How to hot up my Bucket?

[woodyracer]

FXR rims might work but aren't really wide enough, especially the rear, and with a the single side rear swingarm I doubt you could adapt one on easily, and I would think the stock rear rim would be to narrow unless you run a front slick on the rear

my rims are pretty similar to a fxr {so thats a 110 back and 90 front} they arnt perfect but as long as you run high tire pressures they are good

[koba]

Haha, yes it did but either it has to much power or to many bolts fell out.

And yes i am running an Aprilia rs50 with the standard suspension and wheels, i have BT39ss on it and i could be looking for some cheap slicks...

Na mate, if they are standard rims your are probably about right with the BT39 SS, slicks go a funny shape when you squeeze them on rims that narrow.

My suggestion would be to get a few people who know there shit (not people who just think they do) to take it for a ride around the track and see what they think.
I don't know who would be up to that up your way, Paddy Doohan maybe?

[Tyler_94]

Yea, good idea. I think Paddy might have already been out on it. I might get a few apinions.

[NSR143]

They are 17" rims and they do take 125 GP size slicks and Tyler IS too fast already... he needs a pie belt and a six pack or swappa crate strapped to him so I can get back in touch with the Firn Boys.!! The only time i get points out of these guys is when... parts fall off.

[Kickaha]

They are 17" rims and they do take 125 GP size slicks .

There's a difference between "taking 125GP slicks" and actually having the correct rim widths so those tyres work correctly

The only RS50 I have seen had a 16 inch front

[F5 Dave]

This was teh bike Lodge(?) built with Hamish's old RS50. It is a later model with the double sided swing arm & 17s both ends.

[SS90]

This was teh bike Lodge(?) built with Hamish's old RS50. It is a later model with the double sided swing arm & 17s both ends.

Yea, the later ones (96 I think) and up had 17in front and rear.

[koba]

Yea, good idea. I think Paddy might have already been out on it. I might get a few apinions.

Get as many as you can, but don't follow them blindly.

[Tyler_94]

Yes it is the one that Lodge had, but i think he probably rode it a little better than me.

yea its got the double swing arm and both front and rear have 17"s.

Its 1999

[koba]

One thing that might be worth looking at on the engine is the Cam Timing.
Often manufacturing tolerances mean it's not quite optimal, plus the factory probably don't set them up for best performance.
You will probably gain a fair ammount of grunt advancing the cam a bit, it's somthing you either need to read up heaps on or get someone to help you as it requires slotting the cam gears. If you get it wrong it can destroy your engine too.
It may have been done if someone else built the bike.

[TZ350]

The closing point of the inlet valve has more effect on power than the opening point.

Back in the day when I played with fast 4-strokes the hot set up on dragsters was to have a retarding cam and you could buy a kit for it, or make your own. The object was to retard the inlet closing point as the rev's went up for more top end power and advance the closing point for low end grunt. Now there are modern performance cars with "Variable Cam Timing" controlled by the engine management system and oil pressure.

Interesting pics here:- http://www.2carpros.com/how_does_it_...cam_timing.htm

The inlet cam is retarded for top end power........the reason for holding the inlet valve open later past bottom dead center is because of the inertia of the gas column in the inlet tract. Air has weight! and the rapidly moving column can stack more air into the cylinder at higher rpm, so they hold the door open for longer past bottom dead center to allow the cylinder to be over filled.

At lower rpm the air column is moving slower and has less inertia to pack the cylinder so the door needs to be shut earlier to stop any extra air that’s entered the cylinder from backflowing out. The inertia of the air column will keep packing air in even as the piston is rising, up to a point, the trick is to find the right time to close the inlet valve.

[koba]

Ok, after this weekend I'm convinced you would benefit from more power.
Those slicks will prob help too.

I suggest you read up as much as you can about how to make things go faster, there are quite a few good books around.

Here is one:
http://www.scribd.com/doc/11433843/4...heory-Practice
An old version of a good book. I recommend trying to get the current edition, have a look around and see if you can find it cheap, maybe second hand, If not I can get you a copy but it's quite pricey.

[koba]

The closing point of the inlet valve has more effect on power than the opening point.

Back in the day when I played with fast 4-strokes the hot set up on dragsters was to have a retarding cam and you could buy a kit for it, or make your own. The object was to retard the inlet closing point as the rev's went up for more top end power and advance the closing point for low end grunt.

Yep, but top and power at the expense of a punchy midrange isn't really what I would wan't on Roys Hill...

Variable Valve timing on a bucket would be the shizz...

[koba]

I had another thought today, Did you have an air filter on it?
I should have looked. I didn't hear much induction noise.
I have seen lots of loncins with those little air filters on them, the ones that look like V8 rocker cover breathers...
I don't know for sure but I would bet they are restrictive as.

Maybe experimenting with bellmouths and/or an open carb is worthwhile.
Make sure shit isn't going to get flicked off the back wheel and into the carb tho.
If you wan't to run a filter (prob a good idea as I imagine it gets dusty up there in summer) maybe try making somthing with heaps more area, maybe somthing like an RG150 airbox and filter...
Some bike shops sell the foam stuff that is petrol resistant and you can cut it to shape.

You can even gain power in different rev ranges by mucking about with the volume and inlet lengths and sizes on the inlet. Its a nice cheap and easy aspect to play with, you could build a fibreglass airbox or just find some old plastic bxes or somthing and get creative with the hot glue gun to start with.

There is heaps of info on the net about airbox tuning, also have a look in the ESE thread as they are paying with it on their GP125s at the moment, there are some great links.

[Kendog]

I have seen lots of loncins with those little air filters on them, the ones that look like V8 rocker cover breathers...
I don't know for sure but I would bet they are restrictive as.

I had one of those filters on mine at the start, but got rid of it as it was too restrictive.
Ran open from then on with a full cover just in front of the rear wheel to stop road shit being flicked up into it.