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Hurky's gen3 CR250

Posted: May 12th, 2020, 2:57 am
by hurky
Hi there, hope you're well.

We are in lockdown in Spain since more than 8 weeks (they are relaxing things now..) so I finally got some time to work at the project.
Motor was placed in the frame and I installed the MSV manifold and the DEP pipe. I removed the springs from the forks and installed them in the triple clamps to simulate full travel situations. I had a few used tires laying around and picked up the one with the narrowest height, a Mitas C19 in 90/90-21:

Image

This is at full travel with the knobbie just about to touch the spring bracket, If I slightly turn the front tire to the right it is also almost touching the pipe elbow. Pretty close but should be fine like that, BUT, this is a used tire, a new one would have like 2mm larger knobbies and it would rub.

I am no crosser and I rarely bottom the suspensions on my bike but it can eventually happen on a bad jump , is a little interference like that acceptable or is that already dangerous like the tire could get rammed in the compressed position ? I really don't think so and it would just mark the plating on the pipe over time. Not much I could do about the elbow interference but I could easily move the spring braked so it does not touch anymore, maybe moving it to the front and using shorter springs ... Well, maybe it's even enough to just bend the braked a few degrees towards the front to make just a little more room...

What do you guys think ?

Cheers :wink:

Re: Hurky's gen3 CR250

Posted: June 27th, 2020, 11:48 pm
by DEATH_INC.
You'll definitely get rub, there's gonna be some fork flex too. It shouldn't be dangerous, I've seen it on heaps of stuff over the years. Maybe a different pipe?

Re: Hurky's gen3 CR250

Posted: July 4th, 2020, 2:01 pm
by Kuma
I don't think it would be an issue but you could possible have the manifold cut down to 1/2 the thickness or use the stock steel manifold, either way you should be able to make 3-5 mm more clearance.

not a lot of traffic on this site anymore, hope if remains there is a ton of info and it would be a shame to lose it. I sadly grew too old for my bike, too hard on my knees and had to sell, still occasionally stop be to see if anything is happening.

Re: Hurky's gen3 CR250

Posted: November 11th, 2020, 9:36 am
by hurky
hurky wrote: May 12th, 2020, 2:57 am ...maybe it's even enough to just bend the braked a few degrees towards the front to make just a little more room...
Thank you very much for the replies, I did not even notice until now, this forum doesn't seem to send notifications over email...

I did bend the bracket just a bit and it's OK like that I hope, but the entire project did not really move much since May, :twisted: I don't have much time to work on it, and sometimes I like motivation as well, but I am getting closer to be ready to weld the chassis.

I need to make some decisions regarding exhaust/silencer brackets,
For the gen3 AF's out there, do you have any pics on the silencer / exhaust area ? I would like to get some ideas on the lower front pipe mount, I am using a CP500 'Y' and not sure if I will weld it on the frame rails what would leave the support pretty low and probably a little too exposed to rocks etc, or to actually weld it on the 'Y' itself which would turn it up and be in a stealth position, but I don't really like to weld on the Y part itself...
Also, what did you do on the upmost rear silencer mount ? My DEP is pretty large and that support is more or less aligning well with the rear fender bolt.

Cheers !