xr70 to ultimate all around motorcycle

[demidestructo]

I talked to a guy and he said to use xr80 dampening rods in the xr70 forks. I want the extra height of the xr80 forks.I was thinking of getting a set of xr80 forks and putting in the extra firm springs for the xr70. Then pvc spacer to fill the slack and fill with atf.

This would save some cash but I would not have disk brakes, if I swap in a set of piranha forks. The xr80 forks are said to be every bit as good as fastace or martzoti, or any of the 900 dollar forks, and then changing the top mount for the rear shock so I can use the cr80r shock. So Really it will be like a cr80r except .

My pitbike will weight 120 pounds vs 143.

my pitbike will make 20+hp ( 150cc makes 14.6 with 28mm mikuni,now I will be buying the race head v2 package which includes bigger valves 30mm intake vs 27mm 25mm vs 23mm, bigger longer duration higher lift cam, roller tip rockers, and big bore with forged 10-5-1 comp piston, Im going to have it ported and polished as well) . A cr80r makes 20.7 hp on the pipe.

I want to run 17 /14 on this so it will be more stable and taller,or 14/14 would be fine .I plan on using aluminum wheels so I can jump it.

I am still deciding on which to use drums or disc brakes ,I think drums will be fine for this because ,I can go through mud without worry .

thinking of 16 front and 42 rear for a 2.58 ratio .

[demidestructo]

Ok a lot has changed . I can't find a race head for the piranha 150 so I think I will just buy a cam and port and polish the head with a valve job. I put the swingarm on and the cr80r showa shock with it. I will take it to my friends house tommarow to weld a new mount position for the shock mount. I bought heavy duty springs for the 70 forks. I talked to a guy that rebuilds suspension from race-tech and he told me how to build forks to ride just like those expensive forks and keep my drum brakes. He told me that he has a pitbike and he did the same to his and he said you can't beat them price and durabilty of stock fork but able to adjust for weight and performance .I said yes please. So I will build them tommarow he told me they will be a inch and a half taller. I dont think I will need to buy the xr80 forks. Plus I red horror stories of people having big trouble finding a top clamp that will work .I know the one that will work is 125. We will see motor about ready to go before any performance work is to be done I will get it running.

[Weldangrind]

That bike is gonna be awesome!

I had an idea about the upper shock linkage. The Kawasaki ZR6 shock uses an upper link (in the later models), and perhaps you could fabricate and adapt a similar link to your Honda, rather than welding on a new mount.

Picture the link in the attached picture turned 90 degrees towards the existing mount. Maybe you could make something similar that allows you to simply bolt in. You'd need to secure your fabricated link in two places, so it wouldn't move. The stock bolt location is one, and then perhaps you could drill another hole for a second bolt.

[Weldangrind]

I looked at your pics again, and spotted an existing hole. With a U-shaped bracket that captures the original shock bolt hole plus the hole in the picture below, you could drill a third hole to mount your new shock. That would allow you to make the U-shaped bracket as long as you need to for good suspension geometry.

[demidestructo]

GREAT IDEA Weld , sometimes it takes another eye to make things work. I never thought of that. I'm going to go buy some exhaust clamps to see if I can get close and then make a good bracket to finish it. Thanks again bud

[Weldangrind]

If it projects through the seat (and your man bits) after your first jump, I take no responsibility.

[demidestructo]

I'm not planning on having children anyway but it will be fine . LOL I'm thinking of a hybrid of our ideas. I want to be able to have a pin I can pull out to change how much travel will be allowed.For road courses I will use positions 1 and 2 , then for trails and jumps maximum travel will be allowed in positions 3 and 4. That plus the rebound and compression tuning of the shock should allow me to tune it in for different types of racing.

[Weldangrind]

This is gonna be a fun project to follow!

[demidestructo]

I picked this up I think it will make life easier http://www.amazon.com/gp/product/B00...ilpage_o03_s00. Hope it shows up what o you think?

[Weldangrind]

That could be an excellent solution! I'm looking forward to the installation.

[demidestructo]

Here we are I decided that aluminum piece would be weak and might break so I welded a bracket in. It works amazing , you will not believe the amount of travel with this setup! That shock was more than I thought it is nitrogen assisted by air . I fooled with the shocks setting and I can literally jump up and down on the bike. It feels great my friend and I couldn't bottom out that shock and were strong dudes. It sits very high in the back and you can't even see the mod. It looks stock!!!! I can't use xr70 forks ,so I bought xr80 forks and top clamp and I will take the dampening rods out of the xr70 and use them with spacers with those trick fork springs. Man I am so excited ,this is my first time changing the suspension and it went great!

[demidestructo]

How do you measure travel in the rear?

[Weldangrind]

The best way to measure travel is to remove the spring from the shock, install the shock and then cycle the rear up and down. That will indicate more travel than actual, but it'll give you an idea.

I recommend that you weld in another piece of square tube as a gusset, like the black line I inserted in your pic.

[demidestructo]

Im sorry my fault the picture is a before pic ,the bar that was welded is even with the bar that crosses it now.

[Weldangrind]

May we see the finished product?