FXR race cams

[gav]

Anyone got any specs on race cams for a MotoFXR? Can I just get the standard cams reground?

[skidMark]

Anyone got any specs on a race cam for a MotoFXR? Can I just get the standard cam reground?


AFAIK you can't run hot cams in buckets can you?

[speedpro]

Read the far kin rules, geez.

[gav]

AFAIK you can't run hot cams in buckets can you?
Clearly, once again you have proved that you know fark all ...... :rolleyes:
Not allowed in two strokes .... see page 17

[gav]

Oh and specs on a race pipe too, would be handy, thanks.
And, errrr, your input won't be required Mark, so please run along ..... :doh:

[Sideways Sam]

Basically you can do whatever you want with F4 four strokes, the basic limitations are.

Naturally aspirated, ie. no turbos or superchargers (Ram air is OK)
Must be running on petrol, Av-gas is OK but no meth or Nos
Engine must have started life as a non-competition engine. that is trail bike OK, motorcross bike not... Street bike fine, GP bike not...... etc. Some of the Derby 2 strokes are on shakey ground with that rule as they come from the factory in dedicated race bikes etc, check out Metrokit.....

Outside of that you can do pretty much whatever you damned well please which is half the fun of buckets as opposed to Street Stock 150s. The really fast bikes have spent plenty of time on home-made dynos working on compression ratios, exhausts, cams, cam timing, ignition timing, porting etc, etc, etc The sky is the limit if you've got the time and the money. Won't do you anygood at Mt Welly though cause it's all about the corners and power hasn't got a lot to do with it

The reason that some of the CB125 twins go so well is that they've had 30 years to figure out what makes them go faster and stay together. The FXR's have a long way to go till they're in the same league.

Don't take too much notice of some of the BS on this site, half the people on here haven't read the rules and have never touched their engine short of putting oversized carbs and exhausts on them which probably make them go slower.......

[TZ350]

.


The sky is the limit if you've got the time and the money. Won't do you anygood at Mt Welly though cause it's all about the corners and power hasn't got a lot to do with it

This I know to be true. :yes: but you can do pretty much tuning wise whatever you damned well please which for me is half the fun of buckets and the people you meet there are just the best!

.

[Sideways Sam]

.



This I know to be true. :yes: but you can do pretty much tuning wise whatever you damned well please which for me is half the fun of buckets and the people you meet there are just the best!

.
Here, Here. I agree totally

There are some great people in buckets (some of them are very clever engineers too)

[gav]

Basically you can do whatever you want with F4 four strokes, the basic limitations are.

Naturally aspirated, ie. no turbos or superchargers (Ram air is OK)
Must be running on petrol, Av-gas is OK but no meth or Nos
Engine must have started life as a non-competition engine. that is trail bike OK, motorcross bike not... Street bike fine, GP bike not...... etc. Some of the Derby 2 strokes are on shakey ground with that rule as they come from the factory in dedicated race bikes etc, check out Metrokit.....

Outside of that you can do pretty much whatever you damned well please which is half the fun of buckets as opposed to Street Stock 150s. The really fast bikes have spent plenty of time on home-made dynos working on compression ratios, exhausts, cams, cam timing, ignition timing, porting etc, etc, etc The sky is the limit if you've got the time and the money. Won't do you anygood at Mt Welly though cause it's all about the corners and power hasn't got a lot to do with it

The reason that some of the CB125 twins go so well is that they've had 30 years to figure out what makes them go faster and stay together. The FXR's have a long way to go till they're in the same league.

Don't take too much notice of some of the BS on this site, half the people on here haven't read the rules and have never touched their engine short of putting oversized carbs and exhausts on them which probably make them go slower.......

Thanks for all that .....
Kinda why I was hoping someone might share what they have found has worked, this is after all buckets, not MotoGP or WSBK. Maybe some sharing of info might be available?

[Sideways Sam]

I don't know much about the cams that FXR150 sell except that they are new race cams out of Malaysia (definitely not regrinds).

When I can afford some for myself I will get them profiled so we know what we're dealing with.... Apparently they are longer duration but that's all I've been able to find out.

