Pipes!

[motorhead]

What kind of fuel tap are you using? Dont expect any stock fuel tap to keep up with the flow of 2 big main jets at high rpms on WOT.

[chinoy]

something is not right
Did you up the compression more than what I designed ?
You need to go back to what the orignal design was.
The only other option is to

a. Re-cut the heads to drop compression. High compresion is not a good thing for low / midrange motors. Its only good for very high exhaust ports.

b. Change the porting a bit. (Send me the barrels).

A programeable ignition is not the way out. The curves Ive designed will work.
If your detonating at 14 degrees with curve 2 sounds really crazy. Your compression must be very very high.
The easy fix is yes file the slot out some more to let you say run 10 degrees.

What mods did u do to the set ?

Ps: If I did do a programeable ign you would land up runing curve 2 on it anyway. Because it is the best curve for the setup.

You mentioned something about a thiner head gasket and cuting something. This had taken your compresion even higher.

A simple fix is to just keep backing off the timing till it stops detonating.
This setup used to work with 14 degrees or was it 10.

We have changed our honing technique so ring seal is better in the engines and it is possible you need to back off a few more degrees. But your allready firing at TDC and if your detonating even then short of going back to my orignal calcs / droping compresion there is no way out.

[vivekjayasheel]

I wouldn't dare modify your work in any way man.

Only problem I can see is that I am using those thin Vesrah head-gaskets (0.9 to 1 mm thick) instead of the Indian ones (1.2 mm). To make them tighten down properly, we had to grind some metal off the head-gasket SEATS, on the top of the barrels. Haven't modified your porting or heads in any way.

If it requires 10 degrees to work, I will need to extend the mounting holes on the baseplate, but that would kill the low-end even more

I have a pair of stock LT heads which I can try.

Why I think it would benefit from a custom curve is that, she has a great low-end and pipe-kick if I set it to 20 degrees, but as soon as she gets on the pipe (around 4800 to 5000 rpm), she starts detoing almost immediately (within the next 1000 odd rpm). If the timing could drop super-drastically just at this point, I would get the best of both worlds. Is it possible to BORROW a programmable box for a weekend? I don't mind giving you a hefty deposit to ensure its safety

If not, I don't mind sacrificing that low-end for the pipe kick. I wanted a straight-line missile anyway. I'll file out the holes and run 10 degrees.

[atul_astro]

Try running two head gaskets man

[chinoy]

two head gaskets is a joke
try the stick head gasket it was setup for that.
If that dont work then try the stock heads.

[vivekjayasheel]

Finally got my hands on stock heads, stock gaskets, 300 mains and B9HS NGKs, so plugged the chambers back on again.

Does anyone have a gearing calculator here, for all the 6 gears? She did 96 kmph in third last night before running out of road... don't have a tachometer yet so dunno what rpms she is doing. Opening her up in first is almost impossible.

Things left to do: Will upjet the pilots this weekend... presently running the 15s that came with the carbs, with the air-screws turned fully in. She idles coolly at around 1000 rpm, as checked with a hand-held tacho, but would like to see what happens if I upjet to 30 or 35 pilots.

Time to hit some nice straights.

[SunMysore]

Nice to hear that. 15 pilots should be too lean, my bike wont run proplery if not with 20 pilots. on an RX.

You have a digital speedo? Gearing sheet well do a search recently made a post with the link in it.

Hand held tacho, and you say no tacho?

Nice straights eh? good go get rid of the 124KMPH tag

[vivekjayasheel]

Hand held tacho clips onto the plug lead for a reading. Can't ride with that.

I know the gearing conversion for 6th: RPM x 0.02 = Road Speed in KMPH. I want a similar formula for the other 5 gears...

Will do some nice runs on my own this time, before putting her on the gun. I'm hoping the brand new rear tyre has cured the wobble.

[nav75]

She did 96 kmph in third last night before running out of road... don't have a tachometer yet so dunno what rpms she is doing. Opening her up in first is almost impossible.

Time to hit some nice straights.

Has the wobble when ridden solo fixed?

[chinoy]

What is the rolling radius of your rear wheel.
Or Tyre size.

