten the studs down ( torque ) and which grade Loctite to use??

Click to expand...

Standard Triumph crank stroke is 82mm, not 83mm. But my main question is how do you intend to modify the T140 crank to a 270 degree job? They're one piece!?

If you're using JS pistons, why not use JS rods? They'll probably be no heavier than beefed up alloy rods, and they're bomb proof, and beautiful!

Where are you BTW?

Sounds like an interesting bike with a lot of good components. Definitely should be a fun project. My only comment is about your 8500 rpm red line hopes. A good guideline for picking max rpm is mean pistons speed. Something like 20 m/s is a good target for reasonable ring and bore life on a race bike, and with your stroke (whether it's 80.4, 82, or 83 mm) that point is closer to 7500 rpm than 8500. Doesn't mean you couldn't rev it to 8500 now and then safely, but using that as a normal red-line is a likely prescription for early wear and failure. Besides that, I think you're going to see your horsepower peak somewhere between 7000 and 7500 rpm, and start to drop off pretty rapidly over 8000. But I could be wrong. :lol:

My suggestion would be to be sure and get it on a dyno before flogging it on the track. Once you get it jetted properly and see the horsepower curve, you can decide what red-line you want to use to get as much area under the curve in your usable rpm band.

Ken

Hello Ulf, your web site is very interesting reading, thank you. That's a fantastic project for the arctic weather. I am from Binningen by Basel, so not so far. I would love zo have a look when you get on a little.

Martin

As has already been suggested, dyno tuning to optimum performance THEN running the engine where it's best useable power is, is the best plan. Also as suggested, matching the bike's HANDLING abilities to it's power output is VERY important.

I'll state the obvious - all that engine, attempting to transmit all that power to the rear tire contact patch, is going to NEED a reinforced transmission. The standard gearbox will not last long AT ALL, even upgraded to proper superblend layshaft bearings with all new bushings. The case will crack or (most likely) explode.

Hi Ulf. I just checked out your web site, and realized I should have done that before posting my earlier comments. You've addressed the issue of piston speed quite thoroughly, and there was no need for me to point that out to you. This is a very impressive project, and I really enjoyed the details on your site.

Having said all that, I still think you will have a hard time making good power to 9000 rpm with the 80.4 mm stroke and the camshaft and cylinder head you are using. I hope I'm wrong, and look forward to seeing some dyno data in the future.

Ken

I just checked your web site too (great by the way) and answered some of my own questions!

I now see how you intend to modify theT140 crank, but would still question the choice. T140 cranks break in well thrashed T140s, they normally break through the sludge trap. I can't see it holding up to your intended use.

I would get Steve Maney to make Norton crank cheeks to my required stroke and then get a flywheel made to mount the cheeks at the desired angles.

My only question is about the Gardner carbs. I think they are quite an old design. Depending on the rules, I would imagine there are better carbs available.

Great build there Ulf and I appreciate your detailed documentation.

It's a pity you could not secure a Nourish engine for the reasons you stated. I might also add that when everything is said and done, the Nourish engines offer the best performance for the money where they are allowed and appropriate. See NYCNorton.com.

As for your Norton build, if it were me, I would go with an 81 mm bore and shorter stroke. Amongst other things, it allows for larger valves and you give up nothing on the mid range. I also would not bother with the phased crank as it offers little benefit and can cause valve train loading problems (amongst other things, think cam chain and lobe loading and unloading as well as cam bending moments) - this from my first hand experience, and complicates cam fabrication, ignition design and reduces exhaust system options. Simplify your life and stay with a 360 degree crank. There are plenty of light weight reciprocating component options on the market. My 750 Norton 89mm stroke with lightweight rods and pistons is very smooth - I am going to say incredibly smooth. My 81mm bore by 75 mm stroke with alloy rods and custom pistons was also very smooth up until maybe 9,000 rpm when it felt like it was about to jump out of the frame and kick me in the face. I think I may have had a balance factor issue with that one. All bikes cited are Seeley Mk2 frames. None of my Seeley frame have broken.

These are obviously all my opinions.

As for Nourish Race Engineering and the new owner, Chris Bushnell, he has jumped through numerous sticky hoops for my engine needs on at least three occasions and has delivered.

Thanks again for sharing in such a nice detailed format as found on your website.

lcrken said:

Sounds like an interesting bike with a lot of good components. Definitely should be a fun project. My only comment is about your 8500 rpm red line hopes. A good guideline for picking max rpm is mean pistons speed. Something like 20 m/s is a good target for reasonable ring and bore life on a race bike, and with your stroke (whether it's 80.4, 82, or 83 mm) that point is closer to 7500 rpm than 8500. Doesn't mean you couldn't rev it to 8500 now and then safely, but using that as a normal red-line is a likely prescription for early wear and failure. Besides that, I think you're going to see your horsepower peak somewhere between 7000 and 7500 rpm, and start to drop off pretty rapidly over 8000. But I could be wrong. :lol:

My suggestion would be to be sure and get it on a dyno before flogging it on the track. Once you get it jetted properly and see the horsepower curve, you can decide what red-line you want to use to get as much area under the curve in your usable rpm band.

