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Old 09-05-2012, 04:52 AM   #466
blublapp
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No not yet.
Actually I'm running my old 950 because of a crack in the case of the 990...

I will try to fix it in the winter time. The few weeks I had the 990 in my adventure were great. there was much more power, particularly in low and mid ranges. but not in high rpms.
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Old 09-05-2012, 05:21 AM   #467
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I know this is not science...I remember fcr39 on a 520 and fcr41 on a 640...I know revs are a factor but I wouldn’t have thought it would make a big difference....
Getting the correct jetting is important; it also counter intuitive... more fuel doesn’t automatically equal more horses. Lean an engine right out till you reach the max then richen it up for normal use...
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Old 09-05-2012, 05:58 AM   #468
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Quote:
Originally Posted by blublapp View Post
Maybe the FCR 39 is the bottleneck?

Your SD engine has an 48mm intake. the injection bodies are the same size.
The intake from 950 engines is only 43mm, same size as the 43mm CVRD carbs...

I've done a few thoughts about this because i'm still trying to jet my 990 SM engine properly for my adventure, which haden't the full power I anticipated too.
Maybe not so much the carb being a bottleneck per-se, but maybe the shape of the ports in combination with a 39mm carb could be influencing the results of the carb-conversions. The theory with a 39mm carb is to keep intake veocity up by forcing air through a smaller (39mm vs 43) orifice at equivalent vaccum - this is generally considered to improve engine torque, at some sacrifice to full-flow horsepower.

My 950 was flow-ported when I switched to the 39mm FCR, and my engine-builder-guy wound up putting a lot of epoxy into the bottom of the intake ports to reduce the intake port's effective area, and to keep the intake velocity up. Otherwise, he suggested that the intake flow basically "tumbled" into the intake ports at the outlet of the carb, causing the intake velocity to drop suddently.

Maybe the 990 ports are similarly mis-matched to the 39mm FCRs, and possible in a worse way than on the 950 - you might be onto something, but only full-on flow-bench testing would tell the tale...

BTW - don't let the 39mm flat-slide versus 43 mm CV/injector TBs fool you into thinking the 43mm opening flows more fuel/air. The 43mm track on a CV carb has a butterfly valve assembly in it that is actually very restrictive to flow, the flatlides don't, so even though directioannly you'd think that 39mm = less flwo than 43 mm, only a flow bench would tell you for sure... On the other hand, you can make direct comparisons between a 39mm flatslide to a 41mm flatslide...

Flanny screwed with this post 09-05-2012 at 06:03 AM
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Old 09-05-2012, 11:46 AM   #469
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Chris and Peter and I had this discussion when I got the engine. It was Chris' thought that the larger intake tracks were going to be problematic to flow. FI can utilize a larger port size because it's not as dependent on creating a vacuum since it's injecting the fuel under pressure. As we were designing the bellmouth Chris was explaining the idea of port shape and flow and the other day he sent me this photo with a note:




"Now that's an intake port! It only looks like it tapers as it nears the valve but what happens is it gets oval then splits into 2 ports so the port area is nearly constant from the bellmouth to the intake valve."

In many ways putting carbs on a 990 engine is simply not a very good idea - this is something I'm coming to realize over the last year. Can I make it work? It certainly is looking like it. Would I have been better off with a 950? Probably.

Blublap and Flanny are right in a way, the gas flow accelerates through the smaller carb then stalls in the larger intake port of the 990. I asked Chris if I should consider boring the carbs out to 41mm which would also smooth that bump on the FCR and maybe epoxy the port right after the carb but he thought I should just get this working as well as I can for now and I agree. I'm not sure if I want to swap it over to FI or not so there's no point in epoxying the ports up if I eventually go to FI although I could make a tapered sleeve to insert in the port. I would also love to try a set of 41's before I bored mine.

Then there's the notion of swapping in the 950 cams and you could play with degreeing the cams too. It's a can of worms so I need to find a line in the sand and just decide to ride the bike at some point. I'd happily call it good at 110hp but honestly I might stop at my old number of 98 too - it's hard to say.

I've spoken to Flanny and he might come down to the shop for a weekend and we can run his bike as well. Gino's got a good running 990 we can run too as a FI comparison on the same dyno. If nothing else I think it gives a person appreciation for what's involved in making an engine, or an exhaust work or a carb work. It's a complicated system.

Gregor
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Old 09-05-2012, 05:32 PM   #470
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Didn't PowerCell put some FCRs on his 990 engined Super Enduro? I wonder if he would have any feedback?
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Old 09-05-2012, 06:03 PM   #471
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Quote:
Originally Posted by sakurama View Post
Gino's got a good running 990 we can run too as a FI comparison on the same dyno.
Don't know what year your engine is, but don't forget 2009 and up engines have different cams.
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Old 09-05-2012, 06:28 PM   #472
Flanny
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Quote:
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Didn't PowerCell put some FCRs on his 990 engined Super Enduro? I wonder if he would have any feedback?
He did, but then went to FI


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Old 09-07-2012, 05:12 PM   #473
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I have these 150mm Uni-filter pods.



