Rear Shock: What will really fit ?????

Ok, so after much thread searching and reading pages of non-definitive descriptions this is what I've come up with.

1. 400ex shock - will fit with the help of bushings (Ken O' Connor makes the best) and bottom drilled without modification of frame or stock airbox

2. 450r shock - will fit with bushings and bottom drilled must cut fender tab and stock airbox will rub without modification.

3. YFZ450 - pre 09 will fit with custom bushings (not sure about kens) and bottom drilled and reshaped ... lifts rear so re-spring is suggested. Will not work with certain pipes due to the reservoir.

4. TRX 250r and ATC250R Shock - Now this is the best from the look of the shock due to the remote reservoir. The link describing the year (due to length differences and mounting has disappeared so I am wondering the one link I found said 86 and after only???? And there was another thread stating the top of the shock needed to have the width shortened????

If someone could please answer definitively what year and what modification needs done to the 250r/atc shock that would be awesome and any other shock that works and how.

This is for the forum, but also for myself as I am planning on switching. If you do not know please do not answer with you think this or that will work or you will report back as this is what has junked up the other threads on the topic

EYE to EYE lengths would be helpful as well

awk08 said:

i have a trx 250r shock on my sons bike, rides like a dream !!!!!
i believe the ebay ad said it was an 87 ????
with my sons +4 swinger, it raised the assend almost 6 inches, being his was a homebrew extended swinger, it still had the old stock mount, and the new one the builder made, i had to weld 2 rails between the 2, then drilled it for the slightly higher than stock height i wanted, i believe i moved it back 1 1/2" from the homebrew mount

i also had to grind the sleeve that sticks out on both sides for it to fit between the upper mount, then used kens bushings installed on the outsides of the mount, to reduce the bolt diameter to the new shocks upper mount, so the bolt is the same size as kens bushings for all 3...400ex, the 450r i had on my bike, and this trx250r shocks

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@AWK - Do you happen to know whether the ATC is a Showa brand shock?

tyler1blaster said:

I ran an atc250r rear shock and i didnt really notice a huge difference... Mine fit without any mods...

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Not starting an argument so no response is needed but your wrong and maybe yours was modded, but I x2 on what AWK said about the ATC im looking at one in my hands now and know the top bolt and size is not direct and needs modded.


Regardless, I am going to use the info to do a complete write-up someone already opened up another thread on the topic and I plan on combining all So any info (correct), pictures if you can take them and measurements eye to eye will be helpful for the end thread

85-86 ATC is 16.38 eye to eye 87-88 is slightly shorter and the 89 is even shorter still. Still researching so will update as I get info.

BLASTER---Rear stock shock. Shaft-mounted jam nut style preload adjustment only. Eye-to-eye length, 15". Main shaft diameter, 12mm. Travel to bumpstop 1 7/8"(*) Progressive spring. Spring installed height, 9 1/4". Spring free length, 9 3/4". Wire size, 11mm. Bottom eye, 12mm, rubber bushing, no seals. Top eye, 14mm, rubber bushing, no seals.


BANSHEE---Rear Stock shock. Reservoir type. Preload, rebound, compression adjustable. Eye-to-eye length, 13 7/8". Main shaft diameter, 14mm. Trvel to bumpstop, 2 3/4"(*) Spring installed height, 9" (midpoint of preload). Spring free length, 9 1/2". Straight-wound spring (non-progressive). Wire size, 10mm. Bottom eye, 12mm, Heim type. Top eye, 12mm, Heim type.

Triplecrown421 said:

i put a 400z rear shock on my blaster and took about an hour all i needed to do was use smaller bolts on top and bottom cuz thats what the 400z uses then just drill the threats out of four extra nuts that fit those bolts, then spin the nuts on the grinder till there the size to fit into the blasters shock mounting holes. should use bolts with threads at the end so the nuts slid easy and tight. its nice cuz the shocks fully adjustable and is very worth doing. i think it added an inch to height. cost me 50 bucks

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Thanks for adding, that is good to know ... I'm trying to compile as much information and what the modding process is for fitting different possible shocks

Honda TRX 450r 04-05 is 14.75 inches eye to eye which makes it slightly shorter than the stock blaster rear
Honda TRX 450r 06+ is 15.125 inches long eye to eye which makes it the better choice if choosing a 450 shock.

Honda 400ex is 15.5 eye to eye.

All the stock honda shocks are made by Showa and have slight adjustment in length. I found recently that if searching for an aftermarket rear shock you can find a much better deal on a 400ex AM rear than a Blaster AM rear. Recently, their were two Works Supercross Rear Shocks with rezzy for the 400ex on ebay with starting bids of 145$ NEW. I was able to pick one up with no competing bidders for that price (yes thats right a 400ex brand new works with rezzy for 145$). The other went unsold. They were close out shocks so I had it sent directly to works for them to revalve it for my application which is 125$ plus 18$ for kens bushings which I still need to get, but when said and done, that is a Brand New reworked Works rear shock for 288$ set up by Works ... The comparable Blaster rear Works with Rezzy (A-T Steeler) is 759$. Although deals are not like this all the time, I have found it is monetarily easier to find AM 400ex or 450r rear shocks than an AM Blaster rear shock.

With the differing lengths in the ATC shocks between years and models I have decided that although they work with modding they are not the best alternative IMO.

So the verdict on the YFZ rear goes like this ... The top will work with Kan's Bushings ... the bottom needs drilled to match and the ends need reshaped. Mine was an 08 rear which was the last year to not have a bottom mount that matches the top. To get mine to work it was re-valved/shaft shortened and dual springed. Off the quad it sat an inch longer than a stock blaster shock but on the quad at it's lowest adjustablility setting it sags to the stock blaster height. I then adjusted it for greater clearance.

The YFZ was also different lengths. Since the 09+ has a matching top and bottom mount it would need custom bushings for the bottom as well so is not a choice for the blaster you would want to make unless you can machine bushings. Really though unless you are planning onrelocating you rear mounting point or shortening the shaft as was done to mine I would not choose it just for length.

04-05 YFZ450 Rear Shock Length is 18.5 eye to eye
06-08 YFZ450 Rear Shock Length is 19.25 eye to eye
09+ is 10mm longer than the 06-08 eye to eye

The YFZ has one more problem as well and that is the right sitting (from back) reservoir. It does not get in the way of the stock or AM airboxes or the fender mount however it does interfere with the routing of some pipes. Namely the dynoport. From what I have determined, all the left bend pipes will route fine. If anyone is running one with a power pros (trinity/F7/etc.) chime In on whether it clears or not.

Ok, so next option is the KFX450 Rear I do not have experience with this shock but it is also a Showa made shock it is 17 3/8 inches long so I do not think it would be a good option either.