budget sv650 cafe racer

[gt alex]

 

[gt alex]

I talked my grandson into taking pics of me on my sv650 cafe racer. First time I've see it as others do.

 

[gt alex]

Guys on the cafe racer net are giving me a hard time over the bike being too low and the swing arm too flat, I can't disagree the swing arms a bit flat but since it's riding well no rubbing I am happy with it over all. But My goal is performance and style and I think both could be served but raising the rear a little. I made mock bog bones for the rear 5mm shorter(100mm) and fitted them raising the rear a smig over 20mm(3/4")

I felt Looking at the pics the ass is dragging a bit, and raising will help handling(i hope)
This is a copy of my cafe racer forum reply

Its quite common to run shocks up to 13mm(1/2") longer rear shocks on this model for performance applications that equates to approx 40 (bit over 1 1/2") higher rear I think (having not done this myself), and I am extrapolating the effective difference of mine will now be approximately 1" (25mm) with preload wound all the way out with 2cm of bike sag which I could reduce to 1cm,
Overall I could have an effective difference front /rear as little as 15mm.
Front like the rear has been set to 100mm to make this work I am running cartridge emulators, spring upgraded to achieve appropriate sag and 15w castrol oil and oil height was increase to create progressive bottoming if need.
So the front is purpose made not lowered and fingers crossed.
Of course I have to ride it and see how it goes with the latest planned change.but double checking the numbers. I am more confident it's all coming together.

As always feed back is welcome; It all helps, I listen to everything but ultimately decide my own path and sometimes I later change my mind.

 

[gt alex]

I fitted the new dog bones they raised the back 15mm no change to the seat or frame.
the handling is much chuckable I like it but will have to see,

 

[gt alex]

The tank is still not done. but in the tradition of not leaving sleeping dogs lie, I decided to change the exhaust to a current model race system by black widow and adapt it to the 2002 cafe racer build.
Yesterday avo my Black Widow sv650 gen3 race exhaust system arrived on time despite Corona.
So today I ripped off the Gen1 system and started checking out how much needs changing to fit the K2.
Well, It looks pretty promising. The front and mid pipe sit in place without fouling and the rear pipe slips nicely on the short rear head pipe, but fouled on the bolt ant nut for the lower dog bone support.
Now, I don't remember which way this bolts are standard because my dog bogs and shock are non standard and I may have just turned them so dirt from the chain wouldn't build up on the thread.
So if time allows tomorrow I will turn the bottom bolts a around and then we will see.

 

[gt alex]

sv650 Gen3 black widow system on gen1 cafe racer project
Today the lower dog bone bolt and lower shock bolt were turned around providing room for the rear pipe to sit in place.
Now using the gen1 stubby rear cylinder head pipe seems the safest option. using the gen3 pipe which would be extra cost may create more problems, I would try it if I had one but I don't.
The gen1 head pipe must be about 20mm longer increasing the distance between front and rear pipes on the new system, so the collector pipe on the centre section for the rear cylinder will need to be shortened about 20mm and since this part is flared it means a trip to the local exhaust shop,
Once that is done I will work out the new mounting bracket.
Then comes fitting the muffler, odds are a gen 3 slipon would go straight on but I will go the hard way using what I have.
Over all I think It is a good option for sv650 gen1 now that there are less and less options

 

[gt alex]

sv650 gen3 black widow system on gen1,
I went 3 exhaust shops to get the flare lengthened for the rear cylinder entry on the centre section with no joy.
The first was closed and the others said the pipe diameter is too small for their tooling. So if its too small for the exhaust shops I would try the biggest plumber in the town but they wouldn't try it because it is stainless.
So I shortened both the header pipe and the expanded part about 9 mm and DONE
Now I have cut off the gen3 mount and I need to fab 2 mounts to bolt on the gen 1 frame.
The only interference I have spotted is it is hard against the spring post inboard of the side stand.
So far still good

 

[gt alex]

 

[gt alex]

Finished exhaust

 

[ridesolo]

Enjoying your work on this. We don't see a whole lot of these on here, nice bike.

 

[Maritime]

looks good but I would have done a second matching on the other side. But I am biased, I have the same shape pipes in chrome at the same angle on my GL.

 

[gt alex]

new picture

 

[gt alex]

It's hard to find time at the moment, but this was part of my original cafe racer plan, I thought I had better bite the bullet and start swapping out my carbs for a single mechanical throttle body.
So hopefully by the end of the week it will be done. And depending on how well, or not it works will dictate the next step e.g. the tank etc.
What do you think a flat air filter under the tank hidden of a hole in the tank flush to help air flow or whole hog a ram tube thru the tank.
I may even dyno it when done just for kicks

 

[Brodie]

Interesting concept. What is the throttle body off?

How much clearance does the tank have with that manifold fitted to it?

 

[gt alex]

Its a fish "carburettor" an early rethink of fuel induction designed about 1930. It is a mechanical map sensor that compares MAP against at atmospheric pressure and dispenses the correct amount of atomised fuel (whatever the altitude) Using that same pressure difference to push the dose through the spray bar. At max load the air going around the throttle plate creates some venturi effect that assists delivery.
Bet you are sorry you asked
There is about 50mm clearance, Which would defiantly be ok especially with a spacer under the tank.
How ever I am going to fit a modified tank about 50mm shorter and I am yet to workout a TPS for the bikes CDI

 

[gt alex]

My air filter just arrived and I am booked in for dyno tuning 14 Jan 21.
It took a bit to find a dyno operator willing to try something a bit different. some wont look at anything that is not EFI.
I have worked out the throttle linkages but havn't fitted them on yet.

 

[gt alex]

 

[gt alex]

Ok. Time for an update,

If idle speed is correct too much fuel is being delivered thru out the whole range. If I adjust for a 3500 rpm Idle I can get it all good.

So I am going to try a 2nd spray bar I have for the 100 hp version which has smaller holes I am not sure of compatibility with this larger TB but it's the best bet at this time.

 

[gt alex]

Success is not guaranteed This is not paint by the numbers. This item was not sold equipped to suit the bike.
These were sold pre setup for an application but could easily suit similar applications. This is far from a chevy 6 but it is coming together.

I fitted the spray bar with smaller fuel holes and found the air holes are the same size in both. so now the throttle plate is close a little more compared to the fuel metering so when its shut all the way down in idle position it now idles a bit over 2k rpm.

But since there seems to be no secret ratio between the fuel holes and the air holes I have now drilled 1 of the 3 air hole out 0.2 mm.

Next job reassemble and try again.

 

[teazer]

OMG, I haven't seen one of those air cleaners since I bought one for a mark 1 Cortina back in..about 1976 I guess.

That's an interesting car/fuel injection system. Keihin recently introduced a high end carb with a series of fuel supply holes in the needle and it makes sense to put the "jet" in the middle of the air flow and not just at the bottom where airflow is turbulent. Will it work? Who knows, but the only way to know is to try it and keep changing things until it either works or it doesn't.

Goodonya for trying something different.