Ken

Click to expand...

Fits totally with my 77x80.4 experience Ken.

I like the way that it builds between 6000 and 7000, I rarely needed to go over 7500, but it can go on as far as 8000 when needed.

I hope not to be going to 8500 again! that was never in the plan!

In my opinion, my 850 is almost standard and so I try to strictly control the revs to below 7,000. I usually see about 7,200 RPM on every up-change - it will go straight through the top if you let it. The cam is near standard 850, but advanced 12 degrees with a 2 into 1 exhaust (methanol fuel).
I have never believed in that engine and I still have my doubts. I think it is quick but dangerous.

Great looking project.

I dont know how far you have progressed with your exhuast, or whether or not these would fit a Seeley, but Mike's exhausts from here in NZ look very nice and has some good power numbers from the dyno.

into-exhaust-systems-t25824.html

They are designed for that sort of performance engine

Thank you all for your comments / suggestions. I will just briefly correct myself and offer some comments to yours.
The stroke will actually be 80,2 mm - I had not access to the data when I wrote my first posting.
The reason for choosing 77 mm bore was very simple. Steve Maney had no 81 mm cylinders available and they would have been several months down the road, and I did not want to wait.
The 270 degree crank layout of the NRE, and now the new Triumph, engines, plus the literature I have ploughed through, convinced me. And this against the recommendation from Steve Maney himself, claiming there would be no improvement in the vibration department. I am stubborn and I could just not believe what I heard, so there we are,
270 degrees it will be.
The crank is made ( modified ) by Ed G Cranks in Canada. They have convinced me that they know what they are doing, splitting the crank in two pieces, turning the pieces 90 degrees and welding it up again. Turning and grinding and nitriding and I should have my unit. If it will hold up - we´ll see. Remember, I am stubborn and want something that goes against the stream. I guess that can be called stupidity as well.
I bought my first set of Gardner carbs for my NRE and these have now been "stolen" from me by Mr Chris Bushell. Anyway, before buying them I had several conversations with Ron Gardner and he told me of the days when he supplied the Weslake company with his carbs and that they would always produce about 5hp more than any other make they had tried. Ron has now retired and the supply of these instruments have been taken over by Dick Linton of FCL Italian Imports. I do not know much about Dick´s knowledge but I understand he has been around Gardner carbs for many years. Anyway, before I follow his advise and buy a set of 35 mm Gardners I am ready to listen to you guys out there. I just want power , lots of it.
Then we come to power versus or with good handling and rideability. This project is first an exercise to satisfy my desire to use my long ago aquired engineering knowledge for something that I am really interested in. I know for sure that I will not be able to keep up even with the slowest when going around bends, even though I will go fast enough to scare the hell out of myself. Handling will therefore be of secondary importance, although I am doing what I can to build the bike to be a good handler. BUT, and that is my point, since I will lose time against everybody in the corners, I need an engine that will make up for that, and more, when going in straight line between the corners. Hence my obsession with power. And, I am pretty sure I have the brakes needed to reduce the end of stright line speeds to something that my very limited cornering ability can handle. Keep on following my progress and do not stop offering your advise! I will listen carefully before deciding ..........

It is easy to build a bike that will scare yourself shitless. The secret lies in creating a usable weapon. If it doesn't handle, you will probably hate it. I raced for about 12 years using a short stroke 500cc Triton - it was fast in certain places, however it was always ready to grab me by the throat - the anxiety level it created was horrendous. Prior to every race meeting I would lose sleep = who needs that sort of crap ? For what you are spending, you can build yourself a really lovely bike.

My view is that a carb, any carb, is only as good as the person tuning it. The fanciest race carb in the world will still underperform against an Amal concentric if its tuned badly enough!

I'm sure Ron used to get the best out of his carbs, but can you? If you're running a Manx or G50 you have a wealth of knowledge to tap into, but not so with your build. I would be concerned about how to get Gardners right, and how long that might take through trial and error. You could waste an entire season doing this, or more.

I don't know what rules you're running in, but I'd check out if FCRs are allowed, the 35mm FCRs and unique manifold that cNw sell were developed with Jim Comstock for FA heads, so you know you're in the right ballpark from the beginning. And I'm sure Jim could provide advise should fine tuning be required.

If FCRs aren't allowed, then the CR (round slide) is also a great carb.

Because you have a 270 crank, I would stick with a 2:2 exhaust system if I were you, that's unless you're the new Prof Gordon Blair! Cos you don't know how those uneven pulses might interfere with things.

