Suzuki Crank Seal Issues

My Suzuki has been running a bit rough for a while now, the issue is on low throttle openings where the left hand cylinder will run intermittently, at higher throttle openings and on the open road it runs OK but around town it's been pretty horrible to ride. Also when starting on choke the revs tend to run away so it  was pointing to a weak mixture at start up/low revs/low throttle opening.

I checked the basics, changing points, condensor, plugs and resetting the timing. I also rebuilt the LH carb. I did find a split in the carb inlet rubber so thought that was the issue but after replacing all the inlet rubbers there was no improvement.

I then suspected a crankseal on the LH cylinder. I got it running with the generator cover off and sprayed some easy start down the back of the generator. The revs went up so that pointed to a leaky outer crankseal.

The crankseal sits behind the generator stator which is a tapered keyed fit on the left hand end of the crankshaft. The stator has an internal M16 x 1.5mm thread  to allow the use of a puller, in fact the thread is apparently the same as the rear wheel spindle so at a pinch you could use that! However, I thought t easiest to buy a proper puller which I did from ebay.

M16 x 1.5mm Puller

I managed to get a brand new genuine Suzuki crankseal from supplier Suzy Two.

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Crankseal

I removed the stator using the puller to gain access to the old seal. I then found that the seal had moved out from the bearing face and had been rubbing on the back of the stator, it should be held in place with a circlip, however, a previous owner had failed to add the circlip in place last time the seal was replaced. There was quite a bit of oily residue around the seal and in what should be a dry area of the crakcase so that confirmed that the seal had been leaking.

Oil Seal out of position with evidence it had been rubbing on the stator and lots of oily residue where it had leaked.

I removed the seal, and it popped out very easily which it shouldn't do! On inspection I also found that the seal had split.

Oil Seal Removed, note the wear marks from the stator.

Split in the seal

I cleaned everything up and started to try and find a supplier for the circlip. All the main suppliers in the UK and EU had the part listed as no longer available. I did find a couple for sale in the US but the shipping would be expensive and duty would no doubt be added. I contacted a few general circlip suppliers but found that standard circlips that size (62mm) are 2mm thick whereas the groove for the genuine Suzuki clip is only wide enough for a 1mm circlip. I put out the feelers and found that Pete O'Dell of the Motorcycle Works in Peterborough (T500 engine specialists) was able to supply a clip from his stash which was great news. As a back up, Suzuki Spare Supplier Patrick Dubois also could supply from Belgium. So I'm ordering a clip from Pete O'Dell and will complete the job when it arrives.

Groove for Circlip