Anyone have any experience or knowledge of these?

not of that kit. it looks like a very nice one and Fun N Fast made a lot of accessories for various bikes back in the day.

I only played around with the Trickit fork kit and those do work good. I have one of those in a 1975 DT400 which needs help in the suspension department.

the price is not bad and if I had the money, I would jump on it. it is a kit for the 1971 DT1 and RT1 but it may fit the 1972-1973 versions of those bikes but there is no guarantee. they used forks similar to the 1971 versions.

Thanks for the info. Do you have any instructions or literature?

I bought a NOS set in excellent condition on eBay last week for the '71 models, I have several '71 and '73 DT/RT Enduros plus extra forks I'm rebuilding and reconditioning. I've found the '71 and '73 forks are the same. This kit will go on a '73 RT3.

sorry, don't have any more info on that. the others here are some long time Yamaha Enduro owners and owned these bikes when they were brand new. I have no literature on them either and the magazines I saw their adds in are long gone.

Morning…
I have also bought a set of these …. The seller cut me a deal and was a good guy.

I have tried to fit these to a 69/70 set of DT1 forks and I can’t  seem to make them work …. I end up shortening the fork/fork travel so must be doing something wrong or they are for a later version fork ….

I have to compress the bottom tube over the inner to get the bottom bolt hole to reach the Allen key bolt fixing at the bottom of the outer tube …..

Any ideas????

Cheers
T1

Blimey, that's a hell of a long topping out spring. Does it go there or does it go in place of the spacer on top of the fork compression spring. Looks like you'd loose travel by quite a bit if they go where shown. Maybe that's the Trickit Trick Bit. I see its Fun'nFast not trickit. I had one like that on my PE250 forks which was an original topping spring but had about 12 inches of travel to play with.

I think
/assume they replace the stock part in the lower tube on the basis there is a bottom alu cone which has a thread and the top fitting is machined to take the long spring ….
it’s odd but it compresses the fork ….. I must be maki g a mistake…..

cheers
T1   

Forks on the '69-'70 are different from the forks on the '71-'73.

Over recent years I've seen a few of these kits pop up .
There was one kit for 70 DT1 C and another for 71 DT1 E .
Whilst the 70 kit may fit a DT1 C , I'm a bit wary of it fitting earlier DT1's .
The 70 had a top out spring , ( as did 69 1/2 DT1 S ) but the earlier DT1's didn't .
As RT 325 has already noted , the original top out spring was considerably shorter
than your kit spring . That could be the source of your problem .
I'd be tempted to try and replace the kit spring with a stock spring .
I did buy one too , and was a bit surprised there were no instructions included .
If you do sort it out , please post your result . I'd be interested in your findings .

 

At  a guess - I'm with RT325 in that the spring replaces the spacer as a "booster spring".

Attached is a screenshot with some input from enduronut (saved earlier) from a previous post regarding booster springs.

I have one of these kits - also have booster springs, and the springs in this kit are very close in size to the booster springs (happy to measure over the next few days). I have not looked at it in detail but hope to be over the coming months.

Please let me know if you can't read it as the resolution might be too low