There are probably cheaper/easier ways to get some extra HP out of an FXR but first you need to decide what sort of power curve you want which is dictated by the track......

[richban]

Anyone got any specs on race cams for a MotoFXR? Can I just get the standard cams reground?

Yep you can regrind the standard cams. Talk to Kelford cams in CH CH. They are made from not bad steel so can be built up and reground.

[speedpro]

Naturally aspirated, ie. no turbos or superchargers . . . . . . .

Don't take too much notice of some of the BS on this site, half the people on here haven't read the rules

Pot, kettle, black . . . . . . .

[Sideways Sam]

Pot, kettle, black . . . . . . .
Actually, we're talking about an FXR150 and as far as I can ascertian (and I've read the rulebook a couple of times) that's a no go. The rules state "All engines must be normally aspirated except F4 4 stroke engines of less than 100cc capacity, which may be turbo or supercharged."

Last time I looked, the 150 in FXR150 stood for the capacity of the engine which is quite clearly well over the stated max of 100cc for blowers.

In saying that, I've heard a lot of people talk about blowing 100cc engines and in theory you should be able to get some serious hp but never seen anybody do it with reliable success...... It would be fun if I had the time!!!

[gav]

There are probably cheaper/easier ways to get some extra HP out of an FXR but first you need to decide what sort of power curve you want which is dictated by the track......
We race on real tracks, not car parks :Oops:
What would you suggest, currently running GN250 carb, ported head, big bore exhaust.
Have got 32mm Flat Slide carb coming. :woohoo:

[Pumba]

Have got 32mm Flat Slide carb coming. :woohoo:

Saw a Gav biding on of those on trade me, would have bid on it myself if I had the money

[gav]

:innocent:

[speedpro]

Basically you can do whatever you want with F4 four strokes, the basic limitations are.

Naturally aspirated, ie. no turbos or superchargers (Ram air is OK) . . . .

Obviously talking of the rules themselves here, not a particular capacity F4.


The reason that some of the CB125 twins go so well is that they've had 30 years to figure out what makes them go faster and stay together. The FXR's have a long way to go till they're in the same league.......

and NOW the FXRs are mentioned.

[richban]

We race on real tracks, not car parks :Oops:
What would you suggest, currently running GN250 carb, ported head, big bore exhaust.
Have got 32mm Flat Slide carb coming. :woohoo:

Up the compression. That should make a big diff. FXR's don't have much at all. I have a Mikuni TM28mm flat slide on mine and it works a treat. Not a pumper but hard to find a small one pumper that is. I know my bike lacks power down low. I am sure a rise in compression will help heaps.

[Sideways Sam]

For top end power, which I take it you need from your comment about 'real tracks', I would be very tempted to get the Cam sprockets slotted so you can tweak the valve timing for top end power (you might lose your idle). It's an easy mod, you can do it all yourself or get a machinist to machine the sprockets for less than $100

Just need to buy a degree wheel (about $50-) and do a lot of study on the internet re valve timing. It's not particularly hard, just takes time (lots of time). Ideally you'd have access to a dyno but I know a few people who've done it here without one quite adequately.

Feel free to come to the Mt Welly 'car park', all the engine tweaking in the world wont do you any good if you can't maintain corner speed. TZ350 has more horsepower than anybody I know and once he gets the trainer wheels off he might win some races....... (sorry Rob, couldn't resist). As for me, I can't go round corners yet either, my son does about 4 seconds a lap quicker on exactly the same bike!

[Sideways Sam]

:innocent:
Yeah I figured that, wasw just winding you up for the hell of it......

[Sideways Sam]

Up the compression. That should make a big diff. FXR's don't have much at all. I have a Mikuni TM28mm flat slide on mine and it works a treat. Not a pumper but hard to find a small one pumper that is. I know my bike lacks power down low. I am sure a rise in compression will help heaps.
Up the CR is always good and it works right through the rev range. You need to be really careful though. Read my post on FXR conrods breaking....... I would suggest that you wouldn't want to up the CR until you've completely rebuilt (or at least blueprinted) the bottom end. That's the approach I'm taking on my next couple of engines.

