[jedaks]

Thanks Arizoni
I will try a few short runs sans filter and see what happens.

By the way, I appreciate your responses. I don't come here much but you seem to frequently respond to my questions. I appreciate that and thanks again.

PS. I was in Tucson for awhile. Yes, it is a dry heat. A 120 degree dry heat

[Blltrdr]

Thanks mate, yes I can't seem to dial some things in.

I think I got my timing pretty well right. I still get a blue header pipe way down to the second bend when the engine is hot, which can indicate retarded, but when the bike cools the bluing fades pretty much all way. But the degree wheel and strobe timing light say its right.

I believe my carburetor is the key. I have heaps of advice on what jets to use but I still can't seem to get anywhere. It is a black art, tuning a carb.

I have a 27.5 pilot jet in there. I started with it 1.5 turns out from bottom. That gave me a good idle but the engine would die when the throttle was blipped. The engine would also die when 1st gear was engaged unless I rolled the throttle. Lots of popping on deceleration, especially down hill. That tells me its lean. So I screwed in the air bleed screw little by little until all those symptoms went away but my spark plug was black and furry. So I screwed it out again little by little until the symptoms were still gone but the plug was chocolate brown. So I think my idling and low range settings are good.

I have a P2 needle jet and the jet needle clip is on the bottom groove. I consider the bikes performance in the mid ranges to be good or at least good-enough. The bike feels powerful and accelerates up to 100kph (60mph) with no hesitations. I think the mid-range jetting/settings are good or at least good-enough.

The high range is my problem. When I get up to 100-105kph, I am at wide open throttle. That's not right. Most people tell me that with my setup (535 with 8.5:1 piston at 150psi compression) I should be only be around 1/2 to 3/4 throttle at 100kph.

I did some plug chops the other day. I got up to wide open throttle on the highway for 1 minute and killed the motor, pulled the clutch, drifted to a stop. My plug was a pinkish-brown. That was with a 127.5 main jet.

So I put in a 130 main jet and repeated the same test. No change to the plug color and I was wide open throttle for 1 minute. The engine had a tiny bit if stutter/hesitation at one point but it was gone very quickly.

So I have ordered a couple of larger main jets to see what happens. A bloke in the Enfield club here had a bike very similar to mine (535, 19 tooth sprocket, same piston, steel conrond, alpha roller bearing, japanese bearings in the cases, clutch springs 1/2 normal, 1/2 heavy duty, and the Mikcarb VM28). He told me he had to go to a 140 main jet before he got proper top end.

I forgot to mention I have a S&B cone filter on the back of the carb. My exhaust is straight through (no cat converter) but it does have the PAV system. I ordered a blanking nut from Hitchcocks to get rid of that. My muffler is the shorter Indian one. I live at sea level.

I'm not trying to make a crotch rocket out of this. I'm not into 'high performance'. But I rebuilt the engine into a 535 with the above mentioned mods to enable me to ride the highway and keep up with traffic when I can't ride back roads. I'm not a racer or a rev-head. I'm a sedate thumper that wants to have some "oomph" on tap when needed.

And to stay a little on topic, I'm using too much fuel at the moment.

Maybe I am targeting the wrong area and should be looking at the air flow into the carb rather than the jets?

The Secretary of the Treasury has forbidden the purchase of a bigger carburetor at the moment so I need to tune in the Mikcarb.

Thank for hearing my snivels.

Well I know you have mentioned you changed the inlet cam timing. That could be your problem. Are you sure you did it correctly? I'm sure you are following Ace's advice on how to set that up correctly. You would think you would have had these symptoms worked out by know. Is there a chance that you advanced your inlet cam instead of retarding it? What if you tried going one notch the opposite direction and see what your performance is like.

What kind of manuals are you referencing for your carb adjustments. I will post a couple manuals. One is a scooter manual for tuning Mikuni & Keihin PWK carbs, but has some good all around tuning info. http://scootrs.com/tech.cfm?tip=tunecarb

[jedaks]

Thanks Blltrdr

I put the cam timing back to stock. I did try Ace's advice and did several hundred kilometers with the rephased cam. However things have actually improved on the bike by returning to factory stock cam timing. I think rephasing the inlet cam is a trick that can be useful but new Clubman or Fireball cams would be much better.

Thank you for the link to the manual. I have read that and only understand about half of it. Too many squiggly lines on graphs. But I will certainly refer to it.

[Blltrdr]

Thanks Blltrdr

I put the cam timing back to stock. I did try Ace's advice and did several hundred kilometers with the rephased cam. However things have actually improved on the bike by returning to factory stock cam timing. I think rephasing the inlet cam is a trick that can be useful but new Clubman or Fireball cams would be much better.

Thank you for the link to the manual. I have read that and only understand about half of it. Too many squiggly lines on graphs. But I will certainly refer to it.

Check out that scooter link I provided also. There are some good tips there.

[jedaks]

I've been keeping some records of my fuel use and distance traveled to try to narrow down what fuel economy I'm getting.

13 June I filled up the tank with 18ltr (4.75 gallons I think) of premium fuel. I only ever buy premium. Odometer was 13452 klm. (About 900klm on the new rebuilt motor)

21 June, 14 litres, odometer 13695.
06 July 13 litres, odometer 13896
14 July 13 litres, odometer 14127

I am getting about 5.5 litres per 100 kilometers. Thats 17.85 kilometers per 1 litre of petrol.

Imperial measurement. 100 kilometers = 62 miles. 5.5 litres is 1.45 gallons.

Most of my riding is short trips and the engine only has about 1000 miles on it.
So I suppose theoretically if I sustained a certain speed for a longer period of time to allow engine temperatures to stabilise I might do better. Also perhaps fuel economy will improve as the engine further beds in.

Is that reasonable? Do I have anything to complain about?

Regards,
Joe

[LarsBloodbeard]

Sorry to bump an old post, but I wanted to say I found this as entertaining as I did helpful.  I was looking up info on 535 upgrades and found people squabbling over smartphones, computers, pen & paper, etc... You're all right, you know.  Each has it's pros and cons.  Whatever works best for you is the best solution.  And putting someone down for using a smartphone is as silly as putting someone down for using paper.

-Lars

[barenekd]

Off the top of my head, that works out to about >50mpg. That sounds pretty lousy to me, normally getting about 70 mpg. But I haven't read about all you've done to the bike, but it obviously won't get what the 500s will.
However, the low and mid range of the carb is where you should be concentrating. The idle circuit, needle, float level has more effect on your mileage than the main jet unless you're really flogging it. But more importantly, you need to take care of any other  problems that you may have, cams, ignition, etc, before you can get the carb right.
Bare