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You can put as many and as big a carb on it as you like but if you don't change the valve size and or angle too you haven't done much unless the original carb was simply less efficient, the rest of the engine needs changes to seriously benefit from more fuel and air volume available at the intake port.
 

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Discussion Starter · #102 ·
It's all a experiment and although the carby is not designed for this application the biggest impact on performance will be the manifold design. I no its not bad, but is it good? it was a challenge given ports are a V configuration and one cylinder flattish leaning forward and the other more vertical. and the it had to fit under the tank.
I tried to test ride it yesterday all seemed good till I got to the end of the street and it blew a main fuse but after stripping tape from the harness to check for melting or rub throughs I have found two damaged wires in the head light. So now I need rewrap the harness fix the wires and triple check the rest of the connectors and wires in the head light
 

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The SV650 makes what? about 100hp/L in stock form? And imp makes what? 20hp/L?
Feels like we are going backwards here.

Searching ebay to find some wrecked Ducati parts and making a shower injection set up....
Now that would be cool, and might even improve actual performance.
 

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Discussion Starter · #104 ·
I through myself a curve for a couple of days by not pressing to rear of the manifold all the way home. but I should be back on track now.
 

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I tried to test ride it yesterday all seemed good till I got to the end of the street and it blew a main fuse but after stripping tape from the harness to check for melting or rub throughs I have found two damaged wires in the head light. So now I need rewrap the harness fix the wires and triple check the rest of the connectors and wires in the head light
Part of the electrical upgrades?
How did something like that not show up on a meter test? You can buy a multi-meter for about 10 bucks and it comes with instructions on how to use it ;) Highly recommended purchase.
 

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Discussion Starter · #106 ·
It has been a good day, I just had my gen 1 sv650 cafe racer with my single throttle body conversion on the dyno for the first time and it looks promising to me.
62hp at 8800 and over 44 ft/lbs torque almost flat 5000-6500
Still needs work idle is way rich
So I will put some effort into the idle and the a gen1/2 cam conversion before another dyno session.
slight edit over 40 ft/lbs from 4700-7500
 

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Discussion Starter · #108 ·
Aren't they 65hp out of the box?
64.2 hp (47.9 kW) @ 9000 rpm[12]
42.3 lbf⋅ft (57.4 N⋅m) @ 7200 rpm[12] from Wikipedia
So I am both disappointed and pleased
with a single throttle body and a home made manifold I have a better better mid range torque and max power only rolls off 200 rpm early sacrificing 2hp.
I really think I will stick with this and add cams to see what that does. Also the muffler is nothing flash but I like the look at this time.
 

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Discussion Starter · #114 ·
This is my first dyno test on a dynojet dyno. the other numbers are from wiki.
The shop had results from a later efi model with k&n filter and slipon and it had max torque 45ft/lbs near the top rpm but from 4800-6600 mine had more. 7500-10k it had about 4 ft/lbs more than mine almost exactly. I don't have hp numbers.
I will do a bit more on the idle, fit later model cams which have more lift. and maybe a thinner head gasket. and see how that goes
 

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Discussion Starter · #116 ·
Kept in mind this is an experiment using a single vintage throttle body similar to ones used on some early nascar
Unlike a carburettor you set up the max fuel flow and the metering shuts that flow off down to idle, mid range is adjusted by moving the throttle plate so the air supply matches the set fuel,
Because this is a custom application it wasn't designed for motorcycle applications and the throttle plate ended up set way in the rich direction to get enough fuel mid range after restricting the top end adjustment so much to suit the small engine, but the metering can only move so far.
End result rich idle and at full throttle the plate was sitting about 5 deg off full open. That's how it was for this test.
So I hope drilling the fuel spray bar for more fuel will let me open the throttle plate in relation to the spray bar/throttle shaft a little, fixing all issues
Fingers crossed
 

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Discussion Starter · #118 ·
What is
CF: STD smoothing: 5
is that the reason the traces on the charts are so smooth, squished out and flat?
I don't know, but the chart from a later injected sv650 I was shown done on the same dyno had the variations you speak of. I think the smooth result is from the strange metering of the Fish Carburettor.
I have read there is no variation from the mixture set, but this is the first time I have had one run on a dyno
 

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What is
CF: STD smoothing: 5
is that the reason the traces on the charts are so smooth, squished out and flat?
Correction Factor: Standard (vs.SAE). Correction factors used to adjust the numbers for atmospheric conditions (humidity, air pressure, temp, air density, etc). The STD correction factor calculation reads about 4% higher than the more widely accepted SAE correction factor calculations.

Smoothing: has to do with how averaged the adjacent data points are to produce a curve. On a DJ dyno, you can choose 1 to 5. 1 will show a very jagged line (kind of hard to read IMO). 5 shows a very smooth line.
 
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std correction is for impressive #. most use sae.

if the bike has bad chain and sprockets you often get a real sawtooth curve, and the smoothing at 5 (of 5) takes much of it out. probably not so much of a concern on a load dyno, but certainly on a dynojet acceleration dyno it's an issue.
 
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