PDA

View Full Version : FZR250 bucket suspension



speedpro
8th February 2008, 12:17
Little help and advice please. I’m putting together a FZR250 (3LN) chassis as a bucket. The front forks have about 150mm travel which is lots more than another bucket I rode in the weekend that handled superbly. Question is, should I restrict the travel to say about 75mm whilst I have the forks in pieces and, apart from fitting emulators, is there any other mods that would be worth doing? I was thinking of fitting say a 75mm spacer over the top-out spring and cutting a similar amount from the main spring preload spacer. I’m running 3LN wheels front and rear, 2.75” and 3.5” with a single large disc off the earlier model with a late model 4 pot calliper and slicks both ends.

Any thoughts on the rear shock would be appreciated as well. Stock currently but with the major weight reduction not right I would think.

F5 Dave
8th February 2008, 16:50
I would have thought 90mm would be about right, it is a bigger bike, might need a touch more travel. Also look very carefully at the bottoming cones. Shorter travel is going to end up there. Some mod by drilling 1/2 way to reduce the effect till later. Some fit bottoming springs. But there are other alternatives.

Typically yams are very softly sprung. Yours will be considerably lighter than stock though so will have to trial fork travel.

Slingshot
8th February 2008, 16:57
Typically yams are very softly sprung. Yours will be considerably lighter than stock though so will have to trial fork travel.

I'm not sure that stuffing the forks with yams is appropriate, they'll rot pretty quickly which will probably give you too much travel.

F5 Dave
8th February 2008, 17:01
I was being fa-sea-fish.

Yams are out of season.

Maybe parsnip?

diesel pig
8th February 2008, 22:09
I agreed with F5, 90mm would be better. Early RS125 have 90mm fork travel and they are the sweetest handling small bike I have ridden. A other thing to keep in mind is removing coils from a spring rises the spring rate, making the spring firmer.

speedpro
13th February 2008, 21:44
Progress at last, straight triple clamps, straight forks assembled with the more desireable damper rods, springs and spacers. A wheel that fits and matches the rear one with a decent size disc and RS125 brake master cylinder and caliper. Specs - 2.75 X 17 FZR wheel, 320mm disc, and RS brakes.

Motor in next.

Ivan
13th February 2008, 22:16
I spots me a RS125 in your picture under blanky

F5 Dave
14th February 2008, 08:28
& a KX . . .

Ivan
14th February 2008, 17:32
Not under the Blanky tho

F5 Dave
15th February 2008, 08:41
no kidding, the RS has stayed a night or so in my lockup, but I thought the KX was interesting. Time to become an MX dad huh Mike?

speedpro
15th February 2008, 19:27
We're working on it. PW50 to KX80. Had 2 little plays at the beach and he's changing gears nicely and riding in the power. Need to find a nice grassy paddock to play in for a bit more practice and then off to the forest. I need to sort something to follow him around.

Buddha#81
15th February 2008, 20:10
We're working on it. PW50 to KX80. Had 2 little plays at the beach and he's changing gears nicely and riding in the power. Need to find a nice grassy paddock to play in for a bit more practice and then off to the forest. I need to sort something to follow him around.

This sould keep up with the little buggar http://www.trademe.co.nz/Trade-Me-Motors/Motorbikes/Motorbikes/Classic-vintage/auction-140620232.htm

speedpro
3rd March 2008, 19:25
Progress is being made. Motor is transplanted and all connected - throttle, clutch, chain, and ignition. Rear tyre is fitted and just pricing up new (probably) Bridgestone slick for the front. Will probably run with the steel rear subframe to start but it's definitely being replaced with something lighter. The pipe isn't properly mounted yet but it's close. As soon as RT gives me a price I'm ordering emulators for it. Some sort of fuel container is the only bit left to sort out that I'm not sure what I'll do yet..

F5 Dave
4th March 2008, 08:17
Hmm, maybe some sort of faux engine subframe or full fairings may make the engine look a little less dwarfed?

speedpro
4th March 2008, 08:23
or cutting 200mm from the chassis length - I have plans, eventually. Plus I have the budget now that the wife has gone and blown $530 on girl stuff

koba
4th March 2008, 09:40
Have any of you guys using the ZXR250 frames weighed them?
Im kinda curious to see how much they weigh.
And why the ZXR? availability? weight? Size? Price?
It just seems that is is the most commonly used alloy frame for buckets....

Edit: Im bloody stupid, I now read it again and see FZR. dummy! Sytill interested in the weight tho, mainly wanna see how it compares to a MC18 NSR250 frame I'm considering hacking up.

speedpro
4th March 2008, 19:31
I just weighed the new bucket on bathroom scales. It was as per the previous photo and description. 38Kg front and 40Kg rear with the steel subframe and 37Kg without. Not as bad as I thought it might be and still has sidestand and bracket, but no tank.

gav
4th March 2008, 19:55
Do you have any bodywork with that FZR? You seen this?
http://www.trademe.co.nz/Browse/Listing.aspx?id=143150942
Or to flash for you? :innocent:

F5 Dave
5th March 2008, 08:58
are you saying that subframe was only 3kilos? would have guessed 5 at a min, looks enormously heavy. what does it weigh by itself?
Still best place to lose weight (ok after unsprung) is at a bikes extremities & high up.

But yeah not too heavy after all.

bungbung
5th March 2008, 10:23
Interesting, I'll have to weigh the tzr145.
F5 Daves old H with the Pie mods has a bathroom scale total of 61kg wet.

speedpro
5th March 2008, 10:31
Interesting, I'll have to weigh the tzr145.
F5 Daves old H with the Pie mods has a bathroom scale total of 61kg wet.

61Kg is bloody good, "old #6" was 70Kg with 1/2 tank gas and I thought that was OK. Got my new Bridgestone (soft) slick today and the emulators are on the way. If this front end doesn't stick it won't be for lack of trying.

F5 Dave
5th March 2008, 10:31
And on the same scales you weigh 70 kilos?:whistle:


I think it was in the high 70s when I had it. - Mind you I can't remember when I weighed it how much gas it had, but wouldn't make that much diff. That old seat was heavy. But it sure was comfortable.

You must use 2 sets of scales or one set with the other wheel raised the same height.

Used the Auckland &/0r Taumarunui kart scales.

speedpro
5th March 2008, 10:32
what does it weigh by itself?

40 - 37 = ?????

F5 Dave
5th March 2008, 10:34
Yeah I did say 3kg, just I like to weigh stuff individually as well when comparing, just hard to believe only 3kg.

bungbung
5th March 2008, 10:37
And on the same scales you weigh 70 kilos?:whistle:


I think it was in the high 70s when I had it. - Mind you I can't remember when I weighed it how much gas it had, but wouldn't make that much diff. That old seat was heavy. But it sure was comfortable.

You must use 2 sets of scales or one set with the other wheel raised the same height.

Used the Auckland &/0r Taumarunui kart scales.

I will use the same scales and technique for the tzr and report back.
I agree 61kg sounds pretty light, these are nasty scales though.

speedpro
5th March 2008, 11:09
I will use the same scales and technique for the tzr and report back.
I agree 61kg sounds pretty light, these are nasty scales though.

You should be able to sell the scales to some fat chick

F5 Dave
5th March 2008, 11:23
probably make them that way, perhaps they've worked out people are more likely to buy flattering scales than the truthful ones?

Pickle
7th March 2008, 20:17
Still looks like an overweight slow pig to me & I know a slow overweight pig when I see one, just need someone decent to ride it really.