[Sideways Sam]

We race on real tracks, not car parks :Oops:
What would you suggest, currently running GN250 carb, ported head, big bore exhaust.
Have got 32mm Flat Slide carb coming. :woohoo:
Until you've done any serious mods inside the engine itself, I'd always be tempted to leave the airbox in place..... Most people will tell you to drill holes in it etc etc etc but that's all a croc unless they've done about 15 pages of calcs or just fluked it right. Even if you change the carb, try to leave the airbox in place.....

The Suzuki engineers spent millions in research on that airbox to overcome a midrange dip in the power curve, and it works.......... It will continue to work until such time as you change the internal dynamics of the engine eg CR, cam dynamics etc. If you aren't changing any of that stuff the airbox will give you the midrange boost at exactly the right point without sacrificing power anywhere else. Theres a reason most serious racebikes (including MX where weight is a really big deal) run airboxes.....

If you change the internal dynamics of an engine then the airbox needs to change, this is the point where most serious builders on a budget just ditch it. If you've got a degree in airodynamics (my daughter has, yeah baby.....) access to a dyno (still working on that) and unlimited time (that's the tough one) you can create a custom airbox designed specifically to rectify issues in the power curve of your seriously modified engine.....

What tends to happen is the less mechanically minded people just copy what others are doing. So one of the first things they notice on another bike is that the airbox has gone (cause they can see it) so they get rid of their's not realising that until they make some major internal changes to an engine it's a major performance booster

[Sideways Sam]

We race on real tracks, not car parks :Oops:
What would you suggest, currently running GN250 carb, ported head, big bore exhaust.
Have got 32mm Flat Slide carb coming. :woohoo:
When you say 'ported' head. was it flow tested?

I had my last head flow tested.. (before it imploded)

The standard FXR head can flow the equiv of about 24hp (haven't seen anybody get anything like that out of one yet) by the time I'd finished with it, it was theoretically capable of around 28hp if every other component was delivering up to this level.....

I think the standard FXR head is pretty good and the major enhancements are to be had in other places....

[richban]

When you say 'ported' head. was it flow tested?

I had my last head flow tested.. (before it imploded)

The standard FXR head can flow the equiv of about 24hp (haven't seen anybody get anything like that out of one yet) by the time I'd finished with it, it was theoretically capable of around 28hp if every other component was delivering up to this level.....

I think the standard FXR head is pretty good and the major enhancements are to be had in other places....



Yep have had mine flowed and the same conclusion good for about 24hp.

[Buddha#81]

Until you've done any serious mods inside the engine itself, I'd always be tempted to leave the airbox in place.....

The Suzuki engineers spent millions in research on that airbox to overcome a midrange dip in the power curve, and it works..........

What tends to happen is the less mechanically minded people just copy what others are doing. So one of the first things they notice on another bike is that the airbox has gone (cause they can see it) so they get rid of their's not realising that until they make some major internal changes to an engine it's a major performance booster

That good to here about the airbox's, My MotoFXR still has it fitted, no top and filter. I left mine there for wet weather riding, its always good to hear more sciencetific reasons. My motor is standard, carb and pipe are the only changes.

[Kickaha]

My motor is standard, carb and pie are the only changes.

Looking at you, I'd say plenty of pie to <_<

[Sideways Sam]

That good to here about the airbox's, My MotoFXR still has it fitted, no top and filter. I left mine there for wet weather riding, its always good to hear more sciencetific reasons. My motor is standard, carb and pipe are the only changes.
You'll probably find that the filter and the top are all part of the equation. I know that when I removed the filter it lost power significantly so it's got the filter back in now.

Truth is, standard carb, standard airbox. Just some serious jet and needle adjustments and it goes as well as any other FXR at Mt Welly. I'm more suprised than anyone........

[Rick 52]

Are you sure it wasn't the the bike running to lean that buggered your engine ? The aire box was designed to run with the CV carb but if you get a new carb then its no good . Its all about getting a good amount of fuel air mix in and getting the the old air out . I tryed to get the CV carb to run good but its better with a slide carb you then get more control.