I have excellent torque down low and have had the bike dyno'd = 101hp.

My issue is at high speed it runs out of puff, like it's running out of air.

I would sure like to fit a velocity stack inside my filters, so I am very interested in whatever you manage to work out.
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That's what I'm currently running as well. If we could get some honking long velocity stacks to put inside those, it would be pretty cool.
There is a way. These filters go over the velocity stacks and use a cable tie to seal them off. Sutco have a range of stacks of different length



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Old 09-09-2012, 04:12 AM   #474
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Originally Posted by sakurama View Post
I asked Chris if I should consider boring the carbs out to 41mm which would also smooth that bump on the FCR and maybe epoxy the port right after the carb.........
I bored the carb and filled the port on my 650cc Husaberg I raced and the British Championship back in 2003/4. It was a ball ache and it took quite a few hours modelling on the flow bench before I was able to get the optimal solution. Saved a lot of trial and error work though as it worked, first time we fitted the head on the bike. I was running 70rwbhp and 50ft.lbs....nice!

I also built a few CRF450 motors for a European Supermono race team (built the complete chassis too), here I modified the inlet to 'down-draft' it and also filled it to keep the air speed up. We were not too bothered about torque for this application but it put out 68rwbhp...from a 450! It was in a 125GP dimensioned chassis but totally hand built. Do you recognise the radiator??

Wow, my workshop was not as tidy back then, it was my parents garage Hi-jack over.......

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Old 09-09-2012, 10:22 AM   #475
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Wow Pyn, that's a really cool bike. I was running an early Tigcraft back then but it was before the 450's so I was running a bored and stroked 426. The big holes were for extra cooling for the rads. It was a wicked fast bike and when it held together I was always on the box but reliability was not it's strong suit. I used to battle with the big Buells but I had corner speed all over them. It's still my favorite race bike and I'd love to build another.



Yes, I suspect that pulling the heads and epoxying them up on a flow bench is the way to really get the whole thing to work together. I have no flow bench and don't think I want to go to those lengths at the moment but if I can find a good combo with the parts I have right now I might just keep the carbs and do that down the road.

One thing I'll certainly want to change is the throttle springs - they're pretty hefty. It's looking like my next week in NYC will be the end of the month and hopefully it will be the last before I ride her home.

Gregor
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Old 09-09-2012, 10:24 AM   #476
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That, sir, is frickin gorgeous!

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Quote:
Originally Posted by Pyndon View Post
I bored the carb and filled the port on my 650cc Husaberg I raced and the British Championship back in 2003/4. It was a ball ache and it took quite a few hours modelling on the flow bench before I was able to get the optimal solution. Saved a lot of trial and error work though as it worked, first time we fitted the head on the bike. I was running 70rwbhp and 50ft.lbs....nice!

I also built a few CRF450 motors for a European Supermono race team (built the complete chassis too), here I modified the inlet to 'down-draft' it and also filled it to keep the air speed up. We were not too bothered about torque for this application but it put out 68rwbhp...from a 450! It was in a 125GP dimensioned chassis but totally hand built. Do you recognise the radiator??

Wow, my workshop was not as tidy back then, it was my parents garage Hi-jack over.......

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Old 09-09-2012, 10:25 AM   #477
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I also built a few CRF450 motors for a European Supermono race team (built the complete chassis too), here I modified the inlet to 'down-draft' it and also filled it to keep the air speed up.
Is the head backwards on that thing? Man, that is a labor of love.

G
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Old 09-09-2012, 11:19 PM   #478
Pyndon
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Is the head backwards on that thing? Man, that is a labor of love.

G
Gregor, given all the riding I do now, I have no idea where I found the time to do any of this! I only ever build the things from my love for the series, being 6'4" tall and 220lbs never lent itself to a winning combination on that thing.

No, on that particular one, the intake is conventional, although we tried all sorts. I put more late nights in on that project than I ever have.

Having a broken foot, no weight bearing for 6 weeks is driving me crazy!

Pyn
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Old 09-10-2012, 04:32 AM   #479
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Great thread Gregor, thanks for taking the time to share your build. I know how long it takes to keep everyone up to date but I for one do enjoy reading it. Once you've started a thread like this, you have to keep it going.....unless your names Antware.

Good work, a pleasure to follow and some real engineering!
I probably do enough to have a thread, but those 8 threads of Flanny's scared me, I just can't handle the responsibility
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Old 09-10-2012, 04:17 PM   #480
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There is a way. These filters go over the velocity stacks and use a cable tie to seal them off. Sutco have a range of stacks of different length



Had a look at this then remembered why I did not do it...... It exposes the air leak jets to unfiltered atmosphere. Shame really as it would be a easy solution for anyone.......
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