4t tuning thread

[speedpro]

Just for info - Tjebbe Bruin built a speedway sidecar using an XS1100 with 2 cylinders sleeved down. It used modified original CV carbs and a blow through turbo system. I heard it made something in the region of 170hp.

[bucketracer]

Just for info - Tjebbe Bruin built a speedway sidecar using an XS1100 with 2 cylinders sleeved down. It used modified original CV carbs and a blow through turbo system. I heard it made something in the region of 170hp.

Thanks Speedpro for a local example of a blow through system that worked.

[bucketracer]

If you had, lets say, an ordinary 100cc legal bike and decided to strap on a running lawnmower engine to the frame for 'centrafugal ballast',

would it now be capacity wise illegal eventhough the lawnmower engine wasn't connected to the driven wheel?

Wouldn't your idea of a 'self contained self driven' blower unit be more or less the same thing?

That is the direction of my thinking............

[TZ350]

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Reading Sparkplugs......some good pictures for the 4-stroke boys..

http://www.empirenet.com/pkelley2/sparkplugreading.html

[Mudflaps]

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Reading Sparkplugs......some good pictures for the 4-stroke boys..

http://www.empirenet.com/pkelley2/sparkplugreading.html

Those are some good pics and well explained. Even for a lamen like me.

[koba]

Do the CDI`s come with an adjustable rev limiter? I think there unlimited(well most aftermarket) hense the rod problems.Anyone know of a cheap, say scooter aftermarket rev limiter?

Jaycar engine immobiliser/revlimiter.

posting links looks like it won't work but its on their website.

[TZ350]

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Came across this on valves and valve springs while looking for FZR chassis info:-

"Next comes the matter of 'valve springs. From your place on a tall stool in an air-conditioned drafting room, logic tells you that two revolutions of the crank equals one valve-spring fatigue cycle. From the hot dyno cell or race track, the springs see things differently: at high crank speeds the rapid acceleration imparted by the cam lobe approximates a hammer blow. This can make the coils of valve springs "ring" or vibrate end-to-end. This ringing vibration may have a characteristic frequency of hundreds of cycles per second, so it can, if excited at high speed, add up fatigue cycles so fast that springs break prematurely. This spring surge can also cause irregular actions at the valve—float, bounce, etc.—that deteriorate other parts as well."

The rest can be read here:- http://www.motorcyclespecs.co.za/mod...zr750%2087.htm

[Buckets4Me]

if only all 4 strokes where this easy to build

[speedpro]

"Next comes the matter of 'valve springs. From your place on a tall stool in an air-conditioned drafting room, etc etc

Which is why serious V8 drag race motors use titanium valve springs with around 3 turns only. I've mapped their lift profiles at the valve and they're pretty wicked. Stuff like .8-1" (inches, NOT cm) lift with really radical lift rates on a motor that will pull 9,000rpm+. It may have changed but new ones were put in for every run.

[woodyracer]

got to love self assembling motorbikes, :]

[TZ350]

.
A guide to the general principles for increasing the performance of modern engines.

Fundamentally there is a simple rule about getting more performance out of a piston engine. Get it to consume more air (with the right amount of fuel) and it will deliver more performance. More air consumed per cycle will benefit torque, whereas more air in unit time will benefit power. Increasing just air or just fuel rarely achieves much unless the manufacturer got things badly wrong, which is rare. The ratio of fuel to air must remain in the right proportions for proper combustion although some over-richness at full throttle is quite usual as a means of lessening thermal loads on the engine (and catalyst). This may sometimes permit a slight increase in airflow alone to produce a small performance gain.

Those who think that hotter cams are always a good thing should take note - unless they intend to go on the race track. Although the surge as a hot cam starts to work might feel impressive it can be illusory because the torque is just climbing back to where it should have been all along.

This is all quite fortunate because it means that the starting point for more performance is relatively easy and inexpensive and there is no need to do things like swapping cylinder heads. Upgrading the induction, fuel and exhaust systems undoubtedly gives the most performance gain for the money spent. This is true even for racing although for such purposes we offer similar conversions with more bias towards high engine speeds.

Read it all here:- http://www.jagweb.com/aj6eng/technics.php

[richban]

Well after dicking around with Mikuni TM28's for ages and thinking they were the shiz. I thought I would give a cheap PWK knock off a go. The TM worked great on my standard engine but on the tuned one it was as fussy as fock. So I chuck this thing on straight out of the no frills packaging and start it up. What a difference. It needs some fine tuning but man its no where near as fussy as the Mikuni. I had read that they were quite forgiving if not quite setup proper, but this was a surprise. When I get it dialed in on the track I will ad to this.

[Buddha#81:Me]

so biggers not always better........?

[bucketracer]

...... I thought I would give a cheap PWK knock off a go.........So I chuck this thing on straight out of the no frills packaging and start it up. What a difference. It needs some fine tuning but man its no where near as fussy as the Mikuni........

Is this the carb your using, the OKO brand from Taiwan.........

[timg]

so biggers not always better........?

For you mate, Big is Good. Keep up them pies Gotta give us old farts some chance eh?