Earlier you where maxing out at arround 135 right which puts your RPMs at 6800
With the adjustment made for shaving the top of the barrel my calculations say you will peak out at around 8000 RPM in sixth.

With a Rolling Radius of 12.38 or a 110/90/18 rear your 97 Kmph in 3rd equates to around 8500
If you do 8k in sixth this gives you a top speed around 157 if you do 9K RPM it gives 177 I feel your real top speed will be between these two numbers.

[vivekjayasheel]

Ok, finally got the 2 taps fitted, bike runs much better but only a longish trip will say how much better.

The Pulsar tacho is also working now. The pipe hits like a light-switch at around 5800 rpm and pulls VERY STRONGLY till about 8500 (it takes a little more than a second to blitz from 5800 to 8500). After that the pull seems to recede a bit but there is quite a lot of over-rev. The needle swept past 9k rpm in third (ran out of road after that). Will do a proper RPM vs. speed thing tomorrow.

Bike heats up when puttering around (below 6000 rpm) but one good blast on the pipe cools her down. Isn't this a little weird for a chambered bike? Idle speed is comfortable around 1100 rpm so I don't think the pilot circuit is too lean...

I also think that 300 mains seem about right because she fouls the BP9HS plugs quickly even with regular blasting...

[chinoy]

Ive had similar issues with the plugs. Could never get 9s and 10s to run.
Have always stuck to the Mico W5BC.
WIth close inspection of the tip.

How do the two curves effect the way the bike runs.

Hiting the power band is pretty addictive though
I think the bike will hit 9K easy in top gear.

If you dont want the bike to accelrate so hard change to a 16 front.
It will give you solid mileage. More top speed in each gear.

[vivekjayasheel]

Oh the power-band is VICIOUS!!! Can't thank you enough, mate.

Didn't notice TOO much of a difference between the two curves except that the punch would peter out earlier on Curve 2. So I've retained curve 2 and advanced the base timing to almost 22 degrees. This seems to be a better option than using curve 1 and 18 degrees timing. It gives me more pep below the power-band and slightly bigger hit right upto the 9k mark. If this is your idea of a street port, I'm never riding one of your all-out drag bikes LOL. Hats off to Tom.

The only thing that's worrying me is that she runs quite hot especially when puttering around in traffic, below the pipe. The setup is about a thousand kms. old. Will things get better as I keep running her? I plan to switch to bigger pilots on the weekend. The mains seem to be OK at 300 but just in case, ordering a pair of 320s too.

[vivekjayasheel]

Also another thing I wanted to mention is that the pipe is actually a very clever design (I can hear a lot of people going 'duh')... but my reason for saying so is: upto about 4000 to 4500 rpm, she behaves just like a regular LT, shooting out at the slightest throttle and generally very alert and responsive and all. This totally linear power delivery is very useful for cruising at 40 to 80 kmph in traffic, when you don't want any sudden surprises. Only after 4500, a slight hesitation starts building up, upto the 5800 mark. It is a good precursor for what lies ahead.

This availability of power BELOW the power band was missing from the chambers I tried before this. And of course, none of them hit this hard (damn, I dunno why I keep saying this )

[indianchief]

Hehe, one more addicted. I can totally relate to what you are experiencing.

[vivekjayasheel]

Update: I reverted back to the RDD heads That mid-range flat-spot from 4500 to 5800 is all but gone.

Using curve-II now.

It never ceases to surprise me how you can always get a LITTLE more out of this tough little engine. But I've promised myself, I am happy with this setup and won't fiddle around anymore.

[chinoy]

Chief how many Kms / years over on the build now ?

[indianchief]

Only run around 10k, time wise 2+ years without a glitch.

http://s215.photobucket.com/albums/cc26 ... G_2714.jpg

[ajaybiz]

Tempting, Chief is it the same RD having hydralic clutch?
BTW which component is used from JBL .

[SunMysore]

Tempting, Chief is it the same RD having hydralic clutch?
BTW which component is used from JBL .

ahhaha chief dont tell me you have a radio and JBL speakers on the RD