Last bit from me is to say that you sound a lot like me when I built my first race bike (but you're building a far superior beast) in that I also focused on power, power, and power. It does not work sir! You will be far quicker, and enjoy things much more, if you aim for smoothness, good braking, maintaining the best corner speed you can, and having an engine that pulls you quickly out of corners. These really are (at least) as important as power.

Please, please do keep us all posted, its a top notch and very interesting build you're doing!

moppedog said:

The 270 degree crank layout of the NRE, and now the new Triumph, engines, plus the literature I have ploughed through, convinced me. And this against the recommendation from Steve Maney himself, claiming there would be no improvement in the vibration department. I am stubborn and I could just not believe what I heard, so there we are,
270 degrees it will be.

I am ready to listen to you guys out there. I just want power , lots of it.

Then we come to power versus or with good handling and rideability. This project is first an exercise to satisfy my desire to use my long ago aquired engineering knowledge for something that I am really interested in. I know for sure that I will not be able to keep up even with the slowest when going around bends, even though I will go fast enough to scare the hell out of myself. Handling will therefore be of secondary importance, although I am doing what I can to build the bike to be a good handler. BUT, and that is my point, since I will lose time against everybody in the corners, I need an engine that will make up for that, and more, when going in straight line between the corners. Hence my obsession with power. And, I am pretty sure I have the brakes needed to reduce the end of stright line speeds to something that my very limited cornering ability can handle. Keep on following my progress and do not stop offering your advise! I will listen carefully before deciding ..........

Click to expand...

Well, no I won't agree with most of this. My recent experience is returning to racing after a VERY significant break. My return to the track was initially with track days and with a bike that makes much more power than you will get from any Norton twin, a GSXR750 SRAD, dynoed with 120 rwhp. A bike that handles well in the modern sense and stops as well as it accelerates which is enough to frazzle your mind when used to the full! But racing is not track day work and classics are not rockets, you won't ride one that way and it won't help your cause to build this 'missile'

If you want to get around a track in less time, and to pass others whilst doing so, you will need a different tool and to develop your basic skills. You don't know how fast the other guys are compared to you, you imagine that they are faster, that will not help, you have beaten yourself before you even get to the start line

My suggestion would be to build the chassis, gearbox, set up wheels with single front disc and a double disc set up, and build two engines, because I suspect you will only in the end accept the data you collect, not the opinions of guys on forums.

So put in your order for 920 barrels and another cranks etc, and build this missile, in fact build a 1007....

But with your 750, get the head work done if that pleases you, but perhaps you will complete the build sooner with a standard Fullauto, choose a race cam that gives good rideable power, and don't go much above 10.5:1, use a set of cheap and chearful 34 Mikunis, with long inlets.

BTW this is the engine in my Rickman, which gave me 22 race finishes out of 24 in 2015, and 2nd in the CRMC 1300 twins championship and 6th in the 1300 National series (twins and multis) with a best of 4th overall in a wet race at Brands, where that smooth power delivery meant everything as more powerful bikes slid around....this was the 2nd race meeting on the bike and it did wonders for my confidence, this is so important.

BTW You have no choice apart from 2 into 2 if you insist on the 270 crank, 2 into 1 simply won't work. (No I wouldn't bother with the 270, but it has been done sucessfully, though the margin to a 360 is minimal, and with lightweight long rods and pistons I think even less benefit, Dave Watson built one fr Gary Thwaites and he was successful on it, but Dave said he wouldn't do it again)

Fit this engine into the frame with a single disc front wheel and learn to ride it. I think you will also enjoy it more than any missile you might build. A well balanced bike like this will be a good testament to your engineering skills. What you will find is that you will be able to brake deep into corners, turn the bike, and get onto the power early to keep the bike balanced and comfortable and you will build confidence. If you want to know why Marc Marquez beats clearly more powerful bikes (Ducatis) most weekends you need to recognise he has extreme confidence in his own ability. If you want to go quicker, find a way to build your confidence, don't start out telling yourself you will be beaten by corner speed, develop some. And please don't think that the guy with most horsepower wins!

(my approach to this was to run a second bike, a 500 with around 43hp, but capable of much higher cornerspeeds, to develop my confidence, it works, at a tight track I was faster on this bike!)

Now fit the rocketship engine to your chassis and spend some time on the dyno, make sure you understand from the figures just when this extra power is going to hit, fit it to the bike, fit your megastop front brakes, and most likely destroy the confidence you were developing as this thing bites your arse everywhere!

Even if you achieve smooth power delivery in this engine by compromising on max power, it is unlikely to be as rideable until you develop the skills to use it, and the extra power will challenge the basic handling of the chassis and tyre combination, you will spend more time fiddling with set up than 'racing' your competitors.

My race bike has high torque and good horse power, its the torque that gets me the good starts( im a dud qualifier!!) and drive out of the corners(Im not a knee dragger) 2nd overall in the NZCMRR 2016 Open Post Classic (OPC)
Regards Mike