fork question 89 fzr 400/yzf600 motor

[gussy]

Help Need some advice My new fzr 400 has a thundercat motor the forks now bottom out on the fan and the blue dot calipers are on the single pistion 38 mm forks with home made adaptors.
I got a line on some 2003 yzf 600r forks depending on the price will this year bolt right up to my 89 fzr 400Or would I be better off poping in 38 mm fzr 600 dual pistion forks? I need a new back 18 inch tire
Sould I go for the whole shabang and p/u the complete front end and the rear end with the shock and swinger and 17 "? and sell off my parts.
what do you guys think I'll be riding on the street and going for some hwy trips.
cheers gus

[blensen]

I can't say for sure if the yzf forks will fit, but if you decide you want a set of fzr600 forks I have a set for sale. Pm me for details.

[thatkid]

Gus, the forks should be a direct bolt in. Just make sure to get everything for the front end. As for the rear, it's up to you as far as what your level of fab skills are. The swinger isn't a direct swap so you will have some machining to do or have done.

If it's all a good price though, I say why not?

[gussy]

thanks for the replies

[RoadDogma]

A YZF front end will bolt up with little drama. Like TK said swap over the complete front-end. The YZF forks are a big improvement over stock, but will result in 5mm less fork offset. As long as you stick with the 60 series tire, geometry will be more or less the same as the FZR. Swapping the rearend will add weight and wheelbase which pretty much negates the 400s advantage over it's larger counterparts.

[gussy]

Thanks for the info . Maybe I should go for newer fzr 600 forks?

[RoadDogma]

The YZF600 forks (cartridge dampers) a far superior to OEM FZR (damper rod) forks. You just need to pay attention to the changes in geometry. As long as you run the YZF spec 120/60-17 tire, the resulting trail will be mostly unchanged despite having less fork-offset. That said, you could put emulators and straight wound springs in the FZR600 forks, and get very good results that way, as well.

[gkotlin]

Are the forks actually bottomed? Meaning are they at the limit of travel? Or is the fan just hitting before the forks get all the way through their stroke?

If you're hitting the fan, try to move the fan? Find a lower profile fan?

If you put a heavier motor in the bike, you may need heavier springs. Do a sag setup on the bike and see where the numbers are at. This would be cheaper and easier then a whole new front end.

[RoadDogma]

I would think that the reported "bottoming" is due to interference with the radiator and not the fan, as the fan typically mounts behind the radiator. (The YZF radiator is a pretty tight fit in 400s with the YZF motor). Really needs to go "high and tight". The YZF600 fan is thinner than FZR, but a lower profile fan will allow the radiator to move back some. Some just do with out the fan altogether.

[yamaha_george]

Hi,
if you want to go and change the rear end to 17" I suggest you read up my web site stuff on doing just that.

http://www.saltmine.org.uk/fzr/swingarm.html

http://www.saltmine.org.uk/fzr/3tj-mod.html

to give you some idea of what can bolt straight into your 400 frame without any fabbing work or at least minimal work, the draw back is that you will have to source the bits in Europe as ONLY 1WG was ever imported legally in the US of A.

If you do decide to do that I am perfectly happy to help you source bits etc


EDITTED:-
Gussey where are you as I found something you may like on EBAY

[gussy]

thanks for keeping an eye out for me
Im located in vancouver bc canada
cheers gus

[yamaha_george]

thanks for keeping an eye out for me
Im located in vancouver bc canada
cheers gus

Gus,
take a look at:-

http://cgi.ebay.co.uk/YAMAHA-FZR-400-1W ... 3f05eac150

by the way that is NOT a1WG swing arm as you will see from:-


http://www.saltmine.org.uk/kgb/catalogue.html

about 1/3 way down the page

[RoadDogma]

Looks like a 1WG-Deltabox swingarm to me. Although 3EN2s came with those, 1990 U.S. 1WG models were equipped with this swingarm, as well. It is directly interchangeable with the earlier "box section" type. It will not help you to mount a 17" wheel anymore than the other 1WG swinger.

If that swingarm were from a 3TJ (as George may be suggesting) it would be a different story.

[yamaha_george]

Looks like a 1WG-Deltabox swingarm to me. Although 3EN2s came with those, 1990 U.S. 1WG models were equipped with this swingarm, as well. It is directly interchangeable with the earlier "box section" type. It will not help you to mount a 17" wheel anymore than the other 1WG swinger.

If that swingarm were from a 3TJ (as George may be suggesting) it would be a different story.

Hmm now that is interesting !WG in the UK it seems from enquiry only got that box section swing arm , our 3TJ (which is now mounted on my 600 so no room for error there as it is cast marked 3TJ) is what you describe as Delta box (where did that description come from since ) all FZR's are based on so called delta Box style frames.

ALL 400 & 600 swing arms have the same frame throat width of 220mm, the difference as I know (see pictures of my swing arm collection) is the axle diameter & length. The GOTCHA's of doing swaps are well documented on my site's FZR section.

[RoadDogma]

Umm. The swingarm pictured in the auction is commonly referred to as a "deltabox" swingarm to distinguish it from the other (1WG/3EN) swingarms and is so called because of it's constructions and the decal which reads "deltabox" found on the side. The only models I am aware to use this swingarm is the US 1990 1WG and 3EN2s.

The 3TJ swingwarm differs in that it is wider, cast around the pivot area where it bears the designation, "3TJ". The pivot axle is also a larger diameter, but I have measured the same length (pivot axle to wheel axle) on both swingarms.

Regarding the 17" wheel question, either of the 1WG swingers could accept a 17" wheel, but it would be easier with the 3TJ swingarm. Just run the 3TJ wheel.

Hope this clears any confusion.