RZ/RD 350 & Misc. 2-Stroke Tech BBS

Here are a few photos of what was cut off. A little more of the eyelet was ground off than is shown. Only 7mm of threads were left to screw into. The bottom 10mm of the hole was left without threads by KYB. The welds are far stronger than the threaded eyelet and nut, stock.

The first part of the hole needed to beveled to get the eyelet closer to the shock body and make the length worth the extra expense. The first shock body was cut 5mm. This one was cut 12mm including the width of the saw blade.

I was giving my bike a good clean and ended up stripping it to the bare frame, so I took the opportunity to measure the '02 R6 shock I put in about 15 years ago. It is 306mm free length and has a spring rate of 9.3 kg/mm. I am about 60 lbs heavier than you but was also 35 odd pounds lighter when I did this swap and I found the extra rear ride height beneficial even back then. I don't disagree with what you are doing, although I think someone a bit heavier might want to start by just shortening it up to around 300/305 and give it a try, makes for an easier job and removes the risk of heat damage from welding. If I can find a good deal on one of these I will give it a try.
Looking forward to your riding impressions.

Ruzty,

You are right about the R6 shock. The extra length worked great for you and many others. I could not find a R6 shock that did not look hammered at the time I found these shocks. Now I have 2 different lengths to try. One problem is this bike only has a center stand only so the tire being close to the ground is a problem. I know the stock geometry was spot on way back in the 20th century too.... I am hoping for some testing in about 10 days if there are no more parts delays!!

If you have one left over that still has thread left for the bottom eye and want to recover some of your costs let me know.

nice work

This requires 0 frame mods, is that correct?

The only frame mod is the battery bracket just above the reservoir that is close. I bent the end of it up slightly but even without bending it there was no contact with the reservoir. I even put my finger between the two and pushed down on the bike slowly. I could feel the res move slightly. The bracket has a lip turned down on the end and needed to be bent up flat with the rest of the bracket.

I am hoping in a few weeks to finish the bike up. I went through the engine and a few tiny issues need to be addressed. I wanted to go through all of this bike thoroughly anyway. Once my other project, the Honda RC26 was rideable last year, the RZ350 got less attention until wintertime. It was my first summer riding a street bike again in 15 years and it was way good!! The street glacier out front needs to melts soon also. Ed

There are 18" radials available for the RZ now. Look into it.

Thanks! I already have new BT45's on the bike. Only a front 18" was available, a Bridgestone, no rear. I will need a wider rear wheel for anything else so far. Any suggestion? Ed

The material of the eyelet is heat treatable aluminum. It is sold to the shock manufacturer at T6 temper (max strength). Applying TIG welding heat reduces the strength to about 60% of T6, which can lead to premature failure due to fatigue, particularly if the rebound damping is set to hard. I would not do this on my bike.

Sorry for the spoiler, but a catastrophic failure here will be at least expensive, if not dangerous.

Alex, Thanks for bringing this up about aluminum welding and I know you are thinking about our safety!!! I hope you are right about this being T6. Last year when we were building this I was worried about this being T7075 which most T7 is not weldable. However T6 is welded every day. It is using the correct filler rod that is important here. A filler rod in high silicon or magnesium is needed to make the weld strong. Aluminum is not like welding steel and is crack prone. Most shock eyelets on steel shocks ARE welded. This eyelet is also threaded in which helps.

Really the best way to shorten this shock and not butcher it like I have done is to send it to a suspension shop and have it shortened internally. This was brought up earlier by another member that is in the know!! Hey it is only money to burn!! The only other route for these bikes is Ohlin$$ or Wilber$$. And the price is SHOCKING!!

I must say I was disappointed in KYB for not threading the eyelet all the way down to the bottom making for 10mm extra of threads which I would have avoided and welding and just epoxied or Loctite it in and tightened the nut down. It would have been way secured. Ed

Besides the bushings was there anything else required to bolt this shock in? Do you have to remove the swingarm to get to the shock?

I just purchased a 2015 R1 shock. I need to get the bushings now.

The only other route for these bikes is Ohlin$$ or Wilber$$. And the price is SHOCKING!!

There are many choices for shocks for the RZ on the market, certainly not limited to the two listed above, while expensive the shock prices are expected & normal.

Questo vecchio rz wrote:There are many choices for shocks for the RZ on the market, certainly not limited to the two listed above, while expensive the shock prices are expected & normal.

What is unexpected is how cheap these '15-'17 R1 shocks are.

Nice used ones run about $100 usd.

This shock slips in without swing-arm removal with the stock swing-arm or the Ken Brumm swing arm the shock is mounted to currently. You might want to wrap this shock spring lightly with something as the paint scratches easily. There are many new R1 shock on Ebay that look like it came right from the factory for $100. Yes just bushings.

A few months ago I picked up another one to have Race Tech internally shorten it and re-valve it. I was hoping Race Tech would have developed a Gold Valve kit by now for it but when I checked last week, none yet. They are very busy with many other shocks at the moment. Ed