CCM 644 DS Rebuild

So the VHT engine paint I used requires some, fairly, specific heat cycles to cure it. I started the bike to do this and within seconds the header paint bubbled and in plaves started to turn a gold colour. I stopped the engine and once cooled the header paint cracked and lifted off of the pipe, sigh.

The exhaust is painted in flameproof flat aluminium rated to over 1000c and the engine is painted in engine enamel rated to 288c and fuel/oil resistant.

Also when starting one carb slightly leaked and as I wiped the fuel off the starter motor, the engine enamel clear coat came with it, WTF. You can see highlighted in the photos below where the clear coat has smeared as the fuel dissolved it.

I’ve contacted VHT to try and understand what’s happened, as the entire engine is painted with their paints which are supposed to be heat and fuel proof.

I’m hoping you need to complete the heat cycles to cure the engine enamel and before that happens it can be affected by fuel, so you have to be really careful and I was unlucky with carbs leaking on to the starter motor, which is easily removed and repainted.

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Started the bike to cure the engine enamel, more on that later, and noticed the throttle response was poor so decided to check the TPS was correctly adjusted as I just ball parked it on reassemble.

The process its very straight forward, remove the fuel tank, remove the TPS connector and take a resistance reading across the outer pins of the TPS. Once you have this reading multiply it by 0.76 and this gives you the value you should get when checking the top and middle pins at full throttle. In my case it was 5.0 k Ohms, so multiplied by 0.76 gives 3.8, the actual reading was 3.98.

I used a cable tie to hold the throttle wide open and found my value was off, so loosened the two bolts holding the TPS and adjusted it to get the correct reading of 3.8 K Ohms.

Throttle response was much better once adjusted.

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So more tweaks towards the finish line. The front wheel wasn’t right and close inspection was way off line, I checked the parts diagram and realised I’d fitted the spacers incorrectly once that was sorted I fitted the seal and speedo replacement spacer and all was good.

Next was the speedo pickup, so I cut a small slot in the bottom of the fork protector and attached it with a cable tie. Seemed the most pragmatic solution without spending hours making a bracket.

Also removed the sidestand cutout switch, as the sidestand didn’t operate it properly and there was no way it was every going to be 100% reliable due to how poorly it was made in the first place. I made a small loop connector to join the ends together.

Drilled the footrest and mount for the new pins, I did one side ages ago and never got round to the left so finished that and repainted the mount and footrest after drilling the holes out to 10mm.

Then I spotted the lockstop plate barely hit the lockstops so lifted it with a couple of washers and fitted the new front spocket cover.

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Started sorting the chain guides and ran into a few issues. The guides supplied by CCM are for 520 chains and as 644 models use a 525 you need to open up the front guide to make it fit properly, or just let the chain cut its own path, I went for the former using a dremel and sanding drum.

I replaced the lower chain tensioner’s plastic guide with a nylon one from Haines and the lower rear guide still thinking about its purpose, as not sure it adds any value. I fitted the new nylon part by heating it in a cup of boiling water then attached a nut and bolt to one end and gently bent it to shape, will change the nuts for nylock ones.

Once the guides were in place I rivetted the chain together and discovered another issue, the chain hits the tyre. After speaking with Anthony at Haines I adjusted the rim by offsetting it slightly to the right by attaching my dial indicator to the swingarm and loosening and tighting opposite spokes until I had clearance.

Fitted a new rubber shock guard, requires 4mm x 10mm rivets, I added some 4mm washers to the back to ensure the rivet clamped on to the holders. typically ran out of rivets, sigh!

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Got side tracked with a Gas Gas EC250F and a RG250WE. But with the Gas Gas out of the man shed I can now get on with the CCM once again.

Finally sorted the footpeg pins, found some hollow stainless ones on eBay, they were listed as being for a KXF250.

They are a bit longer than required so I cut 5mm off the end and redrilled the split pin hole using a cobalt drill. The mounts of the frame were drilled out using a 10mm drill and then deburred and repainted then the pegs fitted with KTM springs and stainless R clips. At the same time I sandblasted the rear brake pedal and fitted a new pivot bearing.

Finally result is much better than the rubbish CCM nut and bolt arrangement.

Started by cleaning the tank using brake cleaner to remove the old graphic’s marks then polished it using a soft polishing mop and compound mounted on a drill. Then I stripped and rebuilt the fuel tap.

Finished the loom, went to start the bike and got caught out by the elusive hidden resistor. I’d heard about the resistor, but also saw posts saying it wasn’t fitted to all looms, so as I couldn’t findone when stripping the loom carried on building the loom and then couldn’t start the bike.

Decided to check through the old loom and in one group of cables that I didn’t unwrap as they were all black was a broken 100 ohm resistor. If the ECU doesn’t see that resistance on the 6 pin connector’s black wire (pin 6) then it won’t start.

Unwrapped a section of loom and added a resistor, bike started first push of the starter, didn’t run if for any longer than I needed to test the rev counter which is fed by the white/blue cable from the ECU’s 6 pin connector pin 4 . I also had to add a permanent 12v from the battery for the dash, so again unwrapped the loom and fitted the wire and rewrapped the loom, AGAIN!

Once all the circuits were tested, I depinned connectors so that I could make the cable runs as short as possible to tidy the loom up.

I bought some 3M cable clips to hold wires in place under the rear mudguard.

The final thing I did was trim the top of the airbox off using a Dremel, so that cables could run between it and the subframe, there’s a natural line on the moulding to trim along where the top sticks up about 6mm.

Didn’t like how the rear muguard fitted and I’d drilled the holes for the indicators in the wrong place, so bought a new mudguard (UFO YZ125-250 98-02) and did it again, properly.

I ‘eyeballed’ the cut like last time, but did make note of the cutting dimensions and indicator hole positions so anyone can repeat this with minimal grief. Once cut I held the mudguard in place with tape to get the positions for the side bolts then drilled the holes for the rear light mount.

Posts have been a bit limited lately, as I’m dealing with some ‘script kiddy’ who’s trying to hack my site, why you’d want to hack a site about my bike projects fuck knows!

Work has progressed and I’ll do a stack of updates soon.