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1 minute ago, Confederate said:

Was that rear shock designed to be run linkless?

Yes, It is from a KTM85SX PDS suspension. the spring rate was increased to accommodate fat boy stature.

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Today's progress, I painted the frame for test and finish fabrication purposes. Once the bike is tested, it will be powder coated. Rolling chassis is almost complete. Since the swingarm is the stock CRF230F upside down, it was necessary to move the chain guide mount, fabricate a brake stay for the KTM brake caliper, and drill some new mounting holes for the swingarm protector.

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Im trying to understand the point & benefit of replacing a shock and changing from the progressive action of pro link to a non progressive suspension and similarily the use of a 65 cc shock that will require revalving and capacity & travel specs over and above using a ktm exc  125/250 entire setup... im sure you could have made a 125/250 exc swing arm fit quite easily.... just my thoughts.... or was it u had a trashed 65 and thought of putting the parts to some use??

 

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Hondo, looks like we are on the same path. I found a NOS ohlins PDS Shock and then decided to try the 96 KTM swingarm that has the linkage mount through the swingarm vs top mount. I really reinforced the upper shock mount since it is a few inches longer than the stock mount. I have lots of KTM parts that I have collected over the years so that makes it economical for me, also these old KTM parts are dirt cheap. I set the rear up 1” higher than stock and I am going to use XR400 forks so I can match the height in front. That is the only complaint I have on my other modded 230 is the lower ground clearance, it has bit me a few times. This is a fun project and no big deal if it doesn’t work.  One question, what air filter and intake corrugated pipe are you using? I can’t seem to locate that pipe.

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My next project is to transplant a CRF230 engine into this KTM250 frame. Test fitting this 150F motor seems promising, the exhaust header is probably going to be an issue where it exits through the frame. I have a complete rolling chassis for an 06 250F.

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1 hour ago, mike levy said:

Im trying to understand the point & benefit of replacing a shock and changing from the progressive action of pro link to a non progressive suspension and similarily the use of a 65 cc shock that will require revalving and capacity & travel specs over and above using a ktm exc  125/250 entire setup... im sure you could have made a 125/250 exc swing arm fit quite easily.... just my thoughts.... or was it u had a trashed 65 and thought of putting the parts to some use??

 

Mike

Good questions. The suspension is actually 85SX components. I was looking to shave weight and utilize the KTM PDS style suspension. The valving really was no issue as I have a billion shims to choose from (atleast a few hundred to be honest). I could have used any rear suspension for that matter, however there were other factors. I wanted the lightest hubs possible, so based on a previous build by woodsryder I opted for the 85 hubs with freeride rims and spokes. therefore since the shock was part of the donor I modified it and the frame to work. And yes the affordability of the 85SX was due to the rest of it being roasted! 

All good points and had the gods of craigslist presented a different donor, who knows?

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1 hour ago, jeffrow68 said:

Hondo, looks like we are on the same path. I found a NOS ohlins PDS Shock and then decided to try the 96 KTM swingarm that has the linkage mount through the swingarm vs top mount. I really reinforced the upper shock mount since it is a few inches longer than the stock mount. I have lots of KTM parts that I have collected over the years so that makes it economical for me, also these old KTM parts are dirt cheap. I set the rear up 1” higher than stock and I am going to use XR400 forks so I can match the height in front. That is the only complaint I have on my other modded 230 is the lower ground clearance, it has bit me a few times. This is a fun project and no big deal if it doesn’t work.  One question, what air filter and intake corrugated pipe are you using? I can’t seem to locate that pipe.

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I like where you're going with this build. The air box was constructed from aluminum sheet metal. (3 attempts to get it right) the intake pipe is actually a pvc  turned down on the lathe to incorporate the flange. The airfilter is a 50mm X 110mm UNI air pod.

Keep up the awesome work and keep me posted.

Edited by hondahondo

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OK, sounds great and in your opinion , how does the action on the rear end performance wise compare.... im asking , as have a 250 exc and have prolink hondas as well.... ive got no gripe with either the hondas suspension  or my ktms..... and as  i understand the prolink  it realy is progressive over larger bumps and jumps, so if its a woods bike.. yes u would save weight by dumping the linkages /hubs etc... as your not really jumping the thing.... so the idea about this project was weight reduction and.... gaining a rear disk brake and improved suspension all round... nice project  I must say ....enjoy!

 

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Today's progress included, finish wiring, fit body work and confirm mounting tabs, paint swingarm and install new pivot bearings, bleed new stainless brake lines, and drink a lot of beer!

Next update reassemble engine with stroker crank and set sprocket alignment! Then comes the carb and intake manifold, any thoughts would be appreciated. 

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Hondo, a few more questions about your build.  I experimented with the upside down 230 swingarm bus wasn’t convinced that it was semmetrical, it seemed offset for the sprocket. Any issue here? The 230 piece is much lighter than the KTM I am using, so I really wanted to go this direction. Were you able to find a stiff enough spring for that 85 shock? I looked but didn’t see any available. The ohlins shock I am using is 1” shorter than the 85 shock and has several spring options since it was designed for a full size bike.

So you used PVC pipe to attach the carb to the filter? Please give a few specifics on this because I am struggling to make a fit-up.

How did you adapt a 20mm axle to the 230 swingarm?

i am assuming that is the KTM 85 forks, did you check clearance on the front wheel to frame?  I had this issue with the 150R forks on my other 230, it barely rubs now on full compression, not enough to affect safety. I remember woodsryder had this same problem. 

It is nice to have someone to bounce these ideas and issues around! Keep up the good work, Jeff 

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3 minutes ago, jeffrow68 said:

Hondo, a few more questions about your build.  I experimented with the upside down 230 swingarm bus wasn’t convinced that it was semmetrical, it seemed offset for the sprocket. Any issue here? The 230 piece is much lighter than the KTM I am using, so I really wanted to go this direction. Were you able to find a stiff enough spring for that 85 shock? I looked but didn’t see any available. The ohlins shock I am using is 1” shorter than the 85 shock and has several spring options since it was designed for a full size bike.

So you used PVC pipe to attach the carb to the filter? Please give a few specifics on this because I am struggling to make a fit-up.

How did you adapt a 20mm axle to the 230 swingarm?

i am assuming that is the KTM 85 forks, did you check clearance on the front wheel to frame?  I had this issue with the 150R forks on my other 230, it barely rubs now on full compression, not enough to affect safety. I remember woodsryder had this same problem. 

It is nice to have someone to bounce these ideas and issues around! Keep up the good work, Jeff 

jeffrow68

Yes, the sprocket alignment has to be adjusted. I will be doing that next, I have to cut spacers on the lathe for the rear sprocket. you're correct, I weighed three swingarms, and found the 230 just over 8#'s.

As far as the spring goes, I called Paul at race tech and gave him my estimated bike weight and he sent the spring. I will try and find the invoice with the spring rating on it.

I will take the airbox back apart and get some pics of the PVC flange, and how I made it airtight.

As far as the swingarm, I used the 16mm CRF axle, I changed bearings and seals, then machined spacers for the set up. the hardest part was machining the brake side spacer, as this had to step-up for the caliper mount. A lot of aluminum shavings were created on that!!!

Yes the 85 forks are being used. What I did was turn 2 steel collars to 25mm od (I think) and the id to match the KTM steering stem. Then I cut another aluminum spacer to drop the KTM steering stem 10mm. This was installed under the lower bearing, giving me the clearance for the 21" front wheel.

I spoke to Doug before I started, He was a wealth of knowledge on what to do, and more importantly, WHAT NOT TO DO!!!!

Now, back to the intake. I'm using the PWK carb and had to cast a manifold or spigot (depending on whether you're British or 'Merican). I also have modified an insulator between the manifold and the cylinder head. But this part is still in the prototype stage, so it may change before I'm done.

I really have been using this project to practice skills that I have not perfected. I've been a mechanic for 30 years, however, sheet metal and welding has never been my strong points. I'm learning a lot. I also welcome all input and criticism. I plan on posting the two other FAILED air/battery box designs, so that everyone can laugh at my misery!

 

 

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