[TZ350]

Feel free to come to the Mt Welly 'car park', all the engine tweaking in the world wont do you any good if you can't maintain corner speed. TZ350 has more horsepower than anybody I know and once he gets the trainer wheels off he might win some races....... (sorry Rob, couldn't resist).

Bugger taking the trainer wheels of, trying to keep up with you two is scary enough as it is.....:sweatdrop:

[Sideways Sam]

Are you sure it wasn't the the bike running to lean that buggered your engine ? The aire box was designed to run with the CV carb but if you get a new carb then its no good . Its all about getting a good amount of fuel air mix in and getting the the old air out . I tryed to get the CV carb to run good but its better with a slide carb you then get more control.
I've considered that, over and over. Truth is there was no indication of overheating which there should have been if she was running lean.... Who knows????

Right now I'm playing with a computer and injection, if I can make it work (which is looking good) I'll happily throw all the carbs away........ The hardest part is finding a suitable throttle body, rest is a pice of cake. Looking at using a TB off a quad bike. would like one from GSXR600 but don't really want to pull a bank of four to bits

[speedpro]

Use a CV carb without the slide. Fill the slide hole up with bog. OK if you are using a MAP sensor without a TPS though there is probably a not too hard way to add a TPS.

[bucketracer]

Use a CV carb without the slide. Fill the slide hole up with bog. OK if you are using a MAP sensor without a TPS though there is probably a not too hard way to add a TPS.

I am continually astounded by the ideas that bucket racers come up with. Why didn't (couldn't) I think of that! Very clever of speedpro. :yes:

[Rick 52]

Right now I'm playing with a computer and injection, if I can make it work (which is looking good) I'll happily throw all the carbs away........ The hardest part is finding a suitable throttle body, rest is a pice of cake. Looking at using a TB off a quad bike. would like one from GSXR600 but don't really want to pull a bank of four to bits[/QUOTE]

Now that sounds cool and using the old CV carb as the body is a easy way to make it all fit but it would be nicer to have a bigger diameter good luck.
Will you be at the next meeting ?

[speedpro]

I actually took a long time to think of that. I've got a Haltech engine management system that is supposed to be getting fitted to a bucket at some time and I need a throttle or two for that.

Just another 10 year project . . . . eh Dave!

[Sketchy_Racer]

In the long run it would be easier and more effective to get a throttle body, injectors and TPS sensor etc off a modern 600 (designed already for 150cc cylinders)

Hell you could even just run the standard ecu and loom and trim out the extra stuff you don't need.

Obviously there will be other little bits to sort out such as cam position sensor and crank position sensor and MAP sensor (which would be a piece of piss)

If you replicated one cylinder of a modern 600, your 150 single has the potential of about 30hp at a push. wouldn't that be cool.

I wish I had the time and money to do it now!

[gav]

Hey, you've got an old GSXR600, you could build four bikes! Can I've one? :2thumbsup

[Bren_chch]

Hey Gav

I got the std cams and the race cams profiled at Kelfords. Kelfords were overall impressed with the race cams "much better than they look". i have all the info if you need it. in short they give a much greater power output above 8k, ideally you need to increase your compression to make the most out of them, thats something that is not hard to do, we've done it to andy macs, yowlings, dangerous, tonymac and my engines of course.

B

[Yow Ling]

If you replicated one cylinder of a modern 600, your 150 single has the potential of about 30hp at a push. wouldn't that be cool.

I wish I had the time and money to do it now!

Fuel injection dosent give you any more power than a well tuned carb, possibly better emissions control, the reason we dont have 30 hp fxrs or cbrs is a 150 has to push all the losses that are normally shared by 4 cylinders, oil pump, generator etc, also fxrs dont really have optimised inlet and exhaust tracts , fairly basic ignitions , cast iron liners etc etc

[Bren_chch]

cast iron liners etc etc


OH the dark ages!!! i seen some alloy ones coated ya know! :innocent: