Ton up SR250 - a cafe racer by the numbers: 100mph, 100kg, 30hp

wozza

Member
JadusMotorcycleParts said:
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The hardest thing was getting the hot melt glue off afterwards without damaging the paint. I used a plastic 'spudger' from Ifixit (from my Mac repairing days). It was brilliant - a hard and stiff enough plastic that you can scrape with, but soft enough not to gouge the paint.
isopropyl alcohol will help with clean up and removal....Your lucky(or more skilful ;) ) as the few tanks I tried on failed due to the thickness of the metal and the small size of the dents....
 
I had some large shallow dents in my dt400 tank. I used a tool just like that from harbor freight. It did a surprisingly good job. It did take some paint and decals off, but I was stripping it anyway.
 

zap2504

Member
I originally had one of those "bridge" pullers too. Saw the video results of the "slide hammer" tool and got one of those instead (why I recommended it a while back). Better control over force applied, not limited to what structure the "bridge" rests on, etc.
Yes, a plastic body putty spreading tool can also be used (with rubbing/isopropyl alcohol) to remove dried glue. In the video I saw they used a plastic "razor blade" with great effect too.
 

pidjones

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I bought some of the plastic razor blades from West Marine. They are used for removing stickers, labels, stripes, etc.
 

JadusMotorcycleParts

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Gotta get me some plastic razor blades then! Genius!

Zap the slide hammer was in another price category but I understand the use and it would come in handy for future projects no doubt.
 

doc_rot

Oh the usual... I bowl, I drive around...
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crazypj said:
Majority of sport bike axles are much larger diameter. I'm guessing the SR250 has 17mm front axle and 20mm rear? Could probably find a swing arm pivot bolt to fit but it would need cutting and threading. I think Suzuki used 17mm 'gun drilled' on early GSX-R? Not too familiar with other brands so couldn't make a recommendation
Yeah GSXR750 20mm rear 17 or 15mm front depending on year. Easily adaptable. cheap. The factory axles are swaged where the threads are so they are extra thin and light and use a smaller nut.

Just out of curiosity how much was it to EDM those axles?
 

JadusMotorcycleParts

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It cost an arm and a leg! 50 and 60 Euro respectively. To have custom ones machined would have been much more and to modify something else would also have cost a bit - considering I would not have been able to do the work myself.
 

JadusMotorcycleParts

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Found some time this week to start rebuilding the forks! Geeze these ones were shot. I was not expecting to need to order new holding clips (completely rusted out). New seals and dust seals I already have. These, along with the fork emulators, new oil, trimmed springs and the pre-load adjusters I have designed will get installed. The fork legs will also get shaved - to remove the fender mount brackets (will mount the fender on the fork brace) and blasted. The seals were stubborn as hell to get out but with force and heat they came.

Of course I weighed them too - for a before and after. I presume there will be at lease a 100g weight reduction each side here too.

The stanchions have a bit of pitting in them, but it is nowhere near the working/sealing surfaces. So I will polish them up and fill them with epoxy. But the most important thing is they were both straight! And the hard chrome surface down by the damper rods was also ok.
 

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pidjones

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A hint for loosening and removing that bottom bolt - do it vefore you remove the top plug and spring - the spring will help hold the inside from spining. And, use an air impact. I've had to fight those seals out of GoldWing lowers - even made a seal puller that reaches behind them, but still ended up getting them real hot with a propane torch to get them to let go.
 

JadusMotorcycleParts

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Thanks for the tip pid, but I tried that! I am yet to encounter a fork that you can undo that bolt without holding the damper rod in some positive way. Maybe I just work on f*cked bikes ;D I went to extreme lengths to open up some SR250 Classic forks, absolute nightmare haha
 

goldy

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An electric impact driver works extremely well...spins that stubborn little bolt right out in a matter of seconds. Probably the best Christmas gift I've had in a long time; in the past 10 years I only had one set of forks where I had to hold the damper.
 

pidjones

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I've learned to pull that bolt before even loosening the tripple clamps. Drain first, though (unless you like stink oil baths).
 

teazer

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You are all right. If possible, loosen that lower damper rod bolt while the top cap is still in place and the spring is pressing down on the damper rod.

If the bolt turn turns and will not loosen, try an impact driver - or if you don't have one, smack teh wrench with a large mallet and sometimes that will crack it free.

If/when that still doesn't come loose, or the forks were partially dismantled already, that's when you need to use a tool to hold the damper rod still. Some forks need a special tool to match the odd damper rod top, but most work with a bolt. I use a length of steel tube with a Tee handle on top 0 drill a hole through the tube and use a screwdriver or weld a cross tube in place. Then weld a suitable hex nut to the bottom of teh tube to lock the damper rod.

I had to make one the other day for a buddy who had partly stripped his GS1000E forks and it took all of about 15 minutes to make. But I was lucky that I had a spare set of dismantled identical forks to measure what size nut I needed.

Other time you have get away with a long extension and a couple of nuts on a bolt in the socket.

I have even seen a broom handle whittled down at the end and rammed into the top of the damper rod.
 

crazypj

Split personality, I fake being smart
I've used broom handle, still connected to shop broom. Had one of the boys hold fork slider down as tight as her could then used 'burp' gun on it. Always a good idea to smack the Allen down, if only to make sure it's fully seated
 

JadusMotorcycleParts

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Haha, yepp, tried the broom stick trick and a few other home made tools! Mostly because the stupid design of the SR250 Classic forks rip the top of the damper rod and they used an insane amount of Loctite on the form bolt upon install at the factory.

I did a blog post about that nightmare process here: https://www.jadusmotorcycleparts.com/single-post/2017/08/17/SR250-Classic-Fork-RebuildSeal-Replacement
 

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JadusMotorcycleParts

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As mentioned much earlier in this thread while planning the rebuild of the forks I thought I would try something mentioned in the Minton mods... To use a looser fitting fork seal to reduce fork stiction.

The only option for the SR was this seal I found for a 33mm stanchion (as apposed the SR's 32mm) which has the correct outer dimension (44mm) but is a little shorter. But they are press fit so I think the height difference (9mm as opposed to 10.5mm) will not be a problem.

I am not 100% sure the seal will be enough to contain oil in the fork but there is certainly (obviously) much less stiction and the seal still engages a decent amount.

I am also tossing up not installing the fork seals - because even they contribute a lot to stiction. Still undecided here!
 

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sav0r

Member
All those tools of destruction scare me.

On a light bike really low friction suspension is imperative. Not sure about going seal-less, but fork oil is cheap so it might be worth a shot.
 
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